Membrane Fouling Phenomena in Microfluidic Systems: From Technical Challenges to Scientific Opportunities

The almost ubiquitous, though undesired, deposition and accumulation of suspended/dissolved matter on solid surfaces, known as fouling, represents a crucial issue strongly affecting the efficiency and sustainability of micro-scale reactors. Fouling becomes even more detrimental for all the applications that require the use of membrane separation units. As a matter of fact, membrane technology is a key route towards process intensification, having the potential to replace conventional separation procedures, with significant energy savings and reduced environmental impact, in a broad range of applications, from water purification to food and pharmaceutical industries. Despite all the research efforts so far, fouling still represents an unsolved problem. The complex interplay of physical and chemical mechanisms governing its evolution is indeed yet to be fully unraveled and the role played by foulants’ properties or operating conditions is an area of active research where microfluidics can play a fundamental role. The aim of this review is to explore fouling through microfluidic systems, assessing the fundamental interactions involved and how microfluidics enables the comprehension of the mechanisms characterizing the process. The main mathematical models describing the fouling stages will also be reviewed and their limitations discussed. Finally, the principal dynamic investigation techniques in which microfluidics represents a key tool will be discussed, analyzing their employment to study fouling.

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Atenolol removal by nanofiltration: a case-specific mass transfer correlation

Water Science & Technology ◽

10.2166/wst.2020.073 ◽

2020 ◽

Vol 81 (2) ◽

pp. 210-216 ◽

Cited By ~ 3

Author(s):

Alexandre Giacobbo ◽

Elisa Veridiani Soares ◽

Andréa Moura Bernardes ◽

Maria João Rosa ◽

Maria Norberta de Pinho

Keyword(s):

Mass Transfer ◽

Membrane Fouling ◽

Concentration Polarization ◽

Membrane Separation ◽

Film Theory ◽

Operating Conditions ◽

Transfer Coefficients ◽

Specific Mass ◽

Mass Transfer Coefficients ◽

Mass Transfer Correlation

Abstract Concentration polarization is a phenomenon inherent to membrane separation operations and as a precursor of membrane fouling is frequently related to the decrease in the performance of these operations. In the present work, a case-specific mass transfer correlation was developed to assess the concentration polarization when nanofiltration, in different operating conditions, was applied to treat a pharmaceutical wastewater containing atenolol. NF runs with two membranes, two atenolol concentrations and three feed circulating velocities were conducted, and the corresponding experimental mass transfer coefficients were determined using film theory to describe the concentration polarization phenomenon. Higher velocities led to higher mass transfer coefficients and, consequently, lower concentration polarization. These mass transfer coefficients were correlated with the circulating velocity (Re), the solute diffusivity (Sc) and the membrane permeability (LP+) (the membrane is a permeable interface with effect on the concentration profiles developed from the interface towards the bulk feed), yielding the following correlation Sh = 1.98 × 104Re0.5Sc0.33LP+0.32. The good agreement between the calculated and the experimental results makes this correlation a valuable tool for water practitioners to predict and control the concentration polarization during atenolol-rich wastewater treatment by nanofiltration, thereby increasing its productivity and selectivity.

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Membrane Distillation: Recent Configurations, Membrane Surface Engineering, and Applications

Membranes ◽

10.3390/membranes11120934 ◽

2021 ◽

Vol 11 (12) ◽

pp. 934

Author(s):

Sundararajan Parani ◽

Oluwatobi Samuel Oluwafemi

Keyword(s):

Membrane Fouling ◽

Surface Engineering ◽

Membrane Separation ◽

Membrane Surface ◽

Membrane Distillation ◽

Operating Conditions ◽

Toxic Heavy Metals ◽

Hydrophobic Membrane ◽

Future Directions ◽

Vapor Pressure Gradient

Membrane distillation (MD) is a developing membrane separation technology for water treatment that involves a vapor transport driven by the vapor pressure gradient across the hydrophobic membrane. MD has gained wide attention in the last decade for various separation applications, including the separation of salts, toxic heavy metals, oil, and organic compounds from aqueous solutions. Compared with other conventional separation technologies such as reverse osmosis, nanofiltration, or thermal distillation, MD is very attractive due to mild operating conditions such as low temperature and atmospheric pressure, and 100% theoretical salt rejection. In this review, membrane distillation’s principles, recent MD configurations with their advantages and limitations, membrane materials, fabrication of membranes, and their surface engineering for enhanced hydrophobicity are reviewed. Moreover, different types of membrane fouling and their control methods are discussed. The various applications of standalone MD and hybrid MD configurations reported in the literature are detailed. Furthermore, studies on the MD-based pilot plants installed around the world are covered. The review also highlights challenges in MD performance and future directions.

