Effect of iron impregnation ratio on the properties and adsorption of KOH activated biochar for removal of tetracycline and heavy metals

Transforming waste into value: Single-step in situ synthesis of magnetic porous carbon composite adsorbents from sugarcane bagasse and iron scrap

The demand for sustainability is driving research into new ways to make use of waste products. Porous adsorbents with magnetic properties are reusable and do not require a significant external energy source. They are well-suited to the task of decontaminating water on a large scale and, if benignly synthesized from waste products, they would meet the demand for sustainability. In this research, an in situ single-step synthesis is developed that generates a magnetic porous carbon composite from iron scrap and sugarcane bagasse, both of which are abundant waste products. This procedure combines the processes of carbonization, magnetization, and activation in one step. Iron scrap serves as both a magnetic precursor and a self-activating agent, so no additional chemical activators are required. The large surface area (505 m2/g) of the synthesized magnetic porous carbon composite adsorbent and its large capacity for tetracycline adsorption (687.6 mg/g) are suitable properties for the treatment of contaminated wastewater. The synthesis process is straightforward, and the use of waste materials to fabricate an adsorbent that retains its performance even after five cycles of adsorption and desorption ensures both cost-effectiveness and sustainability to support the concept of the circular economy.

Assessing the Performance of Different Treatment Methods in Removing Tetracycline from Wastewater: Efficiency and Cost Evaluation

To tackle the pollution of tetracycline (TC) in aqueous environments, a few treatment methods, including ozonation, adsorption, and photocatalytic degradation, were compared using a novel and sustainable granular activated carbon-based zinc oxide nanoparticle (ZnO@GAC) composite. The results demonstrate that the ZnO@GAC composite towards TC exhibited a high removal efficiency of 82.1% in a batch adsorption system. Moreover, the photocatalytic TC degradation study on ZnO@GAC under UV light yields a maximum degradation efficiency of 86.4% with a pseudo-first-order rate constant value of 0.0059 min-1. Ozonation treatment resulted in TC and total organic carbon (TOC) removal reaching a maximum of 95.3% and 79.7% for 4 mg O3/min and 99.6% and 86.6% for 16 mg O3/min after 10 min. Overall, in comparing the adsorption, photocatalysis, and ozonation techniques, in terms of removal efficiency and time, ozonation was found to be more promising for treating TC, while in terms of cost-effectiveness, the adsorption process is preferable. Finally, the application of the developed composite in municipal and hospital wastewater using adsorption, photocatalytic degradation, and ozonation techniques revealed that the TOC removal efficiencies were higher for hospital wastewater than municipal wastewater. Furthermore, the applicability of these techniques in treating hospital wastewater containing pharmaceuticals, antibiotics, fungicides, and antimicrobial pollutants shows an outstanding result after treatment. In conclusion, the technologies studied in this research can significantly improve the efficiency and effectiveness of wastewater treatment applications, providing a sustainable, cost-effective, and eco-friendly solution.

Single-Step Upcycling of Sugarcane Bagasse and Iron Scrap into Magnetic Carbon for High-Performance Adsorbents

The sugar industry produces significant quantities of waste biomass, while other industrial sectors generate iron scrap as waste. This study seeks to make use of these waste products using an in situ approach that integrates carbonization, activation, and magnetization to convert sugarcane waste and iron scrap into a magnetic carbon composite adsorbent. The porosity of the activated carbon was enhanced by the activating agent potassium hydroxide (KOH) and further improved by the addition of iron scrap, which also imparted magnetic properties to the composite. The developed porosity of the composite increased the overall adsorption capacity of the adsorbent. The synthesis conditions were varied to examine the effects on the properties of the adsorbent. The amount of KOH used in the synthesis influenced the performance of the material. The best-performing adsorbent demonstrated strong potential in the treatment of wastewater by exhibiting an adsorption capacity of 1736.93 mg/g for the antibiotic tetracycline. The magnetic properties of the composite adsorbent enable simple separation and recovery, making the adsorbent reusable and lowering operating costs. This study provides a clear framework for the synthesis of waste-derived magnetic carbon composite adsorbents that can offer financial and environmental advantages while remaining effective in industrial contexts.

