Guangdong Industrial Contaminated Site Remediation Technology and Equipment Engineering Research Center, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou, 510006, PR China; College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642, PR China.
Guangdong Industrial Contaminated Site Remediation Technology and Equipment Engineering Research Center, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou, 510006, PR China; College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642, PR China.
Chemosphere. 2021 Jun;272:129594. doi: 10.1016/j.chemosphere.2021.129594. Epub 2021 Jan 11.
Adsorption characteristics of Cd on the three biochars modified by pyrolysis and calcination were investigated that were derived from rice straw (TRSB), chicken manure (TCMB) and sewage sludge (TSSB). The pH effect, adsorption kinetics, isotherms and thermodynamics, and desorption were determined, and qualitative analysis of adsorption mechanisms was performed by SEM, XRD, FTIR and XPS. Maximum adsorption capacities reached 177.28, 96.03 and 74.04 mg/g for TCMB, TRSB and TSSB, respectively, which were higher than that of many previously reported biochars. Even after five adsorption-desorption cycles, TCMB showed the strongest reusability without losing significantly adsorption capacity. This suggested that thermally modified biochars, particularly TCMB, could be a preferred adsorbent for Cd. Relative distribution of adsorption mechanisms was examined by direct and indirect calculation, in which the precipitation and cation-exchange dominated the whole chemisorption process, jointly accounting for 84% (TRSB) to 95% (TCMB) of total adsorption. While the complexation was of minor importance in total adsorption accounting for 5%-16%. The relationship of each mechanism with the properties of biochar was also discussed. These provided new insights on the adsorption effectiveness and mechanisms for Cd in the aqueous solution that was critical for evaluating the application of modified biochars.
研究了热解和煅烧改性的三种生物炭（稻草衍生的 TRSB、鸡粪衍生的 TCMB 和污水污泥衍生的 TSSB）对 Cd 的吸附特性。测定了 pH 值效应、吸附动力学、等温线和热力学以及解吸，并通过 SEM、XRD、FTIR 和 XPS 对吸附机制进行了定性分析。TCMB、TRSB 和 TSSB 的最大吸附容量分别达到 177.28、96.03 和 74.04 mg/g，高于许多先前报道的生物炭。即使经过五次吸附-解吸循环，TCMB 表现出最强的可重复使用性，而没有明显损失吸附能力。这表明热改性生物炭，特别是 TCMB，可以作为 Cd 的首选吸附剂。通过直接和间接计算考察了吸附机制的相对分布，其中沉淀和阳离子交换主导整个化学吸附过程，共占总吸附的 84%（TRSB）至 95%（TCMB）。而络合在总吸附中占次要地位，占 5%-16%。还讨论了每种机制与生物炭性质的关系。这些为评估改性生物炭的应用提供了关于水溶液中 Cd 的吸附效果和机制的新见解。
