Next Article in Journal
Landslide Traces Inventory and Spatial Distribution Analysis Along the Hubei Section of the Jinsha River–Hubei Ultra-High-Voltage Transmission Line, China
Previous Article in Journal
Comparative Study of Water Absorption and Dimensional Stability Between Bamboo Nodes and Internodes
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Forests
Volume 16
Issue 11
10.3390/f16111684
forests-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Review

Functionalization of Wood for the Removal of Heavy Metal Ions from Waster Water: A Review

by
Yang Liu
1,
Xiaolin Zhang
1,
Yanzhuo Du
1,
Xuebin Du
1,
Yi Zhang
1,
Layun Deng
2,*,
Cheng Li
1,3,* and
Jianhui Guo
1,*
1
College of Fine Arts, Henan University, Kaifeng 475001, China
2
State Key Laboratory of Utilization of Woody Oil Resources Hunan Academy of Forestry, Changsha 410004, China
3
College of Forestry, Henan Agricultural University, Zhengzhou 450026, China
*
Authors to whom correspondence should be addressed.
Forests 2025, 16(11), 1684; https://doi.org/10.3390/f16111684
Submission received: 1 October 2025 / Revised: 31 October 2025 / Accepted: 3 November 2025 / Published: 5 November 2025
(This article belongs to the Special Issue Innovative Approaches to Modifying Wood and Wood-Based Material Properties in the 21st Century)
Browse Figures
Versions Notes

Abstract

As global efforts towards green development intensify, eco-friendly materials have become pivotal to achieving sustainability. Wood, a natural, renewable, and environmentally benign biomass, holds great promise for green material applications due to its abundance and ecological benefits. Recent advances in functional modification techniques—such as oxidation, grafting, and nanoparticle incorporation—have significantly enhanced wood’s physical and chemical properties while introducing new environmental functions. These developments have expanded its applications in pollution control, resource recovery, and environmental restoration. In particular, modified wood exhibits outstanding adsorption capacity for heavy metal ions (Pb2+, Cd2+, Cu2+), offering an efficient and sustainable approach to water pollution remediation. This paper reviews the fundamental structure and properties of wood, summarizes recent progress in the development of functionalized wood for heavy metal ion adsorption, and analyzes the influence of various modification methods on adsorption performance. Finally, it outlines future directions for optimizing wood functionalization technologies, providing theoretical foundations and practical guidance for advancing their applications in wastewater treatment and heavy metal pollution control.

1. Introduction

Among the various bio-adsorbents developed for environmental remediation—such as activated carbon, chitosan, and nanocellulose—wood stands out for its abundance, renewability, biodegradability, relatively low cost, and environmental friendliness, offering a more sustainable and economical alternative to high-cost or resource-limited materials like activated carbon and chitosan [1,2,3,4,5]. Moreover, its naturally hierarchical porous structure provides an excellent framework for pollutant adsorption and facilitates the incorporation of numerous active sites through functional modification [6,7,8,9]. These intrinsic structural features give wood outstanding potential for heavy metal remediation, as its interconnected pores and reactive surfaces enable efficient capture of metal ions [10,11]. Recent advances, such as selective removal of lignin or hemicellulose while preserving the porous network, combined with physical, chemical, or biological treatments, have yielded high-performance wood-based adsorbents with superior adsorption capacity and selectivity [12,13,14,15,16]. These adsorbents hold great promise for diverse environmental applications, including water and air purification and heavy metal removal.
Wood’s adsorption performance is primarily governed by its surface morphology, pore structure, and the type and distribution of functional groups. Functional modification techniques, such as introducing reactive groups (e.g., carboxyl or amino) or applying surface treatments, can significantly enhance its capacity to adsorb heavy metal ions [17,18]. For example, carboxylated wood removes metal ions through ion-exchange mechanisms, forming stable complexes that improve adsorption efficiency [19,20], while aminated wood captures metals via coordination reactions, further increasing its adsorption capacity [21]. These unique characteristics make functionalized wood a competitive, eco-friendly alternative to conventional adsorbents [22,23]. However, achieving large-scale application and long-term performance remains a significant challenge, encompassing not only environmental compatibility, cost control, and performance stability but also the regeneration efficiency and durability of the material after adsorption saturation, along with potential secondary environmental risks arising from chemical reagents used during functionalization. Overcoming these limitations requires the development of greener, more efficient, and sustainable functionalization strategies. With continuous innovation and optimization, functionalized wood is expected to play an increasingly important role in heavy metal pollution control and broader environmental remediation efforts.
This review summarizes recent advances in wood functionalization for heavy metal ion adsorption, discusses its practical advantages and limitations, and outlines future research directions with an emphasis on sustainable and efficient solutions for the treatment of heavy metal-contaminated water.

2. Structural and Functional Modification of Wood

The multi-scale hierarchical structure of wood, spanning from the molecular and cellular levels to the macroscopic scale, imparts unique mechanical properties and diverse functionalities. This intrinsic structure-property relationship not only determines the performance of wood in various applications but also underpins its environmental sustainability and eco-friendly advantages (Figure 1A) [24,25]. At the microscopic level, wood is mainly composed of three biopolymers: cellulose, hemicellulose, and lignin. The molecular structures and interactions among these components play a decisive role in determining the mechanical behavior and functional characteristics of wood (Figure 1B) [26]. Cellulose, a linear polysaccharide with high crystallinity and a dense hydrogen-bonding network, enhances structural stability and provides abundant adsorption sites for heavy metal ions such as cadmium, lead, and copper (Figure 1C) [27]. Hemicellulose, a branched and amorphous polysaccharide, offers flexible binding sites that are particularly effective for the removal of low concentrations of heavy metals from water [28]. Lignin, characterized by its highly branched aromatic and three-dimensional cross-linked structure, contributes to rigidity, resistance to degradation, and enhanced metal ion adsorption capacity. Together, these components form the molecular foundation that supports wood’s effectiveness as a sustainable and multifunctional material for environmental purification (Figure 1D) [29].
Functionalized wood holds great potential for controlling heavy metal pollution, particularly in the removal of highly toxic metals such as lead (Pb2+) and cadmium (Cd2+) (Figure 1E) [30,31,32]. Although natural wood possesses inherent adsorption capability, its efficiency and selectivity are limited. Modification through chemical, physical, or biological methods can significantly enhance its adsorption performance, resulting in higher metal capture efficiency and improved adaptability to environmental conditions [33]. Among these approaches, chemical modification is most widely applied due to its effective control over structural and surface properties. Introducing functional groups such as amino (–NH2), carboxyl (–COOH), and thiol (–SH) onto the wood surface enables ion exchange, coordination bonding, and electrostatic interactions with heavy metal ions, thereby increasing removal efficiency even in complex aquatic environments [34,35,36].
Physical modification, which alters the macrostructure and pore characteristics of wood, can effectively improve its adsorption performance. Sponge-like wood materials, for instance, exhibit increased surface area and a higher density of adsorption sites, leading to greater efficiency in removing metals such as lead and cadmium [37,38,39]. Biological modification employs specific microorganisms (e.g., white-rot fungi) or bio-enzymes to functionalize wood surfaces through biodegradation, biomineralization, or biological surface treatment. These biological agents oxidize lignin or cellulose, exposing additional active sites such as phenolic hydroxyl and carboxyl groups, or facilitating the in situ deposition of adsorptive biominerals. Consequently, the wood’s affinity and selectivity for positively charged heavy metal ions (e.g., Cd2+, Pb2+, Cu2+) are significantly enhanced [40]. Composite modification combines multiple mechanisms to achieve synergistic improvement in both structural and functional properties. A representative example is the amino-functionalized metal–organic framework (MOF)/wood composites, in which MOF crystals are grown in situ within the cellular cavities and micropores of wood. This configuration integrates the high surface area of MOFs with the multi-scale porous architecture of wood. The abundant amino groups in the composite form stable coordination bonds with metal ions such as Hg2+ and Cu2+, while hydrogen bonding and van der Waals interactions between the MOFs and the wood matrix enhance structural stability and recyclability [41,42].

3. Progress in Functionalized Wood for Absorbing Heavy Metal Ions

Rapid industrialization has led to the continuous release of large quantities of heavy metal pollutants into water bodies and soils. These contaminants often infiltrate groundwater through rainwater runoff or irrigation, ultimately entering the food chain and threatening human health. Over time, the accumulation of heavy metal ions can damage the skeletal and nervous systems, hinder development, and even cause cancer. Therefore, developing efficient and eco-friendly adsorption materials for the removal of heavy metal ions has become increasingly important [43,44].

