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Li S.-P.,Shandong University | Cui J.-J.,Institute of Seawater Desalination And Multipurpose Utilization | Jiang Y.-Y.,Shandong University | Fang H.-C.,Shandong University
Gaodianya Jishu/High Voltage Engineering | Year: 2011

In order to study the effect of low-temperature plasma on Nitenpyram (NTP) pesticide containing wastewater treatment, employing reactor with a structure of radial flow sedimentation tank and centered fluid inlet, NTP solution was experimentally treated by low-temperature plasma produced by dielectric barrier discharge process. The influences of different dielectric barrier discharge's input power and different external factors, such as Fe2+, butanol, Na2CO3 and H2O2 on nitenpyram degradation, on treatment results were studied. The results show that NTP could be effectively removed from aqueous solution by the low-temperature plasma. Increasing the input power can increase the degradation efficiency. 82.7% of the NTP in 1L NTP solution (initially 100 mg/L) was degraded after 180 min treatment when the input power was 200 W. Low concentrations of Fe2+ and H2O2 could enhance the degradation, however, they hinder the degradation at higher concentrations. The presence of n-butanol as hydroxide radical scavenger and sodium carbonate as buffer in the aqueous solution decreases the removal efficiency of NTP to some extent. Furthermore, the pH of NTP drops with the degradation processing.

Tamaddondar M.,Tarbiat Modares University | Pahlavanzadeh H.,Tarbiat Modares University | Saeid Hosseini S.,Tarbiat Modares University | Ruan G.,Institute of Seawater Desalination And Multipurpose Utilization | Tan N.R.,HOSSTECH Group
Journal of Membrane Science | Year: 2014

Pervaporation separation of polar/non-polar mixtures is one of the attractive areas in membrane science and technology. In the present study, membranes with highly cross-linked nanometric selective layers were developed through layer-by-layer (LBL) assembly of polyanionic and cationic surfactants and explored for separation of methanol (MeOH)/methyl tert-butyl ether (MTBE) mixtures. Pristine polyelectrolyte surfactant complex (PELSC) composite membranes were fabricated by deposition of dilute and concentrated ionic solutions of sodium cellulose sulfate (NaCS) and hexadecylpyridinium chloride (HDPC) onto the polyacrylonitrile (PAN) ultrafiltration (UF) membrane supports. In addition, nanocomposite PELSC membranes containing different loadings of nano-sized SiO2 particles were fabricated, for the first time, by solution casting method. Morphological and Fourier transform infra-red (FTIR) characterizations confirmed homogeneous morphology of membranes and successful incorporation of nano-silica particles into nanocomposite precipitate. The effects of several fabrication (i.e., number of deposition steps and nano-silica loading) and operational parameters (i.e., feed temperature and concentration) on the separation performance of MeOH/MTBE were investigated. The results revealed that increasing feed temperature enhanced both flux and selectivity in case of pristine PELSC membranes. It was also observed that increasing nano-silica loading from 2wt% to 10wt% in nanocomposite PELSC membranes led to improvement in flux at the expense of selectivity. The highest flux (1.62kg/m2h) was obtained in nanocomposite PELSC membrane containing 10wt% nano-silica particles. This study demonstrates successful development of unique structures of PELSC and nanocomposite PELSC membranes with considerable potential application for pervaporation separation of polar/non-polar mixtures. © 2014 Elsevier B.V.

Zhang Y.,Institute of Seawater Desalination And Multipurpose Utilization
Wei sheng wu xue bao = Acta microbiologica Sinica | Year: 2010

OBJECTIVE: To isolate, identify and characterize a fungus with flocculating activity. METHODS: We used gradient dilution, plaque distribution and 18S rDNA analysis to isolate and identify a fungus with flocculating activity. We used high-speed centrifugation, ultrasonication and qualitative test to determine the nature of flocculating active substances. RESULTS: We isolated a flocculating active fungi and identified it as Penicillium purpurogenum. Ultrasonication test confirmed that the flocculating activity was primarily in the fermentation supernatant. We explored the flocculating activity curve and found that 4 days was the optimum fermentation time for accumulating flocculating active substances. The strain flocculating activity remains unchanged when pH varied from 2 to 11 and temperature varied from -70 degrees C to 100 degrees C. We finally identified the flocculating active substances as saccharides. CONCLUSION: We isolated a flocculating active strain P. purpurogenum EL-02, and identified its flocculating active products as saccharides.

