Magnetic Biochar Research Articles

β-Cyclodextrin modified magnetic luffa biochar for efficient removal of Ni(II) from wastewater

β-Cyclodextrin modified magnetic luffa biochar for efficient removal of Ni(II) from wastewater

Enhanced Adsorption of Uranium (VI) from Aqueous Solutions by Hydrogen Peroxide-Modified Magnetic Biochar: Performance Evaluation and Mechanistic Study

Enhanced Adsorption of Uranium (VI) from Aqueous Solutions by Hydrogen Peroxide-Modified Magnetic Biochar: Performance Evaluation and Mechanistic Study

Efficient activation of N and S co‐doped magnetic biochar for peroxomonosulfate degradation of tetracycline

AbstractN‐S co‐doped magnetic biochar (NSMBC) was synthesized by a two‐step pyrolysis technique and used for the degradation of tetracycline (TC) by activated persulfate (peroxomonosulfate [PMS]). Batch experiments showed that the pyrolysis temperature and doping ratio affected the catalytic performance of NSMBC. The degradation rate of TC in the NSMBC/PMS system prepared at 350°C with a doping ratio of 33% was up to 94.50%, and the system exhibited strong pH adaptability and resistance to environmental interference. The results of free radical burst and electron paramagnetic resonance (EPR) spectroscopy experiments indicated the free radical pathway (SO4•−) for TC degradation. In addition, NSMBC has good stability and excellent magnetic properties favorable for separation and recovery. This study not only provides a new idea for the synthesis of efficient and stable catalysts but also provides a green pathway for the resourceization of pomelo peel waste.

Removal of hexavalent chromium using activated and magnetic Ziziphus Jujube seed biochar — a column study

ABSTRACT In this study, activated and magnetic biochar prepared from Ziziphus Jujube Seeds (ZJS) is used to remove Hexavalent Chromium (Cr(VI)) using Fixed Bed Column Experiment. Physicochemical characteristics of the activated and magnetic biochar such as functional groups, surface area, morphological study, and magnetic properties were analyzed. The column experiment was carried out for varying bed heights (2, 4, 6, 8, 10 cm), flow rates (20, 30 ml/min), and initial chromium concentrations (40, 60, 80 ppm) to determine adsorption performance of the studied biochar. The characteristic study found that magnetic biochar (MB) has good magnetic properties and crystallinity nature with essential functional groups such as C-O, FeO. The study found that Magnetic Biochar (MB) effectively removed 99% of hexavalent chromium through column adsorption under optimal conditions, including bed height of 6 cm, 60ppm Chromium concentration, and flow rate of 20 ml/min. Kinetic model study showed that Magnetic Biochar (MB) showed very good agreement with Adam Bohart Model, with R2 of 0.97, which is best fit model than other model studies whereas the other model showed a lesser R2 value. The study reveals that magnetic biochar from Ziziphus Jujube Seed is optimal adsorbent for removal of Cr(VI) through column adsorption experiment.

Enhanced microplastics removal from sewage effluents via CTAB-modified magnetic biochar: Efficacy and environmental impact

Sewage treatment plants (STPs) are identified as a significant pathway of microplastics (MPs) re-entry into the environment through effluent discharge, thereby emphasizing the need for reliable and efficient treatment methods. This study investigated MPs removal from sewage effluents using cetyl trimethyl ammonium bromide (CTAB)-modified magnetic biochar (RH-MBC-CTAB) as an adsorbent. Biochars from different biomass were synthesized, surface modified, characterized, and compared for their MPs removal efficacy from aqueous matrices. Batch adsorption studies were initially conducted on synthetic water with 1 μm sized polystyrene (PS) MPs using different MP concentrations (1–10 mg/L) and varying adsorbent dosages (1–10 mg/50 mL) to assess the effect of different process parameters, viz. pH (2–10), humic acid (6–25 mg/L), and competitive ions (0.01–0.2 M). The maximum MPs removal (98%) was achieved at the favorable conditions: initial MPs concentration: 10 mg/L, RH-MBC-CTAB dose: 7 mg/50 mL, pH 4, mixing speed: 180 rpm, and contact time: 3 min. Electrostatic attraction and hydrogen bonding were likely to remove MPs while the MPs adsorption was best fitted by the pseudo-second-order kinetics model (R2 = 0.91) and Langmuir isotherm model (R2 = 0.94) with the maximum adsorption capacity of 247.52 mg/g. Further, the application of RH-MBC-CTAB on the real-time sewage effluents from sequencing batch reactor (SBR) and moving bed biofilm reactor (MBBR)-based STPs spiked with MPs showed up to 96% MPs removal. The reusability results revealed that developed RH-MBC-CTAB could maintain good stability for up to three reusability cycles, therefore offering extensive potential for the removal of MPs from sewage effluents.

