Bi-functionalized Ionic Liquid-Thiourea Chitosan for effective decontamination of Cd(II) and Hg(II) from water bodies

Abstract

Chitosan biopolymer was converted to thiourea-chitosan followed by impregnation with ionic liquid Aliquat-336 using microwave irradiation method. The obtained material Ionic Liquid-Thiourea Chitosan (ILTC) was effectively used for decontamination of Cd(II) and Hg(II) from water bodies. FT-IR, SEM-EDX, XRD and TGA-DTA gives insight of ILTC adsorbent. Choro-complexes of Cd(II) and Hg(II) showed strong adsorption on ILTC as compared native Cd(II) and Hg(II) ions hence the adsorption was carried out in the form of chloro complexes. The adsorption behavior of Cd (II) and Hg (II) ions onto ILTC was investigated through batch method and various batch parameters viz. Contact time, adsorbent dose, initial concentration of adsorbate, pH and point of zero charge were optimized. The maximum adsorption capacities for Cd (II) and Hg (II) at 298 ​K were found to be 442.5 ​mg/g and 203.2 ​mg/g respectively at pH 3.0. Kinetic and thermodynamic parameters of the adsorption process were obtained. The results indicated that adsorption process was spontaneous, exothermic and followed pseudo-second-order kinetics model. Column studies were carried out in order to access the applicability of the material for bulk samples at larger volumes. ILTC could be easily regenerated and efficiently reused.

Keywords

• Chitosan
• Adsorption
• Water treatment
• Cadmium
• Mercury