Copyrolysis of rice husk and plastic bags waste from low-density polyethylene (LDPE) for improving pyrolysis liquid product

Abstract

Rice husk is an agricultural waste from the rice milling process that results in environmental problems during its handling. Biomass (such as rice husk) can be transformed into biofuel via pyrolysis. Pyrolysis is a thermal decomposition of organic compounds in biomass at high temperatures in the absence of oxygen. The main difference of pyrolysis liquid compared to fossil fuel is the significant amount of oxygen (O) content instead of its carbon (C) and hydrogen (H). Thus, making pyrolysis liquid has a lower heating value and inferior properties limiting its direct fuel application. On the other hand, plastic bag waste from low-density polyethylene (LDPE) contains a high C and H with almost no O content. This study conducted co-pyrolysis of rice husk and LDPE at a different percentage (%weight) of LDPE (0, 5, 15, 25, 50, and 75). The pyrolysis temperature was measured using a comparison of thermogravimetric analysis (TGA) curves of rice husk powder and LDPE. The pyrolysis liquid resulted was collected and analyzed. The results show that the increase of LDPE content caused the yield of the organic phase (desired as fuel) of pyrolysis liquid to increase. The properties in the term of heating value also increased while the viscosity and density of pyrolysis liquid decreased. These properties were almost similar to diesel fuel with a slightly lower heating value. However, at 50 % LDPE composition, the wax was formed. Therefore, the optimum composition was 25% of LDPE, resulting in 41.69 MJ/kg of heating value.