Characterization and optimization of blending hydrogel formulation from rice husk/fly ash by using response surface methodology (RSM)

Some by-products from agricultural and industrial sectors have been acknowledged as low cost adsorbents and as alternatives to the effective, yet very expensive adsorbent, Activated Carbon (AC). By utilizing these less expensive adsorbents, not only cost can be reduced, it can also help in reducing environmental problems that are related to the management of wastes. In this study, a new method of producing hydrogel biochar is synthesized by using agricultural waste, rice husk and coal combustion residue, fly ash. After rice husk had been pyrolysed at temperature of 450oC using a furnace, it was then blended with fly ash at different ratio of 100%, 80%, 60%, 50%, 40% and 20%. Then, the composite of hydrogel biochar-fly ash composite was produced by embedding the biochar with polymers; Acrylamide (AAm) which acts as monomers, N,N’ methylenebisacrylamide (MBA) as cross-linking material and ammonium persulfate (APS) as initiator. Hydrogel biochar is known to be unique due to its ability to swell and has a modifiable composite, thus it has slowly receiving attention as potential novel adsorbent. The aim of this study is to characterize the hydrogel biochar with different ratio of fly ash, by performing analysis using BET to study the surface area of each formulation, FTIR to determine its functional group and TGA to study the proximate analysis for each of the sample. From the results of the characterization, addition fly ash to the biochar helped in improving the structure and absorption capacity for hazardous gases removal and wastewater treatment, thus, proving its potential as effect adsorbent. Then, in order to determine the optimum blending ration, Response Surface Methodology (RSM) was carried. The results from RSM shows that the optimum condition for the blending ratio, specifically for rice husk is around 50% as it presents the highest potential of surface area and adsorption capacity.