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Nanofiltration of colored surface water: Quebec's experience

Water Science & Technology Water Supply ◽

10.2166/ws.2003.0145 ◽

2003 ◽

Vol 3 (5-6) ◽

pp. 15-22

Author(s):

P. Kouadio ◽

M. Tétrault

Keyword(s):

Drinking Water ◽

Surface Water ◽

Membrane Fouling ◽

Pilot Scale ◽

Operating Conditions ◽

Quebec City ◽

Water Regulation ◽

Eastern Canada

Three colored surface water nanofiltration pilot-scale projects were conducted in the province of Quebec (eastern Canada), between November 2000 and March 2002, by the company H2O Innovation (2000) inc., for the municipalities of Lac Bouchette, Latulipe-et-Gaboury and Charlesbourg (now part of Quebec City). Results indicated that nanofiltration permeate quality has an advance on present drinking water regulation standard in Quebec, but important membrane fouling occurred. Fouling can be controlled by pretreatment and optimization of the operating conditions.

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Separation of Biologically Active Compounds by Membrane Operations

Current Pharmaceutical Design ◽

10.2174/1381612822666161027153823 ◽

2017 ◽

Vol 23 (2) ◽

pp. 218-230 ◽

Cited By ~ 4

Author(s):

Xiaoying Zhu ◽

Renbi Bai

Keyword(s):

Energy Consumption ◽

Bioactive Compounds ◽

Membrane Fouling ◽

Membrane Separation ◽

Separation Efficiency ◽

High Energy ◽

Separation Processes ◽

Membrane Processes ◽

Separation Technology ◽

Pressure Driven

Background: Bioactive compounds from various natural sources have been attracting more and more attention, owing to their broad diversity of functionalities and availabilities. However, many of the bioactive compounds often exist at an extremely low concentration in a mixture so that massive harvesting is needed to obtain sufficient amounts for their practical usage. Thus, effective fractionation or separation technologies are essential for the screening and production of the bioactive compound products. The applicatons of conventional processes such as extraction, distillation and lyophilisation, etc. may be tedious, have high energy consumption or cause denature or degradation of the bioactive compounds. Membrane separation processes operate at ambient temperature, without the need for heating and therefore with less energy consumption. The “cold” separation technology also prevents the possible degradation of the bioactive compounds. The separation process is mainly physical and both fractions (permeate and retentate) of the membrane processes may be recovered. Thus, using membrane separation technology is a promising approach to concentrate and separate bioactive compounds. Methods: A comprehensive survey of membrane operations used for the separation of bioactive compounds is conducted. The available and established membrane separation processes are introduced and reviewed. Results: The most frequently used membrane processes are the pressure driven ones, including microfiltration (MF), ultrafiltration (UF) and nanofiltration (NF). They are applied either individually as a single sieve or in combination as an integrated membrane array to meet the different requirements in the separation of bioactive compounds. Other new membrane processes with multiple functions have also been developed and employed for the separation or fractionation of bioactive compounds. The hybrid electrodialysis (ED)-UF membrane process, for example has been used to provide a solution for the separation of biomolecules with similar molecular weights but different surface electrical properties. In contrast, the affinity membrane technology is shown to have the advantages of increasing the separation efficiency at low operational pressures through selectively adsorbing bioactive compounds during the filtration process. Conclusion: Individual membranes or membrane arrays are effectively used to separate bioactive compounds or achieve multiple fractionation of them with different molecule weights or sizes. Pressure driven membrane processes are highly efficient and widely used. Membrane fouling, especially irreversible organic and biological fouling, is the inevitable problem. Multifunctional membranes and affinity membranes provide the possibility of effectively separating bioactive compounds that are similar in sizes but different in other physical and chemical properties. Surface modification methods are of great potential to increase membrane separation efficiency as well as reduce the problem of membrane fouling. Developing membranes and optimizing the operational parameters specifically for the applications of separation of various bioactive compounds should be taken as an important part of ongoing or future membrane research in this field.

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Optimization of MCM-41 Mesoporous Material Mixed Matrix Polyethersulfone Membrane for Dye Removal

Membranes ◽

10.3390/membranes11060414 ◽

2021 ◽

Vol 11 (6) ◽

pp. 414

Author(s):

Rana J. Kadhim ◽

Faris H. Al-Ani ◽

Qusay F. Alsalhy ◽

Alberto Figoli

Keyword(s):

