College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, PR China.
College of Environmental Science and Engineering, Hunan University, Changsha, 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, PR China.
Chemosphere. 2018 Apr;197:291-298. doi: 10.1016/j.chemosphere.2018.01.042.
This study compared the sorption and extractability of Cu following adsorption (SOR) and coprecipitation(CPT). The effect of solution pH, Fe: organic carbon (OC) ratios and fulvic acid (FA) on the combined removal of Cu was investigated in the batch tests using Fe(III) precipitates as a sorbent. Transmission electron microscope (TEM) images demonstrated that the coexisting FA reduced the particle size of ferrihydrites as expected. Generally, more Cu was eliminated in coprecipitation compared with adsorption and the dissolved Cu left in solutions decreased as the pH increased, most of dissolved Cu was trapped at pH 6 and above. Meanwhile, the inhibition or promotion of Cu removal really depended on the different Fe: OC ratios. The addition of FA led to a further decrease of Cu concentrations in CPT systems with Fe/OC ratio of 1:3, however, Cu removal was hindered in the presence of FA in SOR systems. In the case of extraction experiments, the addition of l-malic acid (MA), oxalic acid (OA) and citric acid (CA) resulted in lower extractability of coprecipitated Cu than adsorption samples. The gaps in extractions were seemed to be a consequence of tight Cu binding in CPT products, and the more feasible desorption of Cu from the surface of SOR samples. Based on the results of Cu adsorption and coprecipitation, coprecipitation of Cu with ferrihydrites was the more effective Cu sequestration mechanism in the removal of Cu. These results are helpful to understand the complicated interactions among Fe(III), FA and Cu (II) in the natural environment.
本研究比较了吸附（SOR）和共沉淀（CPT）后铜的吸附和解吸特性。通过使用 Fe(III)沉淀物作为吸附剂的批量实验，考察了溶液 pH、Fe:有机碳（OC）比和腐殖酸（FA）对 Cu 联合去除的影响。透射电子显微镜（TEM）图像表明，与预期的一样，共存的 FA 减小了水铁矿的颗粒尺寸。通常，与吸附相比，共沉淀中更多的 Cu 被去除，随着 pH 的增加，溶液中溶解的 Cu 减少，大部分溶解的 Cu 在 pH 6 及以上被捕获。同时，Cu 去除的抑制或促进作用确实取决于不同的 Fe:OC 比。FA 的添加导致在 Fe/OC 比为 1:3 的 CPT 体系中 Cu 浓度进一步降低，然而，在 FA 存在的情况下，SOR 体系中 Cu 的去除受到阻碍。在萃取实验中，添加 L-苹果酸（MA）、草酸（OA）和柠檬酸（CA）导致共沉淀 Cu 的萃取性低于吸附样品。萃取中的差距似乎是由于 CPT 产物中 Cu 紧密结合，以及从 SOR 样品表面更可行地解吸 Cu。基于 Cu 吸附和共沉淀的结果，Cu 与水铁矿的共沉淀是去除 Cu 时更有效的 Cu 固定机制。这些结果有助于理解自然环境中 Fe(III)、FA 和 Cu(II)之间复杂的相互作用。
