Synthesis and characterization of thiol-polystyrene microsphere and its adsorption properties of thallium

^1. Key Laboratory of Water Pollution Control Technology, Hunan Research Academy of Environmental Science, Changsha Hunan 410004
^2. Department of Environmental Science and Engineering, College of Environment and Resources, Xiangtan University, Xiangtan, 411105

^* Corresponding author. E-mail: zyyhjgc0601@163.com (Yuanyuan Zhao) and 61080510@qq.com (Yuehui Chen)

Abstract

Thallium (Tl) is highly toxic in the environment. In order to solve the harm of Tl pollution to the environment, thiol-polystyrene microsphere (TPM) with good adsorption properties for Tl were prepared in this paper. The GAUSSIAN software was used to calculate the adsorption performance of the TPM on Tl⁺, and the adsorption mechanism was discussed. The thermogravimetric analysis show that the TPM prepared with chloromethyl polystyrene microspheres (CPM) and thiourea as the main raw materials has good chemical thermal stability. In the Tl⁺ solution of 1mg/L, the adsorption and removal rate of the TPMs in was 99%, with a significant adsorption of Tl⁺ properties. When the dosage of TPM is 0.4L/g, pH is 6-10, temperature is 5-20 °C, and adsorption time reaches 640min, thallium-containing water with Tl⁺ concentration of 5mg/L can be treated to within the national discharge standard (5μg/L). The analytical effect of 0.5mol/L dilute sulfuric acid on TPM can reach 99.96%, and the adsorption capacity of TPM on Tl⁺ is reduced by only 0.1% after repeated use 4 times, which has good regeneration performance. The modified polystyrene microspheres were characterized by EDS, FT-IR, Raman spectra and XPS, and it was proved that the TPM were ligated with Tl⁺ through the grafted mercapto group, so as to adsorb and remove Tl⁺ from the solution. According to the isotherm and kinetic model of TPM adsorption Tl⁺, the maximum saturated adsorption amount of TPM to Tl⁺ can reach 3.47mg/g, mainly chemical adsorption, and the membrane diffusion stage is the main control step of TPM adsorption Tl⁺. The results showed that the TPM could be a promising adsorbent with good adsorption capacity and reusability for Tl⁺ removal from wastewater