Search Results (327)

The escalating release of synthetic dyes from textile and allied industries has become a pressing global environmental issue due to their toxicity, persistence, and resistance to biodegradation. Among the various treatment strategies, adsorption has emerged as one of the most efficient, economical, and sustainable techniques for dye removal from aqueous environments. This review highlights recent advances in bio-derived adsorbents—particularly raw biomass powders, biochars, and activated carbons—developed from renewable waste sources such as agricultural residues, fruit peels, shells, and plant fibers. It systematically discusses adsorption mechanisms, the influence of process parameters, kinetic and thermodynamic models, and regeneration performance. Furthermore, the review emphasizes the superior adsorption efficiency and cost-effectiveness of biomass-derived carbons compared to conventional adsorbents. The integration of surface modification, magnetization, and nanocomposite formation has further enhanced dye uptake and reusability. Overall, this study underscores the potential of biomass-derived materials as sustainable alternatives for wastewater treatment and environmental remediation. Full article

The valorization of agricultural residues helps improve crop economic efficiency and alleviate environmental pressures. Owing to the merits of simplicity, high efficiency, low costs, and scalability, adsorption removal of contaminants using biochar has been widely investigated. The adsorption removal of organic and inorganic contaminants from wastewater using biochar derived from agricultural residue follows the principles of the circular economy and green chemistry, facilitating both environmental remediation and agricultural development. Due to the distinctive precursors—agricultural residues—biochar exhibits unique physicochemical properties, enabling it to interact differently with contaminants in real wastewater. Herein, this review addresses the knowledge gap in wastewater remediation using agricultural residue-based biochar. It compiles the principles of adsorption with agricultural waste-derived biochar, including general concepts, interactions between biochar and wastewater contaminants, and selective adsorption. The preparation, activation, modification, functionalization, and regeneration of such biochar, as well as their application to wastewater remediation, are comprehensively outlined. Furthermore, the economic evaluation and environmental impacts, as well as the future directions and challenges in this field, have also been presented. Full article

Remediating cadmium (Cd) contamination in aquatic and terrestrial environments has become an urgent environmental priority. Biochar has been widely employed for heavy metal removal due to its wide availability, strong adsorption capacity, and potential for recycling agricultural waste. In this study, samples of alkali–Fe-modified biochar (Fe@NaOH-SBC, Fe@NaOH-HBC, and Fe@NaOH-MBC) were prepared from agricultural wastes (ginger straw, Sichuan pepper branches, and kiwi leaves) through NaOH and FeCl₃·6H₂O modification. A comprehensive characterization confirmed that the alkali–Fe-modified biochar exhibits a higher specific surface area, richer functional groups, and successful incorporation of the iron oxides Fe₃O₄ and α-FeOOH. The fitting parameter qmax from the Langmuir model indicates that the alkali–Fe modification of carbon significantly enhanced its maximum capacity for Cd²⁺ adsorption. Furthermore, a synergistic effect was observed between iron oxide loading and alkali modification, outperforming alkali modification alone. Furthermore, a 30-day soil incubation experiment revealed that the application of alkali–Fe-modified biochar significantly increased soil pH, SOM, and CEC while reducing the available cadmium content by 13.34–33.94%. The treatment also facilitated the transformation of highly bioavailable cadmium species into more stable, less bioavailable forms, thereby mitigating their potential entry into the food chain and the associated human health risks. Moreover, short-term spinach seed germination experiments confirmed that treatments with varying additions of alkali–Fe-modified biochar mitigated the inhibition of seed physiological processes by high concentrations of available cadmium to varying degrees. Overall, this study provides a sustainable and effective strategy for utilizing agricultural waste in the remediation of cadmium-contaminated water and soil systems. Full article

