臭氧-CNT膜改性联用工艺阈通量及膜污染分析
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摘要
采用碳纳米管(carbon nanotube,CNT)对聚偏氟乙烯(polyvinylidene fluoride,PVDF)中空纤维超滤膜进行改性,结合臭氧预氧化技术,考察了臭氧-CNT膜改性联用工艺的阈通量及膜表面污染情况.结果表明,原膜阈通量为45 L·(m~2·h)~(-1),联用工艺下阈通量为81 L·(m~2·h)~(-1),联用工艺相对原膜阈通量提高了约80%;且联用工艺的污染速率最低,约为0. 001 37k Pa·min-1·L-1·m~2·h.相同臭氧投量与CNT负载量下,对比联用工艺阈通量与临界通量运行情况,得出阈通量下运行过水量高于临界通量运行,表明阈通量下运行能够缓解膜污染,延长膜组件的运行时间.膜污染碳平衡实验结果表明,采用CNT对膜改性后,膜组件的纳污能力与可恢复性得到明显提高,臭氧氧化能够进一步提高CNT改性膜组件的可恢复性,大幅提高其过水性能和使用时间.
Polyvinylidene fluoride( PVDF) hollow fiber ultrafiltration membranes were modified with carbon nanotubes( CNT).Hybrid pre-ozonation and CNT modification were investigated by experimentally manipulating the ozonation process,threshold flux,and membrane fouling. The results showed that the threshold fluxes of the unmodified membrane and hybrid process were 45 L·( m2·h)-1 and 81 L·( m2·h)-1,respectively. Additionally,the fouling rate of the hybrid process was about 0. 001 37 k Pa·min-1·L-1·m2·h,which was notably lower compared to other process. The results showed that the filtration volume under threshold flux was higher than that under critical flux with the same CNT loading mass and ozone dosage. This comparison indicated that membrane fouling was alleviated under threshold flux and that the corresponding operation period was extended. Through the carbon balance experiment,the fouling capacity and recoverability improved remarkably after CNT modification. Additionally, ozonation could enhance the recoverability of membranes. The hybrid process examined in this study could dramatically improve the permeability and extend the operation time of the ultrafiltration membrane.
Polyvinylidene fluoride( PVDF) hollow fiber ultrafiltration membranes were modified with carbon nanotubes( CNT).Hybrid pre-ozonation and CNT modification were investigated by experimentally manipulating the ozonation process,threshold flux,and membrane fouling. The results showed that the threshold fluxes of the unmodified membrane and hybrid process were 45 L·( m2·h)-1 and 81 L·( m2·h)-1,respectively. Additionally,the fouling rate of the hybrid process was about 0. 001 37 k Pa·min-1·L-1·m2·h,which was notably lower compared to other process. The results showed that the filtration volume under threshold flux was higher than that under critical flux with the same CNT loading mass and ozone dosage. This comparison indicated that membrane fouling was alleviated under threshold flux and that the corresponding operation period was extended. Through the carbon balance experiment,the fouling capacity and recoverability improved remarkably after CNT modification. Additionally, ozonation could enhance the recoverability of membranes. The hybrid process examined in this study could dramatically improve the permeability and extend the operation time of the ultrafiltration membrane.
引文
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[15] Hyung H,Lee S,Yoon J,et al. Effect of preozonation on flux and water quality in ozonation-ultrafiltration hybrid system for water treatment[J]. Ozone:Science&Engineering,2000,22(6):637-652.
[16] Adams C,Wang Y,Loftin K,et al. Removal of antibiotics from surface and distilled water in conventional water treatment processes[J]. Journal of Environmental Engineering,2002,128(3):253-260.
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[18] Ajmani G S,Goodwin D,Marsh K,et al. Modification of low pressure membranes with carbon nanotube layers for fouling control[J]. Water Research,2012,46(17):5645-5654.
[19] Madaeni S S, Zinadini S, Vatanpour V. Convective flow adsorption of nickel ions in PVDF membrane embedded with multi-walled carbon nanotubes and PAA coating[J]. Separation and Purification Technology,2011,80(1):155-162.
[20]王利颖,石洁,王凯伦,等.碳纳米管改性PVDF中空纤维超滤膜处理二级出水抗污染性能研究[J].环境科学,2017,38(1):220-228.Wang L Y,Shi J,Wang K L,et al. Effect of PVDF hollow fiber ultrafiltration membranes modification with carbonnanotube on membrane fouling control during ultrafiltration of sewage effluent[J]. Environmental Science,2017,38(1):220-228.
[21]孙国胜,刘帅,武睿,等.超滤膜处理东江水的阈通量和极限通量的对比[J].膜科学与技术,2016,36(6):126-132.Sun G S,Liu S,Wu R,et al. Comparison between threshold flux and limiting flux in Dongjiang water treatment using ultrafiltration membranes[J]. Membrane Science and Technology,2016,36(6):126-132.
[22] Coble P G,Del Castillo C E,Avril B. Distribution and optical properties of CDOM in the Arabian Sea during the 1995Southwest Monsoon[J]. Deep Sea Research Part II:Topical Studies in Oceanography,1998,45(10-11):2195-2223.
[23] Urban-Rich J, Mc Carty J T, Shailer M. Effects of food concentration and diet on chromophoric dissolved organic matter accumulation and fluorescent composition during grazing experiments with the copepod Calanus finmarchicus[J]. ICES Journal of Marine Science,2004,61(4):542-551.
[24] Imai D,Dabwan A H A,Kaneco S,et al. Degradation of marine humic acids by ozone-initiated radical reactions[J]. Chemical Engineering Journal,2009,148(2-3):336-341.
[25] Ajmani G S,Cho H H,Chalew T E A,et al. Static and dynamic removal of aquatic natural organic matter by carbon nanotubes[J]. Water Research,2014,59:262-270.
