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Mesoporous Activated Biochar for As(III) Adsorption: A New Utilization Approach for Biogas Residue

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journal contribution
posted on 10.09.2019, 18:35 by Dong Xia, Heng Li, Zheng Chen, Peng Huang, Dun Fu, Qingbiao Li, Yuanpeng Wang
To develop a new utilization approach of biogas residues, mesoporous activated biochar (MB) was prepared from biogas residues and used for adsorption of As­(III) from aqueous solution. MB-ZnCl2-600, which was activated with 2.5 M zinc chloride solution at 600 °C, showed superior thermostability and good mesoporous distribution. The total surface area and the mesoporous surface area of the prepared biochar reached up to 892.3 and 701.7 m2/g, respectively, and its pore diameters mainly ranged from 4 to 40 nm. Batch adsorption of As­(III) revealed a high theoretic adsorption capacity of 5861 μg/g. The kinetic data revealed good fitting with the Elovich model, while the adsorption data demonstrated excellent correspondence with the Langmuir model. Experimental results confirmed that As­(III) adsorption capacity is positively correlated with the mesoporous surface area (R2 = 0.813) of the adsorbent, confirming that mesopores in the MB-ZnCl2-600 adsorbent dominated As­(III) adsorption. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy demonstrated that SiO2 provides crucial adsorption sites for the removal of As­(III) and that organic functional groups on the biochar surface bonded with As species during adsorption. This study is the first to prepare MB with good mesoporous distribution from low-cost and wide-source starting material of biogas residues, which can be used as a supporting framework for catalysts and other adsorbent applications.

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