Biochar is widely recognized for its ability to immobilize heavy metals in soil, yet its direct effect on plant physiological metal-sequestration capacity remains poorly understood. This study explores a critical distinction between two mechanisms: direct, concurrent metal immobilization by biochar versus its capacity to physiologically precondition plants, altering their inherent metal uptake and distribution. Using a hydroponic design with pH-matched controls, the latter was isolated by preconditioning rice plants with peanut straw biochar (PSB) or corn straw biochar (CSB) and subsequently removing amendments before cadmium (Cd) exposure. Our results reveal that biochar (PSB) preconditioning may modify root architecture and surface chemistry, enhancing negative zeta potential and functional group density. This modification increased root Cd adsorption capacity by 50.1% and 142.7% within 2 h or 2.2% and 52.6% within 48 h compared to the normal and pH-adjusted controls, respectively, with shifted metal speciation toward stable complexes. However, this enhanced root sequestration coincided with an increased translocation factor, elevating shoot Cd content by 78% compared to the normal control. In contrast, CSB preconditioning showed negligible effects. Our findings suggest that biochar’s net impact on metal distribution is probably the product of two temporally distinct processes: chemical immobilization in growth media versus physiological preconditioning effects. This dual mechanism framework may explain the variability in literature reports on the effect of biochar on heavy metal uptake by plants. It also highlights the need for holistic biochar risk assessment that considers both chemical and plant physiological pathways in both soil and hydroponic systems. Full article

The escalating issue of water pollution has intensified the demand for efficient remediation technologies. Biochar adsorption and photocatalytic degradation have emerged as promising approaches for water treatment, with each offering distinct advantages. Integrating these two strategies into biochar-based photocatalytic composites presents a novel and effective pathway for advanced water purification. This review systematically summarizes recent advances in the preparation of biochar, modification of photocatalysts, and synthesis techniques for their integration. Furthermore, we critically examine the current application landscape and key challenges facing biochar-based photocatalytic materials in water treatment. Promising future research directions are outlined along with identifiable bottlenecks that must be addressed to advance the field. This work aims to offer insightful perspectives and practical guidance for the rational design and development of high-performance biochar-based photocatalytic systems. Full article

Recent advances in agricultural biotechnology and sustainable farming have drawn attention to biochar as a multifunctional material for environmental remediation. Among its emerging applications, biochar has demonstrated remarkable potential in wastewater treatment, particularly as an efficient and sustainable adsorbent for pollutant removal. Numerous studies over the past decades have highlighted its effectiveness in eliminating a wide range of contaminants. This efficiency is mainly due to its abundant feedstock availability, simple production processes, and favorable surface and structural properties. This review summarizes current developments in biochar use for wastewater treatment, emphasizing its adsorption capabilities and the underlying mechanisms responsible for pollutant removal. Key modification strategies, physical, chemical, and biological, are discussed in detail to illustrate how biochar performance can be optimized for specific treatment goals. Furthermore, the prospects of biochar-based technologies are explored, with a focus on their role in addressing both inorganic and organic pollutants. This review also describes the use of biochar in adsorbing metals, organic contaminants, and industrial waste. The integration of biochar into sustainable water management systems presents a promising pathway toward achieving long-term environmental and agricultural resilience. Full article

Sunflower stalks derived biochars were fabricated through sequential alkali/enzymatic pretreatment, carbonization, and chitosan modification, and were used as eco-friendly adsorbents for Cu (II) removal from wastewater. The effects of pH, temperature, adsorption time, and dosage of biochar on Cu (II) adsorption separation from the model solution were comprehensively investigated. Results demonstrated that the chitosan treatment of biochar, obtained from the carbonization of pretreated sunflower straw, significantly altered the porous structure and surface functional groups of the material. Specifically, the biochar carbonized at 500 °C and subsequently treated with chitosan exhibited optimal adsorption performance at pH 5 and 35 °C. Under these conditions, a maximum Cu(II) adsorption capacity of 268.2 mg g⁻¹ (of biochar) was realized. Further analysis indicated the Cu(II) adsorption generally followed pseudo-second-order kinetics (R² > 0.99). Langmuir isotherm modeling revealed that the biochar modified by NaOH and chitosan displayed the highest correlation coefficient (R² > 0.99), suggesting predominantly homogeneous monolayer adsorption. Therefore, the novel low-cost and environmentally friendly biomass-derived adsorbents demonstrate significant potential for effective treatment of the heavy metal-contaminated wastewater. Full article

