Evaluation of microwave assisted alkaline pretreatment for extraction of cellulose from selected lignocellulosic materials

Abstract

The objective of the present study is to evaluate the performance of the microwave assisted pretreatment method by subjecting five selected biomasses; Corn leaves, Corn Husks, Bagasse, Guinea grass and Sugar cane leaves, to obtain the maximum cellulose percentages with optimum pretreatment concentration and minimum exposure time on selected range. This method was performed by using a domestic microwave oven. Different concentrations of three solutions; NaOH - 1.25mol/L, 2.5 mol/L and 5 mol/L were used as pretreatment solutions. Total of 25 g of selected biomass with 250 ml of pretreatment solution was added in a 500 ml beaker and irradiated under microwave power of 170 W for 15minutes, 30 minutes and 45minutes. Forty five treatments consisted of combinations of five biomasses, three NaOH solutions and three expose time for irradiation. Percentages of weight losses of pretreated fibers were measured. In addition, Percentages of cellulose of treaded fibers were evaluated using chlorination method. Data was analyzed by using Minitab 14 version. Additionally, pretreated fibers with the highest percentage of cellulose obtained after evaluation of samples were analyzed using Fourier Transform Infra-Red Spectrometry (FTIR) to confirm extracted fibers were cellulose. Analysis results indicated that bio mass, NaOH concentration, time and (Bio mass × NaOH concentration) were significant for percentage weight loss. Except for time and (NaOH concentration × Time), other factors were significant for percentage cellulose extracted (P <0.05). According to the results of main and interaction effects graphs of percentage of cellulose, all pretreated fibers comprised 65% - 85% of cellulose from pretreatment comprising 5 mol/L NaOH and 15 minutes of 170W microwave dose. FTIR analysis of extracted cellulose fibers from 5 mol/L NaOH and 15 minute treatment confirmed that extracted fibers were cellulose. Best condition for microwave alkaline pretreatment for a selected biomasses was found to be 5 mol/L NaOH and 15 minutes of 170W microwave dose.