Response Surface Optimization of Corn Husk Fiber Mercerization Using NaOH

The optimum mercerization parameters for treatment of corn husk using NaOH were analyzed by response surface methodology (RSM). The surface morphology and chemical structures of the raw and NaOH-treated fibers were studied using scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) to validate the RSM results. The optimum chemical characteristics of corn husk treated with NaOH obtained when 100g of corn husk biomass was mercerized in 2.5Mol/dm3 NaOH for 8 days were: cellulose -70.51%, hemicellulose -8.99%, lignin -6.54, weight loss – 92.27%, ash content -10.11% and extractive -3.78%. The model summary statistics showed that quadratic model best fitted the optimization analysis. The ANOVA results showed that weight loss, hemicellulose, cellulose and lignin contents of corn husk biomass were affected by retting time, retting concentration and weight of biomass. Cellulose content of corn husk was observed to increase with increment in retting time and retting concentration while the reverse is the case for hemicellulose and lignin contents. The NaOH-treated corn husk has higher cellulose content than the untreated corn husk biomass while the reverse is the case for hemicellulose and lignin. SEM images showed that untreated corn husk biomass has irregular cross-section, non-uniform surface and some impurities while NaOH treated is finely packed together. XRD graphs showed that cellulose is the predominant content of the fiber. The FTIR results also indicated a variation of the peaks of the curves after treatment which favors an increase in the cellulose content.