In this study, yak dung was used as a precursor to prepare biochar (KYBC600) via high-temperature pyrolysis and KOH modification for the adsorption of tetracycline hydrochloride (TCH) from aqueous solution. Compared with commonly used biomass feedstocks such as straw and fruit shells, the resource-oriented utilization of yak dung holds dual significance: it contributes to regional environmental management and enables high-value conversion of waste, underscoring its distinct regional relevance and potential for synergistic environmental governance. The physicochemical properties of KYBC600 were characterized using BET surface area analysis, FTIR, XRD, and SEM. Adsorption behavior and mechanisms were systematically investigated through kinetic, isotherm, and thermodynamic studies, supplemented by response surface methodology (RSM). The results demonstrated that the adsorption of TCH onto KYBC600 followed pseudo-second-order kinetics and the Langmuir model, with a maximum adsorption capacity of 54.10 mg·g⁻¹. Multiple synergistic mechanisms governed the adsorption process, including pore filling, π–π stacking, electrostatic interactions, hydrogen bonding, and complexation with Ca²⁺, with chemical adsorption playing a dominant role. KYBC600 demonstrated excellent adsorption performance and regeneration capability across a wide pH range and in various real water matrices. This study provides novel perspectives on the resource utilization of livestock waste in plateau regions and provides a technical reference for treating low-concentration TCH-containing wastewater. Full article

The continuous-cropping obstacles of Pogostemon cablin (patchouli) is severely constrained by autotoxic phenolic acids accumulated in the rhizosphere soil. Biochar adsorption and chemical oxidation are common remediation strategies; they often fail to simultaneously and efficiently remove phenolic allelochemicals while improving the soil micro-ecological environment. To address this issue, this study developed a novel biochar–urea peroxide composite particle (BC-UP). Batch degradation experiments and electron paramagnetic resonance (EPR) analysis confirmed the synergistic adsorption-oxidation function of BC-UP. A pot experiment demonstrated that application of BC-UP (5.0 g/kg) significantly alleviated phenolic acid stress. Specifically, BC-UP application significantly enhanced shoot biomass by 28.8% and root surface area by 49.3% compared to the phenolic acid-stressed treatment and concurrently reduced the total phenolic acid content in the rhizosphere soil by 37.3%. This growth promotion was accompanied by the enhanced accumulation of key bioactive compounds (volatile oils, pogostone, and patchouli alcohol). BC-UP amendment also improved key soil physicochemical properties (e.g., pH, and organic matter) and enhanced the activities of critical enzymes. Furthermore, BC-UP reshaped the microbial community, notably reducing the fungi-to-bacteria OTU ratio by 49.7% and enriching the relative abundance of Firmicutes and Nitrospirota but suppressing the Ascomycota phylum abundance. Redundancy analysis identified soil sucrase and catalase activity, total phenolic acid content, and Ascomycota abundance as key factors influencing patchouli biomass. In conclusion, BC-UP effectively mitigates phenolic acid stress through combined adsorption and radical oxidation, subsequently improving soil properties and restructuring the rhizosphere microbiome, offering a promising soil remediation strategy for patchouli and other medicinal crops. Full article

