Preparation of layered double hydroxide cmposites modified with thiourea derivatives and removal of camium (II) ions from aqueous media

Layered Double Hydroxides (LDH's) are clay minerals containing water and interchelated cations. LDH's is the only clay family which is used as natural anion exchanger. Since 1992 various Mg/Al-LDH containing different anions in the interlayers are produced for sorption of heavy metals. Generally sorption efficiency of LDH's interchelated with organic ligands has been better than unmodified LDH's. In the literature, LDH's have been modified with different organic molecules. However, to the best of our knowledge LDH's modified with thiourea derived compounds have not reported yet. In this thesis sorbent materials –namely ZnCr-LDH, ZnCr-DS-LDH, ZnCr-BT-LDH (BT: Benzoyl Thiourea) and ZnCr-2-FT-LDH (2-FT: 2-Froyl Thiourea)- were synthesized and they were characterized via FT-IR, XRD and 13C-NMR techniques. Their particle sizes and morphologies were examined via SEM/EDX and elemental analysis and elemental analysis and their thermal analysis were made by TG/DTG/DTA. Their pore sizes and volumes were determined by BET analysis. Sorption studies were made by F-AAS. In the sorption studies for Cd (II) metal ion, parameters such as amount of sorbent material, pH, analyte concentration, eluent type and concentration, contact time and flow rate were investigated. Optimum values for sorbent amount, pH, contact time, analyte concentration, flow rate and eluent were found to be 0.5 g, 6.3, 30 minutes, 50ppm, 0.25 mL/min, 1 M EDTA, respectively. Sorption capacities for ZnCr-DS-LDH, ZnCr-BT-LDH and ZnCr-2-FT-LDH were found to be 42,05 mg.g-1, 38,19 mg.g-1 and 17,15 mg.g-1. This study revealed that both unmodified LDH's and those modified with thiourea derivatives can be effectively used in Cd (II) removal as eco-friendly sorbent materials. Key words: LDH, Thiourea derivatives, sorption, cadmium, sorbent materials