Mohammad Hassan Amini

A simple and efficient method was used for surface modification of core-double shell CdSe/CdS/ZnS quantum dots (QDs) by mercaptoacetic acid (MAA) and imidazole (IM) as capping ligands. The resultant QDs were water dispersible and possesed advantages of low toxicity, high photostability and excellent fluorescence in comparison with CdSe QDs. The studies showed that the fluorescence intensity of the modified QDs was selectively quenched in presence of copper ions respect to other common metal cations. Thus, it was used as a nanosensor for detection of copper ions in aqueous solutions. In the optimal conditions, Cu²⁺ ion could be detected in the concentration range of 2.0 × 10^–9–1.38 × 10^–6 mol L^–1 with a limit of detection 1.0 × 10^–9 mol L^–1 (1 nM). The new designed nanosensor based QDs was then successfully applied for the determination of Cu²⁺ ions in real samples including tap water, ground water, human urine and human blood serum with satisfactory recovery of 97.8–102.6%.

A hybrid liquid membrane process was used to remove cadmium cation from a solution using bis-(2-ethylhexyl) phosphoric acid as the carrier for the first time. Different polyethersulphone supporting membranes were prepared by a phase inversion technique. The prepared membrane could be efficiently used as the supporting membranes for the proposed process. The effects of porosity and pore size of the supporting membrane on removal efficiency were investigated. In addition, the effects of various operating parameters such as carrier concentration in organic phase, pH of feed phase, acid concentration, and temperature on the performance of the process were also investigated. It was found that the maximum flux of cadmium is obtained using the supporting membrane with 84.5% porosity and the pore size of 132 nm. The optimum carrier concentration is 0.2 M, the optimum pH of the feed phase is 6, and the optimum concentration of acid in the stripping phase is 0.6 M.