Mechanism and application of sulfhydryl-modified chitosan derivative for decontamination of Pb(II) and Cd(II) in water bodies

The accumulation of lead and cadmium in water bodies is a serious threat to environmental safety and human health, and they must be removed from wastewater. Based on this this study, a novel sulfhydryl-modified chitosan derivative (SHCS) was prepared by grafting method using chitosan as a substrate for the removal of Pb(II) and Cd(II) from polluted water bodies. The results showed that the SHCS derivative was a mesoporous biosorbent with a specific surface area of 0.0505 cm3/g. The adsorption kinetics of the adsorbent on the pollutants conformed to the pseudo-first-order and pseudo-second-order models (R2 > 0.99). The adsorption isotherms all followed the Langmuir model (Pb(II): R2 = 0.9388, Cd(II): R2 = 0.9592). The maximum adsorption capacities of SHCS were 209.27 mg/g and 64.19 mg/g for Pb(II) and Cd(II), respectively. The free energy of adsorption ΔGθ < 0 indicates that the adsorption process is a spontaneous reaction, in which the adsorption of lead is an adsorptive process (ΔHθ > 0) and the adsorption of cadmium is an exothermic process (ΔHθ < 0). The addition of NaNO3 and cations (K+, Ca2+, and Mg2+) did not affect the adsorption process of Pb(II) and Cd(II). The surface complexation and electrostatic attraction mechanisms controlled the decontamination of Pb(II) and Cd(II) by SHCS in water. Most importantly, the SHCS derivative was effective in removing low concentrations of Pb(II) and Cd(II) from three real wastewater samples as well as a simulated electroplating wastewater.

A facile approach to lignin-based biochar derived from black liquor and the study of its removal to tetracycline from water

The present study focuses on preparing lignin-biochar (L-Bio) from papermaking black liquor-lignin and the study its effectiveness and mechanism in removing tetracycline (TC) from water. Results showed that the yield, BET surface area and pore size of L-Bio were 36.3707-40.2567 %, 392.2232-625.3296 m2•g-1 and 2.244-1261.915 μm, respectively. Adsorption experiment results showed that Bio-800 °C has the maximum adsorption capacity of 243.9067 mg•g-1 and it has the best removal effect on TC under neutral conditions. Adsorption kinetics results showed that the quasi second-order kinetic equation can reflect the process better, which indicates that the adsorption process is mainly chemical adsorption. The possible mechanism was proposed. It mainly includes pore filling, ion exchange, electrostatic interaction, hydrogen bonding, etc. The objectives of the study were to (1) provide a new approach for the resource utilization of lignin and achieve waste to waste conversion; (2) analysis the relationship between the structure and properties of L-Bio and propose its possible mechanism for removing TC from water, which can provide theoretical support for L-Bio's practical application.

Efficient removal of cadmium (II) and arsenic (III) from water by nano-zero-valent iron modified biochar-zeolite composite

For the removal of Cd(II) and As(III) from water, this study synthesized a nano-zero-valent iron-loaded biochar-zeolite composite material (nZVI-BCZo) using a liquid-phase reduction method, with biochar, zeolite, and FeSO₄·7H₂O as precursors. The successful incorporation of nZVI onto the BCZo was verified through Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), and Fourier Transform Infrared Spectroscopy (FTIR) analyses, which revealed significant modifications in the surface oxygen-containing functional groups. Batch adsorption experiments were conducted to evaluate the adsorption characteristics and performance of nZVI-BCZo for Cd(II) and As(III). Under optimal conditions (pH 6.0, temperature of 310 K, and an adsorption time of 360 min), the maximum adsorption capacities for Cd(II) and As(III) were found to be 28.09 mg/g and 186.99 mg/g, respectively. The influence of pH on removal efficiency was more pronounced than that of temperature, with nZVI-BCZo exhibiting a higher affinity for As(III) compared to Cd(II). Kinetic analysis showed that the adsorption process is primarily controlled by chemical adsorption and follows a monolayer adsorption mechanism. Regeneration tests demonstrated that nZVI-BCZo retained good adsorption capacity after three cycles, with adsorption efficiencies of 67.78 % for Cd(II) and 53.04 % for As(III), indicating its potential for repeated use in water treatment applications. The economic evaluation revealed that nZVI-BCZo has a lower processing cost. Therefore, this study established nZVI-BCZo as an efficient, reusable, and cost-effective adsorbent for the treatment of heavy metal-laden water.

