Adsorptive Sequestration of Mercury(II) Ions from Simulated Saline Wastewater Using Thiolated Peppermint Waste

International Journal of Chemistry | Vol. 8, No. 3, March 2017 | pp. 17–24

DOI: 10.46882/2017/IJC/000102

Article Type: Original Research Paper

Title: Adsorptive Sequestration of Mercury(II) Ions from Simulated Saline Wastewater Using Thiolated Peppermint Waste

Names of Authors: E. N. Chidi¹, L. M. van der Westhuizen²*

Authors’ Affiliations:
¹Department of Pure and Industrial Chemistry, Nnamdi Azikiwe University, Awka, Nigeria.
²Department of Chemical Engineering, Stellenbosch University, Stellenbosch, South Africa.

Abstract: Industrial wastewater from chlorine-alkali facilities often contains high residual levels of highly toxic mercury(II) ions, requiring affordable and chemically stable biopolymer extraction networks. This paper evaluates the adsorptive performance of modified peppermint (Mentha piperita) waste prepared via chemical functionalization with thioglycolic acid (thiolation). The surface morphology and active site modifications of the matrix were examined through scanning electron microscopy (SEM) and FT-IR spectroscopy. The structural evaluations confirmed that thiolation successfully integrated sulfur-rich thiol (-SH) ligand centers onto the lignocellulosic biomass strands. Batch adsorption tests evaluated variables of baseline solution pH, contact period, adsorbent load, and initial metal concentrations. Maximum Hg(II) extraction occurred at an optimum pH of 5.5, using an equilibrium contact period of 60 minutes. The equilibrium distribution datasets matched closely with the Langmuir isotherm expressions, yielding a high maximum monolayer adsorption capacity of 74.45 mg/g at 298 K. Sorption kinetics conformed perfectly to a pseudo-second-order mechanism with high correlation coefficients (R² > 0.999), proving that strong chemical surface coordination controlled the phase transfer rates. Thermodynamic constants established that the process was spontaneous and endothermic, positioning thiolated biomass as a highly viable material for toxic water remediation.

Keywords: Peppermint waste; Chemical modification; Thiolation; Mercury removal; Sorption kinetics; Coordination chemistry

Manuscript Timeline: Received: June 02, 2016; Revised: July 15, 2016; Accepted: August 10, 2016; Published: March 08, 2017.

Citation: Chidi, E. N., & van der Westhuizen, L. M. (2017). Adsorptive Sequestration of Mercury(II) Ions from Simulated Saline Wastewater Using Thiolated Peppermint Waste. International Journal of Chemistry, 8(3), 17–24.

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