Elimination of toxic azo dye using a calcium alginate beads impregnated with NiO/activated carbon: Preparation, characterization and RSM optimization

Abstract

Nickel oxide nanoparticles supported activated carbon (AC-NiO) was fabricated using thermal activation. Then, AC-NiO composite was immobilized on alginate beads to obtain 3-dimensional network structure ALG@AC-NiO nanocomposite beads for catalytic reduction of Congo red (CR) dye. The resulting nanocomposite beads were identified by various physical techniques. The crystalline nature and dispersion of NiO nanoparticles was defined by the XRD and EDS techniques, respectively. ALG@AC-NiO beads have a Ni element content of 4.65 wt% with an average NiO particle diameter of 23 nm. The statistical approach mathematically describes the catalytic reduction of the CR dye as a function of the NaBH₄ concentration, the catalyst dose and the concentration of the CR dye modeled by a BBD-RSM. According to the statistical modeling and the optimization process, the catalytic optimum conditions were obtained for NaBH₄ concentration of 0.05 M, catalyst dose of 11 mg and CR dye concentration of 80 ppm who permit meet 99.67 % of CR dye conversion. The adjusted coefficient of determination (R² = 0.9957) indicates that the considered model was quite suitable with a good correlation between the experiment and predicted.

Keywords: Activated carbon; Hydrogel beads; Nickel oxides; Reduction; Sodium alginate.