Role of Inherent Inorganic Constituents in SO2 Sorption Ability of Biochars Derived from Three Biomass Wastes

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• 作者：Xiaoyun Xu ; Daxuan Huang ; Ling Zhao ; Yue Kan ; Xinde Cao
• 刊名：Environmental Science & Technology
• 出版年：2016
• 出版时间：December 6, 2016
• 年：2016
• 卷：50
• 期：23
• 页码：12957-12965
• 全文大小：542K
• ISSN：1520-5851

文摘

Biochar is rich in both organic carbon and inorganic components. Extensive work has attributed the high sorption ability of biochar to the pore structure and surface chemical property related to its organic carbon fraction. In this study, three biochars derived from dairy manure (DM-biochar), sewage sludge (SS-biochar), and rice husk (RH-biochar), respectively, were evaluated for their SO<sub>2sub> sorption behavior and the underlying mechanisms, especially the role of inherent inorganic constituents. The sorption capacities of SO<sub>2sub> by the three biochars were 8.87–15.9 mg g<sup>–1sup>. With the moisture content increasing from 0% to 50%, the sorption capacities increased by up to about 3 times, mainly due to the formation of alkaline water membrane on the biochar surface which could promote the sorption and transformation of acidic SO<sub>2sub>. DM- and SS-biochar containing larger mineral constituents showed higher sorption capacity for SO<sub>2sub> than RH-biochar containing less mineral components. CaCO<sub>3sub> and Ca<sub>3sub>(PO<sub>4sub>)<sub>2sub> in DM-biochar induced sorbed SO<sub>2sub> transformation into K<sub>2sub>Ca(SO<sub>4sub>)<sub>2sub>·H<sub>2sub>O and CaSO<sub>4sub>·2H<sub>2sub>O, while the sorbed SO<sub>2sub> was converted to Fe<sub>2sub>(SO<sub>4sub>)<sub>3sub>·H<sub>2sub>SO<sub>4sub>·2H<sub>2sub>O, CaSO<sub>4sub>·2H<sub>2sub>O, and Ca<sub>3sub>(SO<sub>3sub>)<sub>2sub>SO<sub>4sub>·12H<sub>2sub>O in SS-biochar. For RH-biochar, K<sub>3sub>H(SO<sub>4sub>)<sub>2sub> might exist in the exhausted samples. Overall, the chemical transformation of SO<sub>2sub> induced by biochar inherent mineral components occupied 44.6%–85.5% of the total SO<sub>2sub> sorption. The results obtained from this study demonstrated that biochar as a unique carbonaceous material could distinctly be a promising sorbent for acidic SO<sub>2sub> removal in which the inorganic components played an important role in the SO<sub>2sub> sorption and transformation.