Green synthesis of magnetic graphene-like biochar with oxygen vacancies for efficient adsorption and degradation of emerging antivirals from water

In this research, a magnetic biochar derived from the Vicia ervilia plant and possessing graphene-like properties (BC-G/Fe3O4) was used along with the activator persulfate for the adsorption and degradation of emerging pollutants such as Remdesivir and Favipiravir. The morphology, specific surface area, graphitization degree, and surface chemistry properties of the composite were determined using various techniques. The results showed that the synthesized BC-G/Fe3O4 had a high SSA (506.556 m2/g), indicating its suitable adsorption properties for the removal of antiviral drugs. The impact of various factors on the adsorption-oxidation process, including pH, catalyst dosage, oxidant concentration, antiviral concentration, and temperature, was examined and optimized through the utilization of response surface methodology and central composite design. The highest removal percentage of Remdesivir (93 %) and Favipiravir (98 %) was achieved at an initial antiviral concentration of 125 mg/L, catalyst dosage of 7 mg for Remdesivir and 5 mg for Favipiravir, contact time of 120 min, and pH of 7. Through the implementation of radical scavenging experiments, a thorough understanding of the mechanisms involved in PMS activation and the degradation of Favipiravir and Remdesivir was attained. The findings of this study indicate that the BC-G/Fe3O4 catalyst possesses excellent biocompatibility, adsorption-degradation capabilities, and reusability. Consequently, it can be successfully employed to eliminate emerging pollutants from aquatic environments.

Nitrogen-sulfur co-doped magnetic biochar efficiently activates hydrogen peroxide for the degradation of sulfamethazine

To address the issue of low activation efficiency of magnetic biochar (MBC), this research synthesized nitrogen-sulfur co-doped magnetic biochar (NSMBC) using sawdust as the primary material via impregnation pyrolysis method. NSMBC effectively activated hydrogen peroxide and exhibited significant oxidation and degradation capabilities towards sulfamethazine (SMT), a sulfonamide antibiotic. The results demonstrate that under optimal conditions, NSMBC achieves a removal rate of 99.7 % for SMT within 2 h, with a reaction rate constant 8.5 times higher than that of MBC/H2O2 system. Mechanistic investigations unveiled that hydroxyl radicals (·OH) were the primary agents responsible for the degradation of sulfamethazine within the NSMBC/H2O2 system, contributing to 83.26 % of the removal efficiency. Furthermore, the nitrogen-sulfur co-doping facilitates the increase in Fe(II) content, augmentes the defect density, and enriches the number of oxygen-containing functional groups, thereby enhancing the utilization efficiency of H2O2 and consequently boosting the activation performance of magnetic biochar. Notably, the NSMBC/H2O2 system demonstrated excellent degradation efficiency towards various antibiotics, exhibiting potent broad-spectrum activity. Minimal influence on the NSMBC/H2O2 system was observed under conditions of coexisting natural organic matter and anions, rendering it suitable for practical application in the treatment of aquaculture wastewater and providing a novel technology for the application of magnetic biochar in actual water pollution control scenarios.

