膜蒸馏水处理过程中硫酸钙结垢现象 —基于光学相干断层成像技术的机理研究

膜分离技术在解决全球水资源短缺问题上极具潜力。与传统膜分离技术相比，膜蒸馏（membrane distillation，MD）是一种处理高盐度废水的有效方法。然而，膜污染仍然是限制MD技术应用的重要因素，以不同方式显著降低MD的效率。作为一种特殊的膜污染现象，微溶盐结垢通常发生在料液被高度浓缩时。由于难以通过常规方法去除，硫酸钙（CaSO₄）结垢尤为值得关注；而相应的机理研究需要开发新型表征技术，以解析结垢层在疏水分离膜表面的生成和演化。因此，本研究致力于通过探索一系列基于光学相干断层成像技术（optical coherence tomography，OCT）的表征方法，研究MD中CaSO₄结垢行为。所开发的方法被应用于结垢诱发通量下降和润湿现象的探索，并通过对比主体沉积和表面生长的作用深度解析结垢层的演化。

本研究将OCT系统与直接接触膜蒸馏（direct contact membrane distillation，DCMD）装置相结合，利用其能够对半透明介质进行光学切片的功能，对进料液-分离膜界面上形成的CaSO₄结垢层进行原位观察和分析。除了创建层析图像外，还通过建立进料液-分离膜界面为零坐标面的坐标系对OCT数据集进行了多种数值算法分析。一方面，通过估算每个坐标面上由结垢引起的OCT信号强度变化，创建面平均光学强度（surface-averaged intensity，SAI）以及正异常点分率（fraction of positive anomalies，FPAs）剖面曲线，从而为在统计意义上监测和分析结垢层的生长演化提供了有力工具。另一方面，利用所开发的算法精确识别并数字化结垢层，进而估算表面覆盖率、局域厚度的平均值以及局域生长速率。特别地，通过绘制局域生长速率的分布图，揭示了因传热和传质的耦合作用而造成的边界层流体微观流动的失稳现象。

基于OCT的表征首先与数学模型相结合，以确定MD过程中结垢诱发通量下降不同机制的相对重要性。在采用非线性回归获得关键参数的基础上，利用数学模型计算了结垢加剧的温差极化、结垢层的水力压降以及与界面曲率相关的蒸汽压降等因素的影响。在确定的结垢主导期（即结垢层厚度均匀增加的时期）内，将模拟和实验的结果进行比较，以评估不同机制的贡献。通过这一比较可以推断出，在结垢层-分离膜界面发生的致密化现象在实质性降低蒸馏通量上起关键作用。为了从更为深刻的层面认识结垢诱发的润湿现象，基于OCT的表征还被用于数值追踪分离膜表面的位移，进而在Stoney方程的理论框架下解析了晶体-分离膜的相互作用。结果表明，分离膜的界面结构会被初始的结垢拉伸，而随着表面覆盖率的大幅增加，含晶层则会被压缩应力所主导。该分析还揭示了润湿现象的发生与相对高浓缩速率之间的强相关性；即较高的浓缩速率是维持受限晶体的持续生长并形成足够大的结晶压力以导致不可逆的膜孔扩张所必需的条件。此外，揭示结垢层的形态演化是在更基础层面上理解膜蒸馏过程中结垢现象的关键。因此，本研究以协同的方式把基于OCT的表征与传统测量方法相结合，在不同跨膜温差的MD过程中，比较了主体沉积和表面生长对结垢层形成和演化的影响。通过确定主体料液中结晶的开端解耦了不同效应，进而证实了不同机制之间的转变。

本研究不仅证实了OCT在原位表征MD结垢现象方面的潜力，而且也展示了数值分析OCT数据集在方法和应用上的多样性。此外，本研究还凸显了同时开展模型化分析和常规测量的重要性；这些方法的有机融合能够弥补OCT表征的短板，从而形成互补性优势。本研究所有的表征结果都从机理层面更为深刻地解读了MD过程中的结垢现象；这些机理的深入分析将有助于高性能MD过程的开发，并促进其在脱盐和水/废水处理领域的应用。

Membrane separations have been playing a potential role in addressing the global issue of water scarcity. In comparison with conventional membrane processes, membrane distillation (MD) is emerging as a powerful tool for dealing with high salinity water or wastewater. However, MD-based applications are suffering from fouling phenomena that result in flux decline and other negative effects to significantly decrease the efficiency of MD in various ways.  As a special fouling phenomenon, scaling of sparingly soluble salts is dominant when the feed can be highly concentrated by an MD process. In particular, the scaling of calcium sulfate (CaSO₄) is recalcitrant and deserves particular attention in the context of elucidating the underlying mechanisms, which entails novel characterization techniques to resolve the formation and evolution of a scaling layer on the hydrophobic membrane surface. Therefore, this study was aimed at investigating the scaling behavior of CaSO₄ in MD by exploring a series of characterization methods that were based on optical coherence tomography (OCT). The developed methods were further employed to investigate the scaling-induced flux decline and wetting phenomenon. Moreover, the evolution of a scaling layer in MD was analyzed by comparing the roles of bulk precipitation and surface growth.

Taking advantage of the ability to optically section a semitransparent medium, an OCT system was integrated with a setup of direct contact membrane distillation (DCMD) in an effort to in-situ observe and analyze the scaling layer of CaSO₄ gradually developed at the feed-membrane interface. In addition to creating tomographic images, a variety of numerical algorithms were exploited to analyze the OCT datasets. The numerical analysis was based on a coordinate system whose zeroth coordinate surface was determined by the feed-membrane interface. On the one hand, the scaling-induced variations in the intensity were evaluated on each of the coordinate surfaces to create profiles of surface-averaged intensity (SAI) and fraction of positive anomalies (FPAs), which offered a tool for examining the scaling process in a statistical sense. On the other hand, the feed-membrane interface was accurately identified such that the scaling layer could be digitalized for numerically evaluating the surface coverage, the mean of local thicknesses, and the local growth rates. When mapping the local growth rates, it was revealed that the boundary layer could be hydrodynamically instable owing to the coupled heat and mass transfer, thereby giving rise to the striping phenomenon.

