Biochar Research Articles

Feasibility study of denitrification catalyst prepared from badam shell biochar

Badam shells are a common type of fruit shell waste, yet there is scarce research on using them to produce biochar and applying it in the field of denitrification. This study aimed to utilize badam shells as raw material to produce biochar and evaluate the feasibility of badam shell biochar (BC) as a carrier for denitrification catalysts. Badam shells were carbonized under a N2 atmosphere at 600 °C for 120 min to prepare badam shell biochar. After treating BC with acid (H3PO4 or HNO3), Mn or Fe is loaded to obtain denitrification catalysts (BC-HN-Mn, BC-HN-Fe, BC-HP-Mn, and BC-HP-Fe). These catalysts exhibit high denitrification activity within the temperature range of 100–300 °C (>80 %, and exceeding 90 % at 250–300 °C). Moreover, they are characterized by a large number of acidic sites and adsorbed oxygen species distributed on their surface, demonstrating excellent resistance to sulfur dioxide poisoning and maintaining high denitrification activity under low oxygen conditions. This study provides a reference for the application of badam shell in Selective catalytic reduction (SCR) technology.

Effects of Carbon-Based Modified Materials on Soil Water and Fertilizer Retention and Pollution Control in Rice Root Zone

To seek an appropriate stabilization and remediation scheme for cadmium (Cd) and arsenic (As) pollution in farmland, a typical polluted soil sample was selected from a mining area in Southwest China for a soil box simulation experiment. Biochar (BC), a modified type of biochar made from rice husk with different mass ratios of ferric chloride and rice husk, was set up (the mass ratio of ferric chloride to rice husk was 1:9 (defined as LFB), 3:7 (defined as MFB), and 5:5 (defined as HFB) and the control group (BL)) to explore the effects of soil water and fertilizer loss, the bioavailability of Cd and As, and the bioenrichment effects of plant organs during the growth period of rice. The results showed that the porous structure and large specific surface area of biochar effectively regulated soil aggregate composition and improved soil water holding capacity. Compared to the BL treatment, soil water storage under the four carbon-based material control modes increased from 8.98% to 14.52%. Biochar has a strong ion exchangeability and can absorb soil ammonium, nitrogen, and phosphoric acid groups, effectively inhibiting the loss of soil fertilizer. Biochar improves soil pH and reduces the specific gravity of exchangeable Cd. In addition, the oxygen-containing functional groups in biochar can react with metals in a complex manner. The diethylenetriaminepentaacetic acid (DTPA) concentrations of Cd in soils treated with BC, LFB, MFB, and HFB were 79.69%, 72.92%, 64.58%, and 69.27% lower, respectively, than those treated with BL. In contrast, the Fe3+ in ferric chloride combines with As after hydrolysis and oxidation to form amorphous ferric arsenate precipitates or insoluble secondary minerals. Therefore, the curing effect of the modified biochar on As was more potent than that of applied biochar alone. In conclusion, ferric chloride-modified biochar can effectively inhibit the effects of water and fertilizer loss in farmland soil and realize cross-medium long-term inhibition and control of combined Cd and As pollution.

Enhancing maize growth and resilience to environmental stress with biochar, gibberellic acid and rhizobacteria.

