Removal of Fluoride Ions from Strongly Acidic Wastewater Using a Chelating Resin Containing Aluminum

摘要

Strongly acidic wastewater containing fluoride ions generated from nonferrous metal smelting and coal-coking industry is very harmful to the environment, but it has certain recovery value as sulfuric acid from the point of view of resource recovery. Before the wastewater is reused, the removal of fluoride ions is necessary to improve the quality of the recovered sulfuric acid and meet the production requirement of subsequent chemicals. In this paper, a novel macroporous polystyrene aluminum-containing chelating resin(D406) was used to remove fluoride ions in strongly acidic aqueous solution based on the strong coordination interaction between aluminum ions and fluoride ions. The adsorption influence factors, reuse performance, adsorption isotherm model, and kinetics of the chelating resin on fluoride ions were studied systematically. In addition, XPS analysis was conducted on the resin before and after adsorption of fluoride ions, as well as after regeneration. The results showed that under the optimal conditions of resin dosage 30g/l, stirring speed 150 rpm, operating temperature 25℃, and contact time 80min, the corresponding removal rate of fluoride ions reached 95.9%. The XPS results showed there had obvious changes in the content of various elements during adsorption and regeneration, but during the adsorption and regeneration process of the resin, the valence state of aluminum element did not change. After saturation, the resin could be regenerated by using 5% aluminum sulfate solution easily. The absorption performance of the resin decreased only 5.1% after five times regeneration, indicating that the resin has good regeneration performance. In addition, the Freundlich isothermal adsorption model gave the best correlation with the experimental data, and the adsorption process was found to follow the quasi-second-order kinetic model.