The OCT-based characterization was first combined with a mathematical model to identify the relative importance of various mechanisms accounting for the scaling-induced flux decline in an MD process. When determining the cake-dominated regime (i.e., the period when the cake thickness was uniformly increased), the modeling and experimental results were compared to assess contributions of the different mechanisms. It was inferred by this comparison that densification at the cake-membrane interface could play a key role in substantially reducing the vapor flux. In order to provide deeper insights into the scaling-induced wetting phenomenon, the crystal-membrane interaction was resolved by numerically tracking the shift of the membrane surface in the framework of Stoney’s equation. It was indicated that the interfacial membrane structures could be stretched owing to the initial scaling, whereas the crystal-containing layer would be dominated by compressive stress as the surface coverage was substantially increased. The analysis also established a strong correlation between the occurrence of wetting and a relatively high rate of concentrating the feed, which could be essential for maintaining continuous growth of the confined crystals and creating sufficiently large crystallization pressure to irreversibly expand the membrane pores. Moreover, the morphological evolution of a scaling layer is a more fundamental concern to be addressed for better understanding the scaling in MD. The OCT-based characterization and conventional measurements were implemented in a synergistical way to compare the effects of bulk precipitation and surface growth on developing the scaling layer in MD processes with a varied transmembrane temperature. When determining the threshold of bulk crystallization, the different effects were decoupled to provide evidence for a mechanistic transition.

This study not only confirmed the potential of OCT for in-situ characterizing the scaling phenomenon in MD, but also demonstrated the diversity of approaches that can be used to numerically analyze the OCT datasets. In addition, this study highlighted the advantages of implementing modeling-based analysis and conventional measurements in a complementary way to cover the downsides of the OCT-based characterization. All the characterization results in this study refined the mechanistic picture of scaling in MD and would shed light on the development of MD-based applications with enhanced performance for desalination and water/wastewater treatment.

[1] SCHEWE J, HEINKE J, GERTEN D, et al. Multimodel assessment of water scarcity under climate change [J]. Proceedings of the National Academy of Sciences, 2014, 111(9): 3245-3250.
[2] ELIMELECH M, PHILLIP W A. The future of seawater desalination: Energy, technology, and the environment [J]. Science, 2011, 333(6043): 712-717.
[3] PAN C Y, XU G R, XU K, et al. Electrospun nanofibrous membranes in membrane distillation: Recent developments and future perspectives [J]. Separation and Purification Technology, 2019, 221: 44-63.
[4] WHO-UNICEF. Progress in drinking water and sanitation 2012 update, Joint Monitoring Programme for Water Supply and Sanitation [M]. 2012: 1-66.
[5] YIN J, DENG B. Polymer-matrix nanocomposite membranes for water treatment [J]. Journal of Membrane Science, 2015, 479: 256-275.
[6] GREENLEE L F, LAWLER D F, FREEMAN B D, et al. Reverse osmosis desalination: Water sources, technology, and today's challenges [J]. Water Research, 2009, 43(9): 2317-2348.
[7] EKE J, YUSUF A, GIWA A, et al. The global status of desalination: An assessment of current desalination technologies, plants and capacity [J]. Desalination, 2020, 495: 1-17.
[8] JONES E, QADIR M, VAN V M T H, et al. The state of desalination and brine production: A global outlook [J]. Science of the Total Environment, 2019, 657: 1343-1356.
[9] QTAISHAT M R, BANAT F. Desalination by solar powered membrane distillation systems[J]. Desalination, 2013, 308: 186-197.
[10] DESHMUKH A, BOO C, KARANIKOLA V, et al. Membrane distillation at the water-energy nexus: limits, opportunities, and challenges [J]. Energy & Environmental Science, 2018, 11(5): 1177-1196.
[11] ELSAID K, TAHA S E, YOUSEF B A A, et al. Recent progress on the utilization of waste heat for desalination: A review [J]. Energy Conversion and Management, 2020, 221: 1-18.
[12] ALI A, TUFA R A, MACEDONIO F, et al. Membrane technology in renewable-energy-driven desalination [J]. Renewable and Sustainable Energy Reviews, 2018, 81: 1-21.
[13]VILLACORTE L O, TABATABAI S A A, ANDERSON D M, et al. Seawater reverse osmosis desalination and (harmful) algal blooms [J]. Desalination, 2015, 360: 61-80.
[14] BREHANT A, BONNELYE V, PEREZ M. Assessment of ultrafiltration as a pretreatment of reverse osmosis membranes for surface seawater desalination [J]. Water Supply, 2003, 3(5-6): 437-445.
[15] MISSIMER T M, GHAFFOUR N, DEHWAH A H A, et al. Subsurface intakes for seawater reverse osmosis facilities: Capacity limitation, water quality improvement, and economics [J]. Desalination, 2013, 322: 37-51.
[16] ALSARAYREH A A, AL-OBAIDI M A, AL-HROUB A M, et al. Evaluation and minimisation of energy consumption in a medium-scale reverse osmosis brackish water desalination plant [J]. Journal of Cleaner Production, 2020, 248: 1-10.
[17] DRIOLI E, ALI A, MACEDONIO F. Membrane distillation: Recent developments and perspectives [J]. Desalination, 2015, 356: 56-84.
[18] VALLADARES L R, LI Z, SARP S, et al. Forward osmosis niches in seawater desalination and wastewater reuse [J]. Water Research, 2014, 66: 122-139.
[19] CATH T Y, CHILDRESS A E, ELIMELECH M. Forward osmosis: Principles, applications, and recent developments [J]. Journal of Membrane Science, 2006, 281(1): 70-87.
[20] MCGINNIS R L, ELIMELECH M. Energy requirements of ammonia–carbon dioxide forward osmosis desalination [J]. Desalination, 2007, 207(1-3): 370-382.
[21] MCGINNIS R L, HANCOCK N T, NOWOSIELSKI-SLEPOWRON M S, et al. Pilot demonstration of the NH3/CO2 forward osmosis desalination process on high salinity brines [J]. Desalination, 2013, 312: 67-74.
[22] SHAFFER D L, WERBER J R, JARAMILLO H, et al. Forward osmosis: Where are we now? [J]. Desalination, 2015, 356: 271-284.
