Key Laboratory of Hangzhou City for Ecosystem Protection and Restoration, Hangzhou Normal University, Hangzhou 310036, China.
Key Laboratory of Hangzhou City for Ecosystem Protection and Restoration, Hangzhou Normal University, Hangzhou 310036, China.
Sci Total Environ. 2020 May 10;716:137108. doi: 10.1016/j.scitotenv.2020.137108. Epub 2020 Feb 4.
Waste emissions have increased the amount of water and soil contaminated with heavy metals such as Pb. To broaden the methods for the recycling and environmental usage of cow manure (CM) and its vermicompost (CV), CM, CV, and their derived biochars produced by the pyrolysis of CM or CV at 350 and 700 °C were used as adsorbents for Pb removal in this batch adsorption experiment to reveal their different Pb removal efficiencies and the underlying mechanisms. The batch experiment results revealed that all adsorbents rapidly removed Pb within 30 min. A pH between 2.0 and 6.0 positively affected Pb removal by CM and its biochar, whereas that by CV and its biochar was only positively affected by pH between 2.0 and 3.0. CV-derived biochar was more effective in the removal of Pb than the other absorbents, with the maximum adsorption capacities (Qm) fitted from the Langmuir model reaching approximately 230.0 mg·g and the desorption rate (DR) being approximately 0.00-0.02%. Material physiochemical characterization, including X-ray diffraction analysis, showed that high pH, high ash content, rich mineral content, and high mineral contents might have been the main reasons for more effective removal of Pb from aqueous solutions by CV-derived biochar. Fourier-transform infrared analysis indicated that surface functional groups such as -OH, CO, -COO-, and C-O; original and newly produced carbonate; and phosphate in CV also led to more effective Pb removal efficiency from aqueous solution via surface functional group binding. Thus, pyrolyzing CVs may be used to produce biochar as a cost-effective adsorbent for heavy metal remediation in soil and water in the future.
废物排放增加了受 Pb 等重金属污染的水和土壤的数量。为了拓宽牛粪 (CM) 和其蚯蚓粪 (CV) 的回收和环境利用方法，本批吸附实验中使用了由 CM 或 CV 在 350 和 700°C 热解产生的 CM、CV 及其衍生生物炭作为 Pb 去除的吸附剂，以揭示它们不同的 Pb 去除效率和潜在机制。批实验结果表明，所有吸附剂在 30 分钟内迅速去除 Pb。pH 值在 2.0 到 6.0 之间有利于 CM 及其生物炭对 Pb 的去除，而 CV 及其生物炭仅在 pH 值在 2.0 到 3.0 之间时受到促进。CV 衍生的生物炭在去除 Pb 方面比其他吸附剂更有效，Langmuir 模型拟合的最大吸附容量 (Qm) 约为 230.0mg·g-1，解吸率 (DR) 约为 0.00-0.02%。材料物理化学特性分析，包括 X 射线衍射分析，表明高 pH 值、高灰分含量、丰富的矿物质含量和高矿物质含量可能是 CV 衍生生物炭更有效地从水溶液中去除 Pb 的主要原因。傅里叶变换红外分析表明，表面官能团如-OH、CO、-COO-和 C-O；原始和新生成的碳酸盐；以及 CV 中的磷酸盐也通过表面官能团结合导致从水溶液中更有效地去除 Pb。因此，未来可能会利用热解 CV 来生产生物炭作为一种经济有效的土壤和水中重金属修复吸附剂。