Nectarine core-derived magnetite biochar for ultrasound-assisted preconcentration of polycyclic aromatic hydrocarbons (PAHs) in tomato paste: A cost-effective and sustainable approach

A novel ultrasound-assisted magnetic solid-phase extraction coupled with gas chromatography–mass spectrometry (US-MSPE-GC/MS) was developed to detect trace amounts of polycyclic aromatic hydrocarbons (PAHs) in tomato paste, using a magnetic biochar adsorbent derived from nectarine cores. The highest extraction recovery was attained under 10 mg adsorbent mass, 30 min extraction time, 9 % (w/v) sodium chloride, and elution with 200 μL of dichloromethane. Under optimum conditions, the method demonstrated excellent linearity (R2 > 0.992) across a wide concentration range (0.01-100 ng g−1) with high sensitivity (LODs: 0.028-0.053 ng g−1, LOQs: 0.094-0.176 ng g−1) and good repeatability (RSDs <5.96 %). The application of the US-MSPE-GC/MS method was tested on four brands of real tomato paste and no PAHs were detected in unspiked samples, indicating no background contamination. This method showed high relative recoveries 88.03-98.52 %) and good reproducibility (<9.19 %.) at two concentration levels, confirming its effectiveness for PAH analysis in real samples.

The potential of palm frond-based magnetic biochar for peat water treatment

Abstract Riau Province has the largest palm plantation in Indonesia. The amount of palm plantation waste is quite large, so it needs to be managed so as not to pollute the environment. Palm plantation waste has a high lignocellulose content, so it has the potential to be used as a raw material for making biochar. Biochar has high effectiveness in removing organic substances from water. Despite its high adsorption capacity, biochar is difficult to separate from water due to its very small particle size. To solve this problem, magnetic biochar can be used. Magnetic biochar is the result of the magnetization of biochar with the addition of chemicals containing metal ions and pyrolyzed with little or no oxygen. The synthesis of magnetic biochar is strongly influenced by the impregnation ratio and pyrolysis temperature. This study aims to synthesize magnetic biochar from palm fronds by varying the impregnation ratio, pyrolysis temperature, and particle size and testing its ability to adsorb color and natural organic matter in peat water. Magnetic biochar was synthesized by FeCl3 impregnation ratios of 0.4, 0.5, 0.6, and 0.7, pyrolysis temperatures 450°C; 500°C with N2 gas flow, and particle size escaped sieves of 0.595 and 0.177 mm. The adsorption test results showed synthetic magnetic biochar with an impregnation ratio of 0.7, pyrolysis temperature of 500°C and particle size of 0.177 mm had the highest efficiency in removing colors and natural organic substances of 71.8% and 78.6%, respectively. From the proximate test, the magnetic biochar moisture content was 0.5%, the ash content was 3.37%, and the volatile content was 12.02%. This result has met the quality of technical activated carbon in SNI 06-3730-1995. The methylene blue absorption was 12.4 mg/g. This value is below the requirements of SNI 06-3730-1995. The results showed that magnetic biochar synthesized from palm frond has the potential to be used as an adsorbent in peat water treatment.

Unraveling how hydrogen-bonding networks affect the capture of amphetamine-type stimulants by polymerized deep eutectic solvent modified magnetic biochar: Coupling quantum chemical calculations with experiment

The abuse of amphetamine-type stimulants (ATSs) has caused irreversible harm to public safety and ecosystems. A novel polymerized deep eutectic solvent modified magnetic pomelo peel biochar (PMBC) was prepared, and the differences in adsorption of four abused amphetamine-type stimulants (ATSs: AMP, MAMP, MDA and MDMA) were due to varying hydrogen bonds quantities and strengths. PMBC showed excellent chemical reactivity to MDMA, with a maximum adsorption capacity of 926.13 μg g−1, which was 3.25, 2.52 and 1.15 times higher than that of AMP, MAMP and MDA, respectively. Modern spectral analysis showed that there were a series of active centers (-COOH, -NH2 and -OH) on the PMBC, which could form hydrogen bond networks with the nitrogen and oxygen functional groups of ATSs. In various chemical environments: pH level (4–11), inorganic ion and organic matter (humic acid), PMBC maintained high activity towards four ATSs. Additionally, the quantum chemical calculations revealed that the methylenedioxy bridge of ATSs can increase the active sites, and the -NH- and -NH2 groups had different hydrogen bond formation capabilities, which together resulted in the adsorption order of PMBC on the four ATSs: MDMA > MDA > MAMP > AMP. Moreover, the hydrogen-bonding binding energies of several common hydrogen-bonding types were compared, including O-H····O, N-H····O/O-H····N and N-H···N. This study laid an empirical and theoretical foundation for the efficient capture of ATSs in water and contributed to the innovative design of materials.

