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Efficient and recyclable ultra-thin diameter polyacrylonitrile nanofiber membrane: Selective adsorption of cationic dyes. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2022.122109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Gu Q, Ng TCA, Poh W, Kirk CH, Lyu Z, Zhang L, Wang J, Ng HY. 3D spray-coated gradient profile ceramic membranes enables improved filtration performance in aerobic submerged membrane bioreactor. WATER RESEARCH 2022; 220:118661. [PMID: 35661502 DOI: 10.1016/j.watres.2022.118661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 05/12/2022] [Accepted: 05/21/2022] [Indexed: 06/15/2023]
Abstract
Rational design of cross-sectional microstructure in ceramic membranes has shown to improve membrane filtration efficacy without affecting rejection performance. In this work, we adopted 3D spray-coating technique to generate multi-layered membrane layers on macro-porous flat-sheet ceramic supports. The thickness of each layer was controlled by spray-coating cycles, and a gradient membrane layer was rationalized by successively coating three ceramic slurries containing alumina powders of gradually refined particle sizes, followed by co-sintering. Gradient membrane layers on both sides of the various sized flat-sheet ceramic supports were fabricated. Compared to the non-gradient counterpart, the gradient membranes showed both higher pure water flux (at the same TMP) and lower membrane resistance, which clearly evidenced the benefits of gradient profile in the membrane layer. Further, their performance in aerobic membrane bioreactors (AeMBR) was comparably studied for the first time. The treatment performance was not significantly affected by the types of membranes used, while the gradient membrane showed better filtration performance (i.e., a slower rise in TMP). Although the fouling mechanisms were revealed to be similar, the fouling layer in the gradient membrane was composed of a higher percentage of smaller foulants compared to that of the non-gradient counterpart. The observed differences were closely correlated to the larger internal pore structure in the gradient membrane. The present work provides a feasible 3D spray-coating technique for the fabrication of gradient flat-sheet ceramic membranes, and clarifies the benefits in AeMBR for domestic wastewater treatment.
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Affiliation(s)
- Qilin Gu
- Department of Material Science and Engineering, Faculty of Engineering, National University of Singapore, Singapore 117574; State Key Laboratory of Materials-Oriented Chemical Engineering, National Engineering Research Center for Special Separation Membrane, Nanjing Tech University, Nanjing 210009, China.
| | - Tze Chiang Albert Ng
- Centre for Water Research, Department of Civil and Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, Singapore 117576.
| | - Weijie Poh
- Centre for Water Research, Department of Civil and Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, Singapore 117576
| | - Chin Ho Kirk
- Department of Material Science and Engineering, Faculty of Engineering, National University of Singapore, Singapore 117574
| | - Zhiyang Lyu
- Department of Material Science and Engineering, Faculty of Engineering, National University of Singapore, Singapore 117574
| | - Lei Zhang
- Department of Material Science and Engineering, Faculty of Engineering, National University of Singapore, Singapore 117574
| | - John Wang
- Department of Material Science and Engineering, Faculty of Engineering, National University of Singapore, Singapore 117574; Institute of Materials Research and Engineering (IMRE), A*STAR (Agency for Science, Technology and Research), Singapore 138634.
| | - How Yong Ng
- Centre for Water Research, Department of Civil and Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, Singapore 117576; NUS Environmental Research Institute, National University of Singapore, 5A Engineering Drive 1, Singapore 117411.
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Zhang Z, Gu Q, Ng TCA, Zhang J, Zhang X, Zhang L, Zhang X, Wang H, Ng HY, Wang J. Hierarchically porous interlayer for highly permeable and fouling-resistant ceramic membranes in water treatment. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2022.121092] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Du J, Ai D, Xiao X, Song J, Li Y, Chen Y, Wang L, Zhu K. Rational Design and Porosity of Porous Alumina Ceramic Membrane for Air Bearing. MEMBRANES 2021; 11:membranes11110872. [PMID: 34832101 PMCID: PMC8622470 DOI: 10.3390/membranes11110872] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 11/05/2021] [Accepted: 11/06/2021] [Indexed: 11/16/2022]
Abstract
Air bearing has been widely applied in ultra-precision machine tools, aerospace and other fields. The restrictor of the porous material is the key component in air bearings, but its performance is limited by the machining accuracy. A combination of optimization design and material modification of the porous alumina ceramic membrane is proposed to improve performance within an air bearing. Porous alumina ceramics were prepared by adding a pore-forming agent and performing solid-phase sintering at 1600 °C for 3 h, using 95-Al2O3 as raw material and polystyrene microspheres with different particle sizes as the pore-forming agent. With 20 wt.% of PS50, the optimum porous alumina ceramic membranes achieved a density of 3.2 g/cm3, a porosity of 11.8% and a bending strength of 150.4 MPa. Then, the sintered samples were processed into restrictors with a diameter of 40 mm and a thickness of 5 mm. After the restrictors were bonded to aluminum shells for the air bearing, both experimental and simulation work was carried out to verify the designed air bearing. Simulation results showed that the load capacity increased from 94 N to 523 N when the porosity increased from 5% to 25% at a fixed gas supply pressure of 0.5 MPa and a fixed gas film thickness of 25 μm. When the gas film thickness and porosity were fixed at 100 μm and 11.8%, respectively, the load capacity increased from 8.6 N to 40.8 N with the gas supply pressure having been increased from 0.1 MPa to 0.5 MPa. Both experimental and simulation results successfully demonstrated the stability and effectiveness of the proposed method. The porosity is an important factor for improving the performance of an air bearing, and it can be optimized to enhance the bearing's stability and load capacity.
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Affiliation(s)
- Jianzhou Du
- School of Materials Science and Engineering, School of Mechanical Engineering, Yancheng Institute of Technology, Yancheng 224051, China; (J.D.); (D.A.); (X.X.); (J.S.); (Y.L.); (Y.C.)
- State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
| | - Duomei Ai
- School of Materials Science and Engineering, School of Mechanical Engineering, Yancheng Institute of Technology, Yancheng 224051, China; (J.D.); (D.A.); (X.X.); (J.S.); (Y.L.); (Y.C.)
| | - Xin Xiao
- School of Materials Science and Engineering, School of Mechanical Engineering, Yancheng Institute of Technology, Yancheng 224051, China; (J.D.); (D.A.); (X.X.); (J.S.); (Y.L.); (Y.C.)
| | - Jiming Song
- School of Materials Science and Engineering, School of Mechanical Engineering, Yancheng Institute of Technology, Yancheng 224051, China; (J.D.); (D.A.); (X.X.); (J.S.); (Y.L.); (Y.C.)
| | - Yunping Li
- School of Materials Science and Engineering, School of Mechanical Engineering, Yancheng Institute of Technology, Yancheng 224051, China; (J.D.); (D.A.); (X.X.); (J.S.); (Y.L.); (Y.C.)
| | - Yuansheng Chen
- School of Materials Science and Engineering, School of Mechanical Engineering, Yancheng Institute of Technology, Yancheng 224051, China; (J.D.); (D.A.); (X.X.); (J.S.); (Y.L.); (Y.C.)
| | - Luming Wang
- School of Materials Science and Engineering, School of Mechanical Engineering, Yancheng Institute of Technology, Yancheng 224051, China; (J.D.); (D.A.); (X.X.); (J.S.); (Y.L.); (Y.C.)
- Correspondence: (L.W.); (K.Z.)
| | - Kongjun Zhu
- State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
- Correspondence: (L.W.); (K.Z.)
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