Efficient adsorption of dyes by γ-alumina synthesized from aluminum wastes:

Abstract

This study aimed at synthesizing γ-alumina from aluminum residue obtained from a frame fabrication factory, through precipitation followed by calcination, and apply it as an adsorbent to remove dyes from aqueous solution. The produced adsorbent was designated as non-rigid of aggregates of irregularly shaped particles, with a plate format, a mesoporous structure and with high surface area (304.31 m2·g−1). The kinetic studies indicated the adsorption of methylene blue (MB) follows the pseudo-first order model, while the pseudo-second order best fitted in case of the adsorption of crystal violet (CV) and basic fuchsin (BF). The equilibrium studies indicated the adsorption process is exothermic and the Langmuir model best fitted the equilibrium data with qmax equal to 57.81, 32.92 and 31.92 mg·g−1 for MB, BF and CV, respectively. The adsorption capacity of synthesized alumina from waste was compared with commercial ones and proved to be superior in surface area and adsorption capacity, where this was 40–60% higher for the analyzed dyes. The thermal regeneration was effectively reported towards the attainment of 3 complete cycles of dyes adsorption/desorption. The toxicity assays using Artemia salina and Lactuca sativa as biomarkers reinforce adsorption results demonstrating the treatment of dye solutions by γ-alumina can decrease the mortality of the microcrustaces and the phytotoxicity of solutions. The obtained results indicated some minimum feasibility of the proposed material to be applied in real contamination scenarios.