[23] WAE A W A F, AHMAD A L, SENG O B, et al. Biomimetic hydrophobic membrane: A review of anti-wetting properties as a potential factor in membrane development for membrane distillation (MD) [J]. Journal of Industrial and Engineering Chemistry, 2020, 91: 15-36.
[24] HE F, GILRON J, SIRKAR K K. High water recovery in direct contact membrane distillation using a series of cascades [J]. Desalination, 2013, 323: 48-54.
[25] LEE H, HE F, SONG L, et al. Desalination with a cascade of cross-flow hollow fiber membrane distillation devices integrated with a heat exchanger [J]. AIChE Journal, 2011, 57(7): 1780-1795.
[26] ULLAH R, KHRAISHEH M, ESTEVES R J, et al. Energy efficiency of direct contact membrane distillation [J]. Desalination, 2018, 433: 56-67.
[27] SUMMERS E K, ARAFAT H A, LIENHARD J H. Energy efficiency comparison of single-stage membrane distillation (MD) desalination cycles in different configurations [J]. Desalination, 2012, 290: 54-66.
[28] WARSINGER D M, SWAMINATHAN J, GUILLEN-BURRIEZA E, et al. Scaling and fouling in membrane distillation for desalination applications: A review [J]. Desalination, 2015, 356: 294-313.
[29] 环国兰. 膜蒸馏技术研究现状 [J]. 天津工业大学学报，2009：12-18.
[30] KEVIN W. LAWSON D R L. Review membrane distillation [J]. Journal of Membrane Science, 1997, 124: 1-25.
[31] FINDLEY M E. Vaporization through porous membranes [J]. Industrial & Engineering Chemistry Process Design and Development, 1967, 227: 226-230.
[32] SARTI G C, GOSTOLI C. Use of hydrophobic membranes in thermal separation of liquid mixtures: Theory and Experiments [M]. Membranes and Membrane Processes. Boston, MA; Springer US. 1986: 349-360.
[33] SMOLDERS K, FRANKEN A C M. Terminology for membrane distillation [J]. Desalination, 1989, 72: 249-262.
[34] SARTI G C, GOSTOLI C, MATUILI S. Low energy cost desalination processes using hydrophobic membranes [J]. Desalination, 1985, 277-286.
[35] TIJING L D, WOO Y C, CHOI J-S, et al. Fouling and its control in membrane distillation-A review [J]. Journal of Membrane Science, 2015, 475: 215-244.
[36] EL-BOURAWI M S, DING Z, MA R, et al. A framework for better understanding membrane distillation separation process [J]. Journal of Membrane Science, 2006, 285(1-2): 4-29.
[37] ALKHUDHIRI A, DARWISH N, HILAL N. Membrane distillation: A comprehensive review [J]. Desalination, 2012, 287: 2-18.
[38] 吕晓龙. 膜蒸馏过程探讨 [J]. 膜科学与技术，2010：1-10.
[39] KHAYET M, WANG R. Mixed matrix polytetrafluoroethylene/polysulfone electrospun nanofibrous membranes for water desalination by membrane distillation [J]. ACS Applied Materials Interfaces, 2018, 10(28): 24275-24287.
[40] KHAYET M. Membranes and theoretical modeling of membrane distillation: a review [J]. Advances in Colloid and Interface Science, 2011, 164(1-2): 56-88.
[41] RIVIER C, GARCIA-PAYO M C, Marison I W, et al. Separation of binary mixtures by thermostatic sweeping gas membrane distillation I. Theory and simulations [J]. Journal of Membrane Science, 2002, 201(1-2): 1-16.
[42] 张金赫. 膜蒸馏海水淡化过程中的两相流强化实验研究 [J]. 高校化学工程学报，2018：38-41.
[43] 宋瀚文, 宋达, 张辉等. 国内外海水淡化技术、产能、用途综述 [J]. 膜科学与技术，2021：1-11.
[44] 程芳琴 孙 李 郭 郝. 膜蒸馏在废水处理中的研究现状与进展 [J]. 工业用水与废水，2018：7-11.
[45] 李红宾, 刘恒吉, 石文英等. 膜蒸馏技术应用最新研究进展 [J]. 化工新型材料，2022，50(02)：270-273+277.
[46] 姜晓滨, 孙国鑫, 贺高红. 高效膜蒸馏结晶过程的研究进展 [J]. 化工学报， 2020，71(09)：3905-3918.
[47] 李金晶, 钱大玮, 刘红波等. 基于膜技术的中药浓缩研究进展 [J]. 中南药学， 2022，20(02)：388-393.
[48] 康赛, 郑利兵, 魏源送等. 膜蒸馏在高氨氮废水处理与回用中的研究应用进展 [J]. 工业水处理，2021，41(12)：15-21.
[49] HANEMAAIJER J H. Memstill®-low cost membrane distillation technology for seawater desalination [J]. Desalination, 2004, 168.
[50] SONG L, MA Z, LIAO X, et al. Pilot plant studies of novel membranes and devices for direct contact membrane distillation-based desalination [J]. Journal of Membrane Science, 2008, 323(2): 257-270.
[51] PENG W, ESCOBAR I C. Rejection efficiency of water quality parameters by reverse osmosis and nanofiltration membranes [J]. Environmental Science and Technology, 2003, 37(19): 4435-4441.
[52] HOU D, DAI G, WANG J, et al. Boron removal and desalination from seawater by PVDF flat-sheet membrane through direct contact membrane distillation [J]. Desalination, 2013, 326: 115-124.
[53] CHEN X, CHEN T, LI J, et al. Ceramic nanofiltration and membrane distillation hybrid membrane processes for the purification and recycling of boric acid from simulative radioactive waste water [J]. Journal of Membrane Science, 2019, 579: 294-301.
[54] KHAYET M, GARCIA-PAYO M C, GARCIA-FERNANDEZ L, et al. Dual-layered electrospun nanofibrous membranes for membrane distillation [J]. Desalination, 2018, 426: 174-184.