Magnetic biochar conjugated quaternary ammonium salt-constructed hemoperfusion adsorbent for viral removal with rapid and high-performance

Due to variations in virus structures and their high variability, treating viral infections remains challenging. Moreover, developing vaccines and medications for newly emerged viruses demands a significant time investment. Efficient methods are required to prevent dangerous infections caused by unknown pathogens. Hemoperfusion, with its low cost, can effectively remove toxins from the blood quickly, thus achieving therapeutic effects. The core of the hemoperfusion technology lies in the adsorbent. Therefore, the development of a viral adsorbent aiming to combat viruses through hemoperfusion was envisioned, following general principles to effectively save lives and buy time for the research and development of vaccines and medications. Towards this goal, a facile, green, and low-priced magnetic biochar/quaternary ammonium salt (Fe3O4/C-2) was constructed using the hydrothermal carbonization (HTC) method. HIV lentiviruses were used as a model pathogen to quantify the adsorption capacity and elucidate the adsorption mechanism. Benefiting from a macroporous structure and electrostatic interactions, fabricated Fe3O4/C-2 has a high adsorption capacity (965 ng g−1) and strong suppression of infectious activity (99.99%). Moreover, a low hemolysis ratio (<2%), high cell viability (>100%), high activated partial thromboplastin time (APTT) (67.29 s), and low protein adsorption (<5%) indicate outstanding biocompatibility and good anticoagulant activity. Therefore, Fe3O4/C-2 is expected to serve as a simple and efficient pathogen sorbent for viral diseases treatment.

Analyzing the Impact of Annealed Steel Sludge Doses on the Physicochemical Properties of Biochar Obtained from Waste Date Palm Frond

Large quantities of date palm frond waste generated from the pruning process are accumulated or burned in burn barrels, harming the environment and having very little economic value. However, because of the lack of data revealing the characteristic magnetic properties of biochar derived from date palm fronds, further research on low-cost and sustainable strategies could offer a new composite material and serve to extend the way for novel applications. In this study, we prepared biochar derived from palm fronds via pyrolysis under a limited-oxygen atmosphere at a lower temperature of 300 °C for 2 h. We introduced a facile strategy for the production of magnetic biochar with various doses of annealed steel sludge material via ball milling. Various amounts of annealed steel sludge material (5%, 15%, and 25% w) were added to date palm frond biochar, and the obtained product was fabricated by ball milling. The physicochemical characteristics of the magnetic biochar composite were subsequently analyzed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) spectroscopy, and UV-vis spectroscopy. Our findings showed that the ball milling method is a successful step for producing date palm fronds with magnetic biochar material possessing rough and packed pores, as shown by SEM. XRD patterns assumed the existence of magnetic phases of iron oxide (magnetite (Fe3O4), hematite (α-Fe2O3), and maghemite (γ-Fe2O3) at different generated peaks. FTIR outputs exhibited the abundant presence of various oxygen-containing functional groups (- COOH and -OH) on the surface of magnetic biochar material, which help to create chemically reactive sites to adsorb potential surrounding species. The UV spectra showed a noticeable enhancement of the optical properties of the magnetic biochar with an increase in the sludge dose for light absorption in the visible region from wavelengths of 400 – 700 nm . This result signifies the synthetic optimization and potential application of magnetic biochar materials for composites that could be employed in targeted uses including soil amendment, water remediation and energy applications.

Polyvinyl chloride nanoplastics transport inhibited in natural sandy soil by iron-modified biochar.

