Ali Jabbari

Selective transport of mercury as HgCl42− through a bulk liquid membrane using K+-dicyclohexyl-18-crown-6 as carrier

Potassium-dicyclohexyl-18-crown-6 cation complex was used as an excellent carrier for the selective and efficient transport of mercury as HgCl42− complex anion through a chloroform bulk liquid membrane. In the presence of thiocyanate ions as a suitable stripping agent in the receiving phase at optimum experimental conditions, the amount of mercury transported across the liquid membrane after 2 h was 95.4±1.5%. The selectivity of mercury transport from aqueous solutions containing other cations, such as Li+, Tl+, Ca2+, Co2+, Ni2+, Cu2+, Zn2+, Pb2+, Cd2+, Fe3+ and Cr3+, was investigated. With the exception of Mg2+ and Ca2+ with some potential interference, in all other cases, the interfering effect of the cations was found to be negligible; most of the cations did not interfere with the mercury transport even at a Mn+/Hg2+ molar ratio of ≥100.

Transport study of palladium through a bulk liquid membrane using hexadecylpyridinium as carrier

Hexadecylpyridinium bromide (HDPB) was used as an excellent carrier for the uphill transport of palladium(II) as PdBr42− complex anion through a chloroform bulk liquid membrane. The transport efficiency of palladium(II) by HDPB was investigated under various experimental conditions such as pH and concentration of NaBr in source phase, concentration of surfactant (HDPB) in membrane, HBr and thiourea (as stripping agent) concentration in receiving phase and equilibrium time. In the optimum conditions, transport efficiency of palladium(II) for the ten replicate measurements after 110 min was 97.9±1.1%. The selectivity of palladium(II) transport from aqueous solutions containing Sr2+, Ca2+, Ba2+, Co2+, Ni2+, Zn2+, Cu2+, Cd2+, Mn2+ and Hg2+ ions was investigated and found that none of cations used, interfere the palladium(II) transport (at Mn+/Pd2+ mole ratio of 10).The proposed method has been applied to separation of palladium in Silicon–Alumina catalysts. The transport efficiency after 120 min was 98%.

Spectroscopic Study of Some Alkali and Alkaline Earth Complexes with Benzo Crown Ethers in Ethanol Solution

The interaction between Na + , K + , Mg 2+ and Ca 2+ ions and benzo crown ethers B15C5, DB18C6, DB21C7, DB24C8 and DB30C10 in ethanol solution has been studied spectrophotometrically at 25 o C. The formation constants for 1:1 complexes were determined by computer fitting of the resulting UV-absorbance-mole ratio data. In the case of all crown ethers used, K + ion was found to form the most stable complexes. The observed selectivities of different benzo crowns for the cations used are discussed in terms of the cavity-cation size ratio, number of the donating oxygens participating in the cation binding, conformations of the free and complexed ligands and ionic solvation

Conductance Study of Complex Formation of Thallium and Silver Ions with Several Crown Ethers in Acetonitrile, Acetone and Dimethylformamide Solutions

The complexation reactions between Tl+ and Ag+ ions and several crown ethers have been studied conductometrically in acetonitrile, acetone and dimethylformamide solutions at 25°C. The stability constants of the resulting 1:1 complexes were determined, and found to decrease in the order DA18C6>DC18C6>DB30C10>18C6>DB21C7>DB24C8>DB18C6>B15C5 >12C4, in the case of Tl+ complexes, and in the order DA18C6>DC18C6>18C6>DB18C6 >DB24C8>DB30C10≈B15C5>DB21C7 for Ag+ complexes. There is an inverse relationship between the stabilities of the complexes and the Gutamnn donicity of the solvents. The influence of a number of atoms in the macrocycle and of substituents in the polyether ring on the stability of the complexes is discussed.

Specific Membrane Transport of Mercury as [Hg(SCN)4]2− Ion Using K+–Dibenzo-18-crown-6 as Carrier

Potassium-dibenzo-18-crown-6 complex cation was used as carrier for the uphill transport of mercury as [Hg(SCN)4]2− complex anion through a chloroform membrane system. By using 0.2 mol/L EDTA as a metal ion acceptor in the receiving phase at the optimized pH of 10.0, the amount of mercury transport through the liquid membrane after 120 minutes was 94.2 ± 0.7%. The selectivity and efficiency of mercury transport from aqueous solutions containing equimolar mixtures of Co2+, Ni2+, Cu2+, Zn2+, Pb2+, and Cd2+ ions were investigated. In the presence of 0.05 mol/L EDTA at pH 3.2 as a proper masking agent in the source phase, the interfering effects of Zn2+, Pb2+, and Cu2+ ions were eliminated.

Spectrophotometric determination of trace amounts of molybdenum (VI) based on catalytic reduction of safranine by hydrazine dihydrochloride

SummaryA simple and rapid kinetic method for the determination of traces of molybdenum (0.1–4.0 μg/ml) based on its catalytic effect on the reduction of safranine by hydrazine dihydrochloride is reported. The reaction is monitored spectrophotometrically by measuring the decreasing absorbance of safranine at 520 nm by the fixed time method. The method is sensitive, precise and free from interferences from many anions and cations. The experimental limit of detection is 100 ng/ml and the relative standard deviation for 1.0 μg/ml Mo(VI) is 1.56%. The procedure was successfully applied to the determination of molybdenum in a steel alloy.