Preparation polymer-grafted magnetic starch adsorption material St/Fe3O4-g-p(GMA-r-HEMA) used for removal of heavy metals

Heavy metal ion (Cu(II)) wastewater will do great harm to human body and environment, and the adsorption materials used in traditional adsorption methods are easy to hydrolyze, resulting in secondary pollution to water. In this paper, an adsorption material poly(glycidyl methacrylate-random-hydroxyethyl methacrylate) grafted ferric oxide@starch (St/Fe3O4-g-p(GMA-r-HEMA)) was prepared, which had epoxy and hydroxyl group, easy to produce crosslinking, reduce the sensitivity of starch to pH and prevent hydrolysis. Infrared spectroscopy (FTIR), thermogravimetric analysis (TG), scanning electron microscopy (SEM) and magnetometer (VSM) were used to characterize the structure and morphology of the adsorbent. The adsorption properties of the adsorbent for removal of Cu(II) ions were studied via changing the experimental conditions, including the amount of adsorbent, Cu(II) ions solution concentration, pH value, adsorption time, adsorption temperature and so on. Under the optimal adsorption conditions of pH value 7, initial Cu(II) concentration 20 mg/L and adsorption time 160 min, the maximum unit adsorption capacity of St/Fe3O4-g-p(GMA-r-HEMA) was 94.15 mg/g, and the adsorption performance was good. The adsorption process followed Langmuirm model and second-order kinetic model, and was dominated by chemisorption. The thermodynamic model showed that the adsorption process of St/Fe3O4-g-p(GMA-r-HEMA) was endothermic. After 8 adsorption cycles, 93.5% of the first adsorption effect can still be retained, and the renewable performance had been improved.