Department of Chemical Engineering, University of Wyoming, Laramie, WY 82071, USA.
Department of Chemical Engineering, University of Wyoming, Laramie, WY 82071, USA.
J Environ Sci (China). 2019 Feb;76:133-141. doi: 10.1016/j.jes.2018.04.016. Epub 2018 Apr 30.
Elevated arsenic and selenium concentrations in water cause health problems to both humans and wildlife. Natural and anthropogenic activities have caused contamination of these elements in waters worldwide, making the development of efficient cost-effective methods in their removal essential. In this work, removal of arsenate and selenite from water by adsorption onto a natural goethite (α-FeOOH) sample was studied at varying conditions. The data was then compared with other arsenate, selenite/goethite adsorption systems as much of literature shows discrepancies due to varying adsorption conditions. Characterization of the goethite was completed using inductively coupled plasma mass spectrometry, X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, and Brunauer-Emmett-Teller surface area analysis. Pseudo-first order (PFO) and pseudo-second order (PSO) kinetic models were applied; including comparisons of different regression methods. Various adsorption isotherm models were applied to determine the best fitting model and to compare adsorption capacitates with other works. Desorption/leaching of arsenate and selenite was studied though the addition of phosphate and hydroxyl ions. Langmuir isotherm modeling resulted in maximum adsorption capacities of 6.204 and 7.740 mg/g for arsenate and selenite adsorption, respectively. The PSO model applied with a non-linear regression resulted in the best kinetic fits for both adsorption and desorption of arsenate and selenite. Adsorption decreased with increasing pH. Phosphate induced desorption resulted in the highest percentage of arsenate and selenite desorbed, while hydroxide induced resulted in the fastest desorption kinetics.
水中砷和硒浓度的升高会对人类和野生动物的健康造成影响。自然和人为活动导致这些元素在世界范围内的水中受到污染，因此开发高效、经济实惠的去除方法至关重要。在这项工作中，通过吸附到天然针铁矿（α-FeOOH）样品上来研究从水中去除砷酸盐和亚硒酸盐的条件。然后将数据与其他砷酸盐、亚硒酸盐/针铁矿吸附系统进行比较，因为许多文献显示由于吸附条件的不同而存在差异。通过电感耦合等离子体质谱、X 射线衍射、傅里叶变换红外光谱、扫描电子显微镜和 Brunauer-Emmett-Teller 表面积分析对针铁矿进行了表征。应用了伪一级（PFO）和伪二级（PSO）动力学模型；包括比较不同回归方法。应用各种吸附等温线模型来确定最佳拟合模型，并与其他工作进行吸附容量比较。通过添加磷酸盐和羟基离子研究了砷酸盐和亚硒酸盐的解吸/浸出。Langmuir 等温线模型得出的砷酸盐和亚硒酸盐吸附的最大吸附容量分别为 6.204 和 7.740 mg/g。应用非线性回归的 PSO 模型对砷酸盐和亚硒酸盐的吸附和解吸均具有最佳的动力学拟合。吸附随 pH 值的增加而降低。磷酸盐诱导的解吸导致砷酸盐和亚硒酸盐的解吸百分比最高，而氢氧化物诱导的解吸则具有最快的解吸动力学。