Zea mays (maize) is a globally significant cereal crop with diverse applications in food, feed, and industrial products. However, maize cultivation is often challenged by environmental stressors such as heavy metal toxicity and drought stress (DS). Heavy metals like cadmium (Cd) and lead (Pb) can accumulate in soil through industrial activities and improper waste disposal, posing significant threats to plant growth and development. Drought stress further exacerbates these challenges by limiting water availability and affecting physiological processes in plants. This study explores the impact of Cd and Pb toxicity, as well as DS, on maize growth and development, and investigates the potential mitigating effects of various treatments, including gibberellic acid (GA3), biochar (BC), rhizobacteria (RB), and their combinations. The experiment involved maize plants subjected to different stress conditions: cadmium (Cd) at concentrations of 0, 6, and 12 ppm, lead (Pb) at 0 and 400 ppm, and drought stress (DS). Treatments included the application of 10 ppm GA3, 0.75% BC, a combined treatment of 10 ppm GA3 and 0.75% BC, rhizobacteria (RB), and a combined treatment of 0.5% BC and RB. The study measured germination rates, shoot and root lengths, and biochemical parameters such as shoot and root protein, phenolics, and chlorophyll contents under these conditions. In the absence of Cd stress (0 Cd), the application of 10 ppm GA3 and 0.75% BC significantly enhanced germination rates by 72% and 76%, respectively, compared to the control, with the combined treatment exhibiting the highest enhancement of 86%. Under Cd stress (6 ppm Cd), GA3 and BC individually improved germination by 54% and 57%, respectively, with the combined treatment showing the largest increase of 63%. Drought stress influenced germination, with notable improvements observed with the application of 0.5% BC (50% increase) and RB (49% increase). Similar trends were observed in shoot and root lengths, where the combined treatment of GA3 and BC resulted in the most significant improvements. The treatments positively influenced shoot and root protein, phenolics, and chlorophyll contents, particularly under stress conditions. These findings highlight the potential of combined treatments, such as the application of GA3 and BC or BC with RB, in alleviating the adverse effects of heavy metals (Cd and Pb) and drought stress in maize cultivation. The combined treatments not only improved germination rates but also significantly enhanced shoot and root growth, as well as important biochemical parameters under stress conditions. This suggests that GA3 and BC, alone or in combination with RB, can play a crucial role in enhancing maize resilience to environmental stressors. The study highlights the importance of exploring sustainable agricultural practices to mitigate the impacts of heavy metal toxicity and drought stress. Future research should focus on long-term field trials to validate these findings and further investigate the mechanistic pathways involved in stress mitigation by these amendments, as well as their economic feasibility and environmental impact on a larger scale to ensure their practical applicability in real-world agricultural settings.

Biochar/Biopolymer Composites for Potential In Situ Groundwater Remediation.

This study explores the use of pine wood biochar (BC) waste gasified at 950 °C as fillers in polymer matrices to create BC@biopolymer composites with perspectives in groundwater remediation. Four biochar samples underwent different sieving and grinding processes and were extensively characterized via UV-Vis, FTIR, and FESEM-EDS, highlighting the fact that that BCs are essentially graphitic in nature with a sponge-like morphology. The grinding process influences the particle size, reducing the specific surface area by about 30% (evaluated by BET). The adsorption performances of raw BC were validated via an adsorption isotherm using trichloroethylene (TCE) as a model contaminant. A selected BC sample was used to produce hydrophilic, stable polymer composites with chitosan (CS), alginate (ALG), potato starch (PST), and sodium carboxymethylcellulose (CMC) via a simple blending approach. Pilot sedimentation tests over 7 days in water identified BC@PST and BC@CMC as the most stable suspensions due to a combination of both hydrogen bonds and physical entrapment, as studied by FTIR. BC@CMC showed optimal distribution and retention properties without clogging in breakthrough tests. The study concludes that biopolymer-based biochar composites with improved stability in aqueous environments hold significant promise for addressing various groundwater pollution challenges.

Remediation on antimony-contaminated soil from mine area using zero-valent-iron doped biochar and their effect on the bioavailability of antimony

Due to the bioavailability and movement of antimony in trophic web, the overexploitation of antimony mine resulted in antimony contamination that harmed the ecology nearby, raising concerns for public health. Whereas, most researches focused on the removal of antimony in the aqueous instead of the immobilization of antimony in the soil. Herein, the immobilized performance of biochar (BC) loaded with nano zero-valent iron (nZVI-BC) on antimony in the soil near the smelting area was researched through pot experiments for the first time, and its stabilization mechanism on antimony was investigated by valent state variation of antimony. The results demonstrated that BC restricted the cation exchange capacity and catalase activity in the soil, while nZVI-BC had a favorable and negative impact on two variables, respectively. The nZVI-BC showed more stable immobilization capacity on antimony over time than BC, whose exchangeable speciation only marginally rose (2%–6%), although the exchangeable speciation of antimony fell both from 15% to 2% after adding the BC and nZVI-BC, The electron attraction force between nZVI-BC and antimony was also intensified owing to the oxidation-reduction process, which was considered as the stabilizing principle of nZVI-BC on antimony in soil. Furthermore, the decreased bioaccumulation factor for the perennial ryegrass (0.46–0.21) and Galinsoga parviflora Cav. (0.26–0.17) stated that the BC effectively mitigated the bioaccumulation risk of antimony.

