Key Laboratory of Yellow River Water Environment in Gansu Province, Lanzhou Jiaotong University, Lanzhou 730070, China E-mail:
College of Chemistry and Chemical Engineering, Ningxia Normal University, Guyuan 756000, China.
Water Sci Technol. 2022 Dec;86(12):3163-3180. doi: 10.2166/wst.2022.394.
The sulfidation of nanoscale zerovalent iron (nZVI) has received increasing attention for reducing the oxidizability of nZVI and improving its reactivity toward heavy metal ions. Here, a sulfide (S)-modified attapulgite (ATP)-supported nanoscale nZVI composite (S-nZVI@ATP) was rapidly synthesized under acidic conditions and used to alleviate Cd toxicity from an aqueous solution. The degree of oxidation of S-nZVI@ATP was less than that of nZVI@ATP, indicating that the sulfide modification significantly reduced the oxidation of nZVI. The optimal loading ratio was at an S-to-Fe molar ratio of 0.75, and the adsorption performance of S-nZVI@ATP for Cd was significantly improved compared with that of nZVI@ATP. The removal of Cd by S-nZVI@ATP was 100% when the adsorbent addition was 1 g/L, the solution was 30 mL, and the adsorption was performed at 25 °C for 24 h with an initial Cd concentration of 100 mg/L. Kinetics studies showed that the adsorption process of Cd followed the pseudo-second-order model, indicating that chemisorption was the dominant adsorption mechanism. The adsorption of Cd by S-nZVI @ATP is dominated by the complexation between the iron oxide or iron hydroxide shell of S-nZVI and Cd and the formation of Cd(OH) and CdS precipitates.
纳米零价铁（nZVI）的硫化受到越来越多的关注，因为它可以降低 nZVI 的氧化性并提高其对重金属离子的反应活性。在这里，在酸性条件下快速合成了一种硫化物（S）修饰的凹凸棒石（ATP）负载的纳米 nZVI 复合材料（S-nZVI@ATP），并将其用于缓解水溶液中 Cd 的毒性。S-nZVI@ATP 的氧化程度小于 nZVI@ATP，表明硫化修饰显著降低了 nZVI 的氧化程度。最佳负载比为 S 与 Fe 的摩尔比为 0.75，与 nZVI@ATP 相比，S-nZVI@ATP 对 Cd 的吸附性能明显提高。当吸附剂添加量为 1 g/L、溶液为 30 mL、在 25°C 下吸附 24 h、初始 Cd 浓度为 100 mg/L 时，S-nZVI@ATP 对 Cd 的去除率达到 100%。动力学研究表明，Cd 的吸附过程符合准二级动力学模型，表明化学吸附是主要的吸附机制。S-nZVI@ATP 对 Cd 的吸附主要是由 S-nZVI 的氧化铁或氢氧化铁壳与 Cd 的络合以及 Cd(OH)和 CdS 沉淀的形成所主导。