Advancements in Biochar Research Methods for Soil Pollution Remediation: Development and Applications

This review primarily focuses on the advancement of biochar research methods and their application in treating soil pollution and agriculture. Biochar, a novel material for soil treatment, shows great potential because of its high specific surface area, abundant functional groups, and well-developed pore structure. This work first introduces the current state and hazards of soil pollution and the limitations of traditional remediation technologies. It then discusses biochar research methods and advancements in biochar preparation techniques. This paper also discussed the application of biochar in the agricultural field. Although biochar has shown many advantages in soil remediation, technical and economic issues in its production remain to be resolved, and long-term environmental impacts and ecological safety need to be further evaluated. Future research should focus on the functional modification and application optimization of biochar to fully realize its potential in soil remediation and sustainable agricultural development.

The key role of magnetic iron-to-biochar mass ratios in the dissipation of oxytetracycline and its resistance genes in soils with and without biodegradable microplastics

There are challenges involved in the synergistic dissipation of antibiotics and antibiotic resistance genes (ARGs) in soil because ARGs are affected by not only the selective pressure of antibiotics but also microbial community succession and co-existing pollutants. Here, magnetic biochars (MBCs) at various magnetic iron-to-biochar mass ratios (3:1, 2:1, 1:1, 1:2, 1:3, 1:5, and 1:7) were synthesized to develop a strategy for the synergistic dissipation of oxytetracycline (OTC) and its resistance gene (tet) in soils with and without polybutylene adipate terephthalate (PBAT) microplastics (MPs). The results showed that MBC12 (1:2) achieved the greatest dissipation efficiencies of OTC in soils without and with PBAT MPs (95.27% and 94.50%, respectively). The reductive degradation of OTC via promoting the electron transfer during conversion between Fe(III) and Fe(II) overwhelmed biodegradation of OTC. MBCs effectively hindered the spread of tet in soil without PBAT MPs, with the efficiencies more than 60%; but they had little influence on its spread in soil with PBAT MPs, excluding MBC15 (1:5). The absolute abundance of tet, regardless of PBAT MPs, just significantly positively correlated with Serratia (the added exogenous tet-host bacterium), indicating that MBCs inhibited the horizontal transfer of tet at the inter-genus level. Down-regulating the degradation/utilization/assimilation metabolic function by MBCs (excluding MBC31, 3:1) contributed to the hindering class 1 integron gene (intI1)-driven tet propagation. After considering efficiency, cost and toxic effects, MBC12 (1:2) was recommended to use for synergistic dissipation of OTC and tet in soils without and with PBAT MPs.

Core-Shell Magnetic Particles: Tailored Synthesis and Applications

Core-shell magnetic particles consisting of magnetic core and functional shells have aroused widespread attention in multidisciplinary fields spanning chemistry, materials science, physics, biomedicine, and bioengineering due to their distinctive magnetic properties, tunable interface features, and elaborately designed compositions. In recent decades, various surface engineering strategies have been developed to endow them desired properties (e.g., surface hydrophilicity, roughness, acidity, target recognition) for efficient applications in catalysis, optical modulation, environmental remediation, biomedicine, etc. Moreover, precise control over the shell structure features like thickness, porosity, crystallinity and compositions including metal oxides, carbon, silica, polymers, and metal-organic frameworks (MOFs) has been developed as the major method to exploit new functional materials. In this review, we highlight the synthesis methods, regulating strategies, interface engineering, and applications of core-shell magnetic particles over the past half-century. The fundamental methodologies for controllable synthesis of core-shell magnetic materials with diverse organic, inorganic, or hybrid compositions, surface morphology, and interface property are thoroughly elucidated and summarized. In addition, the influences of the synthesis conditions on the physicochemical properties (e.g., dispersibility, stability, stimulus-responsiveness, and surface functionality) are also discussed to provide constructive insight and guidelines for designing core-shell magnetic particles in specific applications. The brand-new concept of "core-shell assembly chemistry" holds great application potential in bioimaging, diagnosis, micro/nanorobots, and smart catalysis. Finally, the remaining challenges, future research directions and new applications for the core-shell magnetic particles are predicted and proposed.

