Response Surface Method to Optimize the Treatment of Cd²⁺-Containing Wastewater with Low-Grade Iron Tailings Loaded with Chitosan

This is a paper in the field of mineral materials and environmental engineering. In this paper, cadmium-containing wastewater was used as the research object, and low-grade iron tailings loaded with chitosan was used as the adsorbent to compare the adsorption effect of low-grade iron tailings on Cd²⁺ before and after loading chitosan. The results showed that the adsorption effect of the composite adsorbent better than low-grade iron tailings adsorbent; At the same time, the Box-Behnken Design (BBD) response surface method is used to design the experiment, and the cadmium ion adsorption rate (Q) is used as the response value. The initial pH value, the amount of adsorbent added and the adsorption time are investigated. The three influencing factors have separate and interactive effects on the adsorption and removal of cadmium by chitosan loaded on low-grade iron tailings, and a nonlinear quadratic multiple regression prediction model of the influencing factors of low-grade iron tailings loaded with chitosan and cadmium ions is established: Q=86.16+14.68×A+5.21×B+1.36×C−1.98×A×B−1.54×A×C−0.46×B×C−6.75×A²+0.12×B²+1.25C², and got the better optimizedexperimental conditions for adsorption. The results show that the primary and secondary order of the influencing factors of the composite adsorbent on the Cd²⁺ adsorption rate is initial pH value> adsorbent added amount> adsorption time. When the initial pH value is 8.00, the amount of adsorbent added is 25.00 g/L, the adsorption time is 15 min, the initial Cd²⁺ concentration is 30 mg/L, and the adsorption temperature is about 25 ℃, the predicted value of the maximum adsorption rate of Cd²⁺ is 99.33%, the experimental value is 99.16%, and the experimental value is basically the same as the predicted value, indicating that the model is reasonable for the Cd²⁺ adsorption optimization model and its optimization conditions are feasible.