The small particle size of nanoplastics allows them to migrate through soil and make them highly bioavailable, posing a potential threat to groundwater. Measures are urgently needed to reduce the migration of nanoplastics in soil. However, there is limited research available on this topic. In this study, two types of iron-modified biochar (magnetic corncob biochar (MCCBC) and magnetic walnut shell biochar (MWSBC)) were selected and their effects on the transport of polyvinyl chloride nanoplastics (PVC-NPs) in natural sandy soil columns under different ionic types and strengths were investigated. The results show that the transport of PVC-NPs in single sandy soil columns was rapid and efficient, with the estimated breakthrough rate of 85.10%. However, the presence of MCCBC and MWSBC (0.5%, w/w) significantly inhibited the transport of PVC-NPs in sandy soil columns (p < 0.05), and MCCBC had a stronger inhibitory effect on the transport of PVC-NPs than MWSBC. This can be attributed to the fact that the adsorption of PVC-NPs on adsorbents followed the order as: MCCBC > MWSBC > sandy soil. The retention of PVC-NPs by MCCBC and MWSBC is determined by ionic type and ionic strength. The presence of coexisting ions enhanced the inhibitory effect of iron-modified biochar on the transport of PVC-NPs, with the following order: Ca2+ > SO2- 4 > Cl- > NO- 3. The inhibitory effect of MCCBC and MWSBC on the transport of PVC-NPs in soil columns increased with increasing ionic strengths. Furthermore, MCCBC and MWSBC inhibited the migration of PVC-NPs in a rainwater-soil system. The mechanisms by which MCCBC and MWSBC affect the transport of PVC-NPs in soil columns were considered to enhancing adsorption and decreasing soil pore volume. The results provide new insights into the management of soil nanoplastic pollution.

PW12/Fe3O4/biochar nanocomposite as an efficient adsorbent for metronidazole removal from aqueous solution: Synthesis and optimization

The growing occurrence of antibiotics in aquatic environments has emerged as a notable environmental issue given their potential detrimental impacts on ecosystems and the well-being of individuals. Therefore, there is a pressing need to develop effective strategies for removing antibiotics from wastewater. Herein, PW12/Fe3O4/biochar nanocomposite as a highly efficient adsorbent was synthesized to remove metronidazole (MNZ) antibiotic from wastewater through a sustainable and environmentally friendly approach. Simple surface modifications, such as chemical and physical modification with acid and base, as well as adding polyoxometalate were employed to enhance the adsorption of MNZ. The physical and chemical characteristics of the adsorbent were extensively analyzed using several techniques as follows, Fourier transform infrared (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) coupled with energy dispersive X-ray (EDX), Brunauer-Emmett-Teller (BET), and transmission electron microscopy (TEM). Experimental results demonstrated a significant increase in the efficacy of MNZ removal when the adsorbent surface was modified with polyoxometalate (H3PW12O40) compared to magnetic biochar (MBC). This improvement favors the pore-filling mechanism, electrostatic, H-bonds, and π-π interactions. To optimize the operating parameters for MNZ removal, response surface methodology (RSM) was employed using Design Expert software, considering the pH of a solution, initial pollutant concentration, adsorbent amount, and contact time. The results revealed that when the conditions were ideal (pH ∼1, initial concentration of MNZ at 5 mg/L, adsorbent amount of 0.6 g/L, and contact time of 60 minutes), the removal efficiency and the adsorption capacity reached 94.28 % and 78.45 mg/g, respectively. The analysis of isotherm and kinetic experiments revealed that the adsorption mechanism followed the Freundlich isotherm and pseudo-second order kinetic models, respectively. Furthermore, the adsorbent demonstrated excellent efficiency and reusability, with a removal efficiency of over 90 % even after four cycles, highlighting its potential and economic viability as an adsorbent for metronidazole removal.

Ferrate (VI) oxidation of sulfamethoxazole enhanced by magnetized sludge-based biochar: Active sites regulation and degradation mechanism analysis

