Optimizing the % swelling and removal of carcinogenic dye from waste-water using polyacrylamide-based hydrogels

Nowadays due to rapid industrialization to assist humans, hazardous and non-biodegradable dyes are eliminated from leather and textile industries in water streams. To eradicate these toxic dyes, the adsorption process opted for wastewater reclamation. Therefore, polyacrylamide-based hydrogels were fabricated using methylene Bis acrylamide and FeCl3 as chemical and physical cross-linkers. Sodium alginate-co-Polyacrylamide-co-acrylic acid a ter-copolymer hydrogel cross-linked via N, N '' methylene bisacrylamide shows maximum %swelling at pH 9 i.e. 751.42% and an equilibrium time of 200 min. The sorption capacity obtained for ASM0.1 was maximum i.e. 43.809 +/- 0.569 mg/g as compared to the sorption capacity of AAM0.05 and AAF0.05 i.e. 41.18 +/- 0.541 mg/g and 35.588 +/- 0.924 mg/g. The kinetic model followed by sorption of methylene blue onto polyacrylamide-based hydrogels was pseudo-second-order whereas diffusion occurred in two phases through macropores and mesopores. The optimized pH recorded for sorption is pH 9 having an adsorption value of 94.16 +/- 1.326 mg/g. Batch experiments revealed that adsorption increases from 37.52 +/- 0.743 mg/g to 104.56 +/- 1.194 mg/g for ASM 0.1 with an increase in concentration from 20 mg/L to 60 mg/L. The isotherm model followed by MB sorption is the Freundlich isotherm model which infers the physical nature of sorption. Moreover, with an increase in temperature, the adsorption slightly increased from 89.31 mg/g to 92.14 mg/g due to an increase in kinetic energy with temperature rise. % Removal stability was investigated for 5 consecutive cycles and inferred that ASM0.1 has decreased its % removal by only 6.5% after five cycles.