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Qiu Y.R.,Central South University | Qiu Y.R.,Key Laboratory of Resources Chemistry of Nonferrous Metals | Han H.N.,Central South University
Advanced Materials Research | Year: 2014

Poly(vinyl chloride) (PVC) hollow fiber membranes were prepared via non-solvent induced phase separation (NIPS), the effect of bore liquid flow rate (BLFR) on the structure and properties of the membrane were investigated. The results show that the prepared PVC hollow fiber membrane has a finger-sponge-finger-like structure, the thickness of the sponge-like intermediate layer decreases with the increase of BLFR. Both the inside diameter and outside diameter increase, while the wall thickness of the PVC hollow fiber membrane decreases with the increase of BLFR. The tensile strength and elongation decrease, the permeate flux increases, while the rejection of the particles decreases little with the increase of BLFR. © (2014) Trans Tech Publications, Switzerland.


Feng Q.,Central South University | Feng Q.,JiShou University | Liu S.,Central South University | Liu S.,Key Laboratory of Resources Chemistry of Nonferrous Metals | And 2 more authors.
Applied Surface Science | Year: 2012

A three-dimensional porous nanostructure electrode composed of copper skeletons and platinum shells (NPC-Pt) was prepared by electroless plating for the first time. The electrochemical behavior of this electrode for electrocatalytic reduction CO 2 in ionic liquid, 1-butyl-3- methylimidazoliumtetrafluoborate (BMIMBF 4), had been studied by cyclic voltammogram and electrochemical impedance spectroscopy with a reduction peak at -2.24 V (vs. Ag) which was more positive 180 mV than that obtained on a pure platinum electrode. The electrolyses experiments were carried out in an undivided cell under mild conditions without any toxic solvents, catalysts and supporting electrolytes, affording the dimethyl carbonate in a good yield (81%). In addition, the current for the CO 2 reduction at NPC-Pt electrode was stable, with a higher current density and current efficiency (83%). Moreover, current efficiency remained after reusing it for five times. © 2011 Elsevier B.V. All rights reserved. All rights reserved.


Li C.,Central South University | Li C.,Key Laboratory of Resources Chemistry of Nonferrous Metals | Zhong H.,Central South University | Zhong H.,Key Laboratory of Resources Chemistry of Nonferrous Metals | And 4 more authors.
Human and Ecological Risk Assessment | Year: 2014

We analyzed the leaching behavior and chemical speciation of heavy metals in a landfill of electrolytic manganese residue (EMR). The results showed that most of Pb, Cr, As, Cu, and Zn were associated with F4 (residual fraction) and Mn and Co were mainly present in F1 (exchangeable and weak acid soluble fraction). In order to evaluate potential risks of heavy metals to the landfill, modified potential ecological risk index (MPER), potential ecological risk index (PER), index of geo-accumulation (Igeo) assessment, and risk assessment code (RAC) were employed. Ranking order for potential risk based on RAC assessment is Mn > Co > Zn > Cu > Cr = As = Pb. Results from Igeo assessment indicates that Mn poses a potential for high risk to human health and the ecosystem. MPER, which integrates the characteristics of PER and RAC, shows that the potential risks of heavy metals are in the order of As > Cu > Mn > Co > Pb > Cr > Zn. The analysis indicates that Mn, Co, As, and Cu within EMR pose a potential risk when this material is placed in landfills and that these metals should be given particular attention when managing the land disposal of EMR. © 2014 Taylor & Francis Group, LLC.


Li W.,Central South University | Li W.,Key Laboratory of Resources Chemistry of Nonferrous Metals | Li J.,Central South University | Li J.,Key Laboratory of Resources Chemistry of Nonferrous Metals | And 6 more authors.
International Journal of Hydrogen Energy | Year: 2010

Tungsten trioxide (WO3) films were prepared by a solution-based method using ammonium metatungstate as the precursor and polyethylene glycol as the structure-directing agent. With the measurements of thermogravimetric and differential thermal analysis, X-ray diffraction, scanning electron microscopy, and ultraviolet and visible absorption spectroscopy, the effect of substrates and temperature on the crystal structure and crystalline formation of WO 3 was investigated. The results show that the WO3 films were crystallized by sintering at over 400 °C, and the films prepared on fluorine-tin oxide glass substrates were distorted cubic in crystalline phase. However, a monoclinic crystal was formed by coating films on graphite and quartz glass substrates. Photoelectrochemical activity was evaluated under visible light irradiation. The WO3 electrode calcined at 450 °C exhibited a photocurrent density of up to 2.7 mA/cm2 at 1.4 V (vs. RHE) under incident 100 mW/cm2 500 W Xe lamp and donor carrier density N D = 2.44 × 1022 cm-3 in 0.5 M H 2SO4 electrolyte. The photoanode was stable up to 90 min, and the photocurrent decreased 39% with continuous gas evolution. © 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.