3.1. Lead Adsorption

Lead is a highly toxic heavy metal commonly present in industrial wastewater, known to cause serious health problems such as hematopoietic disorders and damage to the cardiovascular, renal, and gastrointestinal systems [45,46,47]. Functionalized wood demonstrates strong adsorption potential for removing lead ions (Pb2+) from contaminated water. Chemical modification of wood matrices to introduce specific functional groups significantly enhances their affinity and binding capacity for Pb2+, with adsorption mechanisms varying by functional group type: (1) In amination modification (-NH2/-NH-), protonated amino groups provide electrostatic attraction, while nitrogen atoms with lone-pair electrons form coordination bonds with Pb2+. (2) Carboxylation modification (-COOH) facilitates electrostatic interactions through dissociated carboxyl groups (-COO−), where oxygen atoms coordinate with Pb2+ ions to form stable complexes, accompanied by H+/Pb2+ ion exchange. (3) Sulfurization modification (-SH/-S-) operates via strong affinity between sulfur atoms (soft bases) and Pb2+ (soft acid), resulting in the formation of insoluble thiolates or stable chelate complexes. Furthermore, the incorporation of nanomaterials such as MOFs and metal oxides can synergistically enhance adsorption performance by increasing active surface area and providing additional reactive sites for Pb2+ capture (Figure 2A) [48].
Wood chips serve as effective adsorbents due to their abundance, low cost, renewability, and eco-friendliness. Their naturally porous structure and surface functional groups enable efficient heavy metals adsorption, which can be further enhanced through chemical or other modifications. Hajam et al. [49] investigated Pb2+ adsorption using both raw and chemically activated Dibetou wood sawdust (treated with nitric acid or sodium hydroxide). The results showed maximum Pb2+ removal efficiencies of ~84% for the raw sawdust and ~93% for activated sawdust. Under optimal conditions (pH 6, dosage 0.875 g/100 mL, contact times of 90 min for raw and 47.5 min for activated sawdust, and an initial Pb2+ concentration of 275 mg/L), the removal efficiency reached 94% for raw sawdust and 99% for activated sawdust.
Amino-modified wood, functionalized with amino (–NH2) groups, exhibits significantly improved adsorption capacity for Pb2+ ions. The introduced amino groups enhance hydrophilicity and ion-exchange capability, enabling coordination with Pb2+ to form stable complexes and significantly increasing adsorption efficiency. Obsa et al. [50] enhanced the adsorption performance of wood through ethylenediamine grafting, achieving a Pb2+ adsorption capacity greater than 125 mg/g, several times higher than that of unmodified wood, demonstrating its strong potential as an adsorbent for water treatment (Figure 2B). Similarly, Tan et al. [51] developed an economical and eco-friendly adsorbent (DWF-NH2) by delignifying and amino-modifying waste wood powder. The material exhibited a maximum Pb2+ adsorption capacity of 189.9 mg/g and retained about 80% of its capacity after five adsorption–desorption cycles, indicating excellent reusability. In mixed-metal solutions containing Pb2+, Cu2+, and Zn2+, DWF–NH2 exhibited strong selectivity for Pb2+, with a selectivity coefficient of 2.74.
Mercaptan-modified wood introduces thiol (–SH) groups onto cellulose, significantly increasing the number of active adsorption sites. The sulfur atoms in these groups coordinate with the vacant orbitals of heavy metal ions, forming strong metal–sulfur bonds that provide high selectivity and adsorption efficiency. Chen et al. [52] reported that sulfurized wood achieved a Pb2+ adsorption capacity exceeding 130 mg/g, substantially higher than that of unmodified wood. Yang et al. [53] further advanced this concept by grafting thiol groups onto wood cellulose to develop a three-dimensional mesoporous SH-wood membrane (Figure 2C). This structure creates multiple metal-binding sites, improving the removal of heavy metals from wastewater. The abundant –SH groups promote strong chelation, while the hydrophilic and mesoporous architecture ensures high water permeability and increased ion–site contact. The SH-wood membrane is stackable and modular, offering excellent structural stability and reusability. Experimental results showed outstanding Pb2+ adsorption performance, with a maximum capacity of 384.1 mg/g and consistent efficiency over eight reuse cycles. Moreover, stacked SH-wood filters effectively removed various heavy metals from real wastewater, meeting WHO drinking water standards at a flow rate of 1.3 × 103 L·m−2·h−1.
Forests 16 01684 g002
Figure 2. (A) Spongewood filtration system featuring a highly carboxylated surface and nanostructure for efficient Pb2+ removal. Reprinted with permission from Ref. [48]. 2024, Elsevier; (B) Amino-modified cellulose demonstrating enhanced Pb2+ adsorption from aqueous solutions. Reprinted with permission from Ref. [50]. 2024, Elsevier; (C) Thiol-functionalized wood membrane stack for rapid and efficient adsorption of heavy metal ions. (a) The prepared SH-wood membrane, including a magnified drawing of its mesostructure and chemical composition. The microstructure of the SH-wood membrane contains many irregularly channels aligned along the growth direction. Cellulose in wood is made up of highly oriented glucose chains, which form long compact fibrils (illustrated with green lines in the wood channels), which was modified with −SH functional groups (the gray lines and yellow balls represent PEI and −SH groups, respectively). (b) The multilayer device for large-scale heavy-metal ion removal. The magnified schematic shows that the heavy-metal ions can bond with the −SH groups as the polluted water flows through the modified channels of wood. Reprinted with permission from Ref. [53]. 2020, American Chemical Society.
Figure 2. (A) Spongewood filtration system featuring a highly carboxylated surface and nanostructure for efficient Pb2+ removal. Reprinted with permission from Ref. [48]. 2024, Elsevier; (B) Amino-modified cellulose demonstrating enhanced Pb2+ adsorption from aqueous solutions. Reprinted with permission from Ref. [50]. 2024, Elsevier; (C) Thiol-functionalized wood membrane stack for rapid and efficient adsorption of heavy metal ions. (a) The prepared SH-wood membrane, including a magnified drawing of its mesostructure and chemical composition. The microstructure of the SH-wood membrane contains many irregularly channels aligned along the growth direction. Cellulose in wood is made up of highly oriented glucose chains, which form long compact fibrils (illustrated with green lines in the wood channels), which was modified with −SH functional groups (the gray lines and yellow balls represent PEI and −SH groups, respectively). (b) The multilayer device for large-scale heavy-metal ion removal. The magnified schematic shows that the heavy-metal ions can bond with the −SH groups as the polluted water flows through the modified channels of wood. Reprinted with permission from Ref. [53]. 2020, American Chemical Society.
Forests 16 01684 g002

3.2. Cadmium Adsorption

Cadmium, a highly toxic heavy metal commonly present in industrial wastewater and contaminated soil, poses a serious threat to environmental and human health. Its accumulation in ecosystems can lead to bioaccumulation through the food chain, resulting in liver and kidney damage, inhibition of DNA repair, osteoporosis, carcinogenic effects, nephrotoxicity, osteotoxicity, and pain syndromes [54,55,56]. Functionalized wood has shown significant potential for cadmium ion (Cd2+) removal [57].
Rafatullah et al. [58] investigated Cd2+ adsorption on Liquidambar formosana sawdust under varying physicochemical conditions, including contact time, pH, initial Cd2+ concentration, and adsorbent dosage. Isothermal modeling showed that the Langmuir model best fit the data, suggesting monolayer adsorption with maximum capacities of 175.43, 163.93 and 153.84 mg/g at 30, 40 and 50 °C, respectively. Thermodynamic analysis confirmed a spontaneous, exothermic process, while kinetics followed the pseudo-second-order model. Notably, untreated Liquidambar formosana sawdust exhibited a high adsorption capacity of 175.43 mg/g at 30 °C, setting a strong performance benchmark for further enhancement. To improve adsorption performance, chemical functionalization has been applied to wood-based materials. Jia et al. [59] synthesized aminated and carboxylated lignins (NCLs) via a one-pot hydrothermal method, demonstrating effective Cd2+ removal, with carboxylated wood achieving a maximum capacity of 100 mg/g and maintaining stability across a wide pH range. However, this capacity was lower than that of untreated Liquidambar formosana sawdust (175.43 mg/g at 30 °C) reported by Rafatullah et al. [58], suggesting that simple carboxylation provides limited improvement, possibly due to structural constraints in the lignin matrix. In contrast, sulfur modification introducing thiol (–SH) groups enhances Cd2+ adsorption through the formation of stable coordination complexes, achieving a capacity above 125 mg/g—higher than that of unmodified and carboxylated lignin (100 mg/g), though still below that of untreated Liquidambar formosana sawdust [60].
He et al. [61] treated beech wood with green deep eutectic solvents (DES) to remove lignin and expose cellulose was further grafted with carboxyl and thiol groups onto its surface using citric acid and L-cysteine, producing a three-dimensional porous wood microfilter with abundant active sites. DES treatment increased specific surface area and porosity while preserving the natural layered network, facilitating ion diffusion and capture. The combined effect of carboxyl and thiol groups significantly enhanced Cd2+ adsorption through chelation and complexation, resulting in rapid adsorption kinetics and a high capacity of 173.63 mg/g, surpassing most reported adsorbents. Moreover, a laminated three-layer filtration device fabricated from this material achieved a high water flux of 1.53 × 103 L·m−2·h−1 and over 98% removal efficiency. The device was easy to assemble, disassemble, and regenerate, showing excellent reusability and scalability for modular applications. This work represents a major advancement towards translating high-performance materials into practical engineering applications, combining high adsorption capacity with sustainable design and operational feasibility.