Optimization of Magnetic Biochar Preparation Process, Based on Methylene Blue Adsorption

The search for low-cost and effective adsorbents for the removal of organic dyes from contaminated water is urgently needed. The substantial amount of waste mushroom cultivation substrates generated in practical production can serve as an ideal material for the preparation of adsorbents. In this study, we investigated the main control parameters affecting the performance of magnetic mushroom substrate biochar and optimized the process of preparing biochar by using the Plackett-Burman and central composite design methods. Various analytical techniques including SEM, EDX, BET, and VSM were used to characterize the biochar. The results indicate that the carbonization temperature had the most significant impact on the yield and adsorption performance of biochar. Under the conditions of a carbonization temperature of 600 °C, a carbonization retention time of 1 h, and an impregnation ratio of 0.1, the yield and methylene blue adsorption value of magnetic biochar were 42.54% and 2297.04 μg/g, respectively, with a specific surface area of 37.17 m2/g. This biochar effectively removed methylene blue from the solution, demonstrating a high economic efficiency for wastewater treatment and pollution control. Furthermore, the adsorption-desorption cycle studies revealed its excellent stability and reusability. Additionally, based on the response surface methodology, a three-dimensional surface model of the adsorption performance of magnetic biochar under different carbonization conditions was established, providing a theoretical basis for the preparation of magnetic biochar from agricultural wastes.

Machine learning screening of biomass precursors to prepare biomass carbon for organic wastewater purification: A review

In the past decades, the amount of biomass waste has continuously increased in human living environments, and it has attracted more and more attention. Biomass is regarded as the most high-quality and cost-effective precursor material for the preparation carbon of adsorbents and catalysts. The application of biomass carbon has extensively explored. The efficient application of biomass carbon in organic wastewater purification were reviewed. With briefly introducing biomass types, the latest progress of Machine learning in guiding the preparation and application of biomass carbon was emphasized. The key factors in constructing efficient biomass carbon for adsorption and catalytic applications were discussed. Based on the functional groups, rich pore structure and active site of biomass carbon, it exhibits high efficiency in water purification performance in the fields of adsorption and catalysis. In addition, out of a firm belief in the enormous potential of biomass carbon, the remaining challenges and future research directions were discussed.

A thorough investigation into the adsorption behavior of sophorolipid-modified fly ash towards compound pollution of lead and tetracycline

Heavy metal ions and antibiotics were simultaneously detected in authentic water systems. This research, for the first time, employed synthesized sophorolipid-modified fly ash(SFA) to eliminate tetracycline(TC) and lead(Pb2+) from wastewater. Various characterization techniques, including SEM-EDS, FTIR, XPS, BET, and Zeta, were employed to investigate the properties of the SFA. The results showed that the sophorolipid modification significantly improved the fly ash's adsorption capacities for the target pollutants. The static adsorption experiments elucidated the adsorption behaviors of SFA towards TC and Pb2+ in single and binary systems, highlighting the effects of different Environmental factors on the adsorption behavior in both types of systems. In single systems, SFA exhibited a maximum adsorption capacity of 128.96 mg/g for Pb2+ and 55.57 mg/g for TC. The adsorption of Pb2+ and TC followed pseudo-second-order kinetics and Freundlich isotherm models. The adsorption reactions are endothermic and occur spontaneously. SFA demonstrates varying adsorption mechanisms for two different types of pollutants. In the case of Pb2+, the primary mechanisms include ion exchange, electrostatic interaction, cation-π interaction, and complexation, while TC primarily engages in hydrogen bonding, π-π interaction, and complexation. The interaction between Pb2+ and TC has been shown to improve adsorption efficiency at low concentrations. Additionally, adsorption-desorption experiments confirm the reliable cycling performance of modified fly ash, highlighting its potential as a cost-effective and efficient adsorbent for antibiotics and heavy metals.

