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In contaminated soil, pristine biochar has poor applicability for immobilizing vanadium (V), which mainly exists as oxyanions in soil. To elucidate the immobilization potential and biotic/abiotic stabilizing mechanisms of a ferrous sulfate (FS)-modified sludge biochar in a V-contaminated soil from a mining area, we investigated the effects of biochar addition on the soil characteristics, growth of alfalfa, leachability, bioavailability, speciation, and fractionation of V, and changes in the microbial community structure and metabolic response. The results showed that the water extractable, acid-soluble (F1), and pentavalent fractions of V in soil decreased by up to 99 %, 95 %, and 55 %, respectively, whereas the reducible and (F2) oxidizable (F3) fractions increased by up to 45 % and 76 %, respectively. After the soil was treated with the FS-modified biochar for 90 d, the V concentration in the roots and shoots of alfalfa (Medicago sativa L.) decreased by up to 81.5 % and 96 %, respectively. The changes in the speciation, fractionation, and efficient immobilization of V in the studied soil were due to the combined effects of the biochar-induced decrease in soil pH, adsorption and precipitation by elevated iron concentrations, reduction and complexation due to an increase in the organic matter content, and microbial reduction by Proteobacteria. [Display omitted] • Amorphous FeOOH was formed on biochar surface after ferrous sulfate modification. • Ferrous sulfate modified biochar markedly reduced vanadium mobility in soil. • Soil pH, iron and organic matter contents control vanadium mobility in soil. • Preoteobacteria was responsible for the biotic reduction of V(V) to V(IV) in soil. [ABSTRACT FROM AUTHOR]

Nitrogen-doped biochar (NCMs) has shown great potential as metal-free catalysts for persulfates. To understand the evolution law of properties of NCMs with preparation conditions, eleven NCMs were prepared and characterized by EA, BET, Raman, XPS, and conductivity. Surface area and conductivity can be improved by higher pyrolysis temperature and longer retention time. Distribution of nitrogen species of NCMs was greatly influenced by pyrolysis temperature. Subsequently, these NCMs were applied to activate peroxymonosulfate to degrade 2,4-dichlorophenol. A linear correlation of the initial apparent degradation rate constant (k obs) of 2,4-dichlorophenol with conductivity and ratio of graphitic N was newly established, revealing that conductivity and graphitic N of NCMs would be the key property deciding degradation efficiency of 2,4-dichlorophenol. Positive effect of conductivity can be ascribed to the mediated electron-transfer mechanism. Electron-transfer mechanism is also proved by quenching experiments and solvent deuterium isotope effect experiment. Graphitic N would be the main active site for PMS activation. Understanding the evolvement rule of properties of NCMs with preparation conditions combined with the correlations between reactivity and properties of NCMs is meaningful for preparation of nitrogen-doped biochar as well as the development of carbonaceous materials with high performance in persulfates-based advanced oxidation processes. [Display omitted] • Higher pyrolysis temperature and longer retention time can increase SSA and conductivity. • Nitrogen species was significantly influenced by pyrolysis temperature. • A linear correlation between k obs with conductivity and graphitic N was established. • Mediated electron-transfer and graphitic N would be the main mechanism and active sites. [ABSTRACT FROM AUTHOR]

The migration risk of antibiotic and antibiotic resistance genes (ARGs) have attracted lots of attentions due to their potential threaten to public health. Strategies to reduce their vertical mobilization risk are urgently required for groundwater safety and human health. Biochar enjoys numerous interests due to its excellent sorption affinity. However, little was known about the efficacy of biochar amendment in impeding the vertical mobilization of antibiotic and ARGs. To fill this gap, a column study was carried out to investigate biochar-induced variations in the leaching behavior of dissolved organic matter (DOM), sulfamethazine (SMZ) and ARGs. Results showed that biochar addition enhanced DOM export from soil, changed its composition and impeded the vertical transport of SMZ. Biochar amendment could effectively decrease the occurrence of extracellular and intracellular sul2 in soil and impede its vertical transportation, however, it did not work out with sul1 gene. Structural equation modeling analysis demonstrated that the abundance of sul2 was significantly controlled by SMZ concentration, while the primary drivers of sul1 were SMZ concentration and DOM content. These results indicated the failure in inhibiting the vertical transfer of sul1 under biochar amendment and highlighted the important role of DOM in the leaching of soil ARGs. [Display omitted] • Biochar enhanced the export of DOM from soil and changed its composition. • Biochar reduced the presence of soil sul2 in both eDNA and iDNA but not for sul1. • Biochar can impede the vertical transport of SMZ and sul2, not for sul1 and intI1. • The main driver of sul2 in leachate was SMZ and sul1 was also controlled by DOC. • Biochar-induced elevated DOC might compete with sul1 in eDNA for sorption sites. [ABSTRACT FROM AUTHOR]

