Sintesis dan Pencirian Superabsorben Onggok-g-Asam Akrilat

Abstract

Onggok is a solid waste from tapioca processing. The aim of this study is to modify onggok into superabsorbent polymer. The modification was conducted through grafting and crosslinking of acrylic acid (AA) on onggok backbone, with N,N’-methylene-bis-acrylamide (MBA) as crosslinker, and ammonium persulfate (APS) as initiator. The synthesis was conducted at 70 oC for 3 hours and the water absorption capacity of the copolymer products were then measured. A 761.01 g/g value was obtained from copolymer composed of 4.5 g onggok, 25.5 g AA, 24 mg MBA, and 24 mg APS. The occurence of grafting-crosslinking copolymer was confirmed by infrared spectra, which exhibited all characteristic bands of both polysaccharide fractions of onggok and AA units. The absorbency of superabsorbents were measured in solutions having pH ranging from 2 to 11. The maximum value was 630.65 g/g at pH 6.65. The superabsorbent’s absorbency in salt solution was decreased with increasing ionic strength up to 0.342 M concentration of NaCl. The absorbency kinetics of superabsorbents were studied as well and the rate parameter in water was found to be 2.61 minutes for onngok with 60 mesh particle size.