Microplastics (MPs) and nanoplastics (NPs) are emerging aquatic contaminants that pose environmental and public health risks due to their persistence, ubiquity, and ability to adsorb co-contaminants. This scoping review synthesises findings from 57 experimental studies and five review studies published between 2019 and 2025 on the use of biochar-based materials for the removal of microplastics from water and wastewater. Guided by the hypothesis that surface-modified biochars, such as magnetised, surfactant-coated, or chemically activated forms, achieve high removal efficiencies through multimodal mechanisms (e.g., electrostatic attraction, hydrophobic interactions, π–π stacking, and physical entrapment), this review applies PRISMA-based protocols to systematically evaluate biochar feedstocks, pyrolysis conditions, surface modifications, polymer types, removal mechanisms, and regeneration approaches. Scopus, Web of Science, and PubMed were searched until 30 May 2025 (English-only), and 62 studies were included. The review was not registered, and no protocol was prepared. The results confirm a high removal efficiency (>90%) in most experimental studies, particularly under controlled laboratory conditions and using pristine polystyrene. However, the performance declines significantly in complex matrices (e.g., wastewater and surface water) owing to dissolved organic matter, ionic competition, and particle heterogeneity, thus supporting the guiding hypothesis. This review also identifies critical methodological gaps, including narrow plastic typologies, a lack of standardised testing protocols, and limited field-scale validation. Addressing these gaps through environmentally realistic testing, regeneration optimisation, and harmonised methods is essential for transitioning biochar from a promising sorbent to a practical water treatment solution. Full article

Microplastics have become a major environmental concern due to their resistance to degradation, wide distribution, and potential uptake by organisms. Conventional mitigation strategies often exhibit limitations in efficiency, reuse, and scalability, and may generate secondary pollutants. In this review, we highlight the application of magnetically controlled, sustainable nanorobots based on magnetic hybrid nanoparticles with different functional groups to enhance the removal efficiency of microplastics from the environment. By leveraging hydrophobic interactions, surface modifications, and tailored additives, these magnetic nanorobots provide a sustainable, eco-friendly approach to mitigating microplastic pollution and offer improved magnetic separation performance. Bioinspired and biohybrid magnetic nanorobots, based on green synthesis principles, carbon-based nanomaterials, biochar, nature-inspired swarm motion, and collective behavior, present further advancements that mimic biological systems to capture microplastics with high efficiency and recovery. Achieving removal efficiencies often exceeding 90% in minutes, and maintaining the efficiency after several cycles. The synergistic integration of magnetic separability with tailor-made surface functionalities underpins the effectiveness of these magnetic nanorobots, setting the stage for their future commercialization and widespread adoption in water remediation technologies. Full article

Incorporating biochar into pavement materials is a novel and environmentally sustainable approach that aligns with global sustainability goals and advances greener pavement technologies. Studies have shown that biochar significantly enhances the strength, durability, and stability of pavements, while also contributing to sustainability by lowering the carbon footprint associated with traditional construction materials. Additionally, the incorporation of biochar contributes to the sustainability of asphalt engineering by reducing reliance on petroleum-based products and promoting the valorization of biomass. The primary objective of this review is to critically evaluate and synthesize existing research on the use of biochar in bitumen and asphalt mixtures, identifying key performance trends, influencing factors, and optimum modification conditions. Despite these benefits, several drawbacks and challenges remain. These include variability in biochar properties, determining the optimal dosage for different applications, and the lack of standardized testing methods. This review investigates a wide range of studies and experimental investigations that evaluate the sources and production methods of biochar, as well as its effects on bitumen binders and asphalt mixtures. Furthermore, the paper highlights the environmental consideration of biochar modification, including carbon sequestration and Life cycle assessment. Substantial findings and their engineering implications are presented, along with recommendations for future research aimed at advancing the broader adoption of biochar in sustainable pavement engineering, in alignment with the principles of the circular economy. Full article

