Soft hydrogels for dual use: Template for metal nanoparticle synthesis and a reactor in the reduction of nitrophenols

A novel hydrogel based on poly(sulfopropylmethacrylate) (p(SPM) with different crosslinking degrees was synthesized and characterized. The prepared hydrogels were for the first time, utilized for in situ metal nanoparticle preparation such as Ni, Co, and Cu and employed as a reaction media in catalytic reduction of 4-nitrophenol (4-NP), and 2-nitrophenol (2-NP) to 4-aminophenol and 2-aminophenol, respectively. The experimental parameters that effect reduction rates such as temperature and the amount of catalyst were investigated. The kinetics of the reduction reaction of nitro compounds under different reaction conditions were investigated to determine the activation parameter. Activation energies were found as 33.86 kJ mol− 1 and 24.96 kJ mol− 1 for 4-NP and 2-NP, respectively. It was found that hydrogel–Cu composites can provide 98% activity even at the end of the 7th repetitive usage.