Sequestration of Cd(II) and Cu(II) ions using bio-based hydrogel: a study on the adsorption isotherms and kinetics

The demand for economic heavy metals has recently sparked a lot of interest in various areas of research and industry. The novelty of this work is the synthesis of grafted guar gum hydrogel and using as adsorbent for the recovery of Cd(II) and Cu(II) ions from acidic solutions. Chemical and physical characterizations of the prepared hydrogel were performed via FT-IR, TGA, BET, and SEM-EDX analyses. The optimum experimental settings using batch technique were investigated. The maximum static adsorption capacities of the grafted hydrogel adsorbent were 99 mg/g for Cd(II) ions and 90.3 mg/g for Cu(II) ions. Freundlich, Langmuir, and Temkin models accurately described the sorption isotherm data. Various thermodynamic parameters were determined. The results showed that a pseudo-second order was predominant in the sorption kinetics of both Cd(II) and Cu(II) ions. Both metal ions could successfully be desorbed using 5 M HC1 and 1 M EDTA, while the latter exhibited higher desorption efficiency. The regeneration experiments indicated that prepared hydrogel could maintain adsorption capacities after 5 cycles of adsorption regeneration with negligible decreasing efficiency (less than 1%). As a result, it is regarded as a promising adsorbent in variety of industrial applications. [GRAPHICS] .

Automated summary

The study synthesized grafted guar gum hydrogel as an adsorbent for the recovery of Cd(II) and Cu(II) ions, showing high adsorption capacity and stability during regeneration cycles. The results indicate promising industrial applications for the prepared hydrogel as an adsorbent.