Synthesis, characterization and exploitation of nano-TiO2/feldspar-embedded chitosan beads towards UV-assisted adsorptive abatement of aqueous arsenic (As)
Synthesis, characterization and exploitation of nano-TiO2/feldspar-embedded chitosan beads towards UV-assisted adsorptive abatement of aqueous arsenic (As)
复制标题
DOI：
10.1016/j.cej.2017.01.121
复制
发表时间：
2017-05
影响因子：
15.1
通讯作者：
M. Yazdani;A. Bhatnagar;R. Vahala
中科院分区：
文献类型：
--
作者：
M. Yazdani;A. Bhatnagar;R. Vahala
本研究旨在开发一种生态友好的生物光催化剂，用于水相砷的去除。通过将纳米TiO 2和长石微粒固定在壳聚糖基体中，制备了纳米TiO 2/长石包埋壳聚糖复合材料。采用傅里叶变换红外光谱（FTIR）、X射线衍射（XRD）、扫描电子显微镜（SEM）和能量色散谱（EDX）、比表面积（BET）等方法对复合材料进行了表征。采用紫外光照装置进行了间歇吸附实验，研究了溶液pH、紫外光照和共存离子等操作参数，沿着了吸附过程的动力学、等温线和热力学。与其他TiO 2为基础的修复技术，合成的复合材料有效地去除砷在很宽的pH值范围内，与轻微的去除下降，随着pH值的增加，砷酸盐和pH值的影响可以忽略不计的砷去除。当氟离子和硫酸根离子共存时，对砷酸根表现出选择性去除，而当磷酸根离子浓度较高时，表现出一定的竞争性去除。通过线性和非线性模型研究了吸附等温线和动力学。Sips等温线和准二级动力学模型与实验数据拟合最好。线性和非线性模型的最大吸附容量分别为2000和2025 μg/g。紫外光照射下的吸附-反硝化系统对砷和亚砷酸盐的去除率均较高。紫外光照射使砷和亚砷酸盐（4800 μg/L）的去除率分别从33%提高到73%和23%提高到84%。温度研究揭示了一个化学自发的和有利的过程。通过表征分析，确定了壳聚糖结构上的-NH 2和-OH沿着金属氧化物含量的引入，作为吸附-光活性位点。
This study aimed to develop an ecofriendly bio-photocatalyst for arsenic abatement in the aqueous phase. Nano-TiO2/feldspar embedded chitosan composite was developed by immobilizing nano-sized TiO2and feldspar fine particles in the matrix of chitosan, which was then characterized via Fourier Transform Infrared Spectrometry (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDX), and Brunauer, Emmett and Teller (BET) surface area analyses. Batch adsorption experiments equipped with UV-illumination set-up were conducted to study operational parameters, e.g. solution pH, UV light and co-existing ions, along with the kinetics, isotherm and thermodynamics of the process. Unlike other TiO2-based remediation techniques, the synthesized composite effectively removed arsenic in a wide range of pH, with a slight removal drop with increasing pH for arsenate and negligible pH influence on arsenite removal. It showed selective removal for arsenate in the presence of co-existing ions including fluoride and sulfate, yet, phosphate indicated somewhat competing effect when existed in higher concentrations. The isotherm and kinetics of adsorption were investigated through linear and nonlinear modeling. Sips isotherm and pseudo-second order kinetic models best fitted with the experimental data. Langmuir’s maximum adsorption capacities via linear and nonlinear modeling were found to be 2000 and 2025 μg/g, respectively. The adsorption-photocatalysis system under UV exposure resulted in higher removal of both arsenate and arsenite. UV irradiation enhanced removal efficiencies from 33% to 73% and from 23% to 84% for arsenate and arsenite (4800 μg/L), respectively. Temperature studies revealed a thermodynamically spontaneous and favorable process. Identified through characterization analyses, functional groups on chitosan structure including –NH2and –OH along with the metal oxide contents of the bio-photocatalyst are introduced as the adsorptive-photoactive sites.