Developing non radical systems for antibiotic degradation is crucial for addressing the inefficiency of conventional radical systems. In this study, novel magnetic-modified sludge biochar (MASBC) was synthesized to significantly enhance the oxidative degradation of sulfamethoxazole (SMX) by ferrate (Fe (VI)). In the Fe (VI)/MASBC system, 90.46% of SMX at a concentration of 10 μM and 49.34% of the total organic carbon (TOC) could be removed under optimal conditions of 100 μM of Fe (VI) and 0.40 g/L of MASBC within 10 min. Furthermore, the Fe (VI)/MASBC system was demonstrated with broad-spectrum removal capability towards sulfonamides in single or mixture. Quenching experiments, EPR analyses, and electrochemical experiments revealed that direct electron transfer (DET) and •O2− were mainly responsible for the removal of SMX, with functional groups (e.g., -OH, C=O) and Fe-O (redox of Fe (III)/Fe (II)) acting as the active sites, while the probe experiments showed that Fe (IV)/Fe (V) made a minor contribution to the degradation of SMX. Benefiting from the DET, the Fe (VI)/MASBC system exhibited a wide pH adaptation range (e.g., from 5.0 to 10.0) and strong anti-interference ability. The N atoms and their neighboring atoms in SMX were the prior degradation sites, with the cleavage of bond and ring opening. The degradation products showed low or non-toxicity according to ECOSAR program assessment. The removal of SMX remained within a reasonable range of 71.33%–90.46% over five consecutive cycles. Also, the Fe (VI)/MASBC system was demonstrated to be effectively applied for successful SMX removal in various water matrices, including ultrapure water, tap water, lake water, Yangtze River water, and wastewater. Therefore, this study offered new insights into the mechanism of Fe (VI) oxidation and would contribute to the efficient treatment of organic pollutants.

Synthesis of eco-friendly bio-based coconut shell magnetic biochar for efficient bisphenol S sequestration in aqueous environment: green technology breakthrough

Water pollution has emerged as a critical global challenge, particularly the contamination of water bodies with persistent organic pollutants such as Bisphenol S (BPS), a known endocrine disruptor. This study presents the synthesis and application of eco-friendly bio-based coconut shell magnetic biochar (CSMB) for efficient sequestration of BPS from aqueous environments. Utilizing pyrolysis and co-precipitation techniques, the magnetic biochar was characterized through various methods including surface chemistry (pHpzc), electron dispersive X-ray analysis (EDX), Brunauer-Emmett-Teller (BET) N2 adsorption-desorption, scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), and Fourier transform infrared spectroscopy (FTIR). SEM revealed a porous structure with a high surface area, while FTIR confirmed the presence of functional groups essential for adsorption. X-ray diffraction (XRD) and VSM successfully incorporated magnetic nanoparticles, enhancing the separation process post-adsorption. The CSMB demonstrated a significant surface area of 373 m2 g−1, outperforming regular coconut shell biochar (CSB), with a BPS adsorption capacity of 43.5 mg/g compared to 26.7 mg/g for CSB. Batch adsorption tests assessed the impact of operational factors such as initial BPS concentration (8–150 ppm), contact time (30–150 min), temperature (298.15, 318.15, and 338.15 K), pH (3–11), and CSMB dosage (0.1–0.9 g). The results indicated optimal adsorption at pH 6 with a maximum capacity of 52.3 mg/g. Kinetic studies revealed that the pseudo-second-order model best described the adsorption process, while the Langmuir isotherm model provided an excellent fit for the adsorption data. The reusability of CSMB was validated over five cycles, with adsorption capacity decreasing slightly from 43.5 mg/g to approximately 41 mg/g, making it a sustainable and effective adsorbent for water treatment.

An economical preparation strategy of magnetic biochar with high specific surface area for efficient removal of methyl orange

Magnetic biochar (MBC) was obtained from pepper straw by impregnation-microwave pyrolysis method. The pyrolysis temperature and FeCl3 impregnation concentration were investigated on the structural properties of MBC and the adsorption of methyl orange (MO) in water. Characterization results showed that pyrolysis temperature and iron species significantly increased the specific surface area of MBC, which could reach the maximum of 2038.61 m2/g, and also provided more active adsorption sites by promoting the generation of graphitized structures and surface polar functional groups. MBC0.2–900 was selected as the adsorbent for MO with the maximum adsorption capacity reached 437.18 mg·g−1, 3.4 times higher than the virgin biochar. The adsorption process was dominated by chemisorption as well as spontaneous and exothermic. The adsorption mechanisms included pore-filling interaction, π-π EDA interaction, electrostatic interaction, hydrogen bonding, and Lewis acid-base electron interaction. In addition, MBC also exhibited excellent separability and reusability as a low-cost adsorbent. This study provided some theoretical foundation and technological support for producing high-performance biochar and developing pollutant removal technology in wastewater.

