The production of bio-silica from agro-industrial wastes leached and anaerobically digested rice straws

Silicon extraction from rice straw (RS) has gained attention due to its increasing demand for various applications. This study investigated the potential for producing bio-silica from RS digestates, and RS leached with agroindustrial waste, such as corn-steep liquor (CSTL) and cassava-steep wastewater (CSWW). The results indicated that pretreated (PT) and digested methanogenic RS ash (RSA) samples contain amorphous silica, as confirmed by SEM, EDX and XRD analysis. The EDX results showed high levels of silica with minimal inorganic elements, while the XRD showed that the RSA from methanogenic reactors contained amorphous silica, indicated by a broad peak at 20 ranging from 160 to 280. The leaching potential of CSTL and CSWW was confirmed through SEM and EDX, with the XRD results indicating that CSWW was a more effective leaching agent than CSTL. The CSWW-leached RSA samples showed slight amorphousness with a broad peak at 20 between 160 and 250.