Papers by Author: Dong Zhang

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Authors: Dong Zhang, Yan Li Zhang
Abstract: A new method for the determination of traces of mercury in environmental and biological samples is described. The present methodology combines determined using a hydride generation-atomic absorption spectrometry (HG-AAS) with pre-concentration/separation of the analyte on dithizone-anchored organobentonite (D-O-bentonite). Optimal experimental conditions for the adsorption of the Hg, including pH, contact time, eluent concentration and volume and co-existing ions have been studied. The result showed that the mercury 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 5.0, the adsorption time was 15 min, and capacity of adsorption was 23.2 mg·g-1. The mercury adsorbed on the sorbent could be completely eluated by using 3 mol·L-1 HCl. The adsorption agent has been applied to the pre-concentration/separation of mercury in surface water and human hair samples with satisfied results.
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Authors: Dong Zhang
Abstract: In this paper, a new method for the determination of bismuth in urine and tap water is described. The methodology combines determined using a hydride generation-atomic absorption spectrometry (HG-AAS) with pre-concentration of the bismuth on the modified organobentonite by dithizone (D-O-bentonite). Optimal experimental conditions for the adsorption and elution of the bismuth, including pH, contact time, eluent concentration, eluent volume and co-existing ions have been investigated. The result showed that the bismuth ion could be adsorbed on the D-O-bentonite. The adsorbed quantitive was affected by the pH value and contact time. In the medium of pH 5.0, the shaking time was 10 min, the adsorption capacity was 15.2 mg·g-1. The bismuth adsorbed on the modified organobentonite by dithizone could be completely eluated by using 2 mol·L-1 HNO3. The method has been applied to the pre-concentration/separation of bismuth in the human urine and tap water samples with satisfied results.
884
Authors: Dong Zhang
Abstract: A new method for the preconcentration and separation of cobalt ion in water was described. The methodology combines determination using a flame atomic absorption spectrometry (FAAS) with adsorption and desorption of cobalt on the nano-barium-strontium titanate powder coated by dithizone (BST-dithizone). The operation conditions for the pre-concentration and separation of the cobalt, including pH, contact time, eluent condition and co-existing ions have been investigated. The result showed that the cobalt ion could be adsorbed by BST-dithizone. The adsorption quantity was affected by the pH value of medium and shaking time. In the medium of pH 6.0, the adsorption capacity of BST-dithizone to cobalt ion was 8.92 mg·g-1 when the shaking time was more than10 min. The cobalt adsorbed on the adsorbent could be completely eluated and recovered using 10 g·L−1 ethylene diamine tetraacetic acid (EDTA) solution. The enrichment factor was 100. The detection limit of cobalt was 0.53 ng·L−1. The purposed method has been applied to the pre-concentration and separation of cobalt in the water sample with satisfied results.
166
Authors: Dong Zhang
Abstract: The micro-column packed with porous nano-barium- strontium titanate microspheres, joining with injector, a new manual-controlled injection porous nano-barium- strontium titanate microspheres enricher (PBSTME) was prepared. The enrichment capability of the PBSTME for the heavy metal ions, such as zinc, nickel, copper, manganese, cobalt and silver was investigated. The results showed that all the heavy metals studied could be quantitatively retained by the PBSTME in the pH range of 5–8, and then eluted completely with 2 mol•L-1 HNO3. The detection limits of this method for zinc, nickel, copper, manganese, cobalt and silver ions were 0.028 μg•L-1, 0.2μg•L-1, 0.031 μg•L-1, 0.022 μg•L-1, 0.057μg•L-1 and 0.039 μg•L-1 with an enrichment factor of 50, respectively. A new method has been developed for the determination of trace heavy metal ions based on pre-concentration with a PBSTME prior to their determination by flame atomic absorption spectrometry. The method has been applied to the simultaneous determination of trace amounts of zinc, nickel, copper, manganese, cobalt and silver ions in water sample with satisfactory results.
689
Authors: Dong Zhang, Zhi Jiang Liu
Abstract: Nano-calcium titanate-based coated silica gel G (GCTO) was prepared by the citric acid sol–gel method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectrophotometry (FTIR). Its lead, cadmium and nickel ions adsorption properties from water were studied. Adsorption and elution were investigated under different conditions. The results showed that the nanometer calcium titanate was immobilized on the silica gel G firmly, becoming a new composite adsorbent. The lead, cadmium and nickel ions were quantitatively retained at pH 5-9; their adsorption capacities of GCTO were 114 mg•g-1, 11.2 mg•g-1 and 20.1 mg•g-1, respectively. The adsorbent can be regenerated completely by elution with 1 mol•L-1 HNO3. The adsorbent has a promising prospect in removal or enriching and separation of heavy metals in water.
