High-capacity strong cation exchanger prepared from an inactivated immobilized enzyme and its application to the removal of methylene blue from water

Environmental protection has become a very important issue. The transformation of solid waste into profitable products to remove hazardous chemicals from environmental samples has attracted much attention. In this study, inactivated immobilized enzymes were reutilized by converting into an adsorbent for the first time, and poly(sodium 4-styrene sulfonate) (poly(NASS)) was grafted from the surface of the particles using surface-initiated atom transfer radical polymerization (SI-ATRP) to produce a strong cation exchanger. X-ray photoelectron spectroscopy (XPS) confirmed the successful grafting of poly(NASS). The cation exchanger exhibited very good performance for the adsorption of methylene blue (MB) with a high capacity (409.8 mg g(-1)) and fast speed (equilibrium achieved within 1 min), the removal ratio was more than 96.4-99.2% when the MB concentration ranged from 10 to 800 mg L-1, and the removal efficiency of the cation exchanger for MB was 397.1 mg (g(-1) min(-1)), these properties are much better than those previously reported materials. The cation exchanger can be used for five times with removal ratio higher than 80%. Additionally, the adsorption exhibited no significant pH and temperature dependence, and more than 80% capacity was maintained at high concentrations of sodium chloride up to 0.4 mol L-1, therefore the exchanger is very favorable for removal of MB from wastewater with different pH values and salt concentrations, and can be used in a wide temperature range.