Polydopamine-modified biochar supported polylactic acid and zero-valent iron affects the functional microbial community structure for 1,1,1-trichloroethane removal in simulated groundwater

In-situ enhanced bioreduction by functional materials is a cost-effective technology to remove chlorinated hydrocarbons in groundwater. Herein, a novel polydopamine (PDA)-modified biochar (BC)-based composite containing nanoscale zero-valent iron (nZVI) and poly-l-lactic acid (PLLA) (PB-PDA-Fe) was synthesized to enhance the removal of 1,1,1-trichloroethane (1,1,1-TCA) in simulated groundwater with actual site sediments. Its impact on functional microbial community structure in system was also investigated. The typical characterizations revealed uniform dispersion of PLA and nZVI particles on the BC surface, being smoother after PDA coating. The composite exhibited a significantly higher performance on 1,1,1-TCA removal (82.38%, initial concentration 100 mg/L) than Fe-PDA and PB-PDA treatments. The diversity and richness of the microbial community in the composite treatment consistently decreased during incubation due to a synergistic effect between PLLA-BC and nZVI. Desulfitobaterium, Pedobacter, Sphaerochaeta, Shewanella, and Clostridium were identified as enriched genera by the composite through DNA-stable isotope probing (DNA-SIP), playing a crucial role in the bioreductive dechlorination process. All the above results demonstrate that this novel composite selectively enhances the activity of microorganisms with extracellular respiration functions to efficiently dechlorinate 1,1,1-TCA. These findings could contribute to understanding the responsive microbial community by carbon-iron composites and expedite the application of in-situ enhanced bioreduction for effective remediation of chlorinated hydrocarbon-contaminated groundwater.

Electrochemical remediation of methyl orange over reusable biochar ferrite coated photocatalytic plates

Biochar (BC) obtained from biomass pyrolysis holds immense potential for environmental remediation. The efficiency of BC can further be enhanced by incorporating metal nanoparticles (NPs) in the porous carbon matrix. In the present work nanocomposites (NCs) were prepared by the addition of ferrite nanoparticles (FNPs) into an oxidized BC matrix to create BC /Fe3O4 (BCF). This process improves BC stability, electron transfer, conductivity, and photocatalytic ability for dye degradation. Microstructure and functional group analysis of BCF was performed by SEM, XRD, and FTIR showing intercalation of FNPs with surface functionalities of oxidized BC matrix. The B-H curve of FNPs and BCF reveals super paramagnetic behavior with saturation magnetization (Ms, emu/g) of 67.36 and 20.01 respectively. BET surface area analysis shows surface area (m2/gm) 45.81 and 44.19 for oxidized BC and BCF respectively, that attributed to partial blocking of porous carbon matrix by FNPs. UV-DRS supports the semiconducting behavior of BCF with a significantly reduced band gap (eV) of 2.95 over pristine BC (4.76). BCF-coated photocatalytic plates (PCPs) were developed and utilized for the remediation of methyl orange (MeO) in water samples. Degradation of MeO was investigated over time by electrochemical methods. The square wave voltammetric method showed the limit of detection and quantification of 0.09 ppm and 0.28 ppm respectively for MeO over a glassy carbon electrode in 0.1 M acetate buffer. BCF-derived PCPs rendered ∼99 % degradation efficiency against MeO (50 mgL−1) under UV radiation over 240 min. Developed PCPs demonstrate reusability up to 5 cycles without any further purification step and offer efficient degradation of MeO making them suitable for the treatment of water polluted with dyes.

Enhanced Denitrification in Constructed Wetlands with Low Carbon/Nitrogen Ratios: Insights into Reallocation of Carbon Metabolism Based on Electron Utilization

Constructed wetlands (CWs) are a promising method to treat effluent from wastewater treatment plants (WWTPs). However, low carbon/nitrogen (C/N) ratios of the influent inhibit denitrification in CWs, resulting in poor nitrogen removal efficiency. Herein, we compared traditional (control), biochar (BC), and β-cyclodextrin-functionalized biochar (BC@β-CD) CW systems to investigate nitrogen removal from influent with low C/N ratios, and the mechanisms that enhance this process. The highest nitrogen removal rates were observed in the BC@β-CD group, with rates 45.89% and 42.48% higher than those of the control, accompanied by a 70.57% and 85.45% decrease in nitrous oxide release, when the C/N ratio decreased from 4 to 2, respectively. Metagenomic and enzymatic analyses indicated that BC@β-CD enhances nitrogen removal by coordinately promoting carbon metabolism and increasing denitrification enzyme activities, without affecting microbial species diversity in CWs. Structural equation modeling confirmed that the foremost advantages of BC@β-CD were effective electron generation and transportation resulting from increased activities of nicotinamide adenine dinucleotide (NADH) dehydrogenase and the electron transfer system (ETS), thereby strategically reallocating more carbon metabolic flow to support denitrification. Our results show that the application of BC@β-CD in CWs to optimize the reallocation of electrons from carbon metabolism is a feasible strategy to enhance denitrification under low C/N conditions.

