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Xing D.Y.,Harbin Institute of Technology | Xing D.Y.,Shenzhen Key Laboratory of Water Resource Utilization and Environmental Pollution Control | Dong W.Y.,Harbin Institute of Technology | Dong W.Y.,Shenzhen Key Laboratory of Water Resource Utilization and Environmental Pollution Control | Chung T.-S.,National University of Singapore
Industrial and Engineering Chemistry Research | Year: 2016

In this work, we have examined and compared the interactions between cellulose acetate and different ionic liquids at a molecular level and explored their effects on dope rheology, hollow fiber morphology, and performance. Ionic liquid, 1-ethyl-3-methylimidazolium acetate ([EMIM]OAc), was found to interact with cellulose acetate (CA) more closely with intensive hydrogen bonds than 1-ethyl-3-methylimidazolium thiocyanate ([EMIM]SCN). Thus, the CA/[EMIM]OAc solution exhibits a more pronounced charge-ordered network than the CA/[EMIM]SCN solution. In addition, the former does not obey the Cox-Merz rule, whereas the latter obeys the rule with its shear viscosity η identical to its complex viscosity |η∗| at the equivalent shear rate and angular frequency. These dissimilar factors have contributed to an instantaneous liquid-liquid demixing and resulted in a dense outer skin surface and a porous cross-sectional structure comprising macrovoids for the CA/OAc membrane. In contrast, the CA/SCN membrane has a looser interconnected nodular structure resulting from the delayed liquid-liquid demixing. The effects of spinning conditions on membrane properties have been determined. The higher dope flow rate and take-up speed result in smaller pore size. [EMIM]OAc is a more practical solvent than [EMIM]SCN to fabricate CA hollow fibers with a broader choice of spinning parameters. The newly developed CA/OAc membranes have PWP values of 230 and 260 L/(m2 bar h) and pore sizes of 10-27 nm. This work may provide useful insights to develop polymeric membranes using ionic liquids as solvents and facilitate a greener fabrication method in the membrane industry. © 2016 American Chemical Society. Source

Tian F.,Harbin Institute of Technology | Zhu R.,Harbin Institute of Technology | Zhu R.,Shenzhen Key Laboratory of Water Resource Utilization and Environmental Pollution Control | He Y.,Harbin Institute of Technology | And 2 more authors.
International Journal of Hydrogen Energy | Year: 2014

A series of rare earth (RE) ions (La3+, Ce3+, Gd 3+, Er3+ or Y3+) modified ZnIn 2S4 photocatalysts (RE-ZnIn2S4) were prepared using the hydrothermal method and characterized by various analysis techniques, such as UV-Vis diffusive reflectance spectroscopy, X-ray diffraction, scanning electron microscopy, Brunauer-Emmett-Teller surface analyzer, photoluminescence spectroscopy and X-ray photoelectron spectroscopy. The results indicated that the RE element exists as the oxide RE 2O3 and their modification can reduce ZnIn 2S4 crystallite size, inhibit ZnIn2S 4 grain growth, promote ZnIn2S4 crystallite self-organization into a micro-sphere flower-like morphology, increase ZnIn 2S4 surface area and total pore volume, and bring rich defects to ZnIn2S4. The photocatalytic activities of RE-ZnIn2S4 were evaluated based on photocatalytic hydrogen production from water under visible-light irradiation and the hydrogen production efficiency increased by 46%, 53%, 61%, 69%, and 106% after adding 2.0 wt% of Y, Gd, Er, Ce and La, respectively. The relationship between the photocatalytic activity of RE-ZnIn2S4 and the RE properties was discussed. Copyright © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. Source

Xia X.,Harbin Institute of Technology | Shao M.-F.,Harbin Institute of Technology | Shao M.-F.,Shenzhen Key Laboratory of Water Resource Utilization and Environmental Pollution Control | Lyu X.-M.,Harbin Institute of Technology | And 3 more authors.
Research of Environmental Sciences | Year: 2014

In the present study, denitrifying phosphorus removal sludges with acetate, glycerol and propionate as the sole carbon sources were acclimatized in three sequencing reactors (SBRs) operated under strict anaerobic-anoxic conditions, and the sludges with different carbon sources were systematically investigated by high-throughput sequencing. Stable operation showed that propionate was the optimal carbon source, followed by acetate and glycerol, with average effluent phosphorus concentrations of 0.29, 0.79 and 0.98 mg/L, corresponding to removal rates of 93.4%, 82.5% and 79.2%, respectively. The seed sludge from WWTP had the richest microbial diversity, followed by sludge fed with glycerol, acetate and propionate. Moreover, the two Volatile Fatty Acids (VFAs) feeding sludge (acetate and propionate) exhibited similar bacterial diversity and community structure. At the class level, β-Proteobacteria was most abundant for all the sludge samples. At the order level, Rhodocyclales that most phosphorus removal bacteria belonged to was the most dominant order for the samples from SBRs. Sequence local BLAST (Basic Local Alignment Search Tool) showed that the Ca. Accumulibacter-like PAO abundances of sludge with propionate, acetate and glycerol as carbon sources were 41.5%, 9.5% and 8.0% respectively during the stable operation; propionate feeding sludge had the highest abundance. Compared with acetate and glycerol, propionate showed priority for the enrichment of phosphorus removing bacteria in anaerobic-anoxic system, and the best carbon source for the EBPR. Source

