Search Results (146)

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

Arsenic contamination demands innovative, sustainable remediation. This study presents a fuzzy approach for synthesizing a magnetic biochar nanocomposite from pecan shell agricultural waste for efficient arsenic removal. Using a Multi-Input Fuzzy Rules Emulated Network (MiFREN), a systematic investigation of the synthesis process revealed that precursor type (biochar), Fe:precursor ratio (1:1), and iron salt type were the most significant parameters governing material crystallinity and adsorption performance, while particle size and N₂ atmosphere had a minimal effect. The MiFREN-identified optimal material, the magnetic biochar composite (FS7), achieved > 90% arsenic removal, outperforming the least efficient sample by 50.61%. Kinetic analysis confirmed chemisorption on a heterogeneous surface (q_e = 12.74 mg/g). Regeneration studies using 0.1 M NaOH demonstrated high stability, with FS7 retaining > 70% removal capacity over six cycles. Desorption occurs via ion exchange and electrostatic repulsion, with post-use analysis confirming structural integrity and resistance to oxidation. Application to real groundwater from the La Laguna region proved highly effective; FS7 maintained selectivity despite competing ions like ${Na}^{+}$, ${Cl}^{-},$ and ${SO}_4^{2-}$. By integrating AI-driven optimization with reusability and real contaminated water, this research establishes a scalable framework for transforming agricultural waste into a high-performance adsorbent, supporting global Clean Water and Sanitation goals. Full article

The development of sustainable catalysts from renewable resources is a key challenge for reducing the cost of industrial catalytic processes and waste valorization. In this work, low-cost heterogeneous active catalysts were prepared based on pyrolyzed forest residues, forming valuable porous support materials (Biochar) able to efficiently accommodate the highly active heteropolyacid HPW₁₂. Further, magnetic functionality was incorporated in the novel catalytic materials by the impregnation of NiFe₂O₄. The resulting magnetic composites were characterized by FTIR-ATR, SEM-EDS, ICP-OES, BET, XRD, potentiometric titration and magnetometry. The novel HPW₁₂@NiFe₂O₄@Biochar composites were able to valorize the glycerol to produce the fuel additive solketal with high conversion and high selectivity after only 3 h of reaction via acetalization reaction with acetone. The biochar catalytic composite prepared from cork presented higher pore size than the same prepared from forest biomass. This property was crucial to achieve the best conversion (89%) and the highest solketal selectivity (96%). Additionally, reusability capacity was verified, supporting the potential of the cork-pyrolyzed-based composites as potential low-cost catalytic material to produce fuel additives, such as solketal, under sustainable conditions. This may contribute one step further toward a future with greener energy, increasing the viability of biodiesel industry waste. Full article

This study aimed to synthesize a magnetic biochar@ZIF-8 composite derived from almond shell biomass for the adsorption of fluoroquinolones (FQs) from aqueous media. The biochar was prepared under different pyrolysis conditions using a central composite design (CCD) based on temperature and residence time, with biochar yield (%) and ofloxacin adsorption capacity selected as the response variables. Subsequently, the composite was obtained by combining KOH-activated biochar with ZIF-8 and magnetic particles, producing a hierarchically porous material with enhanced surface area and functional groups favorable for adsorption. The physicochemical and morphological properties of the composite were characterized by SEM–EDS, FTIR, BET, TGA, and XRD analyses, confirming the successful incorporation of ZIF-8 and magnetic phases onto the biochar surface. The adsorption performance was systematically evaluated by studying the effects of pH and contact time. The kinetic data fitted well to the pseudo-second-order model, suggesting that chemisorption predominates through π–π stacking, hydrogen bonding, and coordination interactions between FQ molecules and the active sites of the composite. Furthermore, the material exhibited high reusability, maintaining over 84% of its adsorption capacity after four cycles, with efficient magnetic recovery without the need for filtration or centrifugation. Overall, the magnetic biochar@ZIF-8 composite demonstrates a sustainable, cost-effective, and magnetically separable adsorbent for water remediation, transforming almond shell waste into a high-value material within the framework of circular economy principles. Full article