3.3. Zinc Adsorption

Zinc, an essential yet potentially toxic heavy metal, is widely used in industries such as electroplating, fertilizer manufacturing, and alloy production. However, its excessive release into the environment can lead to serious health and ecological problems, including nausea, vomiting, diarrhea, immune and nervous system impairment, and contamination of soil and water [62,63].
Wood-based materials can significantly enhance their adsorption capacity for heavy metals through chemical modification using minerals, organic acids, alkalis, oxidizing agents, or organic compounds. Kovacova et al. [64] comprehensively studied the adsorption performance of natural and chemically modified wood chips derived from poplar, cherry, spruce, and elm in acidic model solutions. Isotherm analysis revealed that adsorption by most treated wood types (except spruce) followed the Langmuir model more closely than the Freundlich model, suggesting a predominance of monolayer adsorption. Mechanistic analysis indicated that surface complexation and ion exchange were the primary adsorption mechanisms. This study also assessed Zn2+ removal efficiency using alkali-modified sawdust, a cost-effective method offering strong pH buffering capacity. Among the samples, KOH-treated Populus spp. sawdust achieved the highest adsorption efficiency of 98.2% at pH 7.3. All chemically treated wood samples demonstrated superior adsorption compared to untreated samples, primarily due to the introduction of alkaline groups from lignin decomposition during modification, which buffers pH fluctuations in acidic wastewater.
Carboxylated wood, containing -COOH groups, leverages the strong negative charge density of carboxyl groups to interact with zinc ions via ion exchange, resulting in high adsorption capacity and broad pH adaptability for efficient Zn2+ removal [65]. Pereira et al. [66] developed a novel chelating adsorbent derived from Manilkara wood chips and chemically modified sugarcane bagasse using ethylenediaminetetraacetic acid dihydrate (EDTAD). The introduction of carboxyl and amine groups significantly improved its metal-binding performance, achieving a maximum Zn2+ adsorption capacity of 105 mg/g and high removal efficiency even in electroplating wastewater. However, potential leaching of EDTA may reduce cycling stability and weaken the lignocellulosic structure over repeated use. In contrast, amino-modified wood chips, incorporating –NH2 groups, offer enhanced hydrophilicity and form stable coordination complexes with Zn2+, combining high adsorption capacity with improved durability and reusability.
A cellulose nanofiber–polyglutamic acid aerogel synthesized via one-pot cross-linking exhibited abundant carboxyl and amino groups that synergistically enhanced coordination with Zn2+ ions [67]. The aerogel reached optimal Zn2+ removal at pH 5 and followed a pseudo-second-order kinetic model, with equilibrium data fitting the Langmuir isotherm. With a maximum Zn2+ adsorption capacity of 59.26 mg/g, its performance was driven by coordination bonding and electrostatic attraction [68].

3.4. Chromium Adsorption

Functionalized wood has shown excellent adsorption capability for chromium (Cr) ions, especially the highly toxic and mobile hexavalent form, Cr(VI). As a prevalent pollutant in electroplating, chemical, and metallurgical wastewater, Cr(VI) poses severe environmental and health risks due to its strong oxidizing nature, high solubility, and carcinogenic effects. Its ability to penetrate biological membranes to cause DNA damage and bioaccumulate through food chains further amplifies its hazards [69]. Unlike conventional physical adsorbents that only concentrate contaminants, functionalized wood employs tailored modifications that enable both adsorption and in situ reduction of Cr(VI) to less toxic Cr(III). This dual mechanism enhances removal efficiency while simultaneously achieving detoxification, offering a sustainable and highly effective strategy for environmental remediation [70].
The outstanding chromium removal performance of functionalized wood stems from the interplay of multiple mechanisms, particularly redox reactions, which play a crucial role in practical applications. Phosphate-modified wood, for instance, introduces phosphate groups that coordinate with Cr(VI) ions, enhancing adsorption and simultaneously reducing Cr(VI) to the less toxic Cr(III), thereby mitigating environmental hazards. Similarly, sulfur-containing groups with strong nucleophilic properties form stable coordination complexes with Cr(VI), further improving removal efficiency [71]. For example, pine bark (PB) exhibits significantly enhanced Cr(VI) remediation after chemical modification with cetyltrimethylammonium bromide (CTAB). In Cr(VI)-contaminated soil, CTAB-modified pine bark achieved over 93% conversion of Cr(VI) to Cr(III), significantly outperforming unmodified PB [72]. Inspired by the hierarchical pore structure of natural wood and the chelating ability of amino groups, Xie et al. [73] immobilized ethylenediamine-modified MIL-101(Cr) onto a wood aerogel, forming the composite MIL-101(Cr)-ED/WA. This approach leverages the multiscale porosity of the wood aerogel with the strong metal-binding ability of -NH2-functionalized MOF, achieving a synergistic improvement in both structural properties and adsorption performance.
Huang et al. [74] prepared a novel cellulose-based adsorbent by modifying hydroxypropyl methylcellulose with diethylenetriamine. Under optimal conditions (110 min adsorption time, 0.4 g dosage, 100 mg/L ion concentration, pH 5.5), the material achieved up to 99.78% heavy metal removal. The adsorption process followed a pseudo-second-order kinetic model and fitted well to the Langmuir isotherm, with hermodynamic results (negative ΔG and positive ΔH) confirming spontaneous and endothermic behavior. In another study, Yang et al. [75] incorporated oxidized cellulose nanofibers (CNFs) into polyacrylonitrile scaffolds via electrospinning, followed by cysteine grafting to introduce surface thiol groups. The thiol-modified CNF (m-CNF) composite membranes exhibited an outstanding Cr(VI) adsorption capacity of 87.5 mg/g and /105 mg/g—far exceeding benchmark materials such as activated carbon (46.9 mg/g), chitosan (35.6 mg/g), single-walled carbon nanotubes (SWNTs, 20.3 mg/g), and multi-walled carbon nanotubes (MWNTs, 2.48 mg/g) [76]. The adsorption performance of the membranes can be attributed to their large surface area and high density of thiol groups (0.9 mmol–SH/g m-CNF), which provide abundant active binding sites for effective coordination and reduction of Cr(VI) ions. The membranes also demonstrated excellent structural integrity and regeneration performance, maintaining high adsorption efficiency over multiple adsorption–desorption cycles.
In summary, chemical modifications such as phosphorylation and amination significantly enhance the chromium adsorption capacity of wood-based adsorbents. Phosphorylated wood, in particular, demonstrates exceptional Cr(VI) removal efficiency through a coordination-coupled redox mechanism that not only enhances adsorption efficiency but also reduces toxic Cr(VI) to the more stable and less harmful Cr(III) [77]. This redox conversion is environmentally significant, as the stabilization of Cr(III) minimizes chromium’s mobility and bioavailability, thereby ensuring long-term ecological safety and regulatory compliance.

