Optimization of NaOH concentration and cooking time in delignification of mature coconut (Cocus nucifera L.) coir

Abstract

The main product of mature coconuts is coconut meat, while its by-products consisting of coconut water, shell fiber and coir. Coconut coir contains 75% fiber and 25% cork. The high value of fiber in coconut coir provides an opportunity to be utilized in making paper. Coconut fiber has a cellulose content of 26.6%-43.44% and lignin of 29.4%-45.84%. Due to the high lignin content, delignification process should be carried out which can be done using sodium hydroxide (NaOH). This study aims to obtain the optimal point of addition of NaOH and cooking time to produce optimal cellulose and lignin levels in the delignification of the mature coconut fiber pulping process. The research method uses the Response Surface Methodology (RSM) with two factors and two optimized responses. The experimental design was performed with a central composite design. The variables involved were NaOH concentration (5-15%) and cooking time (90-150 minutes). Two responses studied were lignin and cellulose content. The combination of these treatments produces the optimum point of NaOH concentration of 5% and cooking time of 150 minutes, resulting in 15.56% lignin content and 37.29 % cellulose content.