Influence of Soaking Time and Sodium Hydroxide Concentration on the Chemical Composition of Treated Mango Seed Shell Flour for Composite Application

Lignin and hemicelluloses are the major impurities to be removed in natural fibers for it to be suitable in composite application and other uses. This research is based on evaluating the influence of soaking time and sodium hydroxide concentration on the chemical composition of treated mango seed shell (MSSF) by immersing the MSSF in NaOH solution at concentration of 2.5 - 7.5 wt % and soaking time of 2-6 hr, in order to decrease the lignin and hemicellulose content while increasing its cellulose content. The optimum conditions obtained for concentration and soaking time of NaOH were 6.09 % and 5.22 hr, respectively. At these conditions, cellulose content was increased to 94.8002%, while the hemicelluloses and lignin content were reduced to 2.2779% and 0.508502%, respectively. The process parameter of MSSF was optimized using central composite design (CCD) to predict the cellulose, hemicelluloses, and lignin content. The quadratic model of response surface model (RSM) was adopted for the prediction of cellulose, hemicelluloses, and lignin content. The maximum error between the predicted using CCD and experimental results was less 0.38%. These errors in variation for both the predicted by the RSM and the actual gave good alignment with both results. Therefore, at these treatment conditions, MSSF can be utilized for composite application and other industrial purpose.

Keywords
NaOH; Chemical Modification; Mango Seed Shell Flour; Chemical Composition