3.5. Copper Adsorption

Copper, an essential industrial metal used in electrical, metallurgical, electronic, and electroplating industries, becomes hazardous at high concentrations, causing diarrhea, nausea, liver and kidney damage, Wilson’s disease, and ecological toxicity [78]. Industrial wastewater often contains Cu2+ levels far exceeding safety limits [79,80], highlighting the need for developing efficient and sustainable removal materials.
Previous studies have demonstrated the strong application potential of functionalized wood for Cu2+ removal. Nagarajan et al. [81] developed ultra-lightweight wood aerogels through delignification, TEMPO oxidation, and PEI grafting, achieving 94.9% porosity, a density of 77.2 mg/cm3, and an outstanding Cu2+ adsorption capacity of 596.9 mg/g due to abundant carboxyl-amino binding sites (Figure 3A). In contrast, Chu et al. [82] prioritized reusability by designing PEI-modified nanowood with a compressible structure that maintained over 60% efficiency after 50 cycles, although a lower Cu2+ uptake of 93.06 mg/g (Figure 3B). Both materials followed pseudo-second-order kinetics and Langmuir isotherms, indicating chemisorption-driven mechanisms despite differing structural designs, thereby revealing two distinct composite enhancement pathways for optimizing Cu2+ adsorption. Rahman et al. [83] employed ligand functionalization by grafting polyacrylonitrile onto cellulose to form poly(imidazoline) chelating sites with strong pH-dependent affinity (Figure 3C). Xu et al. [84] pursued nanomaterial integration through mussel-inspired biomimetic synthesis, embedding ZnCo-ZIF within cellulose nano-fibers (Figure 3D). The resulting ZnCo-ZIF@GEL composite exhibited a Cu2+ adsorption capacity of 274.73 mg/g, with cobalt doping enhancing structural stability and providing synergistic improvements in adsorption performance under diverse environmental conditions. Expanding functionality, Cai et al. [85] developed a multifunctional adsorbent by delignifying poplar wood, cross-linking with β-cyclodextrin to enhance binding sites, and embedding carbon quantum dots to introduce fluorescence for simultaneous detection and adsorption. This resulting material achieved a maximum Cu2+ adsorption capacity of 60 mg/g at pH 5 and 60 °C within 3 h, effectively coupling adsorption with fluorescence-based detection and demonstrating strong potential for intelligent water treatment applications.
These studies reveal a clear performance hierarchy among Cu2+ adsorption materials: ultra-porous aerogels exhibit the highest capacities, followed by ligand-functionalized composites, nanomaterial composites, and multifunctional materials. However, practical considerations influence material selection; compressible materials offer superior regeneration potential, nanocomposites ensure operational stability, and multifunctional systems enable process monitoring. Despite the structural diversity, all materials adhere to pseudo-second-order kinetics and Langmuir isotherms, indicating that performance improvements primarily stem from capacity optimization rather than changes in adsorption mechanisms. The adsorption capacities of the aforementioned adsorbents for different metal ions (Cu2+, Pb2+, Cd2+, Zn2+) are summarized in Table 1.

4. Conclusions and Perspective

Functionally modified wood, with its natural porosity, renewability, and eco-friendly properties, offers a promising foundation for sustainable applications. Recent advancements have shown that wood-based functional adsorbents possess excellent capabilities for environmental purification. Through targeted modification, these materials gain enhanced environmental responsiveness and adsorption capacity, significantly broadening their applicability in controlling heavy metal pollution in water systems.
Despite notable progress, considerable challenges remain before these materials can achieve large-scale, practical implementation. Most current studies are limited to idealized laboratory conditions that do not reflect the complexities of real-world environments, including pollutant diversity, variable water chemistry, and competing ion effects. This discrepancy creates a substantial gap between laboratory results and field performance, underscoring the need for systematic evaluation under realistic conditions. Additionally, research has primarily focused on a few wood species—such as basswood, poplar, and linden—leaving many abundant alternatives underexplored and restricting the diversification of functional wood materials. The focus on remediation efficiency has often overshadowed critical considerations such as biodegradability, long-term environmental impact, and potential secondary pollution, underscoring the need for comprehensive life cycle assessments and sustainable post-treatment strategies.
Knowledge gaps persist in understanding adsorption mechanisms for priority heavy metals and emerging contaminants. Multi-metal competitive interactions and oxidation-state-dependent removal processes remain insufficiently studied, limiting a holistic view of these materials’ potential. Furthermore, while using agroforestry biomass waste as an alternative feedstock offers economic and sustainability advantages, its heterogeneous composition and impurities complicate modification efficiency and performance consistency. The pretreatment and functionalization processes typically required for these materials often involve high-temperature, high-pressure, or chemical treatments, which result in substantial energy consumption and the generation of secondary waste, potentially undermining their environmental benefits.
Future research should therefore adopt an integrated and multidisciplinary approach to address these challenges. The development of efficient, low-cost, and environmentally friendly pretreatment and functionalization methods for diverse biomass feedstocks should be complemented by rigorous performance testing under realistic conditions, including actual wastewater and contaminated soil systems. These efforts, supported by comprehensive life-cycle assessments, will ensure the development of reliable, scalable, and sustainable wood-based adsorbents for heavy metal pollution remediation and broader environmental applications.

Author Contributions

Conceptualization, J.G., C.L. and Y.L.; methodology, Y.L. and X.Z.; software, Y.D.; formal analysis, Y.L., C.L. and J.G.; investigation, J.G., L.D., C.L. and Y.L.; resources, X.D.; data curation, Y.Z.; writing—original draft preparation, J.G. and Y.L.; writing—review and editing, J.G., C.L., Y.L. and L.D.; supervision, J.G., and C.L.; funding acquisition, J.G., Y.L. and L.D. All authors have read and agreed to the published version of the manuscript.

Funding

This work was supported by the Special Project on Cultural Research for the Revitalization of Culture Project in Henan Province (2023XWH130), Research on Enhancing the Comprehensive Value of Commercial Spaces through Innovative Wood Culture Design (SKH2025023), the Graduate Education Reform Project of Henan Province (2023SJGLX256Y), Technological Innovation Fund of Hunan Forestry Department (XLKY202202) and Joint Fund Project of Natural Science Foundation of Hunan Province (2025JJ80244).