[55] KHUMALO N, NTHUNYA L, DERESE S, et al. Water recovery from hydrolysed human urine samples via direct contact membrane distillation using PVDF/PTFE membrane [J]. Separation and Purification Technology, 2019, 211: 610-617.
[56] TUN L L, JEONG D, JEONG S, et al. Dewatering of source-separated human urine for nitrogen recovery by membrane distillation [J]. Journal of Membrane Science, 2016, 512: 13-20.
[57] GROSSI L B, ALVIM C B, ALVARES C M S, et al. Purifying surface water contaminated with industrial failure using direct contact membrane distillation [J]. Separation and Purification Technology, 2020, 233: 1-12.
[58] DONGARE P D, ALABASTRI A, PEDERSEN S, et al. Nanophotonics-enabled solar membrane distillation for off-grid water purification [J]. Proceedings of the National Academy of Sciences of the United States of America, 2017, 114(27): 6936-6941.
[59] POLITANO A, ARGURIO P, DI P G, et al. Photothermal Membrane Distillation for Seawater Desalination [J]. Advanced Materials, 2017, 29(2): 1-6.
[60] AN A K, GUO J, LEE E-J, et al. PDMS/PVDF hybrid electrospun membrane with superhydrophobic property and drop impact dynamics for dyeing wastewater treatment using membrane distillation [J]. Journal of Membrane Science, 2017, 525: 57-67.
[61] BOO C, LEE J, ELIMELECH M. Omniphobic polyvinylidene fluoride (PVDF) membrane for desalination of shale gas produced water by membrane distillation [J]. Environmental Science and Technology, 2016, 50(22): 12275-12282.
[62] CHEN L H, HUANG A, CHEN Y R, et al. Omniphobic membranes for direct contact membrane distillation: Effective deposition of zinc oxide nanoparticles [J]. Desalination, 2018, 428: 255-263.
[63] LI C, DENG W, GAO C, et al. Membrane distillation coupled with a novel two-stage pretreatment process for petrochemical wastewater treatment and reuse [J]. Separation and Purification Technology, 2019, 224: 23-32.
[64] LI J, ZHOU W, FAN S, et al. Bioethanol production in vacuum membrane distillation bioreactor by permeate fractional condensation and mechanical vapor compression with polytetrafluoroethylene (PTFE) membrane [J]. Bioresource Technology, 2018, 268: 708-714.
[65] YANG F, EFOME J E, RANA D, et al. Metal-organic frameworks supported on nanofiber for desalination by direct contact membrane distillation [J]. ACS Applied Materials Interfaces, 2018, 10(13): 11251-11260.
[66] CALABRD V, JIAO B L, DRIOLI E. Theoretical and experimental study on membrane distillation in the concentration of orange juice [J]. Industrial & Engineering Chemistry Research, 1994, 33: 1803-1808.
[67] BHATTACHARYA M, DUTTA S K, SIKDER J, et al. Computational and experimental study of chromium (VI) removal in direct contact membrane distillation [J]. Journal of Membrane Science, 2014, 450: 447-456.
[68] CRISCUOLI A, BAFARO P, DRIOLI E. Vacuum membrane distillation for purifying waters containing arsenic [J]. Desalination, 2013, 323: 17-21.
[69] SHIRAZI M M A, KARGARI A, TABATABAEI M, et al. Concentration of glycerol from dilute glycerol wastewater using sweeping gas membrane distillation [J]. Chemical Engineering and Processing: Process Intensification, 2014, 78: 58-66.
[70] 吉彦龙, 卢小平, 魏彦艳. 膜蒸馏系统的热质扩散耦合分析 [J]. 膜科学与技术，2021，41(02)：51-55+62.
[71] 韩非, 王康, 汪凯等. 温度极化对膜蒸馏性能的影响研究进展 [J]. 工业水处理，2021，41(09)：31-36.
[72] KHAYET M, GODINO M P, MENGUAL J I. Study of asymmetric polarization in direct contact membrane distillation [J]. Separation Science and Technology, 2005, 39(1): 125-147.
[73] MARTINEZ-DIEZ L, VAZQUEZ-GONZALEZ M I. Temperature and concentration polarization in membrane distillation of aqueous salt solutions [J]. Journal of Membrane Science, 1999, 156: 265-273.
[74] FANE A G, SCHOFIELD R W, FELL C J D. The efficient use of energy in membrane distillation [J]. Desalination, 1987, 231-243.
[75] MARTINEZ-DIEZ L, VAZQUEZ-GONZALEZ M I. Temperature polarization in mass transport through hydrophobic porous membranes [J]. AIChE Journal, 1996, 42(7): 1844-1852.
[76] MARTINEZ-DIEZ L, VAZQUEZ-GONZALEZ M I, FLORIDO-DIAZ F J. Study of membrane distillation using channel spacers [J]. Journal of Membrane Science, 1998, 144(1): 45-56.
[77] CATH T Y, ADAMS V D, CHILDRESS A E. Experimental study of desalination using direct contact membrane distillation: a new approach to flux enhancement [J]. Journal of Membrane Science, 2004, 228(1): 5-16.
[78] LAWSON K W, LLOYD D R. Membrane distillation. I. Module design and performance evaluation using vacuum membrane distillation [J]. Journal of Membrane Science, 1996, 120: 111-121.
[79] LAWSON K W, LLOYD D R. Membrane distillation. II. direct contact MD [J]. Journal of Membrane Science, 1996, 120: 123-133.
[80] LI B, SIRKAR K K. Novel membrane and device for vacuum membrane distillation-based desalination process [J]. Journal of Membrane Science, 2005, 257(1-2): 60-75.
[81] PORTER M C. Concentration polarization with membrane ultrafiltration [J]. Industrial & Engineering Chemistry Product, 1972, 11: 234-248.
[82] YUN Y, MA R, ZHANG W, et al. Direct contact membrane distillation mechanism for high concentration NaCl solutions [J]. Desalination, 2006, 188(1-3): 251-262.
[83] JANG E, NAM S H, HWANG T M, et al. Effect of operating parameters on temperature and concentration polarization in vacuum membrane distillation process [J]. Desalination and Water Treatment, 2014, 54(4-5): 871-880.