Development of biochar using herbal industry waste for removal of hexavalent chromium from aqueous solution: Column study

Biochar is an rich source of carbon formed through biomas’s thermal decomposition. There is a lot of scope of interest in developing biochar derived from biomass in various disciplines to address the most significant ecological challenges. In the present study herbal waste collected from herbal processing industry (Bangalore, India). So, this biomass will be no use after the extraction process. Hence, present work mainly concentrates the conversion this herbal waste to biochar (BC). Research highlights the BC was prepared from herbal industry waste using pyrolysis method. The obtained BC used as adsorbent for adsorption of Cr (VI) from aqueous solution. A characterization of BC was performed using XRD, SEM-EDS and FT-IR which confirms the material. The adsorption experiments were carried out using batch and fixed bed column. The experimental studies were carried out at room temperature with initial Cr (VI) concentrations (IC) of 10–120 ppm using an adsorbent dosage (AD) of 0.05–0.55 g, agitation speed of 150 rpm for contact time (CT) 15–165 min and temperature (20–40 °C). Then various parameters for column study like bed height, flow rate and IC were also studied. The maximum removal of Cr (VI) was 88 % found at a pH 2, AD 0.55g, CT 90 min, and IC 100 ppm at 30 °C. For column study: higher removal of Cr (VI) achieved by bed height (BH) of 6 cm and at lower flow rate (FR), of 3 mL/min.

Biochar improves Pb and Cd-induced stress in mung bean (Vigna radiata L. Wilczek)

Lead (Pb) and cadmium (Cd) are trace elements known for their potential harm to plants. Their toxicity can lead to increased oxidative harm, disturbance in plant metabolism, and deformation in plant structure. Biochar (BC), when utilized as a soil amendment, demonstrates effectiveness in mitigating the toxicity of these heavy metals in polluted soils. To investigate the effects of BC made from sunflower residues on reducing Pb- and Cd-induced stresses in mung bean (Vigna radiata L. Wilczek), a factorial experiment was conducted based on a completely randomized design with three replications in greenhouse conditions. The factors included Pb at three levels (0, 100, and 200 mg kg-1 as Pb (NO3)2), Cd at three levels (0, 10, and 20 mg kg-1 soil as Cd (NO3)2), and BC at three levels (0, 1, and 3 % by weight). The results showed that Pb and Cd-induced stresses reduced all growth characteristics, such as shoot and root dry weights and the number of active root nodules. Maximum soluble sugars (0.46 mg kg-1) and proline content (44.7 µmol g-1) were observed in 200 mg kg-1 of Pb and 20 mg kg-1 of Cd treatment without BC. Also, the application of BC reduced the concentration of Pb and Cd in the shoot by 19.1 % and 13.8 %, respectively, and increased all growth traits. Therefore, the application of BC made from sunflower residues is recommended as a promising and environmentally friendly approach to improves Pb and Cd-induced stress in mung beans.

Arbuscular Mycorrhizal Fungal Interacted with Biochar and Enhanced Phosphate-Solubilizing Microorganism Abundance and Phosphorus Uptake in Maize

