Papers by Author: Yan Li Zhang

Abstract: The adsorption capability of nano-barium-strontium titanate coated by dithizone(BST- dithizone) for mercury in environmental water samples was studied. The optimum experimental parameters for the adsorption and desorption of the mercury, such as pH values, contact time and eluent, have been investigated. The results showed that the mercury ion in water could be adsorbed on the BST- dithizone. The adsorption capability was affected by the pH value of medium and contact time. In the medium of pH 3-8, the adsorption time was more than 15 min, and capacity of adsorption was 15.3 mg·g-1. The used adsorbent could be completely regenerated using 2 mol·L-1 HNO3. A new method for the removal of mercury in water samples was proposed. The method has been applied to the removal of mercury in waste water samples with satisfied results.

Abstract: A new method was proposed for the preconcentration/separation of zinc at trace levels using a modified organo-bentonite with dithizone (D-O-bentonite) and determined by flame atomic absorption spectrometry (FAAS). The influences of some experimental parameters including pH of the sample solution, contact time, and volume of eluent have been investigated. The influences of some matrix elements were also examined. The results show that the zinc ion could be adsorbed on the D-O-bentonite. The adsorbed quantitively was affected by the pH value of medium and contact time. In the medium of pH 4-5, the contact time was 20 min, and capacity of adsorption was 32.0 mg·g^-1. The zinc adsorbed on the sorbent could be completely eluated by using 0.5 mol·L^-1 HNO₃. The method has a good tolerance to matrix interference. The detection limit of the method for zinc ion was 0.013 µg·L^-1. The method was successfully applied to the pre-concentration/separation of zinc ion in the tap water and human urine with satisfactory results.

Abstract: Porous nano-strontium titanate (PST) was successfully prepared by the reversed-phase suspension polymerization and sol-gel method using reversed-phase suspension droplets as the template, and characterized by XRD and SEM. The ability of the new adsorption to remove lead, cadmium, zinc, copper and nickel ions from water samples was assessed. The results showed that the sorbents were porous, perovskite strontium titanate, and the average particle diameter of crystalloid was 30 nm. The lead, cadmium, zinc, copper and nickel ions were quantitatively retained at pH 5-8; their adsorption capacities of PST for lead, cadmium, zinc, copper and nickel ions were 145.9 mg•g^-1, 4.3 mg•g^-1, 25.2 mg•g^-1, 19.6 mg•g^-1and 3.7 mg•g^-1, respectively. The adsorbent can be regenerated completely by elution with 0.5 mol•L^-1 HNO₃. The adsorbent has a promising prospect in removal or enriching of lead, cadmium, zinc, copper and nickel in water.