Data Availability Statement

All the data are provided in this manuscript.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Schubert, M.; Panzarasa, G.; Burgert, I. Sustainability in Wood Products: A New Perspective for Handling Natural Diversity. Chem. Rev. 2023, 123, 1889–1924. [Google Scholar] [CrossRef]
  2. Gao, S.; Wang, J.; Wang, K.; Cai, Y.; Li, C.; Dong, Y.; Li, J. Efficient Solar-Driven Interfacial Desalination of Wood through Surface Furfurylation. Colloids Surf. Physicochem. Eng. Asp. 2025, 709, 136161. [Google Scholar] [CrossRef]
  3. Wang, J.; Gao, S.; Tan, Y.; Dong, Y.; Wang, K.; Li, J. Lauric Acid Encapsulation for Continuous Evaporation of Wood-Based Solar Evaporator. Appl. Therm. Eng. 2025, 280, 128351. [Google Scholar] [CrossRef]
  4. He, Y.; Qiao, Z.; Fan, L.; Xia, Z.; Ma, J.; Zheng, X.; Deng, L.; Xu, X.; Liu, H. Lightweight, Ultra-Compressed, and Environmentally Friendly Wood/Tpu Aerogel Sensor Based on Optimized Performance of Dynamic 3D Pore Structure. J. Colloid Interface Sci. 2025, 678, 188–199. [Google Scholar] [CrossRef] [PubMed]
  5. Malik, H.; Niazi, M.B.K.; Miran, W.; Tawfeek, A.M.; Jahan, Z.; Kamel, E.M.; Ahmed, N.; Saeed Akhtar, M. Wood as a Green and Sustainable Alternative for Environmentally Friendly & Flexible Electronic Devices. Chemosphere 2023, 336, 139213. [Google Scholar] [CrossRef] [PubMed]
  6. Ajdary, R.; Tardy, B.L.; Mattos, B.D.; Bai, L.; Rojas, O.J. Plant Nanomaterials and Inspiration from Nature: Water Interactions and Hierarchically Structured Hydrogels. Adv. Mater. 2021, 33, e2001085. [Google Scholar] [CrossRef]
  7. Zhu, Y.; Wang, S.; Liu, Y.; Han, J.; Duan, G.; Fu, Q.; Han, X.; Zhang, C.; He, S.; Jiang, S. Structure Modifications of Wood-Based Materials for Water Treatment Applications: A Review. Mater. Today 2025, 87, 252–286. [Google Scholar] [CrossRef]
  8. Jiang, J.; Shi, Y.; Ma, N.L.; Ye, H.; Verma, M.; Ng, H.S.; Ge, S. Utilizing Adsorption of Wood and Its Derivatives as an Emerging Strategy for the Treatment of Heavy Metal-Contaminated Wastewater. Environ. Pollut. 2024, 340, 122830. [Google Scholar] [CrossRef]
  9. Huo, H.; Xu, J.; Hou, H.; Yu, Y.; Feng, W.; Lu, M.; Wang, S.; Min, D. Valorizing Wood to Toxic Heavy Metal Ions Biosorbent through in Situ Sulfation of Its Cellulose. Int. J. Biol. Macromol. 2025, 309, 142835. [Google Scholar] [CrossRef]
  10. Shi, J.; Zhang, C.; Cui, J.; Dong, Y.; Cai, J.; Zhou, F.; Lyu, J.; Avramidis, S. Self-Diffusion Coefficient of Bound Water in Longleaf Pine Wood Investigated with Pulsed-Field-Gradient 1h-Nmr and Molecular Simulation. Cellulose 2025, 32, 3567–3581. [Google Scholar] [CrossRef]
  11. Yang, Y.; Guo, Y.; Qiu, Z.; Gong, W.; Wang, Y.; Xie, Y.; Xiao, Z. In Situ Growth of Zr-Based Metal-Organic Frameworks on Cellulose Sponges for Hg2+ and Methylene Blue Removal. Carbohydr. Polym. 2024, 328, 121750. [Google Scholar] [CrossRef]
  12. Qi, X.; Chen, Y.; Liu, M.; Zhang, X.; Zuo, Y.; Ma, Q.; Xie, X.; Guo, X.; Wu, Y. Green and Cost-Effective: Bifunctional Wood for Efficient Adsorption and Sensitive Detection of Pb(II). Ind. Crops Prod. 2024, 210, 118162. [Google Scholar] [CrossRef]
  13. Chao, W.; Wang, S.; Li, Y.; Cao, G.; Zhao, Y.; Sun, X.; Wang, C.; Ho, S.-H. Natural Sponge-Like Wood-Derived Aerogel for Solar-Assisted Adsorption and Recovery of High-Viscous Crude Oil. Chem. Eng. J. 2020, 400, 125865. [Google Scholar] [CrossRef]
  14. Shang, Y.; Gao, R.; Wang, Y.; Dong, X.; Li, X.; Tang, J.; Wang, X.; Liu, J.; Xie, Y.; Li, J.; et al. Scalable Fabrication of Efficient and Recycling Wood Residue-Derived Sponge for Crude Oil Adsorption. J. Hazard. Mater. 2023, 441, 129979. [Google Scholar] [CrossRef]
  15. Xu, Z.; Zhang, Y.; Guo, L.; Wu, M.; Wang, J.; Zhang, L.; Deng, S.; Xie, T.; Zhang, X.; Zhu, G. Scalable Synthesis of Hierarchical Porous Mof-199 Decorated Aminated Wood Sponge as Physisorbent Materials for Carbon Dioxide Capture from Wet Flue Gas. J. Environ. Chem. Eng. 2025, 13, 117128. [Google Scholar] [CrossRef]
  16. Marimuthu, T.; Chee, C.Y.; Sulaiman, N.M.N. A Review on the Use of Cellulose Nanomaterials for Wastewater Remediation of Heavy Metal Ions. Int. J. Environ. Sci. Technol. 2023, 20, 3421–3436. [Google Scholar] [CrossRef]
  17. Choi, H.Y.; Bae, J.H.; Hasegawa, Y.; An, S.; Kim, I.S.; Lee, H.; Kim, M. Thiol-Functionalized Cellulose Nanofiber Membranes for the Effective Adsorption of Heavy Metal Ions in Water. Carbohydr. Polym. 2020, 234, 115881. [Google Scholar] [CrossRef]
  18. Gu, Y.; Ye, M.; Wang, Y.; Li, H.; Zhang, H.; Wang, G.; Zhang, Y.; Zhao, H. Lignosulfonate Functionalized G-C3n4/Carbonized Wood Sponge for Highly Efficient Heavy Metal Ion Scavenging. J. Mater. Chem. A 2020, 8, 12687–12698. [Google Scholar] [CrossRef]
  19. Páez-Hernández, M.E.; Galán-Vidal, C.A.; Ibarra, I.S.; Hernández, P.; Pérez-Silva, I. Recovery of Cd(II) and Zn(II) from Hcl Medium Using Cellulose Acetate Sponges Modified with Cyanex 923. Desalin. Water Treat. 2021, 221, 176–184. [Google Scholar] [CrossRef]
  20. Li, M.; Wang, F.; Ouyang, S.; Liu, Y.; Hu, Z.; Wu, Y.; Qian, J.; Li, Z.; Wang, L.; Ma, S. A Comprehensive Review on Preparation and Functional Application of the Wood Aerogel with Natural Cellulose Framework. Int. J. Biol. Macromol. 2024, 275, 133340. [Google Scholar] [CrossRef]
  21. Huang, W.; Xu, Y.; Chen, N.; Cheng, G.; Ke, H. Amino-Modified Hemp Stem for High-Capacity Adsorption of Cr(VI) from Aqueous Solution. J. Environ. Chem. Eng. 2023, 11, 111441. [Google Scholar] [CrossRef]
  22. Yudaev, P.; Semenova, A.; Chistyakov, E. Gel Based on Modified Chitosan for Oil Spill Cleanup. J. Appl. Polym. Sci. 2024, 141, e54838. [Google Scholar] [CrossRef]
  23. Yudaev, P.; Butorova, I.; Stepanov, G.; Chistyakov, E. Extraction of Palladium(II) with a Magnetic Sorbent Based on Polyvinyl Alcohol Gel, Metallic Iron, and an Environmentally Friendly Polydentate Phosphazene-Containing Extractant. Gels 2022, 8, 492. [Google Scholar] [CrossRef] [PubMed]
  24. Fu, Z.; Lu, Y.; Wu, G.; Bai, L.; Barker-Rothschild, D.; Lyu, J.; Liu, S.; Rojas, O.J. Wood Elasticity and Compressible Wood-Based Materials: Functional Design and Applications. Prog. Mater. Sci. 2025, 147, 101354. [Google Scholar] [CrossRef]
  25. Yu, M.; Du, S.; Zhu, B.; Zhu, L.; Yang, J. All-Natural Photothermal Hydrogel for Efficient Desalination and Heavy Metal Enrichment. Langmuir 2025, 41, 5664–5675. [Google Scholar] [CrossRef] [PubMed]
  26. Ibn Yaich, A.; Edlund, U.; Albertsson, A.-C. Transfer of Biomatrix/Wood Cell Interactions to Hemicellulose-Based Materials to Control Water Interaction. Chem. Rev. 2017, 117, 8177–8207. [Google Scholar] [CrossRef] [PubMed]
  27. Bhardwaj, A.; Bansal, M.; Garima; Wilson, K.; Gupta, S.; Dhanawat, M. Lignocellulose Biosorbents: Unlocking the Potential for Sustainable Environmental Cleanup. Int. J. Biol. Macromol. 2025, 294, 139497. [Google Scholar] [CrossRef]