Decoration of dandelion-like manganese-doped iron oxide microflowers on plasma-treated biochar for alleviation of heavy metal pollution in water

Carbon-based biowaste incorporated with inorganic oxides as a composite is an enticing option to mitigate heavy metal pollution in water resources due to its more economical and efficient performance. With this in mind, we constructed manganese-doped iron oxide microflowers resembling the dandelion-like structure on the surface of cold plasma-treated carbonized rice husk (MnFe2O3/PCRH). The prepared composite exhibited 45% and 19% higher removal rates for Cu2+ and Cd2+, respectively than the pristine CRH. The MnFe2O3/PCRH composite was characterized using XRD, FTIR, FESEM, EDX, HR-TEM, XPS, BET, TGA, and zeta potential, while the adsorption capacities were investigated as a function of pH, time, and initial concentration in batch trials. As for the kinetics, the pseudo-second-order was the rate-limiting over the pseudo-first-order and Elovich model, demonstrating that the chemisorption process governed the adsorption of Cu2+ and Cd2+. Additionally, the maximum adsorption capacities of the MnFe2O3/PCRH were found to be 122.8 and 102.5 mg/g for Cu2+ and Cd2+, respectively. Based on thorough examinations by FESEM-EDS, FTIR, and XPS, the possible mechanisms for the adsorption can be ascribed to surface complexation by oxygen-containing groups, a dissolution-precipitation of the ions with -OH groups, electrostatic attraction between metal ions and the adsorbent's partially charged surface, coordination of Cu2+ and Cd2+ with π electrons by aromatic/graphitic carbon in the MnFe2O3/PCRH, and pore filling and diffusion. Lastly, the adsorption efficiencies were maintained at about 70% of its initial adsorption even after five adsorption-desorption cycles, displaying its remarkable stability and reusability.

Sodium hydroxide/magnesium chloride multistage activated sludge biochar: interfacial chemical behavior and Cd(II) adsorption performance

To enhance the adsorption performance of municipal sludge biochar on Cd(II), modified sludge biochar was prepared by sodium hydroxide/magnesium chloride (NaOH/MgCl2) graded activation, and the Cd(II) adsorption performance on sludge biochar (BC), NaOH-activated sludge biochar (NBC) and NaOH/MgCl2 activated sludge biochar (NBC-Mg) was investigated. The results showed that NaOH/MgCl2 graded activation upgraded the surface structure and enhanced the graphitization of sludge biochar. The adsorption experiments indicated that the adsorption kinetic and adsorption isotherm for Cd(II) were in accordance with the pseudo second-order kinetic and Langmuir model. The adsorption capacity of NBC-Mg (143.49 mg/g) for Cd(II) was higher than that of BC (50.40 mg/g) and NBC (85.20 mg/g). The mechanism of Cd(II) adsorption included ion exchange, complexation, cation-π interaction, and mineral precipitation. After five regeneration, the removal efficiency of Cd(II) by NBC-Mg remained above 90%. This work indicated that sludge biochar prepared by multistage activation could be an effective material for Cd-containing wastewater treatment.