Magnetic biochars (MBCs) have been shown to inhibit the horizontal transfer of antibiotic resistance genes (ARGs) in soils, both with and without microplastics (MPs); however, the underlying molecular biological mechanisms remain unclear. This study examined the effects of MBCs and coexisting polybutylene adipate terephthalate microplastics (PBAT MPs) on the physiological characteristics of Serratia marcescens ZY01 (a host strain carrying the tet gene) and further investigated their relationships with the absolute abundance of the tet gene in soil. The results demonstrated that MBCs promoted prodigiosin synthesis in Serratia marcescens ZY01 by mediating the electron transfer process, the effect of which was further enhanced in the presence of PBAT MPs. In treatments without PBAT MPs, MBCs generally suppressed the production of both proteins and polysaccharides in the extracellular polymeric substances. In contrast, in treatments containing PBAT MPs, the protein content gradually decreased with decreasing iron-to-biochar ratios, while the polysaccharide content remained largely unchanged. MBCs also elevated intracellular ROS levels due to the increased oxidative stress, particularly in treatments with PBAT MPs. A positive correlation between intracellular ROS levels and cell membrane permeability indicates that intracellular ROS was the primary driver of the increased cell membrane permeability. The presence of MBCs and PBAT MPs generally provided favorable habitats for Serratia marcescens ZY01, thereby enhancing its cell viability. Mantel test analysis indicated that MBCs influenced Serratia growth in soil by modulating its cell viability. Furthermore, the increased intracellular ROS level was significantly positively correlated with the absolute abundance of the tet gene in soil, implying the horizontal transfer of the tet gene at the intra-genus level. These findings offer helpful insights for developing environmental remediation strategies based on biochar–iron composites. Full article

The antagonistic geochemical behaviors of cadmium (Cd) and arsenic (As) in co-contaminated soils complicate their simultaneous remediation. This study aimed to develop a synergistic immobilization strategy by converting Spirulina residue into a magnetic biochar-layered double hydroxide composite (FSRBL). The composite was applied to both acidic red and calcareous black soils, and its effects on Cd and As, immobilization efficiency, and ecotoxicity were evaluated. The results showed that FSRBL effectively transforms Cd and As from mobile fractions to stable residual forms. At a 2.5% application rate, FSRBL achieved remarkable immobilization efficiencies of 39.2% for Cd and 57.5% for As, representing effectiveness 3.55 and 5.97 times higher than that of unmodified biochar, respectively. A dose–response relationship between the application amount of FSRBL and the immobilization efficiency of As and Cd was observed and further quantified using a logistic model. The results indicate that while increased FSRBL application enhances immobilization efficiency, the marginal benefit of each additional unit diminishes as the application rate increases, demonstrating a significant diminishing marginal effect. According to the ecotoxicity assessment experiment, the soil leachate from FSRBL-amended soil remarkably decreased the ecological toxicity to rice (Oryza sativa L.). Mechanistic investigations employing SEM/TEM-EDS, XRD, and XPS revealed that the synergistic immobilization could be ascribed to the multi-component cooperation within FSRBL, which resolved the conflicting pH/Eh requirements for the immobilization of Cd and As: (1) the LDH phase efficiently immobilized As oxyanions through anion exchange and isomorphic substitution; (2) the magnetic Fe phase concurrently immobilized Cd²⁺ and As oxyanions via redox transformation and coprecipitation, resulting in the formation of precipitates such as Fe/Ca/Cd–As(V). This work demonstrates a feasible approach to upcycle biomass waste into a value-added material for sustainable remediation of Cd–As co-contaminated soil. Full article

Microplastics (MPs) have emerged as persistent and ubiquitous contaminants in aquatic and terrestrial environments, yet existing reviews often focus narrowly on conventional removal methods and lack an integrated assessment of rapidly emerging technologies. This review addresses this critical gap by providing a comprehensive and comparative synthesis of both established and next-generation approaches for MP removal from water and wastewater systems. Conventional methods such as coagulation–flocculation, sedimentation, and filtration are compared with advanced approaches including membrane separation, adsorption using engineered biochar and nanomaterials, advanced oxidation processes (AOPs), and biodegradation using microbial or enzymatic pathways. Particular emphasis is placed on hybrid and integrated systems, an area seldom summarized in prior reviews, highlighting their synergistic potential to enhance removal efficiency, reduce energy demand, and improve operational stability. Promising front-runner technologies including membrane filtration coupled with coagulation pretreatment and biochar-based magnetic adsorption systems have been identified based on a balanced performance across the key criteria of removal efficiency, scalability, energy demand, cost, byproduct risk, and environmental sustainability. The review concludes by outlining key research priorities such as standardized testing protocols, scalable biophysicochemical integration strategies, and sustainability-oriented life-cycle assessments to guide future innovation in MP management. 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