  28. Li, S.; Duan, Y.; Fang, J.; Chen, S.; Wang, J.; Jiang, H.; Xiao, R.; Ni, C.; Wu, S.; Deng, Q.; et al. Soybean Hull Hemicellulose–Soybean Protein Isolate Composite Aerogel: Adsorption Material for Remediation of Heavy Metal-Polluted Water. Int. J. Biol. Macromol. 2025, 310, 143298. [Google Scholar] [CrossRef]
  29. Zhou, Y.; Zhou, X.; Hu, S.; Wu, H.; Ren, J.; Yue, F. One-Step Isolation of L-Cysteine Functionalized Lignin with High Adsorption Capacity for Heavy Metal Ions. Ind. Crops Prod. 2024, 222, 120026. [Google Scholar] [CrossRef]
  30. An, C.; Zhang, M.; Xiao, Z.; Yang, Q.; Feng, L.; Li, S.; Shi, M. Lignocellulose/Chitosan Hybrid Aerogel Composited with Fluorescence Molecular Probe for Simultaneous Adsorption and Detection of Heavy Metal Pollutants. J. Environ. Chem. Eng. 2023, 11, 111205. [Google Scholar] [CrossRef]
  31. Anang, S.; Ibrahim, M.G.; Nasr, M. Industrial Wastewater Treatment by Downflow Hanging Sponge System: Techno-Economic Analysis, Life Cycle Assessment, and Sustainable Development Goals Fulfillment. J. Environ. Chem. Eng. 2025, 13, 115944. [Google Scholar] [CrossRef]
  32. Babar, Z.B.; Iftikhar, R.; Rizwan, K.; Munir, S.; Urfi, M.; Ashraf, F.; Inam, M.A.; Iqbal, S.; Saad, M.; Mahmood, S.; et al. Biomitigation of Noxious Metal Ions Using Engineered Lignin-Based Nanocomposites for Sustainable Environment. J. Water Process Eng. 2025, 70, 106938. [Google Scholar] [CrossRef]
  33. Jiang, D.; Dai, Y.; Jiang, Y.; Yu, W.; Ma, D.; Bai, L.; Huo, P.; Li, Z.; Liu, Y. Polydopamine/Fe3o4 Modified Wood-Based Evaporator for Efficient and Continuous Water Purification. J. Colloid Interface Sci. 2023, 652, 1271–1281. [Google Scholar] [CrossRef]
  34. Lin, X.; Jin, J.; Guo, X.; Jia, X. All-Carboxymethyl Cellulose Sponges for Removal of Heavy Metal Ions. Cellulose 2021, 28, 3113–3122. [Google Scholar] [CrossRef]
  35. Kenawy, I.M.; Hafez, M.A.H.; Ismail, M.A.; Hashem, M.A. Adsorption of Cu(II), Cd(II), Hg(II), Pb(II) and Zn(II) from Aqueous Single Metal Solutions by Guanyl-Modified Cellulose. Int. J. Biol. Macromol. 2018, 107, 1538–1549. [Google Scholar] [CrossRef]
  36. Yuan, H.; Xing, L.; Wei, J.; Zhao, Z.; Wang, J.; Gao, H.; Nie, Y. Wood Microchannels with Multi-Carboxyl Groups for Selective Adsorption of Fe3+ from Ionic Liquids Aqueous Solution: Experimental and DFT Study. J. Environ. Chem. Eng. 2023, 11, 110348. [Google Scholar] [CrossRef]
  37. Mo, L.; Zhang, S. Bioinspired Highly Anisotropic, Robust and Environmental Resistant Wood Aerogel Composite with Semi-Interpenetrating Polymer Networks for Cu(II) Ion Removal. Cellulose 2022, 29, 8353–8370. [Google Scholar] [CrossRef]
  38. Meng, J.; Guan, H.; Dai, X.; Wang, X. Amino-Functionalized Wood Aerogel for Efficient Removal of Copper Ions from Water. Int. J. Polym. Sci. 2021, 2021, 4913226. [Google Scholar] [CrossRef]
  39. Chen, F.; Gong, A.S.; Zhu, M.; Chen, G.; Lacey, S.D.; Jiang, F.; Li, Y.; Wang, Y.; Dai, J.; Yao, Y.; et al. Mesoporous, Three-Dimensional Wood Membrane Decorated with Nanoparticles for Highly Efficient Water Treatment. ACS Nano 2017, 11, 4275–4282. [Google Scholar] [CrossRef] [PubMed]
  40. Sun, F.; Zhang, M.; Zhu, H.; Huang, Y.; Song, B.; Wang, P.; Jiang, S.; Wang, B. Zif-8-Decorated Wood Sponge Derived from Biomimetic Mineralization of Polydopamine. Green Mater. 2024, 12, 253–260. [Google Scholar] [CrossRef]
  41. Esteves, B.; Cruz-Lopes, L.; Figueirinha, A.; de Lemos, L.T.; Ferreira, J.; Pereira, H.; Domingos, I. Heat-Treated Wood as Chromium Adsorption Material. Eur. J. Wood Wood Prod. 2017, 75, 903–909. [Google Scholar] [CrossRef]
  42. Li, H.; Yang, K.; Huang, J.; Chen, F. Design and Construction of UiO-66-NH2/Wood Composite for Efficient Removal of Trace Heavy Metal Ions from Water. Chem. J. Chin. Univ. 2022, 43, 32–39. [Google Scholar] [CrossRef]
  43. Jiang, B.; Adebayo, A.; Jia, J.; Xing, Y.; Deng, S.; Guo, L.; Liang, Y.; Zhang, D. Impacts of Heavy Metals and Soil Properties at a Nigerian E-Waste Site on Soil Microbial Community. J. Hazard. Mater. 2019, 362, 187–195. [Google Scholar] [CrossRef] [PubMed]
  44. Sharma, P.; Tripathi, S.; Chaturvedi, P.; Chaurasia, D.; Chandra, R. Newly Isolated Bacillus Sp. Ps-6 Assisted Phytoremediation of Heavy Metals Using Phragmites Communis: Potential Application in Wastewater Treatment. Bioresour. Technol. 2021, 320, 124353. [Google Scholar] [CrossRef]
  45. Abdulla, M. Chapter 13—Lead. In Essential and Toxic Trace Elements and Vitamins in Human Health; Prasad, A.S., Brewer, G.J., Eds.; Academic Press: Cambridge, MA, USA, 2020; pp. 181–191. [Google Scholar] [CrossRef]
  46. Das, S.; Nath, T.C.; Rahman, M.; Uddin, J.; Naher, N.; Akter, M.; Rahman, M.; Adhikari, A. Occupational Hazards in Lead-Acid Battery Factories in Bangladesh: Assessing Excess Heat, Noise, Chemical Exposures, and Health Impacts on Workers. Saf. Health Work 2025, 16, 289–296. [Google Scholar] [CrossRef] [PubMed]
  47. Chetyrkina, M.R.; Kameneva, L.; Mishchenko, D.V.; Klimanova, E.N.; Sashenkova, T.E.; Allayarova, U.Y.; Kostyuk, S.V.; Frolova, L.A.; Aldoshin, S.M.; Troshin, P.A. Lead, Tin, Bismuth or Organics: Assessment of Potential Environmental and Human Health Hazards Originating from Mature Perovskite PV Technology. Sol. Energy Mater. Sol. Cells 2023, 252, 112177. [Google Scholar] [CrossRef]
  48. He, W.; Wei, B.; Liang, S.; Wang, R.; Ji, Q.; Hu, G.; Li, W.; He, L.; Yu, J.; Zhu, H.; et al. Highly Nanostructured and Carboxylated Wood Aerogel-Based Adsorption Membrane Reconstructed by Grafting of Polyacrylic Acid for Efficient Removal of Heavy-Metal Ions. Chem. Eng. J. 2024, 493, 152411. [Google Scholar] [CrossRef]
  49. El Hajam, M.; Kandri, N.I.; Plavan, G.-I.; Harrath, A.H.; Mansour, L.; Boufahja, F.; Zerouale, A. Pb2+ Ions Adsorption onto Raw and Chemically Activated Dibetou Sawdust: Application of Experimental Designs. J. King Saud Univ. Sci. 2020, 32, 2176–2189. [Google Scholar] [CrossRef]
  50. Obsa, A.L.; Shibeshi, N.T.; Workeneh, G.A.; Mulugeta, E. Enhanced Lead (II) Adsorption from Aqueous Solution Using Sawdust-Derived Amino-Decorated Cellulose: Optimization, Isotherm, Kinetics, and Reusability Studies. Results Chem. 2024, 7, 101506. [Google Scholar] [CrossRef]
  51. Tan, Y.; Wang, K.; Yan, Q.; Zhang, S.; Li, J.; Ji, Y. Synthesis of Amino-Functionalized Waste Wood Flour Adsorbent for High-Capacity Pb(II) Adsorption. ACS Omega 2019, 4, 10475–10484. [Google Scholar] [CrossRef]
  52. Chen, Z.; Su, X.; Li, K.; Niu, S.; Shen, Z.; Li, X.; Chen, S.; Wu, W. A Thiolated TiO2-Based Degradable Superhydrophobic Wood for Oil–Water Separation and Heavy Metal Treatment. Sep. Purif. Technol. 2025, 354, 128949. [Google Scholar] [CrossRef]
