An alternative application for reuse of leaching residues: Determination of adsorption behaviour for methylene blue and process optimization

Cetintas S.

SUSTAINABLE CHEMISTRY AND PHARMACY, vol.23, 2021 (Journal Indexed in SCI) identifier

  • Publication Type: Article / Article
  • Volume: 23
  • Publication Date: 2021
  • Doi Number: 10.1016/j.scp.2021.100504
  • Keywords: Adsorption performance, Leaching residue, Methylene blue, Response surface methodology, REMOVAL


In this study, the potential efficiency in adsorption process, as a functional use route, of laterite ore residues (LR) produced from atmospheric acid leaching was evaluated for methylene blue (MB) removal representing cationic organic pollutants discharged in large amounts from industry into aquatic environment. Adsorption process was optimized by using Box-Behnken design based on Response Surface Methodology (RSM) to determine correlation between responses as, adsorption efficiency (%) and adsorption capacity (mg/g), and 3 independent variables with 3 levels (pH, initial MB concentration and LR amount). 98.29 +/- 0.63% of adsorption efficiency and 3.072 +/- 0.280 mg/g of adsorption capacity were achieved in determined optimum conditions; pH = 5.2, C-0 = 50 mg/L MB and m = 0.40 g. The good agreement between predicted and experimental values observed by comparison of values showed accuracy of model at 95% confidence level. Furthermore, it was determined that nature of adsorption equilibrium complied Freundlich isotherm model and adsorption mechanism was well defined with pseudo-second-order kinetics model. Thus, process exhibited a heterogeneous multilayer adsorption behavior and mainly controlled by chemical reactions. Furthermore, the adsorption mechanism was determined by characterization of residues, before and after adsorption by scanning electron microscopy with energy dispersive of X-ray (SEM-EDAX), Fourier-transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD).