Optimization of fly ash-g-polyacrylic acid hydrogel via response surface methodology for improved amine loading capacity

Abstract. Amine solvent has shown great sour gases separation capacity from natural gas. This paper studied the optimization of monoethanolamine loading capacity on the fly ash grafted polyacrylic acid hydrogel using response surface methodology. The central composite design was used to determine the effect of three independent variables particularly fly ash as a filler, N, N”-methylene bis acrylamide as a crosslinker, and ammonia peroxide sulphate as an initiator. The optimization study revealed the significance of factors in the following order: cross-linker > fly ash > initiator, with an R² value of 0.99. The fly ash grafted hydrogel achieved a maximum amine loading of up to 1550 wt.% with the addition of 1.1 g of fly ash, 0.07 g of cross-linker, and 0.07 g of initiator. It was investigated that varying the concentration of crosslinker was significantly enhanced the amine loading. Furthermore, SEM and FTIR were performed to analyze the morphology and chemical changes in the optimum fly ash grafted hydrogel. The results depicted that the fly ash grafted hydrogel has porous structure and ample space for amine uptake inside the pores. The fly ash-grafted hydrogel exhibits significant potential for efficient gas separation from natural gas. Its enhanced porosity, hydrophilicity, and capacity to incorporate functional groups, such as amines, enable the selective adsorption of impurities.