Remediation of Cu and As contaminated water and soil utilizing biochar supported layered double hydroxide: Mechanisms and soil environment altering.

Preparing materials for simultaneous remediation of anionic and cationic heavy metals contamination has always been the focus of research. Herein a biochar supported FeMnMg layered double hydroxide (LDH) composites (LB) for simultaneous remediation of copper and arsenic contamination in water and soil has been assembled by a facile co-precipitation approach. Both adsorption isotherm and kinetics studies of heavy metals removal by LB were applied to look into the adsorption performance of adsorbents in water. Moreover, the adsorption mechanisms of Cu and As by LB were investigated, showing that Cu in aqueous solution was removed by the isomorphic substitution, precipitation and electrostatic adsorption while As was removed by complexation. In addition, the availability of Cu and As in the soil incubation experiments was reduced by 35.54%-63.00% and 8.39%-29.04%, respectively by using LB. Meanwhile, the addition of LB increased the activities of urease and sucrase by 93.78%-374.35% and 84.35%-520.04%, respectively, of which 1% of the dosage was the best. A phenomenon was found that the richness and structure of microbial community became vigorous within 1% dosage of LB, which indirectly enhanced the passivation and stabilization of heavy metals. These results indicated that the soil environment was significantly improved by LB. This research demonstrates that LB would be an imaginably forceful material for the remediation of anionic and cationic heavy metals in contaminated water and soil.

Understanding the role of biochar in affecting BDE-47 biodegradation by Pseudomonas plecoglossicida: An integrated analysis using chemical, biological, and metabolomic approaches.

Biochar-assisted microbial degradation technology is considered as an important strategy to eliminate organic pollutants, but the mechanism of biochar in affecting biodegradation has not been systematically studied. To address this knowledge gap, the effect of various biochars on biodegradation of different initial concentrations of BDE-47 by Pseudomonas plecoglossicida was investigated. The results showed that biochar exhibited significant promotion to the biodegradation of BDE-47, especially at concentrations of BDE-47 above 100 µg/L. The promotion effect was negatively influenced by the aromaticity and micropore volume of biochar. Biochar alleviated the cytotoxicity of BDE-47 to P. plecoglossicida and promoted cell proliferation based on toxicity assays. Additionally, biochar acted as shelter and stimulated the secretion of extracellular polymeric substances, which might support P. plecoglossicida to struggle with extreme conditions. Metabolomic analysis indicated that biochar resulted in upregulation expression of 38 metabolites in P. plecoglossicida. These upregulated metabolites were mainly related to glyoxylate and dicarboxylate metabolism, citrate cycle, and serial amino acid metabolism, suggesting that biochar could improve the BDE-47 biodegradation via enhancing oxidative metabolism and energy supply of the bacterial cells. This work elucidates how biochar can affect BDE-47 biodegradation and provides insights for the application prospect of biochar-assisted microbial degradation technology in the environment.

MgO-loaded nitrogen and phosphorus self-doped biochar: High-efficient adsorption of aquatic Cu2+, Cd2+, and Pb2+ and its remediation efficiency on heavy metal contaminated soil.

In this study, the MgO-loaded fish scale biochar (MgO-FB) was synthesized by impregnation of MgCl2 using fish scales as precursor, and the modified biochar was applied for the adsorption of aquatic Cu2+, Cd2+, and Pb2+, and the immobilization of heavy metals in soils. The maximum adsorption capacities of MgO-FB for Cu2+, Cd2+, and Pb2+ were 505.8, 327.2, and 661.2 mg/g, respectively. In addition, MgO-FB can keep the excellent adsorption capacity under various environmental disturbances including pH, humic acid, and high ionic strength. Multiple characterizations and comparative experiments have demonstrated that the hydroxyapatite components and the MgO micro-nanoparticles on MgO-FB enhanced the adsorption capacity for Cu2+, Cd2+, and Pb2+ through ion-exchange and precipitation process. The metal-π electron coordination and complexation with oxygen-, nitrogen-, and phosphorus-containing groups were also responsible for the removal of heavy metal ions. Besides, MgO-FB also performed excellently for the immobilization of Cu, Cd, and Pb in soils, and the contents of available Cu, Cd, and Pb were reduced by 84.2%, 74.2%, and 53.7% respectively with the addition of MgO-FB. In general, these results show that waste fish scales co-pyrolysis with MgCl2 impregnation can be considered as a promising and efficient material for the remediation of heavy metal contaminated waters and soils.