Flocculation of clay suspensions with water‐insoluble starch grafting acrylamide/sodium allylsulfonated copolymer powder

Use of water‐soluble and ‐insoluble starch grafting acrylamide/sodium allylsulfonated copolymers as flocculants to flocculate the clay suspension was investigated. The composition of acrylamide (AM), sodium allylsulfonated (SAS), and starch (St) repeating units in the water‐soluble and ‐insoluble starch‐grafted copolymer is about 0.718, 0.022, and 0.260 and 0.439, 0.014, and 0.547, respectively. For the water‐soluble starch‐grafted copolymer, the fast initial A r decreasing rate and the lowest final A r value occur at pH 2, 80 mg/L water‐soluble starch‐grafted copolymer and 100 mg/L clay suspension. As the suspension contains 1000 mg/L Na + ion, the flocculating capability would be increased. For the water‐insoluble starch‐grafted copolymer, the initial A r decreasing rate and the final A r value are 1.6 times and 0.4 times, respectively, that of the water‐soluble starch‐grafted copolymer at the same test suspension.