Xu J.,Key Laboratory of Marine Chemistry Theory and Technology | Ruan G.,Institute of Seawater Desalination And Multipurpose Utilization | Zou L.,University of South Australia | Gao C.,Key Laboratory of Marine Chemistry Theory and Technology
Desalination | Year: 2010

Bio-fouling results in deterioration of permeate quality and flux in reverse osmosis (RO) process. Cellulose triacetate hollow fiber membrane used for RO in SWRO has anti-chlorine property that makes technical sense compared to polyamide spiral-wound RO for overcoming bio-fouling. Mode of chlorine injection is the controlling factor of sterilization in SWRO system. This work evaluated the effects of five different modes of chlorine injecting system as well as HCl injection on the performance of HF RO system. In addition, effects of HCl and anti-scalants on anti-scale performance of HF RO system were also investigated, respectively. A brief list of chemical costs under different abovementioned operating conditions was covered in a cost analysis. The results indicated that the injecting mode that employed continuous chlorine with a relatively low concentration of 0.3-0.4 mg/L at pH 5.8-6.2 was preferable in the aspects of total bacterial count (TBC) removal, permeate flow rate, differential pressure, permeability (Pp), performance factor (η) and chemical costs. HCl injection could improve the sterilization and prevent scaling on the membrane surface efficiently. The expense of anti-scalant (MDC220) was higher than HCl. © 2010 Elsevier B.V. All rights reserved.

Pan B.,Institute of Seawater Desalination And Multipurpose Utilization | Yan P.,Institute of Seawater Desalination And Multipurpose Utilization | Zhu L.,Institute of Seawater Desalination And Multipurpose Utilization | Li X.,Tianjin Polytechnic University
Desalination | Year: 2013

The potential of using nanofiltration (NF) membranes to concentrate coffee extract was investigated in this study. Six commercial NF membranes were screened using pure water and coffee extract tests. Ultimately NF-2 NF membrane from SEPRO was selected to evaluate the concentration of coffee extracts due to its better performance. A commercial spiral wound NF-2 membrane element was used to evaluate membrane performance at 40. °C and 28 and 40. bar. The theoretical maximum concentrations that can be achieved at 28 and 40. bar were 35% and 39%, respectively, based on model regression. Mass balances were calculated to estimate solid loss during the concentration process. At the two operation conditions, the solid losses are 2.8% and 3.3% over the processes. Overall, it is concluded that NF membranes are capable to concentrate coffee extract to a certain level and have a potential to partially replace conventionally evaporation process. © 2013 Elsevier B.V.

Han Y.,Tianjin University | Zhang M.,Tianjin University | Zhang M.,Institute of Seawater Desalination And Multipurpose Utilization | Li W.,Tianjin University | Zhang J.,Tianjin University
Physical Chemistry Chemical Physics | Year: 2012

First-principles density functional theory studies have been carried out to investigate the effects of perfect and defective anatase TiO 2 supports on the structural stabilities and electronic properties of Pd mAg n(m + n = 2-5) bimetallic clusters. Our results showed that the structures of supported Pd-Ag bimetallic clusters are distorted compared to their structures in the gas phase, which is caused by the balance of the cluster inner-interaction and the metal-support interfacial interaction. In particular, Pd 1Ag 3 and Pd 1Ag 4 clusters prefer to form three-dimensional structures on both perfect and defective anatase TiO 2 support while their most stable structures in the gas phase are planar. In the most stable structures of supported Pd mAg n bimetallic clusters, Pd atoms always occupy the most active sites of TiO 2(101) surface, which induced Pd enriched at the interface of TiO 2 support and Ag atoms exposed at the surface of the bimetallic cluster. As Ag% increases, the perfect TiO 2 support gets more electrons from the Pd-Ag bimetallic cluster, which reduced the stability of the supported Pd-Ag cluster. The Mulliken population and electron density difference analysis demonstrated that the co-deposition of Ag induced the charge of adsorbed Pd on the perfect TiO 2 support from positive to negative as a result of charge transfer from the half-filled s-orbital of Ag(5s 1) to the d-orbit of Pd, and the negative charges of Pd on the defective TiO 2 support were also increased by Pd-Ag charge polarization. Therefore, the selectivity of acetylene hydrogenation is enhanced by anatase-TiO 2 supported Pd-Ag bimetallic catalyst as it serves as an electron donor. This journal is © the Owner Societies 2012.