Sulfamethoxazole (SMX) is frequently detected in the environment and causes a huge threaten to human health. Biochar (BC) is a metal-free adsorbent and generally exhibits a good adsorption capacity for SMX. However, the current activated methods usually result in the high energy consumption and low yield of the biochar. In this study, biochar was activated by boric acid under limited oxygen condition. The yield of biochar was increased by 103% after the activated by boric acid. The specific surface area of BC was significantly increased from 766.6 m2 · g−1 to 1190.6 m2 · g−1. The intensity of the (111) diamond peak of B-BC was higher than that of BC, suggesting that boric acid affected the surface pyrolysis temperature of biochar. The proposed roles of boric acid in the activation process were to: 1) enhance the generation of micropores during the pyrolysis process; 2) improve the yield of biochar via the transformation pathways of C-corresponding bonds and physical blocking. The boric acid activated biochar (B-BC) had a higher adsorption capacity for SMX than BC under the various aqueous conditions. Hence, boric acid activated biochar is a promising porous adsorbent to enhance the removal of SMX and achieve practical application. [Display omitted] ● Boric acid could be as the activator for the preparation of biochar. ● The yield of biochar was increased by 103% with addition of boric acid. ● Specific surface area of biochar was improved by the activation of boric acid. ● B-BC showed a higher SMX adsorption capacity than BC. ● Adsorption capacity of SMX by B-BC could reach 64.62 mg·L−1 after five times. [ABSTRACT FROM AUTHOR]

Sulfamethoxazole (SMX) is frequently detected in the environment and causes a huge threaten to human health. Biochar (BC) is a metal-free adsorbent and generally exhibits a good adsorption capacity for SMX. However, the current activated methods usually result in the high energy consumption and low yield of the biochar. In this study, biochar was activated by boric acid under limited oxygen condition. The yield of biochar was increased by 103% after the activated by boric acid. The specific surface area of BC was significantly increased from 766.6 m2 · g−1 to 1190.6 m2 · g−1. The intensity of the (111) diamond peak of B-BC was higher than that of BC, suggesting that boric acid affected the surface pyrolysis temperature of biochar. The proposed roles of boric acid in the activation process were to: 1) enhance the generation of micropores during the pyrolysis process; 2) improve the yield of biochar via the transformation pathways of C-corresponding bonds and physical blocking. The boric acid activated biochar (B-BC) had a higher adsorption capacity for SMX than BC under the various aqueous conditions. Hence, boric acid activated biochar is a promising porous adsorbent to enhance the removal of SMX and achieve practical application. [Display omitted] ● Boric acid could be as the activator for the preparation of biochar. ● The yield of biochar was increased by 103% with addition of boric acid. ● Specific surface area of biochar was improved by the activation of boric acid. ● B-BC showed a higher SMX adsorption capacity than BC. ● Adsorption capacity of SMX by B-BC could reach 64.62 mg·L−1 after five times. [ABSTRACT FROM AUTHOR]

At present, it is very common to wear mask outdoors in order to avoid coronavirus disease 19 (COVID-19) infection. However, this leads to the formation of numerous plastic wastes that threaten humans and ecosystem. Against this major background, a novel co-pyrolysis coupled chemical vapor deposition (CVD) strategy is proposed to systematically convert mask and heavy fraction of bio-oil (HB) into biochar, bio-oil, and three-dimensional graphene films (3DGFs) is proposed. The biochar exhibits high higher heating value (HHV) (33.22–33.75 MJ/kg) and low ash content (2.34%), which is obviously superior to that of the walnut shell and anthracite coal. The bio-oil contains rich aromatic components, such as 1,2-dimethylbenzene and 2-methylnaphthalene, which can be used as chemical feedstock for insecticides. Furthermore, the 3DGF 800 has a wide range of applications in the fields of oil spill cleanup and oil/water separation according to its fire resistance, high absorbability (40–89 g g-1) and long-term cycling stability. This research sheds new light on converting plastic wastes and industrial by-products into high added-value chemicals. [Display omitted] • Green production of high added-value products from HB and mask. • The biochar has high HHV (33.22–33.75 MJ/kg) and low ash content (2.34%). • The bio-oil contains a series of aromatic compounds such as 1,2-dimethylbenzene. • The 3DGF 800 exhibits high absorbability (40–89 g g-1) and excellent reusability. [ABSTRACT FROM AUTHOR]