In this study, mulberry tree stems were used as raw material to prepare magnetic modified biochar, Fe-BC-500, using the co-precipitation method. The structure of Fe-BC-500 was systematically characterized and tested for arsenic (As) adsorption in batch experiments by varying parameters such as solution pH (3–11), the concentrations of co-existing anions (2–20 mg/L), and ionic strength (0–0.5 mol/L NaNO₃). The results indicate that Fe-BC-500 exhibited optimal adsorption capacity at pH 4 and an initial As(V) concentration of 20 mg/L. The influence of co-existing anions on As(V) adsorption followed the order PO₄³⁻ > SO4²⁻ > NO₃⁻. Kinetic analysis showed that adsorption of Fe-BC-500 on As(V) followed a pseudo-second-order kinetic model, with a correlation coefficient of 1.00, indicating chemical adsorption. The Langmuir model accurately described the isothermal adsorption results, indicating monolayer adsorption. Mechanistic analysis showed that As(V) was fixed on the Fe-BC-500 surface through complexation reactions, demonstrating adsorption specificity. This study provides a theoretical basis and highlights the application potential of magnetically modified biochar for removing As(V) from water. Full article

Bio-waste from potato shell agro-waste-based photocatalyst is introduced using potato shell integrated with Fe₃O₄ nanoparticles as a novel photocatalyst for photo-Fenton oxidation reaction. The catalyst was prepared via thermal activation of biochar, followed by co-precipitation of magnetite nanoparticles, resulting in a stable and reusable material. X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques augmented with the energy dispersive X-ray spectroscopy (EDX) analysis with elemental mapping were used to assess the prepared sample. The prepared material, PtS200–Fe₃O₄, is then applied for oxidizing Procion Blue dye using biochar-supported magnetite catalyst. The oxidation process was evaluated under varying operational parameters, including pH, temperature, catalyst loading, oxidant dosage, and dye concentration. Results revealed that the system achieved complete dye removal within 20 min at 60 °C and pH 3, demonstrating the strong catalytic activity of the composite. Furthermore, the kinetic modeling is evaluated and the data confirmed that the degradation followed first-order kinetics. Also, the thermodynamic parameters indicated low activation energy with PtS200–Fe₃O₄ composite in advanced oxidation processes. The system sustainability is also assessed, and the reusability test verified that the catalyst retained over 70% efficiency after six consecutive cycles, highlighting its durability. The study confirms the feasibility of using biochar-supported magnetite as a cost-effective, eco-friendly, and efficient catalyst for the treatment of textile effluents and other dye-contaminated wastewater. Full article

Magnetic biochar (Zn/Fe-BC) was prepared from jujube branches via an impregnation pyrolysis–coprecipitation technique to eliminate Cr(VI) from water. ZnFe₂O₄ was introduced through ZnCl₂-based impregnation and pyrolysis, which can regulate the microstructure of hydrocarbon frameworks. Furthermore, FeSO₄·7H₂O was used as the precursor for co-precipitation to embed Fe₃O₄ into the material, improving its reducibility and magnetism. The results demonstrated that Zn/Fe-BC exhibited excellent Cr(VI) removal efficiency. Under optimal conditions (an initial Cr(VI) concentration of 50 mg/L, pH 2, and an adsorbent dosage of 2 g/L), the maximum adsorption capacity of Zn/Fe-BC reached 27.85 mg/g, which was significantly higher than that of unmodified biochar (23.20 mg/g). Following five cycles of adsorption and desorption, the desorption efficiency was still higher than 60.35%. The following were the inhibitory effects of coexisting anions on the elimination of Cr(VI): CO₃²⁻ > PO₄³⁻ > SO₄²⁻ > NO₃⁻. According to kinetic and isothermal adsorption experiments, the adsorption process adhered to the Freundlich isotherm and followed a pseudo-second-order kinetic model, indicating a multilayer adsorption process. Cr(VI) removal by Zn/Fe-BC was driven by physical adsorption and chemical reduction, involving a synergistic combination of electrostatic attraction, reduction, complexation, precipitation, and pore filling. These findings demonstrate the potential of the Zn/Fe-BC magnetic biochar as an effective adsorbent for Cr(VI) remediation in water treatment applications. Full article