[84] BANDINI S, GOSTOLI C, SARTI G C. Separation efficiency in vacuum membrane distillation [J]. Journal of Membrane Science, 1992, 73(2): 217-229.
[85] MARTINEZ-DIEZ L, VAZQUEZ-GONZALEZ M I. Effects of polarization on mass transport through hydrophobic porous membranes [J]. Industrial & Engineering Chemistry Research, 1998, 37(10): 4128-4135.
[86] LAGANA F, BARBIERI G, DRIOLI E. Direct contact membrane distillation: modelling and concentration experiments [J]. Journal of Membrane Science, 2000, 166(1): 1-11.
[87]HE F, GILRON J, LEE H, et al. Potential for scaling by sparingly soluble salts in crossflow DCMD [J]. Journal of Membrane Science, 2008, 311(1-2): 68-80.
[88] SHAN H, LIU J, LI X, et al. Nanocoated amphiphobic membrane for flux enhancement and comprehensive anti-fouling performance in direct contact membrane distillation [J]. Journal of Membrane Science, 2018, 567: 166-180.
[89] GOH P S, LAU W J, OTHMAN M H D, et al. Membrane fouling in desalination and its mitigation strategies [J]. Desalination, 2018, 425: 130-155.
[90] SHIRAZI S, LIN C-J, CHEN D. Inorganic fouling of pressure-driven membrane processes — A critical review [J]. Desalination, 2010, 250(1): 236-248.
[91] AL-ANEZI K, HILAL N. Scale formation in desalination plants: effect of carbon dioxide solubility [J]. Desalination, 2007, 204(1-3): 385-402.
[92] GRYTA M. Alkaline scaling in the membrane distillation process [J]. Desalination, 2008, 228(1-3): 128-134.
[93] KARAKULSKI K, GRYTA M. Water demineralisation by NF/MD integrated processes [J]. Desalination, 2005, 177(1): 109-119.
[94] GRYTA M. Influence of polypropylene membrane surface porosity on the performance of membrane distillation process [J]. Journal of Membrane Science, 2007, 287(1): 67-78.
[95] CHANG Y S, OOI B S, AHMAD A L, et al. Vacuum membrane distillation for desalination: Scaling phenomena of brackish water at elevated temperature [J]. Separation and Purification Technology, 2021, 254: 1-16.
[96] GRYTA M. Calcium sulphate scaling in membrane distillation process [J]. Chemical Papers, 2009, 63(2): 146-151.
[97] BAO Z, LI J, WANG W. Solubility of calcium sulfate in distiller liquor [J]. Chemical Engineering, 1995.
[98] HOANG T A, ANG H M, ROHL A L. Effects of temperature on the scaling of calcium sulphate in pipes [J]. Powder Technology, 2007, 179(1-2): 31-37.
[99] LEE S, LEE C H. Effect of operating conditions on CaSO4 scale formation mechanism in nanofiltration for water softening [J]. Water Research, 2000, 34(15): 3854-3866.
[100]UCHYMIAK M, LYSTER E, GLATER J, et al. Kinetics of gypsum crystal growth on a reverse osmosis membrane [J]. Journal of Membrane Science, 2008, 314(1): 163-72.
[101]SEEWOO S, VAN H R, LEWIS A. Aspects of gypsum precipitation in scaling waters [J]. Hydrometallurgy, 2004, 75(1): 135-146.
[102]DECKERS J M, LASH J E, BURNS G. Heats of crystallization of CaSO4.2H2O [J]. Bulletin des Sociétés Chimiques Belges, 1984, 93(4): 271-280.
[103]CHRISTOFFERSEN M R, CHRISTOFFERSEN J, WEIJNEN M P C, et al. Crystal growth of calcium sulphate dihydrate at low supersaturation [J]. Journal of Crystal Growth, 1982, 58(3): 585-595.
[104]SHIH W-Y, RAHARDIANTO A, LEE R-W, et al. Morphometric characterization of calcium sulfate dihydrate (gypsum) scale on reverse osmosis membranes [J]. Journal of Membrane Science, 2005, 252(1-2): 253-263.
[105]ANTONY A, LOW J H, GRAY S, et al. Scale formation and control in high pressure membrane water treatment systems: A review [J]. Journal of Membrane Science, 2011, 383(1-2): 1-16.
[106]LI Z Y, YANGALI-QUINTANILLA V, VALLADARES-LINARES R, et al. Flux patterns and membrane fouling propensity during desalination of seawater by forward osmosis [J]. Water Research, 2012, 46(1): 195-204.
[107]GILRON J, LADIZANSKY Y, KORIN E. Silica fouling in direct contact membrane distillation [J]. Industrial & Engineering Chemistry Research, 2013, 52(31): 10521-10529.
[108]吕晓龙. 疏水膜的污染、润湿与干燥探讨 [J]. 膜科学与技术，2020，40(01)： 196-203.
[109]CHEW N G P, ZHAO S, LOH C H, et al. Surfactant effects on water recovery from produced water via direct-contact membrane distillation [J]. Journal of Membrane Science, 2017, 528: 126-134.
[110]WANG Z, CHEN Y, SUN X, et al. Mechanism of pore wetting in membrane distillation with alcohol vs. surfactant [J]. Journal of Membrane Science, 2018, 559, 183-195.
[111]CASSIE A B D, BAXTER S. Wettability of porous surfaces [J]. Transactions of the Faraday Society, 1944, 40(0): 546-551.
[112] 李小兵, 刘莹. 固体表面润湿性机理及模型[C]. 第六届中国功能材料及其应用学术会议，中国湖北武汉，2007.
[113]CHRISTIE K S S, YIN Y, LIN S, et al. Distinct behaviors between gypsum and silica scaling in membrane distillation [J]. Environmental Science and Technology, 2020, 54(1): 568-576
[114]CHRISTENSON H K. Two-step crystal nucleation via capillary condensation [J]. CrystEngComm, 2013, 15(11): 2030-2039.
[115]WU W, NANCOLLAS G H. Interfacial free energies and crystallization in aqueous media [J]. Journal of Colloid and Interface Science, 1996, 182(2): 365-373.