Pan B.,Institute of Seawater Desalination And Multipurpose Utilization | Zhu L.,Institute of Seawater Desalination And Multipurpose Utilization | Li X.,Tianjin Polytechnic University
Polymer Composites | Year: 2013

The spinnabiliy of polyvinylidene fluoride (PVDF)/CaCO3 microparticle dope solution were explored via a thermally induced phase separation process, and composite hollow fiber (CHF) membranes were prepared successfully. The experiment results showed that the self-supporting property of CHF got improved after adding CaCO3 at low concentration of PVDF, so the control of spinning process became easy. The effects of CaCO3 on the structure and properties of hollow fiber membrane were investigated in terms of morphology, water flux, porosity, breakage strength, and crystallization. The results indicated that CHF presented a uniform bicontinuous structure. The permeability and porosity of CHF increased obviously when CaCO3 was removed by acid, while the breakage strength decreased slightly. CHF presented a good drying stability. © 2013 Society of Plastics Engineers.

Feng J.-M.,Tianjin University | Feng J.-M.,Institute of Seawater Desalination And Multipurpose Utilization | Dai Y.-J.,Tianjin University
Nanoscale | Year: 2013

Combining carbon nanotubes (CNTs) with graphene has been proved to be a feasible method for improving the performance of graphene for some practical applications. This paper reports a water-assisted route to grow graphene on CNTs from ferrocene and thiophene dissolved in ethanol by the chemical vapor deposition method in an argon flow. A double injection technique was used to separately inject ethanol solution and water for the preparation of graphene/CNTs. First, CNTs were prepared from ethanol solution and water. The injection of ethanol solution was suspended and water alone was injected into the reactor to etch the CNTs. Thereafter, ethanol solution was injected along with water, which is the key factor in obtaining graphene/CNTs. Transmission electron microscopy, scanning electron microscopy, X-ray diffraction, and Raman scattering analyses confirmed that the products were the hybrid materials of graphene/CNTs. X-ray photo-electron spectroscopy analysis showed the presence of oxygen rich functional groups on the surface of the graphene/CNTs. Given the activity of the graphene/CNT surface, CdS quantum dots adhered onto it uniformly through simple mechanical mixing. This journal is © 2013 The Royal Society of Chemistry.

Wu D.,Nankai University | Wu D.,Institute of Seawater Desalination And Multipurpose Utilization | Song X.,Nankai University | Tang T.,CAS Changchun Institute of Applied Chemistry | Zhao H.,Nankai University
Journal of Polymer Science, Part A: Polymer Chemistry | Year: 2010

Well-defined macromolecular brushes with poly (N-isopropyl acrylamide) (PNIPAM) side chains on random copolymer backbones were synthesized by "grafting from" approach based on click chemistry and reversible additionfragmentation chain transfer (RAFT) polymerization. To prepare macromolecular brushes, two linear random copolymers of 2-(trimethylsilyloxy) ethyl methacrylate (HEMA-TMS) and methyl methacrylate (MMA) (poly(MMA-co-HEMA- TMS)) were synthesized by atom transfer radical polymerization and were subsequently derivated to azide-containing polymers. Novel alkyne-terminated RAFT chain transfer agent (CTA) was grafted to polymer backbones by copper-catalyzed 1,3-dipolar cycloaddition (azide-alkyne click chemistry), and macro-RAFT CTAs were obtained. PNIPAM side chains were prepared by RAFT polymerization. The macromolecular brushes have well-defined structures, controlled molecular weights, and molecular weight distributions (M w/Mn ≦ 1.23). The RAFT polymerization of NIPAM exhibited pseudo-first-order kinetics and a linear molecular weight dependence on monomer conversion, and no detectable termination was observed in the polymerization. The macromolecular brushes can self-assemble into micelles in aqueous solution. © 2009 Wiley Periodicals, Inc.

Guo R.,Tianjin University | Wang X.,Tianjin University | Guo C.,Institute of Seawater Desalination And Multipurpose Utilization | Dong A.,Tianjin University | Zhang J.,Tianjin University
Macromolecular Chemistry and Physics | Year: 2012

The novel fluorescence-labeled RAFT agents 2-(4-benzyl)benzoxazole benzodithioate (BBB) and 2-(4-benzyl)benzoxazole 9H-carbazole-9-carbodithioate (BBCC) were synthesized via a nucleophilic substitution reaction between commercially available 2-(4-(chloromethyl)phenyl)benzoxazole (CMPB) and excessive carbodithioate or dithiocarbamate salts. BBB bearing benzoxazole at R-group and BBCC carrying benzoxazole and carbazole at R- and Z-group can be applied to directly obtain α- and α,ω-end-fluorescence-labeled polymers, respectively. Considering the mild reaction conditions and readily available dyes, the reactions between CMPB and dithiocarbamate or carbodithioate salts should be a very simple and promising approach to synthesize fluorescent RAFT agents and polymers. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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