Removal and recovery of copper and nickel ions from aqueous solution by poly(methacrylamide-co-acrylic acid)/montmorillonite nanocomposites

Nanocomposite hydrogels based on poly
(methacrylamide-co-acrylic acid) and nano-sized montmorillonite were prepared by aqueous dispersion and in situ radical
polymerization. Optimum sorption conditions were determined as a function of montmorillonite content, contact time,
pH, and temperature. The equilibrium data of Cu2+ and Ni2+
conformed to the Freundlich and Langmuir isotherms in terms
of relatively high regression values. The maximum monolayer
adsorption capacity of the nanocomposite hydrogel (with
3 wt% montmorillonite content), as obtained from the
Langmuir adsorption isotherm, was found to be 49.26 and
46.94 mg g−1 for Cu2+ and Ni2+, respectively, at contact time=
60 min, pH=6.8, adsorbent dose=100 mg/ml, and temperature=318 K. Kinetic studies of single system indicated that the
pseudo-second order is the best fit with a high correlation
coefficient (R2=0.97–0.99). The result of five times sequential
adsorption–desorption cycle shows a good degree of desorption and a high adsorption efficiency.