835
Authors: Dong Zhang
Abstract: Nanometer calcium titanate immobilized on Aluminum oxide (ACTO) was successfully prepared by the citrate acid sol-gel method and characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The adsorption capability of ACTO for Pb2+, Cd2+and Zn2+ from water was studied. Adsorption and elution were investigated under different conditions. The results show that nanometer calcium titanate could be immobilized on the aluminum oxide firmly, becoming a composite adsorbent. The Pb2+, Cd2+and Zn2+ were retained at pH 5-9, their adsorption capacities of ACTO were 124 mg•g-1, 8.58 mg•g-1 and 13.86 mg•g-1, respectively. The adsorption agent can be regenerated by elution with 2 mol•L-1 HNO3. The adsorbent has a promising prospect in removal or enriching and separation of heavy metals in water.
670
Authors: Dong Zhang, Chun Li Zhang
Abstract: Nanometer barium-stroutium titanate immobilized on aluminum oxide (ABST) was prepared by the citric acid sol–gel method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectrophotometry (FTIR). Its Pb2+ and Cd2+ adsorption properties from water were studied. Adsorption and elution were investigated under different conditions. The results showed that the nanometer barium-strontium titanate was immobilized on aluminum oxide firmly, becoming a composite adsorbent. The lead and cadmium ions were quantitatively retained at pH 5-8; their adsorption capacities of ABST were 70.28 mg•g-1 and 8.12 mg•g-1, respectively. The adsorbent of adsorped lead and cadmium ions were regenerated completely by elution with 1 mol•L-1 HNO3. The adsorbent had a promising prospect in analyticl chemistry and water treatment.
682
Authors: Dong Zhang
Abstract: Nano-strontium titanate based on glass fiber filter (GFST) was successfully prepared by sol-gel method and characterized using XRD and SEM. The adsorptive potential of GFST for heavy metal ions, such as lead, cadmium, zinc and nickel, was investigated. The results showed that the nano-strontium titanate could crystal based on glass fiber, gaining a new block adsorbent like a leaf. The lead, cadmium, zinc and nickel ions were quantitatively retained at pH 6-9; their adsorption capacities of GFST for lead, cadmium, zinc and nickel ions were 153.21 mg•g-1, 8.32 mg•g-1, 21.36 mg•g-1 and 4.80 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 and nickel ions in water.
2140
Authors: Dong Zhang
Abstract: A manual-controlled injection barium-strontium titanate based on glass fiber filter enricher(MIBSTE) was prepared, and its application in speciation of Cr(III) and Cr(VI) from water was studied. The optimum experimental parameters for preconcentration and separation of the Cr(III) and Cr(VI) have been investigated. The results showed that the BBST had adsorption capacity towards the Cr(III) and Cr(VI) at the different conditions. And two forms of chromium show different adsorption capacities at different pH values, Cr (III) could be adsorbed at pH ≥ 10, but Cr(VI) can’t be adsorbed. Whereas Cr (VI) retained at pH ≤ 2, but Cr(III) can’t be adsorbed. Therefore, it is possible that the two forms of chromium are complete separated. The Cr(III) and Cr(VI) could be completely eluted with 1 mol•L−1 HCl and 1 mol•L−1 NaOH, respectively. The chromium concentration was measured by atomic absorption spectroscopy. A new method for determination of the speciation of chromium in environmental water samples based on the manual-controlled injection enricher and atomic absorption spectroscopy determination was proposed. The method was successfully applied for the determination of Cr(III) and Cr(VI) in environmental waters with satisfactory results.
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Authors: Dong Zhang
Abstract: The ability of porous nano-barium-stroutium titanate (PBST) to remove heavy metal (lead, nickel and zinc) ions by sorption from aqueous solution was assessed. The effects of process parameters such as pH, contacttime, regeneration conditions and the effects of common coexisting ions on heavy metal (lead, nickel and zinc) ions uptake were investigated. The results showed that the lead, nickel and zinc ions studied could be quantitatively retained at a pH value range of 5~8. The adsorption capacities of PBST for lead, nickel and zinc were found to be11 6.5mg•g-1, 4.8mg•g-1 and 8.3 mg•g-1, respectively. Desorption studies were carried out successfully with diluted HNO3 solutions. The results indicate that PBST can be used as an effective adsorbent for the treatment of wastewaters contaminated with lead, nickel and zinc ions.
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