In agricultural production, it is crucial to increase the availability of phosphorus (P) in cultivated soil to solve the P limitation. Arbuscular mycorrhizal fungi (AMF) have been proven to promote crop nutrient absorption effectively, while biochar can lead to improvements in soil properties. However, the possible synergistic effect of AMF and biochar on P uptake by crops as well as its underlying mechanisms are unclear. In this study, we conducted a pot experiment to explore the effects of biochar and AMF (Glomus etunicatum) on the community of rhizospheric phosphate-solubilizing microorganisms (PSMs) of maize (Zea mays L. Xianyu-335) using metagenomic methods. The experiment used 0 mg P2O5 g·kg−1 soil (P0) and 30 mg P2O5 g·kg−1 soil (P30) application rates. Each P application rate included 0 (NC), 20 g·kg−1 biochar (BC) addition, inoculation AMF, and without AMF treatments (NM) for a total of eight treatments. During the experiment, both the P uptake and the biomass of maize were measured. The study found that the combination of AMF and biochar significantly increased the mycorrhizal colonization rate of maize roots, regardless of P application level. It was observed that the P uptake by maize was significantly increased when exposed to a combination of AMF and biochar. The increase in P uptake in P0 treatments was 67% higher than the sum of the effects of biochar and AMF inoculation alone. The increase was only 35% higher in P30 treatments, demonstrating a substantially higher interactive effect under P0 than under P30 conditions. The AM-BC treatments significantly increased the abundance of Streptomyces, Bacillus, and Pseudomonas, genera that are known to contain PSMs. In addition, the abundance of genes related to P-cycling (gcd, phoD, and ugpQ) in PSMs increased significantly by 1.5–1.8 times in AM-BC treatments compared with NM-BC and AM-NC treatments under P0 conditions. This increase was significantly and positively correlated with the P uptake. Overall, the results suggest that biochar can help AMF colonize the roots, increasing the functional roles of PSMs in the rhizosphere, which in turn promotes P uptake and biomass in maize. This study provides a new way to improve P-use efficiency and reduce the need for P-fertilizer application in agricultural production.

Effect of biochar and iron ore tailing waste amendments on cadmium bioavailability in a soil and peanut seedling system.

Biochar and iron ore tailing waste have been widely separately applied for remediation of various contaminants, but the remediation effect of their combination on cadmium (Cd) pollution is unclear. In this study, the peanut biochar (BC), thermally activated iron ore tailing waste (TS), and the products of the co-pyrolysis of peanut shell and iron ore tailing waste (TSBC) were prepared for stabilizing Cd and reducing its bio-accessibility in soil and peanut seedling system. Present amendments enhanced soil pH, cation exchange capacity, electrical conductivity, and organic carbon content. The application of BC, TS, and TSBC led to decreases in acid-extractable Cd proportion of 2.2-8.81%, 2.43-7.20%, and 7.84-11.57%, respectively, and increases in the residual Cd proportion of 3.48-8.33%, 3.27-11.50%, and 9.02-13.45%, respectively. There were no significant differences in Cd accumulation in peanut roots due to three amendments treatments, especially at low Cd concentrations (i.e., Cd concentration of 0, 1, and 2mg·kg-1), and with a relatively small reduction (2.16-9.05%) in root Cd accumulation under the high Cd treatments of 5 and 10mg·kg-1. The Cd concentrations in seedling roots were significantly positively related to the acid-extractable Cd fraction, with a Pearson correlation coefficient of r = 0.999. The maximum toxicity mitigating effects were found in TSBC treatment, with increases in the ranges of 9.80-17.58% for fresh weight, 5.59-14.99% for dry weight, 5.16-10.17% for plant height, 5.96-10.34% for root length, 5.43-21.67% for chlorophyll a content, 17.17-71.28% for chlorophyll b content, and 13.11-39.60% for carotenoid content in peanut seedlings. Therefore, TSBC is a promising amendment for minimizing Cd contamination in peanut crops and utilizing industrial solid waste materials efficiently.

Adsorptive removal of phosphate from water with biochar from acacia tree modified with iron and magnesium oxides

A novel biochar (BC) from Acaciatortilis trees pruning waste was synthesized and tested for the removal of phosphate from aqueous solutions. The BC was prepared by calcination at 600 °C and doped with Fe3O4 and MgO by hydrothermal process. The presence of iron and magnesium ions in the modified BC was confirmed by EDS analysis and X-ray diffraction (XRD) methods. Both unmodified and doped BCs were tested for phosphate removal from synthetic 1–500 ppm aqueous solutions. While the unmodified BC did not show any significant removal of phosphate from aqueous solutions, the modified BC almost completely removed phosphate from water. The enhancement in removal efficiency is due to an increase in the overall surface charge and surface area of BC as a result of doping with Fe3O4 and MgO salts. The average porosity and BET surface area corresponding to the plain BC increased by more than 20% from 322 to 394 m2/g after modification by impregnation with iron oxide and magnesium oxide. The modificaiton of BC with Fe3O4 and MgO nanoparticles was observed to increase the point of zero electric charge (PZC) from pH 3.4 (corresponding to plain BC) to pH 5.3 (corresponding to modified BC). The adsorption process was very fast and a phosphate removal value of 82.5% was reached only after 30 min of adsorption, while the removal efficiency after 4 h of adsorption was 97.5%. The rapid removal efficiency in short contact time is attributed to the high surface area of BC and strong bonding between the modified BC surface and PO43− ions. The highest adsorption capacity was observed to correspond to 98.5 mg/g which was achieved at PO43− concentration of 500 ppm and pH 8.5. Moreover, after fitting the adsorption data onto four of the most widely used adsorption isotherm models, the adsorption of PO43− onto BC can be better described by the Langmuir isotherm model.

