Processing of rice production residues with lignin extraction

Abstract

Goal. To develop a method of extracting lignin from rice production waste with simultaneous utilization of the husk. Methods. The cleaned rice husk was grounded in a centrifugal mill. Fractionation according to the granulometric composition of the grinding was carried out using a sieve analysis. The extraction of lignin from rice husk grinding was carried out using an original laboratory setup equipped with a thermostated reactor with a propeller stirrer. IR-spectroscopy was used to determine the chemical composition of rice husk before and after extraction. The degree of lignin extraction from rice husk was determined taking into account the results of gravimetry. Results. The influence of the composition of the extractant on the degree of lignin extraction from rice husk was determined. The dependence of the degree of lignin extraction on the temperature and duration of the process was obtained. The influence of the average particle size of rice husk grinding on the rate of lignin extraction was studied. Conclusions. A method of extracting lignin from rice husks with simultaneous utilization of rice production waste was developed. Lignin extraction was proposed to be carried out using an alcohol-acid solution with a concentration of hydrochloric acid of 1.5% at a temperature not exceeding 80°C. The maximum degree of lignin extraction was 31%. The maximum speed of the process was observed in the case of using a grinding fraction of about 40 µm.