  53. Yang, Z.; Liu, H.; Li, J.; Yang, K.; Zhang, Z.; Chen, F.; Wang, B. High-Throughput Metal Trap: Sulfhydryl-Functionalized Wood Membrane Stacks for Rapid and Highly Efficient Heavy Metal Ion Removal. ACS Appl. Mater. Interfaces 2020, 12, 15002–15011. [Google Scholar] [CrossRef]
  54. Nordberg, G.F.; Nogawa, K.; Nordberg, M. Chapter 32—Cadmium. In Handbook on the Toxicology of Metals, 4th ed.; Nordberg, G.F., Fowler, B.A., Nordberg, M., Eds.; Academic Press: San Diego, CA, USA, 2015; pp. 667–716. [Google Scholar] [CrossRef]
  55. Sattar, S.; Yahya, M.; Aslam, S.; Hussain, R.; Shah, S.M.M.; Rauf, Z.; Zamir, A.; Ullah, R.; Shahzad, A. Environmental Occurrence, Hazards, and Remediation Strategies for the Removal of Cadmium from the Polluted Environment. Results Eng. 2025, 25, 104322. [Google Scholar] [CrossRef]
  56. Chen, Y.; Zhen, C.; Zeng, L.; Feng, H.; Wang, J.; Ai, Q.Y.H.; Ai, S.; Zhang, J.; Liang, Y.Y.; Xue, H.; et al. Association of Blood Cadmium and Physical Activity with Mortality: A Prospective Cohort Study. Ecotoxicol. Environ. Saf. 2025, 290, 117541. [Google Scholar] [CrossRef]
  57. Baldev; Kumar, G.; Sharma, V.; Nemiwal, M. Biomass-Derived Zirconium Composite: An Adsorbent for Preferential Removal of Heavy Metals and Contaminants in Wastewater. J. Water Process Eng. 2025, 69, 106778. [Google Scholar] [CrossRef]
  58. Rafatullah, M.; Sulaiman, O.; Hashim, R.; Ahmad, A. Removal of Cadmium (II) from Aqueous Solutions by Adsorption Using Meranti Wood. Wood Sci. Technol. 2012, 46, 221–241. [Google Scholar] [CrossRef]
  59. Jia, Z.; Liang, F.; Xu, X.; Zhou, H.; Zhang, Y.; Liang, P. One-Pot Amination and Carboxylation Functionalization of Lignin for Efficient Adsorption of Cr(VI) and Cd(II): Influence of Functional Groups on Adsorption Equilibrium and Mechanism. Colloids Surf. Physicochem. Eng. Asp. 2024, 703, 135278. [Google Scholar] [CrossRef]
  60. Saeed, A.; Akhter, M.W.; Iqbal, M. Removal and Recovery of Heavy Metals from Aqueous Solution Using Papaya Wood as a New Biosorbent. Sep. Purif. Technol. 2005, 45, 25–31. [Google Scholar] [CrossRef]
  61. He, L.-T.; Zhao, L.-D.; Sun, W.; Fang, J.; Liu, X.-W.; Qi, J.-J.; Qian, Y.; Li, H. 3d Wood Microfilter for Fast and Efficient Removal of Heavy Metal Ions from Water. Langmuir 2023, 39, 15319–15327. [Google Scholar] [CrossRef] [PubMed]
  62. El-Sorogy, A.S.; Al-kahtany, K.; Alharbi, T.; Alarifi, S.S. Distribution Patterns, Health Hazards, and Multivariate Assessment of Contamination Sources of as, Pb, Ni, Zn, and Fe in Agricultural Soils. J. King Saud Univ. Sci. 2024, 36, 103489. [Google Scholar] [CrossRef]
  63. Osredkar, J. Copper and Zinc, Biological Role and Significance of Copper/Zinc Imbalance. J. Clin. Toxicol. 2011, S3, 0495. [Google Scholar] [CrossRef]
  64. Kovacova, Z.; Demcak, S.; Balintova, M.; Pla, C.; Zinicovscaia, I. Influence of Wooden Sawdust Treatments on Cu(II) and Zn(II) Removal from Water. Materials 2020, 13, 3575. [Google Scholar] [CrossRef]
  65. Scholz, P.; Vogel, C.; Schuck, G.; Simon, F.-G. Speciation of Copper and Zinc Compounds Relevant for the Hazard Property (Hp) 14 Classification of Municipal Solid Waste Incineration Bottom and Fly Ashes. Waste Manag. 2024, 189, 421–426. [Google Scholar] [CrossRef]
  66. Pereira, F.V.; Gurgel, L.V.A.; Gil, L.F. Removal of Zn2+ from Aqueous Single Metal Solutions and Electroplating Wastewater with Wood Sawdust and Sugarcane Bagasse Modified with Edta Dianhydride (Edtad). J. Hazard. Mater. 2010, 176, 856–863. [Google Scholar] [CrossRef]
  67. Syeda, H.I.; Muthukumaran, S.; Baskaran, K. Shape-Memory Cellulose Nanofiber/Polyglutamic Acid-Based Aerogels as Novel Adsorbents for the Removal of Heavy Metals from Aqueous Solutions. J. Water Process Eng. 2024, 58, 104780. [Google Scholar] [CrossRef]
  68. Keshvardoostchokami, M.; Braghiroli, F.L.; Neculita, C.M.; Koubaa, A. Advances in Modified Wood-Based Adsorbents for Contaminant Removal: Valorization Methods, Modification Mechanisms, and Environmental Applications. Curr. For. Rep. 2023, 9, 444–460. [Google Scholar] [CrossRef]
  69. Shao, T.; Yin, Q.; Bai, J.; Zhu, J.; Gan, M. Adsorption and Catalytic Reduction of Hexavalent Chromium Based on Nanomaterials: A Review on Metal, Metallic Oxide, Metallic Sulfide and Carbon-Based Catalyst. Environ. Res. 2025, 266, 120449. [Google Scholar] [CrossRef] [PubMed]
  70. den Braver-Sewradj, S.P.; van Benthem, J.; Staal, Y.C.M.; Ezendam, J.; Piersma, A.H.; Hessel, E.V.S. Occupational Exposure to Hexavalent Chromium. Part II. Hazard Assessment of Carcinogenic Effects. Regul. Toxicol. Pharmacol. 2021, 126, 105045. [Google Scholar] [CrossRef] [PubMed]
  71. Iyer, M.; Anand, U.; Thiruvenkataswamy, S.; Babu, H.W.S.; Narayanasamy, A.; Prajapati, V.K.; Tiwari, C.K.; Gopalakrishnan, A.V.; Bontempi, E.; Sonne, C.; et al. A Review of Chromium (Cr) Epigenetic Toxicity and Health Hazards. Sci. Total Environ. 2023, 882, 163483. [Google Scholar] [CrossRef]
  72. Luo, M.; Duan, W.; Li, S.W.; Yang, Y.; Yang, G.; Li, H.; Yu, X. Remediation of Hexavalent Chromium in Water and Soil by Pristine and Chemically Modified Pine Barks: Effects and Mechanisms. Environ. Technol. Innov. 2024, 36, 103876. [Google Scholar] [CrossRef]
  73. Xie, T.; Wang, Y.; Zhang, Q.; Shen, S.; Guo, W.; Chen, X.; Wang, Q.; Qu, L.; Li, C. Wood Aerogels Decorated Amino-Functionalized Mil-101(Cr) as Efficient Filter for Multistage Purification of Wastewater. Chemosphere 2024, 350, 141052. [Google Scholar] [CrossRef] [PubMed]
  74. Huang, H.; He, D.; Tang, Y.; Guo, Y.; Li, P.; Qv, W.; Deng, F.; Lu, F. Adsorption of Hexavalent Chromium from an Aqueous Phase by Hydroxypropyl Methylcellulose Modified with Diethylenetriamine. J. Chem. Eng. Data 2019, 64, 98–106. [Google Scholar] [CrossRef]
  75. Yang, R.; Aubrecht, K.B.; Ma, H.; Wang, R.; Grubbs, R.B.; Hsiao, B.S.; Chu, B. Thiol-Modified Cellulose Nanofibrous Composite Membranes for Chromium (VI) and Lead (II) Adsorption. Polymer 2014, 55, 1167–1176. [Google Scholar] [CrossRef]
  76. Jung, C.; Heo, J.; Han, J.; Her, N.; Lee, S.-J.; Oh, J.; Ryu, J.; Yoon, Y. Hexavalent Chromium Removal by Various Adsorbents: Powdered Activated Carbon, Chitosan, and Single/Multi-Walled Carbon Nanotubes. Sep. Purif. Technol. 2013, 106, 63–71. [Google Scholar] [CrossRef]
  77. Lu, W.; Duan, C.; Zhang, Y.; Gao, K.; Dai, L.; Shen, M.; Wang, W.; Wang, J.; Ni, Y. Cellulose-Based Electrospun Nanofiber Membrane with Core-Sheath Structure and Robust Photocatalytic Activity for Simultaneous and Efficient Oil Emulsions Separation, Dye Degradation and Cr(VI) Reduction. Carbohydr. Polym. 2021, 258, 117676. [Google Scholar] [CrossRef] [PubMed]
  78. Ellingsen, D.G.; Møller, L.B.; Aaseth, J. Chapter 35—Copper. In Handbook on the Toxicology of Metals, 4th ed.; Nordberg, G.F., Fowler, B.A., Nordberg, M., Eds.; Academic Press: San Diego, MA, USA, 2015; pp. 765–786. [Google Scholar] [CrossRef]
