Polyacrylamide

The physical properties of polyacrylamides are decided by copolymerizing with a variety of different vinylic monomers. Polyacrylamide can be manufactured as cationic, non-ionic, or anionic polymer. Both cationic and anionic polyacrylamides are produced by the process of copolymerisation of acrylamide. Cationic polyacrylamides are useful for flocculation of sewage sludge and various industrial wastes, as well as retention aids in the paper industry (Barvenik, 1994).

Large quantities of acrylamide are used in the production of polyacrylamide gel as a grouting agent to stabilize mineshafts in the mining industry, tunnels, and dams to increase the strength and to restrict the flow of water through a structure (Mona et al., 2001). In the mining process, polyacrylamides are used as flocculants to separate solids from aqueous solutions. It is also used in the disposal of industrial wastes and in the cleansing of water supplies (European Commission, 2002). Polyacrylamide allow more concentrated sludge when they are used as sludge conditioning or dewatering agent than inorganic coagulants. When polyacrylamide is used in potable water treatment, it must not exceed of 0.05% of its monomer; however there are polyacrylamides containing 0.1-5% of monomer used as industrial coagulants (Croll et al., 1974). The principle of the coagulation process is when the polymers bind with the particles, it will form heavy aggregates that quickly settle out of solution and leave clear supernatant (Barvenik, 1994). The most effectual polymer is the one that have high molecular weight cationic polyacrylamide (1.5 X106 g mol-1) as it obtains a high exclusion efficiency % with dosage as low as 64 mg L-1 (Arifin et al., 2004).