The present study investigated the co-transport behavior of three REEs3+ (La3+, Gd3+, and Yb3+) with and without biochar nanoparticles (BC NPs) in water-saturated porous media. The presence of REEs3+ enhanced the retention of BC NPs in quartz sand (QS) due to decreased electrostatic repulsion between BC NPs and QS, enhanced aggregation of BC NPs, and the contribution of straining. The distribution coefficients (K D) in packed columns in the co-transport of BC NPs and three REEs3+ were much smaller than in batch experiments due to the different hydrodynamic conditions. In addition, we, for the first time, found that REE fractionation in the solid-liquid phase occurred during the co-transport of REEs3+ in the presence and absence of BC NPs. Note that the REE fractionation during the co-transport, which is helpful for the tracing application during earth surface processes, was driven by the interaction of REEs3+ with QS and BC NPs. This study elucidates novel insights into the fate of BC NPs and REEs3+ in porous media and indicates that (i) mutual effects between BC NPs and REE3+ should be considered when BC was applied to REE contaminated aquatic and soil systems; and (ii) REE fractionation provides a useful tool for identifying the sources of coexisting substances. [Display omitted] • REE fractionation occurs during the co-transport with and without BC NPs. • Both quartz sand and BC NPs result in more Yb3+ enrichment during the co-transport. • REE fractionation in their co-transport is subject to the lanthanide contraction. • Mutual effects between BC NPs and REEs3+ are found in their co-transport. • Batch tests overestimate the adsorption of REEs3+ by BC NPs compared to column data. [ABSTRACT FROM AUTHOR]

• Geobacter -biochar combined system enhanced the rate of nitrobenzene reduction. • Sludge biochar as mediator promoted extracellular electron transfer of Geobacter. • Geobacter triggered the extracellular reduction of Fe(III) to Fe(II) in biochar. • Biogenic Fe(II) contributed to the reduction of nitrobenzene to aniline. In this work, the incorporation of Fe-bearing sludge-derived biochar greatly enhanced both biotic and abiotic reduction of nitrobenzene (NB) to aniline, which was attributed to the concomitant microbial dissimilatory iron reduction. Biogenic Fe(II) produced by Geobacter sulfurreducens dominated the anaerobic reduction of NB following the pseudo-first-order kinetic. Besides, the increase of pyrolysis temperature from 600 to 900 ℃ to generate biochar resulted in an accelerated removal rate of NB in Geobacter -biochar combined system. The morphology and structural characterization of biochar with G. sulfurreducens confirmed the formation of conductive bacteria-biochar aggregates. Electrochemical measurements suggested the presence of graphitized domains and quinone-like moieties in biochar as redox-active centers, which might play an important role in accelerating electron transfer for microbial dissimilatory iron reduction and NB degradation. This study provides a feasible way of using Fe-bearing sludge as a valuable feedstock for biochar generation and its application with electrochemically active bacteria for the bioremediation of nitroaromatic compounds-polluted wastewater. [ABSTRACT FROM AUTHOR]

Low-cost biochar adsorbent owning great potential for environmental remediation faces a bottleneck in application for its unsatisfied adsorption performance. Compared to the efforts on increasing adsorption capacity, improving adsorption speed which is important for treatment efficiency is often neglected. Herein, a hierarchical porous biochar (HPB) derived from shrimp shell was prepared and exhibited good adsorption capacity (Q m >300 mg/g) and fast adsorptive equilibrium (≤10 min) towards three typical aromatic organics, whose adsorption universality was further proved by two-way ANOVA analysis. Whereafter, model analysis demonstrated that, the adsorptive forms (mono- and multi-layers) on HPB depended on whether the contaminant is charged. Compared to the benzene-ring site of organics, the charged site contributed 5.13 times to adsorption promotion in monolayer but -0.49 times in inhibition for multilayers forms. Simultaneously, functional group sites contributed relatively weak (0.023 to 0.342 times only). Following structural control revealed that, hierarchical pore structure of HPB was the key for the fast adsorption speed, and highly graphitic structure was important for the high adsorption capacity. This study aims to provide an advanced biochar adsorbent, not only in adsorption capacity but also in adsorptive speed, and reveal the relationship between the structure and adsorption performance of biochar. [ABSTRACT FROM AUTHOR]