A simple spectrophotometric study of adsorption of Hg(II) on glycine functionalised magnetic nanoparticle entrapped alginate beads

ABSTRACT

In this study, a simple spectrophotometric method has been applied to investigate the adsorption of Hg(II) from aqueous solution on glycine functionalised magnetic nanoparticles entrapped calcium alginate beads (GFMNPECABs) from aqueous solution. The adsorbent was characterised by Fourier Transform Infrared (FT-IR) spectroscopy, Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and Brunauer-Emmett-Teller (BET) analysis. The influence of pH, contact time, temperature, adsorbent dose etc. were studied and optimised. The results of batch adsorption experiment showed that maximum adsorption capacity of 3.59 mg g^‒1 was obtained at pH 5 and 65 minutes of contact time.The adsorption behaviour of Hg(II) was evaluated using Langmuir, Freundlich and Temkin isotherm and it was found that the data best fitted with the Freundlich model. The kinetic study revealed that the adsorption follows pseudo-second-order kinetics with a high correlation coefficient of R² = 0.9998. The thermodynamic investigation verified the endothermic and spontaneous nature of the adsorption process with an enthalpy change (∆H) and entropy change (∆S) of 20.25 kJ mol⁻¹ and 79.88 J mol^‒1 K, respectively. The adsorption studies were monitored based on the reaction of Hg(II) with iodine and leucocrystal violet. This study shows that GFMNPECABs is a promising adsorbent for removal of Hg(II) from aqueous solution and the above spectrophotometric method could be satisfactorily applied for adsorption studies.

KEYWORDS:

• Mercury
• adsorption
• magnetic nanoparticles
• glycine functionalised
• calcium alginate
• spectrophotometric method

Acknowledgments

One of the Authors(S L) acknowledge Pt. Ravishankar Shukla University for Research Scholarship (no. 3114/8/Fin./Sch.//2018), NIT Raipur for XRD studies, SAIF Cochin for FTIR, SEM analysis and MNIT Jaipur for BET analysis. The authors are thankful to the Department of Chemistry of the Govt. V.Y.T. PG Autonomous College, Durg, Chhattishgarh, India for providing the necessary lab facilities.

Disclosure statement

The authors declare that they have no conflict of interest.

Additional information

Funding

This work was supported by the Pt. Ravishankar Shukla University Raipur from Pt. Ravishankar Research Fellowship Scheme, grant number V.R. No. 3114/8/Fin./Sch.//2018.