LAUSR

This work reports about a rubber-based hydrogel from liquid natural rubber (LNR) and acrylic acid (AAc) by using potassium persulfate (KPS) as an initiator and N,N-methylenebisacrylamide (MBA) as a crosslinking agent. The structure, stability, and morphology of the hydrogel were confirmed by using Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscope. The optimisation of the swelling capacity and Ni2+ removal percentage by the rubber-based hydrogel was conducted by using 5-level-2-factor response surface methodology. The effect of AAc:LNR ratio (0.59–3.41 g/g) and MBA concentration (0.02–0.23 M) parameters was studied with constant KPS concentration (0.05 M) used. Quadratic models for both responses (swelling and Ni2+ removal percentage) were successfully developed by using statistical analysis. The swelling degree and Ni2+ removal percentage of hydrogel were improved when high AAc:LNR ratio and lower MBA concentration were used. The R2 values for these quadratic models were 0.9891 and 0.9939 (swelling and Ni2+ removal percentage), respectively, which showed that the models were well-fitted with the experimental data. From the analysis, the optimum conditions for maximum swelling capacity (1181.90%) and Ni2+ removal percentage (26.74%) were hydrogel with AAc:LNR ratio 3.00 g/g and 0.05 M of MBA.