Judul: Microwave Initiated Synthesis of Flocculants Based on Modified Sago Starch for the Treatment of Suspended Solid in Water.
Abstrak: Flocculants usually are polymer. There are two types of polymer, synthetic polymer and natural polymer. The properties of synthetic polymer, for example polyacrylamide (PAM), are nonbiodegradable, forming a fragile floc (low shear stability), can be used at small amount with high performance of flocculation, and has a better shelf life. Natural polymers properties such as polysaccharides (starch) are biodegradable, forming a high shear stability floc, should be use in a higher amount of flocculant compare to the synthetic one, and has a shorter shelf life. A new polymer contained both of them can be produced by using microwave irradiation with graft copolymerization technique. The utilization of microwave irradiation on graft copolymerization is more preferred because of its selective reaction site, short reaction time and electronically easy to control. This research are aimed to identify the best process conditions for synthesizing of flocculants (using two treatment factors: amount of acrylamide and microwave irradiation time) and to identify the performance of flocculants on reducing suspended solids contained in water. The research’s steps are physico-chemical properties analysis of sago starch, sago starch carboxymethylation reaction to produce carboxymethyl starch (CMS), graft copolymerization reaction of CMS with acrylamide by using microwave irradiation to produce CMS-g-PAM floculant, physico-chemical properties analysis of CMS-g-PAM and flocculation performance test of CMS-g-PAM on river water. Sago starch’s proximate analysis result indicate that sago starch properties are as follow: water content 5.93%, ash content 0.02%, protein content 1.05%, oil or fat content 0.97%, raw fiber content 0.15%, and carbohydrate content 91.88%. Starch content of sagu starch is 67.48%, a third (15.42%) of it is amylose and the rest of it is amylopectin (52.06%). FTIR test results on sago starch, CMS and CMS-g-PAM indicated a slightly change in the functional group structure. This is probably due to the reaction conducted does not perfectly occurred. The reason is gelatinization reaction when synthesis CMS is not completely occurred and copolymerization temperature does not not reach the gelatinization temperature. More than 90% CMS can be graft-copolymerized with acrylamide and result in CMS-g-PAM. The highest conversion rate is 99.82% and it is resulted from the treatment combination of amount of acrylamide 100 ml (equivalent to 50 g or 0.70 moles) and 3 minutes copolymerization reaction time. Analysis of variance (ANOVA) results at 95% confidence level on conversion rate indicate that the amount of acrylamide, copolymerization reaction time and interaction of both of them does not significantly change the value of conversion rate. Grafting ratio (GR) and grafting efficiency (GE) yielded by the treatment of acrylamide concentration and microwave irradiation length time are vary, 0.87% to 10.06% for GR and 0.076% to 0.349% for GE. The test results of analysis of variance (α=0.05) indicate that GR and GE values are significantly affected by amount of acrylamide, copolymerization reaction time and interaction both of them. Each level of all treatment has significantly different effect on the GR and GE value changing. Only the treatment level of amounts of acrylamide 50 and 100 ml that is not significantly different effect on the GE values. Based on the conversion rate value and
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