[2] Alpatova A,Kim E S,Sun X H,et al. Fabrication of porous polymeric nanocomposite membranes with enhanced anti-fouling properties:effect of casting composition[J]. Journal of Membrane Science,2013,444:449-460.
[3] Tian J Y,Ernst M,Cui F Y,et al. Correlations of relevant membrane foulants with UF membrane fouling in different waters[J]. Water Research,2013,47(3):1218-1228.
[4] Field R W,Wu D,Howell J A,et al. Critical flux concept for microfiltration fouling[J]. Journal of Membrane Science,1995,100(3):259-272.
[5] Lee N, Amy G, Croue J P, et al. Identification and understanding of fouling in low-pressure membrane(MF/UF)filtration by natural organic matter(NOM)[J]. Water Research,2004,38(20):4511-4523.
[6] Yuan W,Zydney A L. Humic acid fouling during ultrafiltration[J]. Environmental Science&Technology,2000,34(23):5043-5050.
[7] Field R W,Pearce G K. Critical,sustainable and threshold fluxes for membrane filtration with water industry applications[J]. Advances in Colloid and Interface Science,2011,164(1-2):38-44.
[8] Zhang Y P,Fane A G,Law A W K. Critical flux and particle deposition of fractal flocs during crossflow microfiltration[J].Journal of Membrane Science,2010,353(1-2):28-35.
[9] Xu J,Gao C J. Study of critical flux in ultrafiltration of seawater:new measurement and sub-and super-critical flux operations[J].Chemical Engineering Journal,2010,165(1):102-110.
[10] Beier S P,Jonsson G. Critical flux determination by flux-stepping[J]. AIChE Journal,2010,56(7):1739-1747.
[11] Tao M M,Liu F,Xue L X. Hydrophilic poly(vinylidene fluoride)(PVDF)membrane by in situ polymerisation of 2-hydroxyethyl methacrylate(HEMA)and micro-phase separation[J]. Journal of Materials Chemistry,2012,22(18):9131-9137.
[12] Tang S J,Wang Z W,Wu Z C,et al. Role of dissolved organic matters(DOM)in membrane fouling of membrane bioreactors for municipal wastewater treatment[J]. Journal of Hazardous Materials,2010,178(1-3):377-384.
[13] Zheng X,Ernst M,Jekel M. Identification and quantification of major organic foulants in treated domestic wastewater affecting filterability in dead-end ultrafiltration[J]. Water Research,2009,43(1):238-244.
[14]关羽琪,王凯伦,祝学东,等.臭氧-CNT膜改性联用工艺对PVDF中空纤维膜污染进程的缓解[J].环境科学,2018,39(8):3744-3752.Guan Y Q,Wang K L,Zhu X D,et al. Effect of hybrid process of pre-ozonation and CNT modification on hollow fiber membrane fouling control[J]. Environmental Science,2018,39(8):3744-3752.
[15] Hyung H,Lee S,Yoon J,et al. Effect of preozonation on flux and water quality in ozonation-ultrafiltration hybrid system for water treatment[J]. Ozone:Science&Engineering,2000,22(6):637-652.
[16] Adams C,Wang Y,Loftin K,et al. Removal of antibiotics from surface and distilled water in conventional water treatment processes[J]. Journal of Environmental Engineering,2002,128(3):253-260.
[17] Gallagher M J,Huang H,Schwab K J,et al. Generating backwashable carbon nanotube mats on the inner surface of polymeric hollow fiber membranes[J]. Journal of Membrane Science,2013,446:59-67.
[18] Ajmani G S,Goodwin D,Marsh K,et al. Modification of low pressure membranes with carbon nanotube layers for fouling control[J]. Water Research,2012,46(17):5645-5654.
[19] Madaeni S S, Zinadini S, Vatanpour V. Convective flow adsorption of nickel ions in PVDF membrane embedded with multi-walled carbon nanotubes and PAA coating[J]. Separation and Purification Technology,2011,80(1):155-162.
[20]王利颖,石洁,王凯伦,等.碳纳米管改性PVDF中空纤维超滤膜处理二级出水抗污染性能研究[J].环境科学,2017,38(1):220-228.Wang L Y,Shi J,Wang K L,et al. Effect of PVDF hollow fiber ultrafiltration membranes modification with carbonnanotube on membrane fouling control during ultrafiltration of sewage effluent[J]. Environmental Science,2017,38(1):220-228.
[21]孙国胜,刘帅,武睿,等.超滤膜处理东江水的阈通量和极限通量的对比[J].膜科学与技术,2016,36(6):126-132.Sun G S,Liu S,Wu R,et al. Comparison between threshold flux and limiting flux in Dongjiang water treatment using ultrafiltration membranes[J]. Membrane Science and Technology,2016,36(6):126-132.
[22] Coble P G,Del Castillo C E,Avril B. Distribution and optical properties of CDOM in the Arabian Sea during the 1995Southwest Monsoon[J]. Deep Sea Research Part II:Topical Studies in Oceanography,1998,45(10-11):2195-2223.
[23] Urban-Rich J, Mc Carty J T, Shailer M. Effects of food concentration and diet on chromophoric dissolved organic matter accumulation and fluorescent composition during grazing experiments with the copepod Calanus finmarchicus[J]. ICES Journal of Marine Science,2004,61(4):542-551.
[24] Imai D,Dabwan A H A,Kaneco S,et al. Degradation of marine humic acids by ozone-initiated radical reactions[J]. Chemical Engineering Journal,2009,148(2-3):336-341.
[25] Ajmani G S,Cho H H,Chalew T E A,et al. Static and dynamic removal of aquatic natural organic matter by carbon nanotubes[J]. Water Research,2014,59:262-270.
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