Optimization of Xanthan Gum/Poly(acrylic acid)/Cloisite 15A Semi-IPN Hydrogels for Heavy Metals Removal

Semi-interpenetrating networks (semi-IPNs) of Xanthan gum/poly (acrylic acid) containing Cloisite 15A were prepared via radical polymerization using a novel acrylic-urethane crosslinker. Response surface methodology (RSM) was used to optimize the conversion, swelling, and networking of synthesized hydrogels as a function of three variables: xanthan gum, cross-linker, and clay. FT-IR, UV-Vis, XRD, BET, TEM and SEM techniques were used to analyze and confirm the formation and efficiency of the synthesized hydrogels. The surface areas of the XG/PAA and XG/PAA/Cloisite 15A samples were 1.3536 and 1.759 m(2) g(-1), respectively, demonstrating that Cloisite 15A nano-sheets are effective in increasing hydrogel surface area. Adsorption behavior of Co2+, Cu2+, Ni2+ by optimized hydrogel was defined using kinetic and isotherm models. The kinetic analysis revealed that the pseudo-second-order best explains the kinetic mechanism (R-2 = 0.999). At 15,000 g mL(-1) initial concentration, the adsorption capacity for Co2+, Cu2+, Ni2+ were 436.62, 530.14, and 511.74 mg g(-1), respectively. The results show that the Xanthan-based hydrogel has a porous structure and high adsorption capacity. Moreover, the cycling absorption performance of XG/PAA/Cloisite 15A is promising. Metal ions were removed by XG/PAA/Cloisite 15A at about 45 and 30% in the 1st and 5th cycles, respectively. [GRAPHICS] .

Automated summary

Semi-interpenetrating networks (semi-IPNs) of Xanthan gum/poly (acrylic acid) containing Cloisite 15A were prepared and optimized using response surface methodology (RSM). The analysis showed that Cloisite 15A nano-sheets effectively increased the surface area of the hydrogel, which exhibited a porous structure and high adsorption capacity. The XG/PAA/Cloisite 15A hydrogel also demonstrated promising cycling adsorption performance.