Biochar is one of the most promising crop straw utilization pathways. However, its capacity for adsorbing heavy metals is limited, and there is a potential risk of secondary pollution, highlighting the importance of developing efficient and environmentally friendly bio-modification methods. Here, we utilized glomalin-related soil protein (GRSP), a byproduct from arbuscular mycorrhizal fungi, to modify straw biochar, developing a novel composite material and systematically evaluating its performance in removing copper ion (Cu²⁺) from aqueous solutions. Biochar samples derived from maize, wheat, and rice straw were prepared at three pyrolysis temperatures (300 °C, 500 °C, and 700 °C), followed by surface functionalization with GRSP to produce GRSP-modified straw biochar for Cu²⁺ adsorption experiments. The results demonstrated that the abundant functional groups (e.g., amino and carboxyl groups) in GRSP and the porous structure of the straw biochar exhibited a significant synergistic effect, enhancing the adsorption capacity for Cu²⁺. Notably, the GRSP-modified wheat straw biochar prepared at 700 °C achieved an adsorption capacity of 193.2 mg g⁻¹ for Cu²⁺, representing a 76% improvement over the unmodified material. Fourier transform infrared spectroscopy and scanning electron microscopy with energy-dispersive X-ray spectroscopy revealed that hydroxyl, carboxyl, and ether groups served as key adsorption sites for Cu²⁺, while the hydrophobic-acid precipitation characteristics of GRSP further enhanced the material’s recoverability. By systematically characterizing the material’s microstructure and its adsorption behavior toward Cu²⁺, this study elucidated the role of critical functional groups in the adsorption mechanism. This work not only offers a low-carbon and efficient strategy for agricultural waste valorization and heavy metal pollution control, but also advances the mechanistic understanding of “bio-abiotic” synergy in environmental remediation. Full article

With a complex molecular structure, oxytetracycline (OTC) has characteristics such as bioaccumulation and poor degradability. As a result, if it accumulates in the environment, it can cause bacteria to develop drug resistance, thereby affecting human health. There is a considerable cultivation area for macadamia nuts in southwestern China. This study mainly focuses on macadamia nut shells, preparing macadamia nut shell biochar (MBC) and cobalt-modified macadamia nut shell biochar (Co-MBC) for activating permonosulphate (PMS) to remove OTC in the water. To determine the optimal preparation conditions for the biochar, the effects of the pyrolysis temperature and the mass ratio of biomass to cobalt sulfate heptahydrate were investigated. The study shows that after modification, the surface roughness of the material increased, transforming into a micro-pore structure; thus, the specific surface area increases significantly and new functional groups appear on the surface. The optimal pyrolysis temperature for the biochar was determined to be 600 °C, and the optimal mass ratio of biomass to cobalt sulfate heptahydrate was 15:1. Under such conditions, the removal rate of OTC by a Co15-MBC600/PMS system in 20 min can reach 95.53%. The reaction mechanism involves pathways of the free radical (SO₄⁻) and non-free radical (¹O₂), and the Co²⁺/Co³⁺ cycle can promote the activation of PMS. Finally, the OTC can be mineralized into CO₂ and H₂O by reactions such as demethylation and decarboxylation. Co-MBC is highly effective and green and can be reused; therefore, it has good prospects for the removal of OTC in waste water. Full article

Phosphorus (P) scarcity and pollution demand sustainable recovery strategies. This study engineered a functional straw biochar (F-SBC) from corn straw through synergistic KOH activation and MgCl₂ modification for efficient P recovery and slow release. Characterization revealed that KOH pretreatment expanded pore size and enhanced MgO loading. Batch adsorption experiments demonstrated F-SBC achieved a remarkable P adsorption capacity of 24.70 ± 0.57 mg·g⁻¹, and exhibited > 95% removal efficiency across pH 5~9. Adsorption kinetics followed the pseudo-second-order model, and isotherms fitted the Langmuir model, indicating chemisorption-dominated monolayer adsorption. Mechanistic studies identified synergistic contributions from chemical precipitation, inner-sphere complexation, bi-metallic electrostatic attraction, and physical confinement. F-SBC exhibited slow-release properties, alongside sustained adsorption capacity. Competitive anions (HCO₃⁻/CO₃²⁻) significantly promoted desorption, while Cl⁻ showed minimal impact. This KOH/MgCl₂ co-modification strategy creates a cost-effective, regenerable biochar with superior P recovery and controlled-release potential, advancing sustainable P management from agricultural waste towards a circular bioeconomy. Full article