Separation and Pre-concentration of Some Metals Using Amino-azole Derivatives Supported on Silica

摘要

The present study aimed to evaluate the efficiency of amino-azole derivatives supported on silica gel for the separation of some heavy metals e.g., Cu~(2+), Cd~(2+) and Hg~(2+). Silica gel was modified by using 3-chloropropyltriethoxysilane and sorption parameters were determined. The newly modified phases were characterized using IR, NMR and elemental analysis and sorption efficiency parameters were determined. The results indicated that the surface coverage and sorption capacity values ranged from 0.48 to 0.54 mmol and 0.03 to 0.45 mmol/g of modified silica, respectively and separation capacity values increased by increasing pH values and did not affected by increasing temperature. Thermal analysis demonstrated non-catalytic degradation effects due to the formation of metals chelates on the silica surface. In addition it was found that 20-30 min was sufficient to complete sorption and 85-90 % of the sorbed metals occurred within the first 5-10 min. On the other hand. HCl was found to be most potent acid to elute the tested metals at a concentration of 0.2 mol/L. Higher stability and higher distribution coefficient (K_d) of the modified silica were found compared to non-modified silica as well as the possibility of using it is. Real samples collected from industrial areas located at Al-Qassin region, Kingdom of Saudi Arabia illustrated the validity and feasibility of the proposed procedure for the separation and pre-concentration of the selected metals.