[116]REZAEI M, WARSINGER D M, LIENHARD V J, et al. Wetting phenomena in membrane distillation: Mechanisms, reversal, and prevention [J]. Water Research, 2018, 139: 329-352.
[117]YAO M, TIJING L D, NAIDU G, et al. A review of membrane wettability for the treatment of saline water deploying membrane distillation [J]. Desalination, 2020, 479: 1-22.
[118]CHOUDHURY M R, ANWAR N, JASSBY D, et al. Fouling and wetting in the membrane distillation driven wastewater reclamation process – A review [J]. Advances in Colloid and Interface Science, 2019, 269: 370-399.
[119]WONG P W, YIM V M, GUO J, et al. Noninvasive real-time monitoring of wetting progression in membrane distillation using impedance spectroscopy[J]. Environmental Science and Technology, 2022, 56(1): 535-545.
[120]CHANG H, LIU B, ZHANG Z, et al. A critical review of membrane wettability in membrane distillation from the perspective of interfacial interactions [J]. Environmental Science and Technology, 2021, 55(3): 1395-1418.
[121]MBOGORO M M, PERUFFO M, ADOBES-VIDAL M, et al. Quantitative 3D visualization of the growth of individual gypsum microcrystals: Effect of Ca2+:SO42– ratio on kinetics and crystal morphology [J]. The Journal of Physical Chemistry C, 2017, 121(23): 12726-12734.
[122]LI H, FANE A G, COSTER H G L, et al. Direct observation of particle deposition on the membrane surface during crossflow microfiltration [J]. Journal of Membrane Science, 1998, 149(1): 83-97.
[123]DING Z, LIU L, LIU Z, et al. Fouling resistance in concentrating TCM extract by direct contact membrane distillation [J]. Journal of Membrane Science, 2010, 362: 1-2): 317-325.
[124]CHEN L, TIAN Y, CAO C Q, et al. Interaction energy evaluation of soluble microbial products (SMP) on different membrane surfaces: role of the reconstructed membrane topology [J]. Water Research, 2012, 46(8): 2693-2704.
[125]SIM S T V, CHONG T H, KRANTZ W B, et al. Monitoring of colloidal fouling and its associated metastability using Ultrasonic Time Domain Reflectometry [J]. Journal of Membrane Science, 2012, 401-402: 241-253.
[126]MAIRAL A P, GREENBERG A R, KRANTZ W B. Investigation of membrane fouling and cleaning using ultrasonic time-domain reflectometry [J]. Desalination, 2000, 130(1): 45-60.
[127]GAO Y, HAAVISTO S, LI W, et al. Novel approach to characterizing the growth of a fouling layer during membrane filtration via optical coherence tomography [J]. Environmental Science and Technology, 2014, 48(24): 14273-14281.
[128]CHILCOTT T C, CHAN M, GAEDT L, et al. Electrical impedance spectroscopy characterisation of conducting membranes: I. Theory [J]. Journal of Membrane Science, 2002, 195(2): 153-167.
[129]GAEDT L, CHILCOTT T C, CHAN M, et al. Electrical impedance spectroscopy characterisation of conducting membranes: II. Experimental [J]. Journal of Membrane Science, 2002, 195(2): 169-180.
[130]ANTONY A, CHILCOTT T, COSTER H, et al. In situ structural and functional characterization of reverse osmosis membranes using electrical impedance spectroscopy [J]. Journal of Membrane Science, 2013, 425-426: 89-97.
[131]CEN J, VUKAS M, BARTON G, et al. Real time fouling monitoring with Electrical Impedance Spectroscopy [J]. Journal of Membrane Science, 2015, 484: 133-139.
[132]MARSELINA Y, LE-CLECH P, STUETZ R, et al. Detailed characterisation of fouling deposition and removal on a hollow fibre membrane by direct observation technique [J]. Desalination, 2008, 231(1): 3-11.
[133]MARSELINA Y, LIFIA, LE-CLECH P, et al. Characterisation of membrane fouling deposition and removal by direct observation technique [J]. Journal of Membrane Science, 2009, 341(1-2): 163-171.
[134]LORENZEN S, YE Y, CHEN V, et al. Direct observation of fouling phenomena during cross-flow filtration: Influence of particle surface charge [J]. Journal of Membrane Science, 2016, 510: 546-558.
[135]ZHANG T C, BISHOP P L. Density, porosity, and pore structure of biofilms [J]. Water Research, 1994, 28(11): 2267-2277.
[136]CHAN R, CHEN V. Characterization of protein fouling on membranes: opportunities and challenges [J]. Journal of Membrane Science, 2004, 242(1-2): 169-188.
[137]WANG Y N, WEI J, SHE Q, et al. Microscopic characterization of FO/PRO membranes--a comparative study of CLSM, TEM and SEM [J]. Environmental Science and Technology, 2012, 46(18): 9995-10003.
[138]REICHERT U, LINDEN T, BELFORT G, et al. Visualising protein adsorption to ion-exchange membranes by confocal microscopy [J]. Journal of Membrane Science, 2002, 199(1): 161-166.
[139]PODOLEANU A G. Optical coherence tomography [J]. Journal of Microscopy, 2012, 247(3): 209-219.
[140]FERCHER A F. Optical coherence tomography - development, principles, applications [J]. Zeitschrift Fur Medizinische Physik 2010, 20(4): 251-276.
[141]LI W, LIU X, WANG Y N, et al. Analyzing the evolution of membrane fouling via a novel method based on 3D optical coherence tomography imaging [J]. Environmental Science and Technology, 2016, 50(13): 6930-6939.
[142]HUANG D, SWANSON E A, LIN C P, et al. Optical coherence tomography [J]. Science, 1991, 254(5035): 1178.
[143]FARID M U, GUO J, AN A K. Bacterial inactivation and in situ monitoring of biofilm development on graphene oxide membrane using optical coherence tomography [J]. Journal of Membrane Science, 2018, 564: 22-34.
[144]LIU X, LI W, CHONG T H, et al. Effects of spacer orientations on the cake formation during membrane fouling: Quantitative analysis based on 3D OCT imaging [J]. Water Research, 2017, 110: 1-14.