Steric and energetic studies on the influence of cellulose on the adsorption effectiveness of Mg trapped hydroxyapatite for enhanced remediation of chlorpyrifos and omethoate pesticides

Magnesium-trapped hydroxyapatite (Mg.HP) was hybridized with cellulose fiber to produce a bio-composite (CLF/HP) with enhanced adsorption affinities for two types of toxic pesticides (chlorpyrifos (CF) and omethoate (OM)). The enhancement influence of the hybridized cellulose on the adsorption performances of Mg.HP was illustrated based on the determined steric and energetic factors. The computed CF and OM adsorption performances of CLF/HP during the saturation phases are 279.8 mg/g and 317.9 mg/g, respectively, which are significantly higher than the determined values using Mg/HP (143.4 mg/g (CF) and 145.3 mg/g (OM)). The steric analysis demonstrates a strong impact of the hybridization process on the reactivity of the surface of the composite. While CLF/HP reflects effective uptake site densities (Nm) of 93.3 mg/g (CF) and 135.3 mg/g (OM), the estimated values for Mg.HP are 51.2 mg/g (CF) and 46.11 mg/g (OM), which explain the reported enhancement in the adsorption performances of the composite. The capacity of each uptake site to be occupied with more than one molecule (n (CF) = 3-3.74 and n (OM) = 2.35-3.54) suggests multimolecular uptake. The energetic factors suggested physical mechanistic processes of spontaneous and exothermic behaviors either during the uptake of CF or OM.

The application of P-modified biochar in wastewater remediation: A state-of-the-art review

Phosphorus modified biochar (P-BC) is an effective adsorbent for wastewater remediation, which has attracted widespread attention due to its low cost, vast source, unique surface structure, and abundant functional groups. However, there is currently no comprehensive analysis and review of P-BC in wastewater remediation. In this study, a detailed introduction is given to the synthesis method of P-BC, as well as the effects of pyrolysis temperature and residence time on physical and chemical properties and adsorption performance of the material. Meanwhile, a comprehensive investigation and evaluation were conducted on the different biomass types and phosphorus sources used to synthesize P-BC. This article also systematically compared the adsorption efficiency differences between P-BC and raw biochar, and summarized the adsorption mechanism of P-BC in removing pollutants from wastewater. In addition, the effects of P-BC composite with other materials (element co-doping, polysaccharide stabilizers, microbial loading, etc.) on physical and chemical properties and pollutant adsorption capacity of the materials were investigated. Some emerging applications of P-BC were also introduced, including supercapacitors, CO2 adsorbents, carbon sequestration, soil heavy metal remediation, and soil fertility improvement. Finally, some valuable suggestions and prospects were proposed for the future research direction of P-BC to achieve the goal of multiple utilization.

Constructing N,S co-doped network biochar confined CoFe2O4 magnetic nanoparticles adsorbent: Insights into the synergistic and competitive adsorption of Pb2+ and ciprofloxacin

To solve the problem of biochar lack of adsorption sites for heavy metal ions and the difficulty of recycling, CoFe2O4 magnetic nanoparticles confined in nitrogen, sulfur co-doped 3D network biochar matrix (C-CoFe2O4/N,S-BC) was designed and fabricated successfully. The obtained C-CoFe2O4/N,S-BC displays remarkable adsorption performance for both Pb2+ and ciprofloxacin (CIP) removal at the single or binary system due to the role of N,S as metal ion anchoring compared to the N,S-free sample (CoFe2O4/BC). N,S co-doped BC not only participates in adsorption reaction but also effectively inhibites the agglomeration of CoFe2O4 nanoparticles and increases the active sites as a carrier at the same time. In the single system, CoFe2O4/N,S-BC demonstrates a fast adsorption rate (equilibrium time: 30 min) and high adsorption capacity (224.77 mg g-1 for Pb2+, 400.11 mg g-1 for CIP) towards Pb2+ and CIP. The adsorption process is befitted pseudo-second-order model, and the equilibrium data are in great pertinence with Langmuir model. In the binary system, the maximum adsorption capacity of CoFe2O4/N,S-BC for Pb2+ and CIP is 244.80 mg g-1 (CIP: 10.00 mg L-1) and 418.42 mg g-1 (Pb2+: 10.00 mg L-1), respectively. The adsorption mechanism is discussed based on the experimental results. Moreover, C-CoFe2O4/N,S-BC shows good practical water treatment capacity, anti-interference ability and stable reusability (the removal efficiency＞80% after eight cycles). The rapid, multifunctional, reusable, and easily separable adsorption properties make C-CoFe2O4/N,S-BC promising for efficient environmental remediation. This study also offers a viable method for the construction of adsorption material for complex wastewater treatment.

