Regeneration of methylene blue-saturated biochar by synergistic effect of H2O2 desorption and peroxymonosulfate degradation.

Biochar, as an adsorbent, is widely used for the removal of organic pollutants in water body. Hence, after saturated adsorption, regeneration treatment is required to recover the adsorption performance of biochar. In this study, a biochar (P-GBC) prepared by phosphoric acid activation showed high adsorption capacity for methylene blue (MB) with the maximum adsorption capacity (Qm) of 599.66 mg/g. Then, regeneration treatments using 4 mM peroxymonosulfate (PMS), 0.2 M hydrogen peroxide (H2O2) and their mixture were used to regenerate MB-saturated biochar with regeneration efficiencies of 58.24%, 66.01% and 94.88%, respectively. Combining with degradation and quenching experiments, it is found that synergistic effect of H2O2 desorption and PMS degradation is responsible for the enhancement of regeneration efficiency of P-GBC in H2O2-PMS system and enables a high mineralization rate of 82.68% for the MB adsorbed on P-GBC. Furthermore, EPR tests indicate that singlet oxygen (1O2) is assigned as the primary activate species for the degradation of MB and XPS analyses confirm that graphite nitrogen and carbonyl on P-GBC are the main active sites for the activation of PMS. Compared with conventional regenerants, H2O2-PMS system has the advantages of low dosage, high mineralization efficiency, and easy accessibility, and is also effective, sustainable and environmentally friendly for the regeneration of organic pollutants-saturated biochar.

Low-Temperature Reduction Synthesis of γ-Fe2O3-x@biochar Catalysts and Their Combining with Peroxymonosulfate for Quinclorac Degradation.

Biochar loading mixed-phase iron oxide shows great advantages as a promising catalyst owing to its eco-friendliness and low cost. Here, γ-Fe2O3-x@biochar (E/Fe-N-BC) composite was successfully prepared by the sol-gel method combined with low-temperature (280 °C) reduction. The Scanning Electron Microscope (SEM) result indicated that γ-Fe2O3-x particles with the size of approximately 200 nm were well-dispersed on the surface of biochar. The CO derived from biomass pyrolysis is the main reducing component for the generation of Fe (II). The high content of Fe (II) contributed to the excellent catalytic performance of E/Fe-N-BC for quinclorac (QNC) degradation in the presence of peroxymonosulfate (PMS). The removal efficiency of 10 mg/L of QNC was 100% within 30 min using 0.3 g/L γ-Fe2O3-x@biochar catalyst and 0.8 mM PMS. The radical quenching experiments and electron paramagnetic resonance analysis confirmed that •OH and SO4•- were the main radicals during the degradation of QNC. The facile and easily mass-production of γ-Fe2O3-x@biochar with high catalytic activity make it a promising catalyst to activate PMS for the removal of organic pollutants.

N, P, O-codoped biochar from phytoremediation residues: a promising cathode material for Li-S batteries.

Environment and energy are two key issues in today's society. In terms of environmental protection, the treatment of phytoremediation residues has become a key problem to be solved urgently, while for energy storage, it tends to utilize low-cost and high specific energy storage materials (i.e. porous carbon). In this study, the phytoremediation residues is applied to the storage materials with low-cost and high specific capacity. Firstly, the phosphorous acid assisted pyrolysis of oilseed rape stems from phytoremediation is effective in the removal of Zn, Cu, Cd and Cr from the derived biochar. Moreover, the derived biochar from phytoremediation residues shows abundant porous structure and polar groups (-O/-P/-N), and it can deliver 650 mAh g-1with 3.0 mg cm-2sulfur, and keeps 80% capacity after 200 cycles when employing it as a sulfur host for lithium-sulfur (Li-S) batteries. Hence, phosphorous acid assisted pyrolysis and application in Li-S battery is a promising approach for the disposal of phytoremediation residues, which is contributed to the environmental protection as well as energy storage.

Emerging disposal technologies of harmful phytoextraction biomass (HPB) containing heavy metals: A review.

Phytoextraction is an effective approach for remediation of heavy metal (HM) contaminated soil. After the enhancement of phytoextraction efficiency has been systematically investigated and illustrated, the harmless disposal and value-added use of harmful phytoextraction biomass (HPB) become the major issue to be addressed. Therefore, in recent years, a large number of studies have focused on the disposal technologies for HPB, such as composting, enzyme hydrolysis, hydrothermal conversion, phyto-mining, and pyrolysis. The present review introduces their operation process, reaction parameters, economic/ecological advantages, and especially the migration and transformation behavior of HMs/biomass. Since plenty of plants possess comparable extraction abilities for HMs but with discrepancy constitution of biomass, the phytoextraction process should be combined with the disposal of HPB after harvested in the future, and thus a grading handling strategy for HPB is also presented. Hence, this review is significative for disposing of HPB and popularizing phytoextraction technologies.