Synthesis of sodium silicate solution using rice hull ash waste from a local salt refinery / Ben John L. Menor

UTHESIS (Bachelor of Science in Ceramic Engineering)

Bibliography : leaves 30-32

Sodium silicate solution (Na2SiO3) is commonly used in ceramics as deflocculant and as industrial additive across various industries. It is commercially prepared by mixing sand as silica (SiO2) source and sodium hydroxide (NaOH) or sodium carbonate as source of sodium oxide then heated to a very high temperature. This study, synthesized Na2SiO3 as SiO2 source (11.5 g) using waste rice hull ash (RHA), an agricultural waste with minimal value, from a local salt refinery, and commercial NaOH (60 mL, 1.5 M). The mixtures were reacted at low temperature (100 oC) at varying reaction times (1, 2, and 3 hours) labelled as 1 HRT, 2 HRT, and 3 HRT, respectively. Properties such as specific gravity, viscosity, pH, electrical conductivity, and as deflocculant in clay slurry of the as-synthesized and adjusted Na2SiO3 were evaluated. The chemical composition particularly the SiO2 percentage present in the collected and processed RHA as well the residue in the synthesis process were analyzed using XRF technique. Chemical analysis showed that the amount of SiO2 in RHA is 95.14 % while the residue in the synthesis still contains unreacted SiO2. In addition, the calculated SiO2/Na2O ratio of 1 HRT, 2 HRT, 3 HRT were 1.85, 2.09, and 2.34, respectively. The amount of SiO2 reacted increased with longer reaction time. Further, the viscosity and electrical conductivity decreased with longer reaction time. Moreover, results of the clay slurry deflocculation tests using the Na2SiO3 synthesized at different reaction time revealed that 2HRT and 3HRT are comparable to the commercial. These results validate the potential of waste RHA as source of SiO2 in producing valuable Na2SiO3 thereby, promoting waste valorization.