Extraction of palm tree cellulose and its functionalization via graft copolymerization

Abstract

The work in this paper was planned with the aim of extracting the cellulosic component of palm tree waste and functionalizing this cellulose through graft copolymerization with acrylic acid. The cellulose extraction included hot alkali treatment with aqueous sodium hydroxide to remove the non-cellulosic binding materials. The alkali treatment was followed by an oxidative bleaching using peracid/hydrogen peroxide mixture with the aim of removing the rest of non-cellulosic materials to improve the fiber hydrophilicity and accessibility towards further grafting reaction. Optimum conditions for cellulose extraction are boiling in 5% (W/V) NaOH in a material to liquor ratio of 1:20 for 1h then bleaching with 60ml/l bleaching mixture at initial pH value of 6.5 for 30min. The pH of the bleaching medium is turned to the alkaline range 11 and bleaching continues for extra 30min. Graft copolymerization reaction was initiated by potassium bromate/thiourea dioxide redox system. Optimum conditions for grafting are 30mmol of potassium bromate, 30mmol of thiourea dioxide and 150g of acrylic acid (each per 100g of cellulose). The polymerization reaction was carried out for 120min at 50°C using a material to liquor ratio of 1:20.