Isolation and Characterization of Lignin from Oil Palm Shells using a Precipitation Method with Sulfuric Acid and Polyaluminum Chloride as Coagulant

Lignin has useful and significant properties such as stiffness, resistance to UV radiation, antioxidant, antimicrobial, high thermal stability, and high carbon content. Due to these properties, lignin can be used for several applications including wood adhesive, carbon-based material, and can be developed as a functional material composite. Isolation and utilization of lignin from lignocellulosic biomass offers significant opportunities in various now and future industrial applications mainly for development advanced materials. In this study, isolation and characterization of lignin from oil palm shells (OPS) was conducted. Lignin was isolated from OPS using the precipitation method with sulfuric acid and coagulation using polyaluminum chloride (PAC). The isolated lignin was identified using Fourier Transform Infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM). Based on the FTIR analysis, lignin was successfully separated from cellulose. The crystallite size of isolated lignin is the smallest (25.37 nm) as compared to commercial alkaline lignin (28.49 nm) and OPS (25.99 nm). The isolated lignin is amorphous with crystallinity of 6.43 % and its morphology is a spherical. Overall, this study shows that the isolation method using sulfuric acid (H2SO4) and PAC is not only effective in separating lignin from OPS, but also minimizes the environmental impacts, thus certainly making it a promising choice for more environmentally friendly industrial applications.