Characteristics of chemical aged biochars and their adsorption behaviors for norfloxacin

The biochar after long-term application will inevitably undergo ageing, thus promoting or inhibiting its remediation efficiency for antibiotics due to the differences in feedstocks and ageing process. To elucidate the adsorption performance and mechanisms of norfloxacin (NOR) by the different aged biochars, a batch of fresh biochars (BCs) prepared from Platanus orientalis Linn. leaf at 400 and 700 ℃ were aged by H2O2 (HBCs) and KMnO4 (MBCs) to simulate the natural ageing process. Compared with BCs, HBCs and MBCs showed larger specific surface area, richer micropores and O-containing functional groups. The maximum adsorption capacities of MBCs (43.96–49.32 mg g−1) and HBCs (18.38–19.79 mg g−1) were generally greater than those of BCs (16.44–20.01 mg g−1), which was resulted from the enhanced pore filling and hydrogen bonds. Furthermore, MBCs introduced with MnOx showed higher adsorption performances than those of HBCs, mainly due to the surface complexation. Na+ and Ca2+ inhibited the NOR adsorption by all the aged biochars. Humic acid and citric acid enhanced NOR adsorption at pH 3.0 but weakened the adsorption at pH 7.0. Furthermore, the NOR removal efficiency of BCs and aged biochars in the natural waters were reduced by 20–25 % and 6–17 %, respectively, showing the excellent sorption performance of the aged biochars. Our findings clarified the enhanced adsorption capacities of NOR by the aged biochar and the potential adsorption mechanism, providing the evidence for predicting the environmental fate of antibiotics in water environment and designing the functional biochars for controlling antibiotic pollution.

Synergistic degradation of 2,4-dichlorophenoxyacetic acid in water by interfacial pre-reduction enhanced peroxymonosulfate activation derived from novel zero-valent iron/biochar

Iron-based biochar exhibits great potential in degrading emerging pollutants and remediation of water environments. In this study, a highly efficient catalytic Fe0/biochar (MZB-800) was synthesized by the co-pyrolysis of poplar sawdust and K2FeO4 at 800 °C. A novel water purification technology of pre-reduction followed by PMS activation for MZB-800 was proposed to degrade the refractory 2,4-dichlorophenoxyacetic acid (2,4-D) pesticide. The corrosive effect of the strong oxidizing potassium salt endowed the MZB-800 surface with more Fe0 and porous structure, achieving greater 2,4-D adsorption binding energy. The removal efficiency of MZB-800 on 2,4-D was greater than that of biochar (BC) and conventional Fe0/biochar (Fe-BC) prepared by FeCl3·6 H2O as the precursor. The proposed novel water purification technology showed the synergistic effect between the interfacial pre-reduction and the PMS activation derived by MZB-800. Regarding 2,4-D degradation and dechlorination performance, the synergistic coefficient between pre-reduction and subsequent PMS activation for MZB-800 were 2 and 1.4 respectively. Based on the normalized kinetic analysis and the Langmuir-Hinshelwood model, we proposed the underlying mechanism of MZB-800 interfacial pre-reduction and subsequent PMS activation for synergistic removal of 2,4-D. The large amount of Fe2+ and hydroxyl density accumulated by the Fe0 and hydroquinone structures on the MZB-800 surface during the pre-reduction stage provided abundant active sites for the subsequent activation of PMS. The improved activation reaction rate generated more reactive oxygen species, further strengthening the removal efficiency of 2,4-D. This work manifested that the novel water purification technology of pre-reduction/PMS activation of iron-based biochar is feasible for removing emerging pollutants in the water environment. Environmental ImplicationExtensive abuse of 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide with high solubility and refractory degradation has caused environmental pollution and ecological deterioration. This manuscript described a novel water purification technology, centered on high-efficiency Fe0/biochar and utilizing pre-reduction and PMS reactivation strategies to synergistically degrade 2,4-D, which had strong environmental relevance. By elucidating the synergistic removal mechanism, the research provided valuable insights into removing emerging pollutants, thus promoting environmental sustainability and safeguarding ecosystem health. Overall, it is of high importance to provide a feasible and efficient method for removing hazardous 2,4-D from water environments, which contributes to addressing pressing environmental problems.

