Influence of Rice Husk Processing Methods on the Chemical Composition of Bio-based Materials and Wastewater

Abstract

Bio-based materials from rice husk were obtained by processing rice rusk with acid (HCl, H2SO4, and H3PO4 0.1 mol·L-1), alkali (NaOH 0.1 mol·L-1, 0.25 mol·L-1 and 0.5 mol·L-1) and water. The chemical composition of rice husk, obtained from its bio-based materials and generated wastewater, was studied. After obtention of bio-based materials, wastewater produced in rice husk processing was treated by heterogeneous photo-Fenton. Substances soluble in water, pentosanes, lignin, cellulose, easy and difficult hydrolyzable polysaccharides were determined. Results showed that the chemical composition of rice husk and bio-based materials processed with water are similar. It is shown that bio-based materials processed with alkali contain more lignin, pentosans, and cellulose than when it is processed with water and acid. Wastewater, obtained while processing rice husk, was treated by a heterogeneous photo-Fenton process using SiO2-based RH-Fe-300 obtained from rice husk under visible and solar irradiation in the presence of hydrogen peroxide. Wastewater treatment by photo-Fenton presents decreased color, turbidity, phenolic compounds, and COD by 30-99% compared to the initial data. Achieved results are important for obtaining bio-based materials from rice husk and the treatment of wastewater generated during their production.