Qiu Y.-R.,Central South University | Qiu Y.-R.,Key Laboratory of Resources Chemistry of Nonferrous Metals | Mao L.-J.,Central South University | Mao L.-J.,Key Laboratory of Resources Chemistry of Nonferrous Metals
Desalination | Year: 2013

Copolymer of maleic acid and acrylic acid (PMA-100), combining with polyvinyl butyral (PVB) hollow fiber ultrafiltration membrane were applied into a complexation-ultrafiltration process for the removal of heavy metal ions from an aqueous solution. Potentiometric and conductimetric titrations of the copolymer revealed that carboxylic group content was 9.5mmol.g-1 and the degree of deprotonation as pH was plotted. When low concentration (10mg/L) of solution containing heavy metal ion was processed, like Cu2+, Zn2+, Ni2+ and Mn2+, two most important factors (mass ratio of copolymer to metal and pH) were investigated and optimized to maximize both the rejection rate and permeate flux. The results show that at pH6.0 and copolymer/metal ratio 6-7 (w/w), the complexation is rapid and completed within 5min, reaching a removal efficiency above 98.8%. The copolymer could be efficiently regenerated by acidification-diafiltration and the residual concentration of Cu2+ in the concentrated copolymer solution decreased from 100mg/L to 2.6mg/L. In addition, the difference in binding ability to copolymer was studied and the relative affinity was Cu2+>Zn2+>Ni2+>Mn2+. The sequence is of great importance for guiding the selective separation of these metal ions in the future work. © 2013 Elsevier B.V.


Qiu Y.-R.,Central South University | Qiu Y.-R.,Key Laboratory of Resources Chemistry of Nonferrous Metals | Mao L.-J.,Central South University | Wang W.-H.,Central South University
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2014

Copolymer of maleic acid and acrylic acid (PMA-100), combining with polyvinyl butyral (PVB) ultrafiltration membrane was used for the removal of Mn(II) from waste water by complexation-ultrafiltration. The carboxylic group content of PMA-100 and the rate of complexation reaction were measured. Effects of the mass ratio of PMA-100 to Mn(II) (n), pH, background electrolyte, etc on the rejection rate (R) and permeate flux (J) were investigated. The results show that carboxylic group content of PMA-100 is 9.5 mmol/g. The complexation of Mn(II) with PMA-100 is rapid and completed within 5 min at pH 6.0. Both R and J increase with pH increasing in the range of 2.5-7.0, and R increases with the increase of n at pH 6.0 while J is little affected. The background electrolyte leads to the decrease of R, and CaCl2 has much greater effect on R than NaCl at the same ionic strength. © 2014 The Nonferrous Metals Society of China.


Huang J.,Central South University | Huang J.,Key Laboratory of Resources Chemistry of Nonferrous Metals | Wang G.,Central South University | Wang G.,Key Laboratory of Resources Chemistry of Nonferrous Metals | And 2 more authors.
Chemical Engineering Journal | Year: 2011

A series of novel β-naphthol-modified hyper-cross-linked poly(styrene-co-divinylbenzene) resins were synthesized and the adsorption behaviors of the synthesized resins towards salicylic acid from aqueous solution was investigated. Among the synthesized five resins, HJ-G02 possessed the largest adsorption capacity towards salicylic acid. The molecular form of salicylic acid was favorable for the adsorption and mono-anion of salicylic acid can also be adsorbed by the resin. Low concentration of phenol posed a positive effect while high concentration of phenol posed a negative effect on the adsorption. The isotherms could be fitted by Freundlich model and the kinetic data could be characterized by pseudo-second-order rate equation. The breakthrough point of HJ-G02 towards salicylic acid was 108.8. BV and HJ-G02 could be regenerated by 1% of sodium hydroxide solution. © 2011 Elsevier B.V.