Assembly of root-associated bacterial community and soil health in cadmium-contaminated soil affected by nano/bulk-biochar compost associations

Biochar (BC) has been proven effective in promoting the production of safety food in cadmium (Cd)-polluted soil and the impact can be further enhanced through interaction with compost (CM). However, there existed unclear impacts of biochar with varying particle sizes in conjunction with compost on microbiome composition, rhizosphere functions, and soil health. Hence, in this study, two bulk-biochar derived from wood chips and pig manure were fabricated into nano-biochar using a ball-milling method. Subsequently, in a field experiment, the root-associated bacterial community and microbial functions of lettuce were evaluated in respond to Cd-contaminated soil remediated with nano/bulk-BCCM. The results showed that compared to bulk-BCCM, nano-BCCM significantly reduced the Cd concentration in the edible part of lettuce and the available Cd in the soil. Both nano-BCCM and bulk-BCCM strongly influenced the composition of bacterial communities in the four root-associated niches, and enhanced rhizosphere functions involved in nitrogen, phosphorus, and carbon cycling, as well as the relative abundance and biodiversity of keystone modules in rhizosphere soil. Furthermore, soil quality index analysis indicated that nano-BCCM exhibited greater potential than bulk-BCCM in maintaining soil health. The data revealed that nano-BCCM could regulate the Cd concentration in lettuce shoot by promoting microbial biodiversity of keystone modules in soil-root continuum and rhizosphere bacterial functions. These findings suggest that nano-biochar compost associations can be a superior strategy for enhancing microbial functions, maintaining soil health, and ensuring crop production safety in the Cd-contaminated soil compared to the mix of bulk-biochar and compost.

Biochar/poly(aniline-pyrrole) modified graphite electrode and electrochemical behavior for application in low-cost supercapacitor

An attempt is made to use biochar (BC), a carbon rich low-cost green material, as a platform to house conducting polymer for fabricating stable graphite electrodes for application in next generation supercapacitor devices. Here, BC is first prepared from sucrose solution using a simple hydrothermal method. The seeded chemical oxidative copolymerization of aniline and pyrrole is then carried out at identical comonomer weight ratio using BC as seed particles. Two different BC to mixed monomer (w/w) ratios (1:0.7 and 1:1) have been used and the prepared composites are named as BC/P(Ani-Py)1:0.7 and BC/P(Ani-Py)1:1 respectively. Independent of composition, both BC seed and composite particles are spherical. The smooth homogeneous surface of BC turned heterogeneous after composite formation. The average size of BC seed particles is 2.56 µm and those of composites prepared at weight ratios of 1:0.7 and 1:1.0 are 2.72 and 2.90 µm respectively. Cyclic voltammetry (CV), galvanostatic charging discharging (GCD), and electrochemical impedance spectroscopy (EIS) are used to evaluate the electrochemical properties. Comparatively, the BC/P(Ani-Py)1:1 composite modified graphite electrode exhibited the highest capacitance value (274.27 F g−1 at a current density of 1.0 A/g) and is capable of acting as a supercapacitor electrode. A long-term cycling test of the BC/P(Ani-Py)1:1 modified electrode at a current density of 5.0 A/g displayed a capacitance retention of 96.6 % after 1000 cycles of charge and discharge, indicating a very good cycle stability.

Quantitative Soil Characterization for Biochar-Cd Adsorption: Machine Learning Prediction Models for Cd Transformation and Immobilization.