Membrane Fouling ◽

Mesoporous Material ◽

Optimization Technique ◽

Operating Conditions ◽

Mixed Matrix ◽

Pareto Chart ◽

Significance Level ◽

Pes Membrane ◽

Wasted Energy ◽

Mcm 41

The aim of this work is the optimization of the operating conditions under which MCM-41-mesoporous material can be incorporated into polyethersulfone (PES)/MCM-41 membranes for nanofiltration (NF) applications. MCM-41 mesoporous material mixed matrix PES membranes have the potential to reduce membrane fouling by organic dye molecules. Process optimization and modeling aim to reduce wasted energy while maintaining high flow during the operation to handle the energy efficiency problems membranes often have. An optimization technique was applied to obtain optimum values for some key parameters in the process to produce a certain amount of flux above the desired values. Response surface methodology (RSM) and analysis of variance (ANOVA) were used as mathematical and statistical analyses to improve the performance of the process on a larger scale. This work investigated the influence of the operating parameters, such as the feed pH values (3–11), MCM-41 content (0–1 wt.%), and the feed dye concentration (10–100 ppm) for each of the two studied dyes, acid black 210 (AB-210) and rose bengal (RB), and their interactions on the PES membrane permeability. The results showed that the PES membrane had the best performance at 64.25 (L·m−2·h−1·bar-1) and 63.16 (L·m−2·h−1·bar-1) for the AB-210 and RB dyes, respectively. An MCM-41 content of nearly 0.8 wt.% in the casting solution, feed dye concentration of 10 ppm for the studied dyes, and feed pH of 3 for the RB dye was found to be the optimal parameters for eliciting the response. The pH had no significant influence on the response for the AB-210 dye, while the pH shows some minor effects on response with the RB dye, and the Pareto chart of the standardized effects on the permeation flux of both dyes using statistically significant at the 5% significance level support these results.

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Removal of heavy metal ions from wastewater: a comprehensive and critical review

npj Clean Water ◽

10.1038/s41545-021-00127-0 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Naef A. A. Qasem ◽

Ramy H. Mohammed ◽

Dahiru U. Lawal

Keyword(s):

Heavy Metal ◽

Metal Ions ◽

Large Volume ◽

Heavy Metal Ions ◽

Membrane Separation ◽

Cost Effective ◽

Operating Conditions ◽

Future Research ◽

Sludge Formation ◽

Metals Removal

AbstractRemoval of heavy metal ions from wastewater is of prime importance for a clean environment and human health. Different reported methods were devoted to heavy metal ions removal from various wastewater sources. These methods could be classified into adsorption-, membrane-, chemical-, electric-, and photocatalytic-based treatments. This paper comprehensively and critically reviews and discusses these methods in terms of used agents/adsorbents, removal efficiency, operating conditions, and the pros and cons of each method. Besides, the key findings of the previous studies reported in the literature are summarized. Generally, it is noticed that most of the recent studies have focused on adsorption techniques. The major obstacles of the adsorption methods are the ability to remove different ion types concurrently, high retention time, and cycling stability of adsorbents. Even though the chemical and membrane methods are practical, the large-volume sludge formation and post-treatment requirements are vital issues that need to be solved for chemical techniques. Fouling and scaling inhibition could lead to further improvement in membrane separation. However, pre-treatment and periodic cleaning of membranes incur additional costs. Electrical-based methods were also reported to be efficient; however, industrial-scale separation is needed in addition to tackling the issue of large-volume sludge formation. Electric- and photocatalytic-based methods are still less mature. More attention should be drawn to using real wastewaters rather than synthetic ones when investigating heavy metals removal. Future research studies should focus on eco-friendly, cost-effective, and sustainable materials and methods.

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Utilization of Mango, Apple and Banana Fruit Peels as Prebiotics and Functional Ingredients

Agriculture ◽

10.3390/agriculture11070584 ◽

2021 ◽

Vol 11 (7) ◽

pp. 584

Author(s):

Hafza Fasiha Zahid ◽

Chaminda Senaka Ranadheera ◽

Zhongxiang Fang ◽

Said Ajlouni

Keyword(s):

Lactobacillus Rhamnosus ◽

Fruit Weight ◽

Banana Fruit ◽

Fruit Peel ◽

Tropical Fruit ◽

Functional Ingredients ◽

Potential Applications ◽

Mango Peel ◽

Pharmaceutical Industries ◽

Physical And Chemical

Among the waste by-products generated by the fruit industry (peels, seeds, and skins), fruit peel constitutes the major component. It is estimated that fruit peel accounts for at least 20% of the fresh fruit weight. Fruit peels are considered as major sources of dietary fiber and anticipated to be successfully utilized as prebiotics. This study examined the chemical composition, functional properties and the prebiotic effects of three major tropical fruit peels (apple, banana and mango). The prebiotic effect was tested using three commercial probiotic strains (Lactobacillus rhamnosus, L. casei and Bifidobacterium lactis) individually and in combination. Each probiotic culture was fortified with different concentration (0%, 2% and 4%) of selected fruit peel powder (FPP). Results revealed that all tested FPP significantly (p < 0.05) enhanced the probiotics viable counts, which reached >10 logs after 24 h of incubation. However, the concentration of 2% and 4% FPP showed no significant differences (p > 0.05) on the probiotic viable counts. Additionally, the prebiotic effects of FPP were the same when applied to individual and mixed cultures. This investigation demonstrated that small amount (2%) of apple, banana and mango peel powder could be successfully utilized as prebiotics to enhance the growth of lactic acid bacteria (LAB). Additionally, the studied physical and chemical characteristics of FPP demonstrated their potential applications in the food and pharmaceutical industries as functional ingredients.

