Synthesis and Characteristics of Rice Husk Ash Based Magnetic Hydrogel (RHA-MH) for H2 Generation

Abstract

Abstract: In this study, magnetic hydrogel was synthesized from rice husk ash (RHA-MH) using two methods, i.e. sol-gel and cross-linking methods. The prepared rice husk ash based magnetic hydrogel (RHA-MH) were used as a catalyst for H2 generation through hydrolysis of sodium borohydride (NaBH4). Factors effecting hydrolysis reaction such as effect of RHA calcination temperature and method used to synthesis the catalyst were investigated. The RHA-MH1200 synthesised via cross-linking and sol-gel methods (using RHA calcined at 1200°C) shows the shortest time taken (5.64 min and 11.18 min, respectively) to produce 40 mL of H2 gas as compared to RHA-MH600 (i.e. 10.47 min and 13.18 min respectively, for both methods using RHA calcined at 600°C). The prepared and spent RHA-MH were also characterized using Scanning Electron Microscopy (SEM)/Energy Dispersive X-ray (EDX) analysis. From SEM image, it could be concluded that silica (SiO2) could successfully be utilized as the supporting material for stabilizing magnetic iron oxide (Fe3O4) nanoparticles. The SEM image also showed that the overall structure was relatively porous. Moreover, the SEM images of magnetic hydrogel before and after the hydrolysis of NaBH4 exhibited similar physical structures. Keywords: Hydrogen; NaBH4 hydrolysis; Rice husk ash based magnetic hydrogel (RHA-MH); Sol-gel; Cross-linking