Soil pollution with cadmium (Cd) poses serious health and environmental consequences. The study investigated the incubation of several soil samples and conducted quantitative soil characterization to assess the influence of biochar (BC) on Cd adsorption. The aim was to develop predictive models for Cd concentrations using statistical and modeling approaches dependent on soil characteristics. The potential risk linked to the transformation and immobilization of Cd adsorption by BC in the soil could be conservatively assessed by pH, clay, cation exchange capacity, organic carbon, and electrical conductivity. In this study, Long Short-Term Memory (LSTM), Bidirectional Gated Recurrent Unit (BiGRU), and 5-layer CNN Convolutional Neural Networks (CNNs) were applied for risk assessments to establish a framework for evaluating Cd risk in BC amended soils to predict Cd transformation. In the case of control soils (CK), the BiGRU model showed commendable performance, with an R2 value of 0.85, indicating an approximate 85.37% variance in the actual Cd. The LSTM model, which incorporates sequence data, produced less accurate results (R2=0.84), while the 5-layer CNN model had an R2 value of 0.91, indicating that the CNN model could account for over 91% of the variation in actual Cd levels. In the case of BC-applied soils, the BiGRU model demonstrated a strong correlation between predicted and actual values with R2 (0.93), indicating that the model explained 93.21% of the variance in Cd concentrations. Similarly, the LSTM model showed a notable increase in performance with BC-treated soil data. The R2 value for this model stands at a robust R2 (0.94), reflecting its enhanced ability to predict Cd levels with BC incorporation. Outperforming both recurrent models, the 5-layer CNN model attained the highest precision with an R2 value of 0.95, suggesting that 95.58% of the variance in the actual Cd data can be explained by the CNN model's predictions in BC-amended soils. Consequently, this study suggests developing ecological soil remediation strategies that can effectively manage heavy metal pollution in soils for environmental sustainability.

Synergetic effect of biochar and intermittent electricity stimulation on mitigating the adverse effects of tannic acid on anaerobic granular sludge in wastewater

Tannic acid (TA), a common industrial contaminant in sectors such as papermaking and leather production, affects the anaerobic treatment of wastewater by forming complexes with proteins in sludge granules, thereby inhibiting microbial efficiency and promoting sludge deflocculation. Although techniques such as intermittent electricity can promote microbial growth, they do not effectively resolve sludge deflocculation. Additionally, although biochar (BC) enhances the abundance of microbes, it does not significantly improve microbial activity or treatment performance. This study aimed to alleviate the adverse effects of TA on anaerobic granular sludge (AnGS) by synergistically applying intermittent electrical stimulation and BC. Co-treatment with 1 h-on/off intermittent electricity and 3 g/L BC notably reduced granular sludge deflocculation. Consequently, the chemical oxygen demand (COD) removal efficiency in wastewater reached 91.73 %, with a maximum methane production per cycle of 230.59 mL/g COD, 16.95 % higher than that of the control reactor (197.17 mL/g COD). This improvement was attributed to the synergistic action of intermittent electricity and BC, which enriched the functional microorganisms and stimulated their activity, thereby facilitating direct interspecies electron transfer. Additionally, enhancing the polysaccharide and protein levels in extracellular polymeric substances improved the stability of granular sludge, ultimately mitigating the adverse effects of TA on AnGS.

Biochar with root pore channels loaded copper cobalt bimetallic metal organic framework for effective peroxomonosulfate activation to degrade organic pollutants

Biochar (BC) with root pore channel structure was used as the carrier, and bimetallic organic framework (CuCo-MOF) as the main active site. The CuCo-MOF was successfully dispersed in the internal channels of BC by in situ reaction, forming a composite catalyst (BC/CuCo-MOF(10 %)) with unique reaction channels. The degradation efficiency of ciprofloxacin (20 mg/L) in only 25 min was 96.4 %, and its catalytic performance was superior to that of the single BC and CuCo-MOF. On the one hand, abundant CuCo-MOF reaction sites were distributed in the relatively closed porous reaction channel of BC, which accelerated the mass transfer process (short mass transfer distance) during the CIP degradation process and improved the CIP degradation performance. On the other hand, highly conductive BC facilitates electron transfer between Cu2+/Cu+ species and HSO5-, accelerating the redox cycle of Cu2+/Cu+, thereby improving catalytic activity. Besides, the composite catalyst was still able to achieve a degradation efficiency of 87.6 % for CIP after five cyclic degradation experiments. The concentrations of Cu and Co ions in the reaction solution were only 0.04 and 0.03 mg/L. Therefore, the composites have excellent catalytic activity and stability. Both non-radical 1O2 and radicals (SO4·- and ·OH) were involved in the reaction, and the non-radical 1O2 pathway played a dominant role in the CIP degradation process.