Study of time reaction on alkaline pretreatment applied to rice husk on biomass component extraction

Rice husk (RH) residue was submitted to a sequence of experimental procedures, specifically to investigate the reaction time influence of NaOH pretreatment on the extraction of silica, hemicellulose, and lignin components. In order to follow the extraction of each non-cellulosic components of rice husk, techniques such as Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction analysis, and scanning electron microscopy were performed on untreated RH and samples collected from the NaOH reaction media at several different reaction times, as well as the sample after alkaline-peroxide treatment. Under the process parameters used in the present study, the results showed that a great part of hemicellulose and silica contents was removed during the first 30 min of reaction time in NaOH pretreatment. Although there is evidence that NaOH pretreatment also removed some lignin content, the complete delignification process was more effective just after alkaline-peroxide reaction, which produced material rich in type I cellulose.