Rapid and efficient removal of multiple heavy metals from diverse types of water using magnetic biochars derived from antibiotic fermentation residue

Pyrolysis is a promising method to treat antibiotic fermentation residue (AFR), a hazardous waste in China, with the benefits of detoxification and resource recycling. However, the application of the AFR-derived biochar has been limited yet, restricting the use of pyrolysis to treat AFR. Herein, for the first time, we reported the use of magnetic biochars derived from vancomycin fermentation residue to rapidly and efficiently co-adsorb multiple heavy metals from diverse types of water with complex matrices. The biochar prepared at 700 °C (labeled as VBC700) exhibited high affinity and selectivity for multiple heavy metals, especially for Ag(I), Hg(II), Pb(II), and Cu(II). The kinetics for Ag(I), Hg(II), and Pb(II) were ultrafast with an equilibrium time of only 5 min, while those for Cu(II) were relatively slower. The maximum adsorption capacity calculated from the Langmuir model for Ag(I), Hg(II), Pb(II), and Cu(II) reached 177.4, 105.9, 387.1, 124.5 mg/g, respectively, which were superior to much previously reported adsorbents. Impressively, Na(I), K(I), Ca(II), Mg(II), and salinity did not affect the capture of these heavy metals, and thus >99% of Ag(I), Pb(II), and Cu(II) were concurrently removed from complex water matrices including seawater, which has rarely been reported before. Furthermore, VBC700 remained high adsorption performance at pH ≥ 3. The adsorption mechanisms included ion exchange, precipitation, and inner-sphere complexation. Overall, the results demonstrate that VBC700 would be an excellent adsorbent to co-capture multiple heavy metals from diverse types of water, highlighting the feasibility of using pyrolysis to achieve a win-win goal for AFR management and heavy metal pollution control.

Utilizing adsorption of wood and its derivatives as an emerging strategy for the treatment of heavy metal-contaminated wastewater

The rapid development of the industrial sector has resulted in tremendous economic growth. However, this growth has also presented environmental challenges, specifically due to the substantial sewage generated and its contribution to the early warning of global water resource depletion. Large concentrations of poisonous heavy metals, including cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), and nickel (Ni), are found in industrial effluent. Therefore, various studies are currently underway to provide effective solutions to alleviate heavy metal ion pollution in sewage. One emerging strategy for sewage pollution remediation is adsorption using wood and its derivatives. This approach is gaining popularity due to the porous structure, excellent mechanical properties, and easy chemical modification of wood. Recent studies have focused on removing heavy metal ions from sewage, summarising and analysing different technical principles, affecting factors, and mainstream chemical modification methods on wood. Furthermore, this work provides insight into potential future development direction for enhanced adsorption of heavy metal ions using wood and its derivatives in wastewater treatment. Overall, this review aims to raise awareness of environmental pollution caused by heavy metals in sewage and promote green environmental protection, low-carbon energy-saving, and sustainable solutions for sewage heavy metal treatment.

Recent advances in the synthesis and application of magnetic biochar for wastewater treatment

Magnetic biochar (MBC) is a novel bio-carbon material with both desired properties as adsorbent and magnetic characteristics. This review provides an up-to-date summary and discussion on the latest development of MBC, which covers the progress on its synthesis, application, and techno-economic analysis. The review indicates that the direct hydrothermal synthesis has been catching more research attention to produce MBC due to its mild reaction conditions. Instead of the Fe-loaded MBC, there is a trend of using Mn for the magnetization. For the MBC application, how to improve its adsorption performance for water decontamination, ideally to match that of the biochar (BC) or activated carbon, is important. In addition, more studies on the environmental impacts of MBC and life-cycle assessment decoding the process optimization options are necessary. This review will provide valuable references for the development of MBC and MBC-based materials for wastewater treatment.