[145]TRINH T A, LI W, HAN Q, et al. Analyzing external and internal membrane fouling by oil emulsions via 3D optical coherence tomography [J]. Journal of Membrane Science, 2018, 548: 632-640.
[146]HAN Q, LI W, TRINH T A, et al. A network-based approach to interpreting pore blockage and cake filtration during membrane fouling [J]. Journal of Membrane Science, 2017, 528: 112-125.
[147]FORTUNATO L, QAMAR A, WANG Y, et al. In-situ assessment of biofilm formation in submerged membrane system using optical coherence tomography and computational fluid dynamics [J]. Journal of Membrane Science, 2017, 521: 84-94.
[148]FORTUNATO L, JANG Y, LEE J G, et al. Fouling development in direct contact membrane distillation: Non-invasive monitoring and destructive analysis [J]. Water Research, 2018, 132: 34-41.
[149]LEE J G, JANG Y, FORTUNATO L, et al. An advanced online monitoring approach to study the scaling behavior in direct contact membrane distillation [J]. Journal of Membrane Science, 2018, 546: 50-60.
[150]GUO J, FARID M U, LEE E J, et al. Fouling behavior of negatively charged PVDF membrane in membrane distillation for removal of antibiotics from wastewater [J]. Journal of Membrane Science, 2018, 551: 12-9.
[151]GUO J, FORTUNATO L, DEKA B J, et al. Elucidating the fouling mechanism in pharmaceutical wastewater treatment by membrane distillation [J]. Desalination, 2020, 475: 1-11.
[152]ELCIK H, FORTUNATO L, VROUWENVELDER J S, et al. Real-time membrane fouling analysis for the assessment of reclamation potential of textile wastewater processed by membrane distillation [J]. Journal of Water Process Engineering, 2021, 43: 1-10.
[153]GUO J, WONG P W, DEKA B J, et al. Investigation of fouling mechanism in membrane distillation using in-situ optical coherence tomography with green regeneration of fouled membrane [J]. Journal of Membrane Science, 2022, 641: 1-12.
[154]BAUER A, WAGNER M, SARAVIA F, et al. In-situ monitoring and quantification of fouling development in membrane distillation by means of optical coherence tomography [J]. Journal of Membrane Science, 2019, 577: 145-152.
[155]BAUER A, WAGNER M, HORN H, et al. Operation conditions affecting scale formation in membrane distillation - An in situ scale study based on optical coherence tomography [J]. Journal of Membrane Science, 2021, 623: 1-8.
[156]NAIDU G, JEONG S, VIGNESWARAN S. Influence of feed/permeate velocity on scaling development in a direct contact membrane distillation [J]. Separation and Purification Technology, 2014, 125: 291-300.
[157]XIAO Z, ZHENG R, LIU Y, et al. Slippery for scaling resistance in membrane distillation: A novel porous micropillared superhydrophobic surface [J]. Water Research, 2019, 155: 152-161.
[158]LIU Y, HORSEMAN T, WANG Z, et al. Negative pressure membrane distillation for excellent gypsum scaling resistance and flux enhancement [J]. Environmental Science and Technology, 2022, 56(2): 1405-1412.
[159]LI W, GAO Y, TANG C Y. Network modeling for studying the effect of support structure on internal concentration polarization during forward osmosis: Model development and theoretical analysis with FEM [J]. Journal of Membrane Science, 2011, 379(1-2): 307-321.
[160]ZYDNEY A L. Stagnant film model for concentration polarization in membrane systems [J]. Journal of Membrane Science, 1997, 130(1): 275-281.
[161]FERNANDEZ-PINEDA C, IZQUIERDO-GIL M A, GARCIA-PAYO M C. Gas permeation and direct contact membrane distillation experiments and their analysis using different models [J]. Journal of Membrane Science, 2002, 198(1): 33-49.
[162]GUTTEL S, TISSEUR F. The nonlinear eigenvalue problem [J]. Acta Numerica, 2017, 26: 1-94.
[163]GRYTA M, TOMASZEWSKA M. Heat transport in the membrane distillation process [J]. Journal of Membrane Science, 1998, 144: 211-222.
[164]VENEGAS P, PEREZ N, ZAPATA S, et al. An approach to automatic classification of Culicoides species by learning the wing morphology [J]. PLoS One, 2020, 15(11): 1-23.
[165]GOH S, ZHANG Q, ZHANG J, et al. Impact of a biofouling layer on the vapor pressure driving force and performance of a membrane distillation process [J]. Journal of Membrane Science, 2013, 438: 140-152.
[166]SHEN A, LIU Y, FAROUQ A S M. A model of spontaneous flow driven by capillary pressure in nanoporous media [J]. Capillarity, 2020, 3(1): 1-7.
[167]GALVIN K P. A conceptually simple derivation of the Kelvin equation [J]. Chemical Engineering Science, 2005, 60(16): 4659-4660.
[168]CHEW J W, KRANTZ W B, FANE A G. Effect of a macromolecular- or bio-fouling layer on membrane distillation [J]. Journal of Membrane Science, 2014, 456: 66-76.
[169]NGHIEM L D, CATH T. A scaling mitigation approach during direct contact membrane distillation [J]. Separation and Purification Technology, 2011, 80(2): 315-322.
[170]GEBAUER D, RAITERI P, GALE J D, et al. On classical and non-classical views on nucleation [J]. American Journal of Science, 2018, 318(9): 969-988.
[171]WANG Y W, KIM Y Y, CHRISTENSON H K, et al. A new precipitation pathway for calcium sulfate dihydrate (gypsum) via amorphous and hemihydrate intermediates [J]. Chemical Communications (Camb), 2012, 48(4): 504-506.
[172]MARIAMPILLAI A, STANDISH B A, MORIYAMA E H, et al. Speckle variance detection of microvasculature using swept-source optical coherence tomography [J]. Optics Letters, 2008, 33(13): 1530-1532.
[173]ANG W L, MOHAMMAD A W. Mathematical modeling of membrane operations for water treatment [M]. Advances in Membrane Technologies for Water Treatment. 2015: 379-407.
[174]IRITANI E, KATAGIRI N. Developments of blocking filtration model in membrane filtration [J]. KONA Powder and Particle Journal, 2016, 33: 179-202.
