Treatment of Low Concentration Cadmium-Containing Wastewater by Modified Starch

The low concentration cadmium-containing wastewater is generally difficult to dispose in industry and can cause seriously side effect on the environment. The way of grafting acrylamide onto starch and then reacting with mercaptoacetic acid was attempted to settle this problem. An investigation was mainly carried out to discuss the effect of St/AM (weight ratio of starch to acrylamide) on grafting ratio and grafting efficiency in graft copolymerization, and the thiol (SH) group content of the final product. The high cadmium removal percentage was achieved by using high grafting ratio, grafting efficiency and thiol group conten product in the treatment of low concentration cadmium-containing wastewater under the conditions of pH=8 and the addition concentration of 2.0 g.L^-1. Simultaneously, the results were compared between product with single graft reaction and that with thiol reaction subsequently, and then the mechanism was explored.