Huang J.,Central South University | Huang J.,New Mexico State University | Huang J.,Key Laboratory of Resources Chemistry of Nonferrous Metals | Yuan B.,New Mexico State University | And 2 more authors.
Journal of Colloid and Interface Science | Year: 2012

Adsorptive removal of aromatic compounds from aqueous solutions by polymeric adsorbents has attracted many concerns in recent years. A comparative adsorption study including equilibria, kinetics and column dynamics of β-naphthol from aqueous solutions was carried out using two hypercrosslinked polymeric adsorbents (HJ-1 and TEPA) we developed and two commercial polymeric adsorbents (XAD-4 and XAD-7). The adsorption isotherms could be well described by the Freundlich equation, and the adsorption equilibrium capacities of β-naphthol followed an order of q e(TEPA)>q e(HJ-1)>q e(XAD-4)>q e(XAD-7). The isosteric adsorption enthalpies on HJ-1 and TEPA decreased with increasing adsorption fractional loading, while a constant enthalpy was observed for XAD-4 and XAD-7, implying that HJ-1 and TEPA had a heterogeneous surface while XAD-4 and XAD-7 possessed a homogenous surface. The surface energetic heterogeneity of HJ-1 and TEPA could be well characterized by the Do's model. The adsorption kinetics were fitted by both pseudo-first-order and pseudo-second-order rate equations, and the intra-particle diffusion was found to be the rate-limiting step. The adsorption breakthrough data were well correlated by the Thomas and Clark models, and the dynamic capacities for TEPA, HJ-1, XAD-4 and XAD-7 adsorbents were calculated to be 341.7, 321.6, 268.0 and 173.8mg/g dry resin, which were within 90% of the corresponding equilibrium capacities obtained in the batch experiments. © 2012 Elsevier Inc.


Zhao G.,Central South University | Zhong H.,Central South University | Zhong H.,Key Laboratory of Resources Chemistry of Nonferrous Metals | Qiu X.,General Research Institute for Nonferrous Metals, China | And 7 more authors.
Minerals Engineering | Year: 2013

In this paper, cyclohexyl hydroxamic acid (CHA) was investigated as a new collector for scheelite flotation by the Density Functional Theory (DFT) calculation, mineral flotation tests, adsorption measurement and zeta potential determination. The DFT computation results indicated that the dianion of CHA or benzoylhydroxamic acid (BHA) exhibited stronger chemical reactivity than their anions and neutral molecules, and that the replacement of phenyl group by cyclohexyl group in BHA molecule significantly impacted the electron donating ability of hydroxamate collectors. In alkaline aqueous solutions, the two oxygen atoms in the dianions of CHA or BHA charged more negative charges than other atoms, and hence became their reactive center. The dianion of CHA exhibited higher atomic charge value, HOMO (Highest Occupied Molecular Orbital) energy, bigger dipole moment and binding energy with Ca2+, thus it had stronger collecting ability for scheelite than that of BHA. In addition, the results of flotation tests, adsorption measurement and zeta potential determination validated that the collecting capability of CHA was stronger than that of BHA, which achieved excellent agreement with computational analysis. © 2013 Elsevier Ltd. All rights reserved.


Huang J.,Central South University | Huang J.,Key Laboratory of Resources Chemistry of Nonferrous Metals | Zha H.,Central South University | Jin X.,Central South University | Deng S.,New Mexico State University
Chemical Engineering Journal | Year: 2012

Phenol is a typical organic pollutant in industrial wastewater and efficient adsorptive removal of phenol from aqueous solution has attracted many attentions in recent years. In the present study, a diethylenetriamine-modified hypercrosslinked styrene-divinylbenzene (PS) resin, HJ-M05, was synthesized, characterized and evaluated for adsorptive removal of phenol from aqueous solution, and two typical commercial polymeric adsorbents, Amberlite XAD-4 and XAD-7, were employed as references. The equilibrium capacity on HJ-M05 was much larger than those on XAD-4, XAD-7 and the precursor, HJ-55. The degree of the surface energetic heterogeneity of HJ-M05 was proven to be higher than XAD-4 and XAD-7 while the adsorbate-adsorbate interaction of the adsorbed phenol molecules on HJ-M05 was much less than that on XAD-4 and XAD-7. The kinetic data on HJ-M05 could be well plotted by the micropore diffusion model while those on XAD-4 and XAD-7 could not be fitted by this model. Thomas and Yoon models were more suitable for describing the dynamic data than the Clark model and the dynamic capacities on HJ-M05, HJ-55, XAD-4 and XAD-7 were calculated to be 201.7, 178.1, 107.5 and 74.80. mg/g dry resin, respectively. 15.0. BV (1. BV = 10. ml) 1% of sodium hydroxide could regenerate the HJ-M05 resin column completely and the dynamic desorbed amount was almost equal to the dynamic adsorption amount. © 2012 Elsevier B.V.

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