School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China.
Water Res. 2012 Mar 1;46(3):854-62. doi: 10.1016/j.watres.2011.11.058. Epub 2011 Dec 1.
Lead sorption capacity and mechanisms by sludge-derived biochar (SDBC) were investigated to determine if treatment of acid mine drainage (AMD) containing metals with SDBC is feasible. It was found that the biochar derived from pyrolysis treatment of sewage sludge could effectively remove Pb(2+) from acidic solution with the capacities of 16.11, 20.11, 24.80, and 30.88mgg(-1) at initial pH 2, 3, 4 and 5, respectively. Lead sorption processes were pseudo-second order kinetic and faster at a higher pH. Furthermore, the relative contribution of both inorganic mineral composition and organic functional groups of SDBC for Pb(2+) removal mechanisms, was quantitatively studied at pH 2-5. The results showed that Pb sorption primarily involved the coordination with organic hydroxyl and carboxyl functional groups, which was 38.2-42.3% of the total sorbed Pb varying with pH, as well as the coprecipitation or complex on mineral surfaces, which accounted for 57.7-61.8% and led to a bulk of Ca(2+) and Mg(2+) release during sorption process. A new precipitate was solely observed on Pb-loaded SDBC as 5PbO·P(2)O(5)·SiO(2)(lead phosphate silicate) at initial pH 5, confirmed by XRD and SEM-EDX. The coordination of Pb(2+) with carboxyl and hydroxyl functional groups was demonstrated by FT-IR, and the contribution of free carboxyl was significant, ranging from 26.1% to 35.5%. Results from this study may suggest that the application of SDBC is a feasible strategy for removing metal contaminants from acid solutions.
研究了污泥衍生生物炭（SDBC）的铅吸附容量和机制，以确定用 SDBC 处理含金属的酸性矿山排水（AMD）是否可行。结果发现，通过对污水污泥进行热解处理得到的生物炭可以有效地从酸性溶液中去除 Pb(2+)，在初始 pH 值为 2、3、4 和 5 时的吸附容量分别为 16.11、20.11、24.80 和 30.88mg/g。铅吸附过程符合准二级动力学，在较高 pH 值下更快。此外，定量研究了 SDBC 中无机矿物成分和有机官能团对 Pb(2+)去除机制的相对贡献，在 pH 值为 2-5 时。结果表明，Pb 吸附主要涉及与有机羟基和羧基官能团的配位，这占总吸附 Pb 的 38.2-42.3%，随 pH 值而变化，以及矿物表面的共沉淀或络合，占 57.7-61.8%，导致大量 Ca(2+)和 Mg(2+)在吸附过程中释放。在初始 pH 值为 5 时，仅在负载 Pb 的 SDBC 上观察到一种新的沉淀物，即 5PbO·P(2)O(5)·SiO(2)(磷酸铅硅酸盐)，这通过 XRD 和 SEM-EDX 得到证实。Pb(2+)与羧基和羟基官能团的配位通过 FT-IR 得到证明，游离羧基的贡献很大，范围为 26.1%至 35.5%。本研究结果表明，SDBC 的应用是从酸性溶液中去除金属污染物的一种可行策略。
