Hu Hao, Zhao Donglin, Wu Changnian, Xie Rong
Key Laboratory of and Functional Molecule Design and Interface Process, Anhui Jianzhu University, Hefei 230601, China.
Materials (Basel). 2022 May 30;15(11):3898. doi: 10.3390/ma15113898.
In this study, sulfidized nanoscale zerovalent iron (S-nZVI) supported by oyster shell (OS) powder (S-nZVI@OS) was synthesized by controlling the initial S/Fe ratios (0.1-0.5) to explore the potential synergistic effects during the adsorption and reduction of Cr (VI). X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) analyses showed that Fe (0) and FeS were well dispersed on the OS surface. Furthermore, the stability of S-nZVI@OS composite was higher than that of nZVI, which was proved by the material ageing experiment. The effects of different S/Fe molar ratios, time, temperature, the initial concentration of Cr (VI), and initial pH on the removal efficiency were also studied. The results indicated that with the increase of the S/Fe molar ratio, the removal capacity of Cr (VI) first increased rapidly and then decreased slowly. Batch experiments showed that an optimal S/Fe molar ratio of 0.2 offered a Cr (VI) removal capacity of about 164.7 mg/g at pH 3.5. The introduction of S can not only promote Cr (VI) reduction but also combine with Cr (III) by forming precipitate on S-nZVI@OS mainly as CrFe OOH and CrS. The adsorption thermodynamics and kinetics demonstrated that the Langmuir model and pseudo-second-order kinetics model can describe the adsorption isotherms and kinetics. These results suggest that S-nZVI@OS is an effective and safe material for removing Cr (VI) from aqueous solutions.
在本研究中，通过控制初始S/Fe比（0.1 - 0.5）合成了由牡蛎壳（OS）粉末负载的硫化纳米零价铁（S-nZVI@OS），以探索在Cr（VI）吸附和还原过程中的潜在协同效应。X射线衍射（XRD）、透射电子显微镜（TEM）和X射线光电子能谱（XPS）分析表明，Fe（0）和FeS在OS表面分散良好。此外，材料老化实验证明S-nZVI@OS复合材料的稳定性高于nZVI。还研究了不同S/Fe摩尔比、时间、温度、Cr（VI）初始浓度和初始pH对去除效率的影响。结果表明，随着S/Fe摩尔比的增加，Cr（VI）的去除能力先迅速增加，然后缓慢下降。批次实验表明，在pH 3.5时，最佳S/Fe摩尔比为0.2时，Cr（VI）的去除能力约为164.7 mg/g。S的引入不仅能促进Cr（VI）的还原，还能通过在S-nZVI@OS上形成主要为CrFe OOH和CrS的沉淀物与Cr（III）结合。吸附热力学和动力学表明，Langmuir模型和准二级动力学模型可以描述吸附等温线和动力学。这些结果表明，S-nZVI@OS是一种从水溶液中去除Cr（VI）有效且安全的材料。
