Study on the Effect of Thermal Activation on Arsenic Removal from Industrial Wastewater

Industrial wastewater contains a large amount of arsenic, which will cause serious harm to the environment unless it is treated effectively. Due to the fact that P2S5 does not contain metal cations and does not affect the reuse of acids, it is used for arsenic removal instead of the traditional sulfurizing agents, Na2S and NaHS. The experimental results show that under the optimal conditions of S/As molar ratio 2.1:1, reaction temperature 70°C, and reaction time 45 min, the removal rate of arsenic reached 98.36%. An increase of temperature can effectively reduce the viscosity of a solution and improve the overall reaction rate. The viscosity of this solution was 1.08 mPa s at 25°C, and was reduced by more than half, to 0.49 mPa s, at 65°C. XRD, XPS, and SEM-EDS were used to analyze the residue. The structure of the residue was loose, and the main component was arsenic sulfide. Through kinetic research, diffusion control dominates the process of arsenic removal by P2S5, with an apparent activation energy of Ea = 28.08 kJ/mol. This study contributes to the further exploration of arsenic removal from industrial high arsenic wastewater.