| Summary: | Hydrogel based on liquid natural rubber (LNR) crosslinked with acrylic acid (AAc) was synthesised and applied for
the adsorption of methylene blue (MB) in aqueous solutions. The LNR/AAc hydrogel was prepared by free-radical
polymerisation using potassium persulfate (KPS) and N,N-methylenebisacrylamide (MBA) as the initiator and the
crosslinking agent, respectively. The effect of three variables (i.e., AAc:LNR weight ratio, KPS concentration and
MBA concentration) on the hydrogel preparation for MB removal was further investigated using response surface
methodology (RSM). A quadratic polynomial model with the analysis of variance (ANOVA) results yielding R2
value of 0.9833 was consequently obtained. The optimum conditions for the hydrogel preparation were identified as
AAc:LNR weight ratio of 2.59 g/g, KPS concentration of 0.08 M and MBA concentrations of 0.08 M and resulting a
high percentage of MB removal about 92.57% was obtained. Therefore, the kinetic and isotherm models of MB removal
were represented by the pseudo-second order and Freundlich model, respectively, and reusability studies were also
investigated resulting in the hydrogel can be used up to four cycles.
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