  79. Ameh, T.; Sayes, C.M. The Potential Exposure and Hazards of Copper Nanoparticles: A Review. Environ. Toxicol. Pharmacol. 2019, 71, 103220. [Google Scholar] [CrossRef]
  80. Ugwu, C.E.; Igbokwe, A.M.; Suru, S.M.; Dike, C.C.; Mbachu, A.N.; Maduka, H.C.C. Evaluating the Human Health Risks of Heavy Metal Contamination in Copper and Steel Factory Effluents in Nnewi, Anambra State, Nigeria. Toxicol. Rep. 2024, 12, 614–621. [Google Scholar] [CrossRef]
  81. Nagarajan, D.; Venkatanarasimhan, S. Kinetics and Mechanism of Efficient Removal of Cu(II) Ions from Aqueous Solutions Using Ethylenediamine Functionalized Cellulose Sponge. Int. J. Biol. Macromol. 2020, 148, 988–998. [Google Scholar] [CrossRef]
  82. Chu, Z.; Zheng, P.; Yang, Y.; Wang, C.; Yang, Z. Compressible Nanowood/Polymer Composite Adsorbents for Wastewater Purification Applications. Compos. Sci. Technol. 2020, 198, 108320. [Google Scholar] [CrossRef]
  83. Rahman, M.L.; Shamrih, S.A.; Azlyzan, N.A.; Sarjadi, M.S.; Arsad, S.E.; Sarkar, S.M.; Kumar, S. Removal of Heavy Metal Ions from Wastewater Using Modified Cornstalk Cellulose-Derived Poly(Amidoxime) Ligand. Carbohydr. Polym. Technol. Appl. 2025, 9, 100633. [Google Scholar] [CrossRef]
  84. Xu, C.; Liu, Q.; Han, Y.; Hu, S.; Xu, S. Efficient Adsorption of Cu2+ Using Znco Bimetallic Organic Frameworks Loaded Cellulose-Based Modified Aerogel: Adsorption Behavior and Mechanism. Environ. Res. 2025, 269, 120877. [Google Scholar] [CrossRef] [PubMed]
  85. Cai, Y.; Wu, Y.; Yang, L.; Yang, F.; Wang, Y.; Cheng, T. A Wood Sponge Sensor for Heavy Metal Ion Detection and Adsorption. Wood Sci. Technol. 2022, 56, 1175–1190. [Google Scholar] [CrossRef]
  86. Mautner, A.; Kwaw, Y.; Weiland, K.; Mvubu, M.; Botha, A.; John, M.J.; Mtibe, A.; Siqueira, G.; Bismarck, A. Natural Fibre-Nanocellulose Composite Filters for the Removal of Heavy Metal Ions from Water. Ind. Crops Prod. 2019, 133, 325–332. [Google Scholar] [CrossRef]
Forests 16 01684 g001
Figure 1. (A) Schematic illustration of heavy metal adsorption by wood-based eco-friendly hydrogel. Reprinted with permission from Ref. [25]. 2025, American Chemical Society; (B) Structural role of hemicellulose in wood. Reprinted with permission from Ref. [26]. 2017, American Chemical Society; (C) Schematic representation of wood cellulose bio-adsorbent. Reprinted with permission from Ref. [27]. 2025, Elsevier; (D) Adsorption mechanism of heavy metals by aminated lignin material. Reprinted with permission from Ref. [29]. 2024, Elsevier; (E) Preparation process of wood-based composite aerogel. Reprinted with permission from Ref. [30]. 2023, Elsevier.
Figure 1. (A) Schematic illustration of heavy metal adsorption by wood-based eco-friendly hydrogel. Reprinted with permission from Ref. [25]. 2025, American Chemical Society; (B) Structural role of hemicellulose in wood. Reprinted with permission from Ref. [26]. 2017, American Chemical Society; (C) Schematic representation of wood cellulose bio-adsorbent. Reprinted with permission from Ref. [27]. 2025, Elsevier; (D) Adsorption mechanism of heavy metals by aminated lignin material. Reprinted with permission from Ref. [29]. 2024, Elsevier; (E) Preparation process of wood-based composite aerogel. Reprinted with permission from Ref. [30]. 2023, Elsevier.
Forests 16 01684 g001
Forests 16 01684 g003
Figure 3. (A) Reaction scheme depicting the synthesis of the amine-functionalized cellulose sponge. Reprinted with permission from Ref. [81]. 2020, Elsevier; (B) Schematic illustration of the adsorption–desorption process. Reprinted with permission from Ref. [82]. 2020, Elsevier; (C) Ethylenediamine-functionalized cellulose sponge for efficient removal of Cu(II) ions from aqueous solutions. Reprinted with permission from Ref. [83]. 2025, Elsevier; (D) Adsorption behavior and mechanism of Cu2+ removal by wood sponge. Reprinted with permission from Ref. [84]. 2025, Elsevier.
Figure 3. (A) Reaction scheme depicting the synthesis of the amine-functionalized cellulose sponge. Reprinted with permission from Ref. [81]. 2020, Elsevier; (B) Schematic illustration of the adsorption–desorption process. Reprinted with permission from Ref. [82]. 2020, Elsevier; (C) Ethylenediamine-functionalized cellulose sponge for efficient removal of Cu(II) ions from aqueous solutions. Reprinted with permission from Ref. [83]. 2025, Elsevier; (D) Adsorption behavior and mechanism of Cu2+ removal by wood sponge. Reprinted with permission from Ref. [84]. 2025, Elsevier.
Forests 16 01684 g003
Table 1. The adsorption capacity values of various wood modifiers and synthetic adsorbents for various metal ions.
Table 1. The adsorption capacity values of various wood modifiers and synthetic adsorbents for various metal ions.
MaterialLead
Adsorption
(mg/g)		Cadmium Adsorption (mg/g)Zinc Adsorption
(mg/g)		Chromium Adsorption
(mg/g)		Copper Adsorption
(mg/g)		Ref.
Highly nanostructured and carboxylated wood aerogel-based adsorption film268.00255.00 248.00[46]
activated Dibetou sawdust61.73 [47]
amino-decorated cellulose53.86 [48]
Sulfhydryl—Functionalized Wood Membrane Stacks384.10593.90 169.50[49]
Meranti wood 175.43 [56]
One-pot amination and carboxylation functionalization of lignin 103.10 1298.60 [58]
Cellulose grafted with carboxyl and thiol groups 173.63 153.30[60]
wood sawdust, Manilkara sp. 80.00 [63]
Cellulose nanofiber/polyglutamic acid-based aerogels101.81 59.26 100.59[64]
wood aerogel6.46 [71]
Amine modified cellulose sponge 596.96[79]
nanowood with polyethyleneimine 93.06[80]
cellulose nanofibril composite 274.73[81]
wood sponge 60.00[82]
poly(amidoxime) ligand 220.00310.00[86]
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Liu, Y.; Zhang, X.; Du, Y.; Du, X.; Zhang, Y.; Deng, L.; Li, C.; Guo, J. Functionalization of Wood for the Removal of Heavy Metal Ions from Waster Water: A Review. Forests 2025, 16, 1684. https://doi.org/10.3390/f16111684

AMA Style

Liu Y, Zhang X, Du Y, Du X, Zhang Y, Deng L, Li C, Guo J. Functionalization of Wood for the Removal of Heavy Metal Ions from Waster Water: A Review. Forests. 2025; 16(11):1684. https://doi.org/10.3390/f16111684

Chicago/Turabian Style

Liu, Yang, Xiaolin Zhang, Yanzhuo Du, Xuebin Du, Yi Zhang, Layun Deng, Cheng Li, and Jianhui Guo. 2025. "Functionalization of Wood for the Removal of Heavy Metal Ions from Waster Water: A Review" Forests 16, no. 11: 1684. https://doi.org/10.3390/f16111684

APA Style

Liu, Y., Zhang, X., Du, Y., Du, X., Zhang, Y., Deng, L., Li, C., & Guo, J. (2025). Functionalization of Wood for the Removal of Heavy Metal Ions from Waster Water: A Review. Forests, 16(11), 1684. https://doi.org/10.3390/f16111684

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop