Adsorptive Potential of 2-Mercaptobenzimidazole-Immobilized Organophilic Hydrotalcite for Mercury(II) Ions from Aqueous Phase and Its Kinetic and Equilibrium Profiles

• Published in: Water, air, and soil pollution Vol. 196; no. 1-4; pp. 127 - 139
• Main Authors: Anirudhan, T. S, Suchithra, P. S, Divya, L
• Format: Journal Article
• Language: English
• Published: Dordrecht Dordrecht : Springer Netherlands 2009; Springer Netherlands; Springer; Springer Nature B.V
• Subjects: Adsorbents; Adsorption; Applied sciences; Aqueous solutions; Atmospheric Protection/Air Quality Control/Air Pollution; Chelating agents; Chemistry; Climate Change/Climate Change Impacts; desorption; Diffusion; Earth and Environmental Science; Environment; Environmental monitoring; Equilibrium; Exact sciences and technology; General and physical chemistry; Heavy metals; Hydrogeology; Immobilization; Industrial wastewaters; Ionic strength; Ions; Isotherms; Kinetics; Mass transfer; Mercury; Metal concentrations; Metal ions; pH effects; Pollution; Potentiometric titration; Sodium; Soil Science & Conservation; sorption isotherms; Studies; Surface physical chemistry; Surfactants; wastewater treatment; Wastewaters; water pollution; Water Quality/Water Pollution; Water treatment and pollution; 2-Mercaptobenzimidazole; Organophilic hydrotalcite; Mass transfer model; Hg(II) adsorption; Isotherm; Desorption; Kinetics; Metallic adsorbate; Thiol; Isotherm, Desorption; Liquid solid adsorption; Adsorption isotherm; 2-Mercaptobenzimidazole, Organophilic hydrotalcite, Hg(II) adsorption; Chemical reaction kinetics; Mass transfer; Heavy metal; Sulfonate; Anionic surfactant; Hydrotalcite; Organic-inorganic hybrid materials; Industrial waste water; Chelating agent; Physicochemical purification; Desorption isotherm; Adsorbent; Waste water purification; Mercury; Modified material
• ISSN: 0049-6979; 1573-2932
• DOI: 10.1007/s11270-008-9762-4

An organophilic calcined hydrotalcite (OHTC) was prepared by treating calcined hydrotalcite (HTC) with sodium dodecylbenzene sulphonate (an anionic surfactant) to achieve a high loading of thiol functionality through the immobilization of 2-mercaptobenzimidazole (MBI) as a chelating agent. The adsorbent (MBI-OHTC) obtained was characterized using XRD, FTIR, SEM, TG/DTG, surface area analysis and potentiometric titration. The adsorption of MBI-OHTC to remove Hg(II) ions from aqueous solutions was studied as a function of pH, contact time, metal ion concentration, ionic strength and adsorbent dose. The optimum pH range for the maximum removal of Hg(II) was 6.0-8.0. The maximum value of Hg(II) adsorption was found to be 11.63 and 21.52 mg g⁻¹ for an initial concentration of 25 and 50 mg l⁻¹, respectively at pH 8.0. The equilibrium conditions were achieved within 3 h under the mixing conditions employed. A reversible pseudo-first-order used to test the adsorption kinetics. The adsorption mechanism consisted of external diffusion and intraparticle diffusion and the intraparticle mass transfer diffusion was predominated after 20 min of experiment. Extent of adsorption decreased with increase of ionic strength. The experimental isotherm was analyzed with two parameters (Langmuir and Freundlich) and three parameters (Redlich-Peterson) equations. The isotherm data were best modeled by the Freundlich isotherm equation. Complete removal ([almost equal to]100%) of Hg(II) from 1.0 l of chlor-alkali industry wastewater containing 9.86 mg Hg(II) ions, was possible with 3 g of the adsorbent dose at pH 8.0. About 95.0% of Hg(II) can be recovered from the spent adsorbent using 0.1 M HCl.