Mechanochemical synthesis of calcium-biochar for decontamination of arsenic-containing acid mine drainage

Ca-biochar is an efficient material for As(III)-containing acid mine drainage (AMD) decontamination, while it is challenging to fabricate Ca-biochar with oyster shell waste as the Ca source due to its complex structure. Herein, a mechanochemical method was proposed to activate oyster shell waste and wood waste for Ca-biochar design and production, and its efficacy and relevant mechanisms for AMD detoxification were evaluated. The smaller size Ca-biochar produced by the medium-speed ball milling showed a higher As(III) removal (74.0 %) compared to high-speed ball milling (60.9 %), attributed to the formation of finer Ca(OH)2 while avoiding particle aggregation, which could release more Ca (89.0 mg/g) and alkalinity for the co-precipitation of As. Meanwhile, wood-based biochar substrate served as a platform for co-precipitation, and its surface functionality supported the oxidative immobilization of As. This study presents a promising route for upcycling food and wood waste to produce Ca-biochar for AMD decontamination.

Efficient and effective immobilization of tetracycline and copper from wastewater by zero-valent iron fabricated hydrochar derived from walnut peel

Antibiotics and heavy metals often coexist as non-point-source contaminants in wastewater and their quite contrary physiochemical properties make their co-removal processes challenging. In this work, a bifunctional zero-valent iron-modified hydrochar derived from walnut peel (MWPHC) was synthesized, which was then applied for the simultaneous removal of tetracycline (TC) and Cu(II) from wastewater. Based on the characterizations, Fe0 species were successfully distributed on the surface of the walnut peel substrates. The TC and Cu(II) could be synergistically immobilized, and bridging effects were observed between them, and MWPHC exhibited excellent ability on the simultaneous removal of TC (qmax = 433.59 mg/g) and Cu(II) (qmax = 586.25 mg/g). Furthermore, the engineering feasibility of the MWPHC was evaluated using column and regeneration experiments. These results shed light on the tailored MWPHC as an environmental functional material for pollution control of co-existing antibiotic and heavy metal contaminants in agro-industrial wastewater.

Life Cycle Assessment of Raw and Fe-Modified Biochars: Contributing to Circular Economy

Biochar is a carbonaceous material, which can be decorated with metals, that has been garnering attention to be used in the treatment of water due to its contribution to waste management and circular economy. This study presents the life cycle assessment (LCA) regarding the generation of Pinus patula raw biochar and its modification with iron (Fe-modified biochar). SimaPro 9.3.0.3 software was used to simulate the environmental impacts of both carbonaceous materials. The potential environmental effects obtained from the production of Pinus patula raw biochar were mainly ascribed to the source of energy utilized during this process. The potential impacts demonstrated that the generation of gases and polycyclic aromatic hydrocarbons are the main concern. In the case of Fe-modified biochar, the potential environmental effects differed only in the stage of the biomass modification with the metal. These effects are associated with the extraction of Fe and the generation of wastewater. These findings provide an insight into the environmental effects linked to the production of raw and Fe-modified biochar. However, further LCA research should be performed concerning other materials and compounds than can be generated during the biomass thermochemical conversion.

Hydrothermal Pretreatment of KOH for the Preparation of PAC and Its Adsorption on TC

The environment has been heavily contaminated with tetracycline (TC) due to its excessive use; however, activated carbon possessing well-developed pores can effectively adsorb TC. This study synthesized pinecone-derived activated carbon (PAC) with high specific surface area (1744.659 cm²/g, 1688.427 cm²/g) and high adsorption properties (840.62 mg/g, 827.33 mg/g) via hydrothermal pretreatment methods utilizing pinecones as precursors. The results showed that PAC treated with 6% KOH solution had excellent adsorption properties. It is found that the adsorption process accords with the PSO model, and a large amount of C=C in PAC provides the carrier for π-πEDA interaction. The results of characterization and the isothermal model show that TC plays a key role in the adsorption process of PAC. It is concluded that the adsorption process of TC on PAC prepared by hydrothermal pretreatment is mainly pore filling and π-πEDA interaction, which makes it a promising adsorbent for TC adsorption.