[175]HO C-C, ZYDNEY A L. Theoretical analysis of the effect of membrane morphology on fouling during microfiltration [J]. Separation Science and Technology, 1999, 34(13): 2461-2483.
[176]VORA A, ALI S. Prolonged hypercalcemia from antibiotic-eluting calcium sulfate beads [J]. AACE Clinical Case Reports, 2019, 5(6): e349-e351.
[177]CHONG T H, WONG F S, FANE A G. Implications of critical flux and cake enhanced osmotic pressure (CEOP) on colloidal fouling in reverse osmosis: Experimental observations [J]. Journal of Membrane Science, 2008, 314(1-2): 101-111.
[178]SCHERER G W. Crystallization in pores [J]. Cement & Concrete Research, 1999, 29(8): 1347-1358.
[179]FISHER L R. Experimental studies on the applicability of the Kelvin equation to highly curved concave menisci [J]. Journal of Colloid and Interface Science, 1981, 80(2): 523-539.
[180]TAN Y Z, CHEW J W, KRANTZ W B. Effect of humic-acid fouling on membrane distillation [J]. Journal of Membrane Science, 2016, 504: 263-273.
[181]LARSEN P S. A stability model for the striping phenomenon in ultrafiltration [J]. Journal of Membrane Science, 1991, 57(1): 43-56.
[182]KIEFER F, PRABST A, RODEWALD K S, et al. Membrane scaling in vacuum membrane distillation - Part 1: In-situ observation of crystal growth and membrane wetting [J]. Journal of Membrane Science, 2019, 590: 1-15.
[183]HORSEMAN T, YIN Y, CHRISTIE K S S, et al. Wetting, scaling, and fouling in membrane distillation: State-of-the-art insights on fundamental mechanisms and mitigation strategies [J]. ACS ES&T Engineering, 2021, 1(1): 117-140.
[184]SCHOFIELD R W, FANE A G, FELL C J D. Heat and mass transfer in membrane distillation [J]. Journal of Membrane Science, 1987, 33: 299-313.
[185]GRYTA M. Fouling in direct contact membrane distillation process [J]. Journal of Membrane Science, 2008, 325(1): 383-394.
[186]LI Z, LIU X, CHEN G, et al. Effects of membrane morphology on the rejection of oil droplets: Theoretical analysis based on network modeling [J]. Journal of Membrane Science, 2019, 588: 1-13.
[187]GRYTA M, TOMASZEWSKA M, MORAWSKI A W. Membrane distillation with laminar flow [J]. Separation and Purification Technology, 1997, 11(2): 93-101.
[188]WARSINGER D M, TOW E W, SWAMINATHAN J, et al. Theoretical framework for predicting inorganic fouling in membrane distillation and experimental validation with calcium sulfate [J]. Journal of Membrane Science, 2017, 528: 381-390.
[189]DOGONCHI A S, NAYAK M K, KARIMI N, et al. Numerical simulation of hydrothermal features of Cu–H2O nanofluid natural convection within a porous annulus considering diverse configurations of heater [J]. Journal of Thermal Analysis and Calorimetry, 2020, 141(5): 2109-2125.
[190]RUBIO-AVALOS J C, MANZANO-RAMIREZ A, YANEZ-LIMON J M, et al. Development and characterization of an inorganic foam obtained by using sodium bicarbonate as a gas generator [J]. Construction and Building Materials, 2005, 19(7): 543-549.
[191]SU M, TEOH M M, WANG K Y, et al. Effect of inner-layer thermal conductivity on flux enhancement of dual-layer hollow fiber membranes in direct contact membrane distillation [J]. Journal of Membrane Science, 2010, 364(1-2): 278-289.
[192]MOULIN A M, O'SHEA S J, BADLEY R A, et al. Measuring surface-induced conformational changes in proteins [J]. Langmuir, 1999, 15(26): 8776-8779.
[193]STONEY G G. The tension of metallic films deposited by electrolysis [J]. Proceedings of the Royal Society of London Series A, Containing Papers of a Mathematical and Physical Character (1905-1934), 1909, 82: 172-175.
[194]VILMS J, KERPS D. Simple stress formula for multilayered thin films on a thick substrate [J]. Journal of Applied Physics, 1982, 53(3): 1536-1537.
[195]STEIGER M. Crystal growth in porous materials—I: The crystallization pressure of large crystals [J]. Journal of Crystal Growth, 2005, 282(3-4): 455-469.
[196]TONG T, WALLACE A F, ZHAO S, et al. Mineral scaling in membrane desalination: Mechanisms, mitigation strategies, and feasibility of scaling-resistant membranes [J]. Journal of Membrane Science, 2019, 579: 52-69.
[197]LAPIDOT T, SEDRANSK C K L, HENG J Y. Model for interpreting surface crystallization using quartz crystal microbalance: Theory and experiments [J]. Analytical Chemistry, 2016, 88(9): 4886-4893.
[198]LIN N H, COHEN Y. QCM study of mineral surface crystallization on aromatic polyamide membrane surfaces [J]. Journal of Membrane Science, 2011, 379(1-2): 426-433.
[199]TANG C Y, CHONG T H, FANE A G. Colloidal interactions and fouling of NF and RO membranes: a review [J]. Advances in Colloid and Interface Science, 2011, 164: 1-2): 126-143.
[200]CHRISTIE K S S, HORSEMAN T, WANG R, et al. Gypsum scaling in membrane distillation: Impacts of temperature and vapor flux [J]. Desalination, 2022, 525: 1-11.
[201]MESSNAOUI B, BOUNAHMIDI T. On the modeling of calcium sulfate solubility in aqueous solutions [J]. Fluid Phase Equilibria, 2006, 244(2): 117-127.
[202]ABDEL-AAL E A, RASHAD M M, EL-SHALL H. Crystallization of calcium sulfate dihydrate at different supersaturation ratios and different free sulfate concentrations [J]. Crystal Research and Technology, 2004, 39(4): 313-321.
[203]Xie M, Gray S R. Gypsum scaling in forward osmosis: Role of membrane surface chemistry [J]. Journal of Membrane Science, 2016, 513: 250-259.