Resumen
Microwave assisted synthesis method was employed to graft polyacrylamide onto the backbone of cellulose extracted from waste newspapers (WNP) resulting polyacrylamide grafted cellulose (PAM-g-cellulose). This method combined microwave radiation and chemical free radical initiator (ceric ammonium nitrate) to create free radical sites on the backbone of cellulose which then initiated the chain growth polymerization. The cellulose used was extracted from WNP via alkaline treatment and bleaching treatment. Characterization results of Fourier transform infrared (FTIR) spectrophotometer and scanning electron microscope (SEM) confirmed the present of cellulose and the changes of WNP properties after chemical treatment. Graft copolymerization of acrylamide onto cellulose was studied by varying the ratio of cellulose to acrylamide, reaction time and initiator dosage. The results obtained show that the best developed flocculant with grafting percentage of 320% could be achieved at a cellulose to acrylamide ratio of 7, initiator dosage of 0.6g, and response time of 90 seconds. The successfulness of copolymer grafting was confirmed by SEM and FTIR. The flocculation performance of the PAM-g-cellulose was evaluated via jar test method using a synthetic kaolin suspension at various flocculant dosages and pH conditions. It was found that PAM-g-cellulose with molar ratio of cellulose to acrylamide is 1:7 exhibited a highly effective flocculation capability (96.23%) as compared to other synthesized grafted copolymer. The results indicated that the flocculant dosage and pH affected the flocculation efficiency significantly. The highest percentage turbidity removal of kaolin suspension was achieved at flocculant dosage of 200 ppm in an acidic condition of pH 3. Overall, the results demonstrated the potential of PAM-g-cellulose extracted from WNP to serve as eco-friendly flocculants in water treatment.