Lv X.,Harbin Institute of Technology | Shao M.,Harbin Institute of Technology | Shao M.,Shenzhen Key Laboratory of Water Resource Utilization and Environmental Pollution Control | Li C.,Harbin Institute of Technology | And 6 more authors.
Journal of Industrial Microbiology and Biotechnology | Year: 2014

Operation performances of phosphorus removal sludge with different electron acceptors in three parallel SBRs were firstly compared in the present study, and the effect of post-aeration on denitrifying phosphorus removal was also studied. Moreover, community dynamics of different phosphorus removal sludge was systematically investigated with high-throughput sequencing for the first time. TP removal rates for nitrate-, nitrite-, and oxygen-based phosphorus removal sludge were 84.8, 78.5, and 87.4 %, with an average effluent TP concentration of 0.758, 0.931, and 0.632 mg/l. The average specific phosphorus release and uptake rates were 20.3, 10.8, and 21.5, and 9.43, 8.68, and 10.8 mgP/(gVSS h), respectively. Moreover, electron utilization efficiency of denitrifying phosphorus removal sludge with nitrate as electron acceptor was higher than nitrite, with P/e- were 2.21 and 1.51 mol-P/mol-e-, respectively. With the assistance of post-aeration for nitrate-based denitrifying phosphorus removal sludge, settling ability could be improved, with SVI decreased from 120 to 80 and 72 ml/g when post-aeration time was 0, 10, and 30 min, respectively. Moreover, further phosphorus removal could be achieved during post-aeration with increased aeration time. However, the anoxic phosphorus uptake was deteriorated, which was likely a result of shifted microbial community structure. Post-aeration of approximately 10 min was proposed for denitrifying phosphorus removal. Nitrate- and nitrite-based denitrifying phosphorus removal sludge exhibited similar community structure. More phosphorus accumulating organisms were enriched under anaerobic-aerobic conditions, while anaerobic-anoxic conditions were favorable for suppressing glycogen-accumulating organisms. Significant differences in pathogenic bacterial community profiles revealed in the current study indicated the potential public health hazards of non-aeration activated sludge system. © 2014 Society for Industrial Microbiology and Biotechnology. Source

Li T.,Harbin Institute of Technology | Wang H.,Harbin Institute of Technology | Wang H.,Shenzhen Key Laboratory of Water Resource Utilization and Environmental Pollution Control | Dong W.,Harbin Institute of Technology | And 6 more authors.
Chemical Engineering Journal | Year: 2014

A coagulant dosed pre-anoxic activated sludge reactor is proposed to configure prior to the BAF reactor to reduce the contents of phosphorus and suspend solids in wastewater, efficiently utilize the carbon source for denitrification, and avoid the problems caused by direct addition of coagulant into BAF reactor. A series of laboratory experiments were carried out to examine the feasibility and suitability of using Fe(II) as a coagulant. The performance on phosphorus removal and dinitrification, the determination of an optimal Fe(II), and any adverse effect brought by dosing Fe(II) are of interests. Base on the results of the continuously operated experiment, it was observed that dosing Fe(II) in the proposed pre-anoxic reactor demonstrated fair effectiveness in phosphorous removal and simultaneous denitrification. Enhanced denitrification efficiency was observed in the presence of Fe(II), probably resulting from the increased returned sludge amount and the promoted denitrification related to microbial Fe(II)-dependent nitrate reduction after dosing Fe(II). Overdosing Fe(II) would however result in suppressed TSS, TCOD and TP removal in the settling tank effluent due to the formation of fine microbial flocs. A Fe(II) dose with Fe:P molar ratio of 2-2.2:1 was selected as an optimal dose, which showed good performance in phosphorus removal, denitrification, and COD reduction, as well as, avoided the adverse effects caused by Fe(II) overdosing. Besides enhancing wastewater treatment in pre-anoxic reactor, dosing Fe(II) also improved sludge sedimentation and dewaterability, which were beneficial for the subsequent operation of dealing with excessive sludge. © 2014 Elsevier B.V. Source

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