Recently, researchers have been focused on the recycling as well as transforming of bio-waste streams into a valuable resource. Banana peels are promising for such application, due to their wide availability. In this context, the integration of banana peel-derived biochar with environmentally benign magnetite has significantly broadened its potential applications as a solar photocatalyst compared to the conventional photocatalysts. The materials are mixed in varied proportions of Ban-Char500-Mag@-(0:1), Ban-Char500@Mag-(1:1) and Ban-Char500@Mag-(2:1) and characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) augmented with dispersive X-ray spectroscopy (EDX). Such modification is leading to an improvement in its application as a solar photocatalyst using the photochemical solar collector facility. The study discusses the factors controlling acetaminophen removal from aqueous effluent within 30 min of solar illumination time. Furthermore, the highlighted optimum parameters are pH 3.0, using 10 mg/L of the Ban-Char500@Mag-(1:1) catalyst and 100 mg/L of the hydrogen peroxide as a Fenton combination system for removing a complete acetaminophen from wastewater (100% oxidation). Also, the temperature influence in the oxidation system is studied and the high temperature is unfavorable, which verifies that the reaction is exothermic in nature. The catalyst is signified as a sustainable (recoverable, recyclable and reusable) substance, and showed a 72% removal even though it was in the six cyclic uses. Further, the kinetic study is assessed, and the experimental results revealed the oxidation process is following the first-order kinetic reaction. Also, the kinetic–thermodynamic parameters of activation are investigated and it is confirmed that the oxidation is exothermic and non-spontaneous in nature. Full article

Chlorinated aliphatic hydrocarbons (CAHs) are some of the most widely distributed organic pollutants in underground environments and have high biological toxicity. This research aims to prepare an effective adsorbent comprising biochar and magnetite (MBC) to remove CAH pollution from soil. Optimization of the preparation and adsorption performance of MBC was investigated. The results of the adsorption experiment, combined with scanning electron microscopy (SEM) observations, show that the best raw material and pyrolysis temperature were coconut shell and 500 °C respectively. The Fourier transform infrared (FTIR) and X-ray diffraction (XRD) pattern characterizations, as well as the adsorption results, demonstrated the successful synthesis and enhancement effect of MBC for CAHs. The adsorption of CAHs on Fe₃O₄-loaded biochar was improved by 34.40–222.25% during pyrolysis at 500–900 °C. Additionally, MBC with a 10% Fe₃O₄ content had the best effect on three types of CAHs at low concentrations. A comparative pore analysis of MBC with different doses of Fe₃O₄ was carried out to reveal the relationship between the pore characteristics and adsorption properties. Furthermore, competitive adsorption experiments demonstrated that 4 wt% MBC addition significantly reduced the soil-bound TCE by 48.6%. Overall, these results indicated that MBC was an effective adsorbent for CAH removal from the polluted underground environment. Full article

In this study, a novel low-temperature (300–500 °C) carbothermal reduction route employing potassium ferrate and sodium hydroxide was developed to synthesize magnetic zero-valent iron-doped biochar for removing tetracycline and ciprofloxacin from aqueous solutions. Carbothermal reduction occurred effectively at 400 °C, generating sufficient small reductive molecules for the reduction of iron species into zero-valent iron. This process led to the impregnation of abundant zero-valent iron along with nano-magnetite into the carbon matrix, while nano-magnetite was also dispersed and stabilized on zero-valent iron. Simultaneously, abundant functional groups were formed, contributing to anchoring iron species and adsorbing pollutants. The magnetic biochar exhibited high adsorption capacities for tetracycline (1106.25 mg/g) and ciprofloxacin (182.03 mg/g), along with high saturation magnetization (56.3 emu/g) and superior reusability. Moreover, the magnetic biochar showed broad applicability for efficient removal of tetracycline and ciprofloxacin derivatives. Overall, carbothermal reduction efficiently transformed iron oxides into zero-valent iron at a relatively low temperature, providing a viable approach for manufacturing magnetic biochar doped with zero-valent iron. Full article

This study evaluates Fe₃O₄ magnetic biochar synthesized from pecan nutshells for arsenic removal. Surface modification with Fe₃O₄ significantly enhanced arsenic adsorption selectivity and efficiency compared to raw biomass (PM). Synthesis variables (precursor type, particle size, Fe/precursor ratio, N₂) and adsorption conditions (such as concentration, pH, agitation) were investigated. The modified biochar achieved >90% arsenic removal efficiency under various conditions, demonstrating the modification’s critical role. A fuzzy decision network was employed to analyze experimental results and identify optimal conditions for maximizing performance. This approach effectively leverages knowledge for scenario-specific optimization, offering a sustainable strategy for advanced water treatment materials. Full article