Efficient removal of Cr6+ by magnetically modified biochar from aqueous solution:Removal mechanism investigation

The magnetic biochar is prepared by one-pot method using waste wooden building formwork as feedstock in the existence of the FeCl3 for Cr6+ removal form wastewater. Characterization analysis indicates that magnetic biochar exists Fe3O4 with specific surface area of the 333.89–496.35 m2/g, contributing to Cr6+ removal. Cr6+ removal process can be well analyzed by the Pseudo-second order and Hill models with adsorption capacity of 30.41 mg/g. The adsorption process analysis indicates that Cr6+ removal mechanism includes surface complexation, electrostatic attraction, reduction and pore filling. The influence of Fe2+ on Cr6+ removal is analyzed, indicating Fe2+ participation into Cr6+ removal by reduction. The magnetic biochar has excellent reusability after three cycles. The Cr6+ removal process is also investigated using column adsorption experiment, indicating that magnetic biochar has column adsorption amount of the 56.64 mg/g. The economic feasibility of the magnetic biochar is investigated and calculated with the production cost of $2.48/1kg. The waste wooden building formwork is converted into the efficient magnetic biochar for Cr6+ removal from wastewater.

Cobalt-Modified Biochar from Rape Straw as Persulfate Activator for Degradation of Antibiotic Metronidazole

A cobalt-loaded magnetic biochar (Co-MBC) catalyst was synthesized to enhance the removal of metronidazole (MNZ). Study explored the performance and mechanism of MNZ degradation by Co-MBC activated permonosulfate (PMS). Results showed that cobalt oxides were effectively deposited onto the biochar surface, new oxygen functional groups were added to the modified biochar, and the presence of the metallic element Co enhanced the efficiency of PMS activation in the composite. More than 90% of MNZ was removed after 60 min with a catalyst dosage of 0.2 g/L and a PS concentration of 1 mM. After four reuses, Co-MBC still showed excellent catalytic performance to degrade over 75% of MNZ. The reaction system performed well even in the presence of inorganic anions and organic macromolecules. However, the degradation rate was inhibited under alkaline conditions. The quenching experiment indicated that •SO4−, •OH, 1O2, and •O2− synergistically degraded MNZ, and that•SO4− played a dominant role. LC-MS was applied to assess intermediate degradation products, in which CO2, H2O, and NO3− were the final degradation products, and potential degradation pathways were suggested. In conclusion, Co-MBC was an efficient and stable catalytic material, and its ability to activate PMS was improved to effectively degrade antibiotics, a typical priority pollutant.

Magnetic biochar enhanced microbial electrolysis cell with anaerobic digestion for complex organic matter degradation in landfill leachate

Combining microbial electrolytic cells with anaerobic digestion (MEC-AD) was considered as an important method for enhancing complex organic matter degradation. However, the magnetic biochar (MBC) addition would be an effective approach for enhancing biodegradation in MEC-AD. By designing orthogonal experiments, the optimal parameters of MBC-enhanced MEC-AD system for landfill leachate treatment were determined. The results indicated that the optimal conditions were identified as HRT of 72 h, electrode spacing of 2.5 cm, and applied voltage of 0.8 V. Under these conditions, the COD removal efficiency reached a maximum of 54.7 %. Additionally, the UV–vis, 3D-EEM, and GC–MS indicated the macromolecules 13-Docosenamide (Z), Bis(2-ethylhexyl) benzene-1,4-dicarboxylate and bis(2-ethylhexyl) phthalate were degraded. 13-Docosenamide (Z) was almost completely removed under the conditions of 0.8 V applied voltage, 2.5 cm electrode spacing and 24 h HRT, with a removal efficiency of 99.91 %. Significant differences were observed in the microbial core genera among the MEC-AD systems. The core genera in the anodic and cathodic biofilms were primarily fermentative and electroactive bacteria, including Soehngenia (2.2 % - 32.1 %, 3.2 % - 26.4 %) and Desulfomicrobium (1.1 % - 10.2 %, 2.0 % - 29.3 %). Fermentative bacteria, norank_f__Bacteroidetes_vadinHA17, established cooperative relationships with electroactive bacteria Acinetobacter. The enrichment of electrochemically active bacteria optimized microbial interactions, thereby synergistically enhancing the biotransformation of complex organic matter in landfill leachate.