Adsorption studies of Cr(VI) and Cu(II) metal ions from aqueous solutions by synthesized Ag and Mg co-doped TiO₂ nanoparticles

ABSTRACT

This communication provides the eliminating of heavy metals from water resources using Ag-Mg/TiO₂ nanoparticles. The nanoparticles with a size of 15 nm were prepared using sol-gel technique and used for the removal of Cr(VI) and Cu(II) from waste waters. Batch sorption studies were carried out to investigate the adsorption of the above metal ions for a concentration range of 0.1–10 mg/L. The maximum sorption capacity values were found to be 2.42 mg/g for Cr(VI) and 2.03 mg/g for Cu(II) at a concentration of 0.1 ppm. The mechanism of adsorption was also investigated. The results showed that both Freundlich and Dubinin–Radushkevitch isotherms were found to be the best fit for the adsorption of metals. The results from kinetic data reveal that the pseudo-second-order and Reichenberg film diffusion models were found to be well fit for the experimental data. The value of the thermodynamic parameter ΔH° revealed the endothermic adsorption process and negative value of ΔG° shows the feasibility and spontaneity of material–anion interaction. In addition, the method is considered to be simple and cost-effective, and shows excellent adsorption removal properties on heavy metals for industrial applications.

KEYWORDS:

• Silver and magnesium co-doped TiO₂
• sol-gel
• isotherms
• kinetic studies

Acknowledgments

The authors would like to thank the Department of Chemistry, GITAM Institute of Science, GITAM (Deemed to be University), Andhra Pradesh, India, for providing necessary laboratory facilities under DST-FIST program. The authors are also grateful to Sophisticated Test and Instrumentation Centre (STIC) Cochin University, India, for providing instrumental support such as SEM, EDAX, and HR-TEM and Sophisticated Analytical Instrument Facility (SAIF), IIT Bombay for ICP-AES.