Optimization of Alkali Pretreatment Conditions for Wax Removal from Bamboo Culm

Appropriate chemical reagents were selected for removing the wax layer of bamboo culm, and optimal treatment conditions with the selected agents were determined in this study. Solutions of potassium carbonate, potassium hydroxide, sodium carbonate, and sodium chloride, along with their mixtures with 1% sodium dodecyl sulfate, were tested for efficacy of wax removal on culms of giant timber bamboo (Phyllostachys bambusoides S. et Z.), hachiku bamboo (Phyllostachys nigra var. henosis Stapf), and moso bamboo (Phyllostachys pubescens Mazel). Of the tested reagents, the mixture of potassium hydroxide and sodium dodecyl sulfate showed the best capability. The effects of varying concentrations of the selected reagents and reaction times at 90 °C were investigated by response surface methodology (RSM). Quadratic regression models representing the degree of wax removal at various treatment conditions were determined. The coefficients of determination of the fitted models were greater than 0.98, meaning that the models were highly accurate in predicting the degree of wax removal. According to the fitted models, the optimal conditions of potassium hydroxide concentration, sodium dodecyl sulfate concentration, and reaction time were 5.08%, 3.6%, and 63 min, respectively. The use of an RSM model offers considerable flexibility for practical uses because it allows multiple solutions with any desired level of wax removal.