Removal of Cu (ll) from industrial wastewater using poly (acrylamide-co-2-acrylamide-2-methyl propane sulfonic acid)/graphene oxide/sodium alginate hydrogel: Isotherm, kinetics, and optimization study

Here, Graphene oxide/poly (acrylamide -2-acrylamide-methyl-propanesulfonic acid)/sodium alginate (GO/PAAMPS/SA) hydrogel was synthesized through a free-radical polymerization approach. The impact of Graphene Oxide (GO) content on mechanical strength, swelling behavior, and the adsorption performance of prepared hydrogel was studied. The operating parameters, including contact time, solution pH, and initial Cu(II) content on the adsorption capacity of the hydrogel, were studied. The maximum Cu(II) adsorption capacity of 230.8 mg/ g was obtained for GO/PA-AMPS/SA under a pH of 5, the contact time of 270 min, and adsorbent content of 0.5 g/L at 25 degrees C. The high value of adsorption capacity after six adsorption-desorption cycles indicated excellent reusability of the hydrogel absorbent. The adsorption capability of synthesized hydrogel was also evaluated for Cu(II) elimination from industrial wastewater. The Cu(II) concentration of wastewater decreased from 2.6 mg/L to 0.1 mg/L in the presence of synthesized hydrogel adsorbent. The kinetic and isotherm investigation of Cu(II) adsorption for prepared hydrogels revealed that the pseudo-second-order and Langmuir models fitted well with the kinetics and the isotherm data, respectively. The obtained E value of 0.01 kJ/mol using the DubininRadushkevitch (D-R) isotherm model indicates that the physical adsorption dominates the adsorption process. The relationships between the critical parameters in hydrogel and acquired adsorption data were investigated using the analysis of variance (ANOVA) technique.

Automated summary

The research synthesized a graphene oxide/poly (acrylamide-2-acrylamide-methyl-propanesulfonic acid)/sodium alginate hydrogel and studied its adsorption performance on Cu(II). The synthesized hydrogel showed significant removal of Cu(II) from industrial wastewater and demonstrated excellent reusability.