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Effect of Pre-Oxidation on Coagulation/Ceramic Membrane Treatment of Yangtze River Water

Membranes ◽

10.3390/membranes11050369 ◽

2021 ◽

Vol 11 (5) ◽

pp. 369

Author(s):

Shengji Xia ◽

Xinran Zhang ◽

Yuanchen Zhao ◽

Fibor J. Tan ◽

Pan Li ◽

...

Keyword(s):

Water Treatment ◽

Membrane Fouling ◽

Membrane Filtration ◽

Ceramic Membrane ◽

Membrane Separation ◽

Membrane System ◽

Coagulation System ◽

Fouling Control ◽

Filtration System ◽

Membrane Treatment

The membrane separation process is being widely used in water treatment. It is very important to control membrane fouling in the process of water treatment. This study was conducted to evaluate the efficiency of a pre-oxidation-coagulation flat ceramic membrane filtration process using different oxidant types and dosages in water treatment and membrane fouling control. The results showed that under suitable concentration conditions, the effect on membrane fouling control of a NaClO pre-oxidation combined with a coagulation/ceramic membrane system was better than that of an O3 system. The oxidation process changed the structure of pollutants, reduced the pollution load and enhanced the coagulation process in a pre-oxidation-coagulation system as well. The influence of the oxidant on the filtration system was related to its oxidizability and other characteristics. NaClO and O3 performed more efficiently than KMnO4. NaClO was more conducive to the removal of DOC, and O3 was more conducive to the removal of UV254.

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Zeolite membrane reactors: from preparation to application in heterogeneous catalytic reactions

Reaction Chemistry & Engineering ◽

10.1039/d0re00388c ◽

2021 ◽

Author(s):

I. G. Wenten ◽

K. Khoiruddin ◽

R. R. Mukti ◽

W. Rahmah ◽

Z. Wang ◽

...

Keyword(s):

Chemical Reaction ◽

Membrane Reactor ◽

Membrane Separation ◽

Process Intensification ◽

Catalytic Reactions ◽

Membrane Reactors ◽

Zeolite Membrane ◽

Heterogeneous Catalytic

Coupling chemical reaction with membrane separation or known as membrane reactor (MR) has been demonstrated by numerous studies and showed that this strategy has successfully addressed the goal of process intensification.

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Dynamic Modeling of CATOFIN® Fixed-Bed Iso-Butane Dehydrogenation Reactor for Operational Optimization

International Journal of Chemical Reactor Engineering ◽

10.1515/ijcre-2015-0087 ◽

2016 ◽

Vol 14 (1) ◽

pp. 491-515 ◽

Cited By ~ 3

Author(s):

Zeeshan Nawaz

Keyword(s):

Coke Formation ◽

Fixed Bed ◽

Process Intensification ◽

Operating Conditions ◽

Catalytic Dehydrogenation ◽

Heating Rates ◽

Reactor Model ◽

Fuel Gas ◽

Bed Temperature ◽

Operational Optimization

AbstractThe catalytic dehydrogenation of iso-butane to iso-butylene is an equilibrium limited endothermic reaction and requires high temperature. The catalyst deactivates quickly, due to deposition of carbonaceous species and countered by periodic regeneration. The reaction-engineering constraints are tied up with operation and/or technology design features. CATOFIN® is a sophisticated commercialized technology for propane/iso-butane dehydrogenation using multiple adiabatic fixed-bed reactors having Cr2O3/Al2O3 as catalyst, that undergo cyclic operations (~18–30m); dehydrogenation, regeneration, evacuation, purging and reduction. It is always a concern, how to maintain CATOFIN® reactor at an optimum production, while overcoming gradual decrease of heat in catalyst bed and deactivation. A homogeneous one-dimensional dynamic reactor model for a commercial CATOFIN® fixed-bed iso-butane dehydrogenation reactor is developed in an equation oriented (EO) platform Aspen Custom Modeler (ACM), for operational optimization and process intensification. Both reaction and regeneration steps were modeled and results were validated. The model predicts the dynamic behavior and demonstrates the extent of catalyst utilization with operating conditions and time, coke formation and removal, etc. The model computes optimum catalyst bed temperature profiles, feed rate, pre-heating, rates for reaction and regeneration, fuel gas requirement, optimum catalyst amount, overall cycle time optimization, and suggest best operational philosophy.

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