Membrane distillation technology for molecular separation: A review on the fouling, wetting and transport phenomena

Innovative Trends in Modified Membranes: A Mini Review of Applications and Challenges in the Food Sector

Membrane technologies play a pivotal role in various industrial sectors, including food processing. Membranes act as barriers, selectively allowing the passage of one or other types of species. The separation processes that involve them offer advantages such as continuity, energy efficiency, compactness of devices, operational simplicity, and minimal consumption of chemical reagents. The efficiency of membrane separation depends on various factors, such as morphology, composition, and process parameters. Fouling, a significant limitation in membrane processes, leads to a decline in performance over time. Anti-fouling strategies involve adjustments to process parameters or direct modifications to the membrane, aiming to enhance efficiency. Recent research has focused on mitigating fouling, particularly in the food industry, where complex organic streams pose challenges. Membrane processes address consumer demands for natural and healthy products, contributing to new formulations with antioxidant properties. These trends align with environmental concerns, emphasizing sustainable practices. Despite numerous works on membrane modification, a research gap exists, especially with regard to the application of modified membranes in the food industry. This review aims to systematize information on modified membranes, providing insights into their practical application. This comprehensive overview covers membrane modification methods, fouling mechanisms, and distinct applications in the food sector. This study highlights the potential of modified membranes for specific tasks in the food industry and encourages further research in this promising field.

Improving membrane distillation performance by Fe(II) activated sodium percarbonate oxidation during the treatment of shale gas produced water

Membrane distillation (MD) offers promise for recycling shale gas produced water (SGPW), while membrane fouling is still a major obstacle in standalone MD. Herein, sodium percarbonate (SPC) oxidation was proposed as MD pretreatment, and the performance of the single MD, SPC-MD hybrid process and Fe(II)/SPC-MD hybrid process for SGPW treatment were systematically evaluated. Results showed that compared to raw SGPW, the application of SPC and Fe(II)/SPC led to the decrease of the fluorescent organics by 28.54 % and 54.52 %, respectively. The hydrophobic fraction decreased from 52.75 % in raw SGPW to 37.70 % and 27.20 % for SPC and Fe(II)/SPC, respectively, and the MD normalized flux increased from 0.19 in treating raw SGPW to 0.65 and 0.81, respectively. The superiority of SPC oxidation in reducing the deposited membrane foulants and restoring membrane properties was further confirmed through scanning electron microscopy observation, attenuated total reflection fourier transform infrared, water contact angle and surface tension analyses of fouled membranes. Correlation analysis revealed that hydrophobic/hydrophilic matters and fluorescent organics in SGPW took a crucial role in MD fouling. The mechanism of MD fouling mitigation by Fe(II)/SPC oxidation was attributed to the decrease in concentrations and hydrophobicity of organic by synergistic oxidation, coagulation and adsorption.

Carbon-Based Nanocomposite Membranes for Membrane Distillation: Progress, Problems and Future Prospects

The development of an ideal membrane for membrane distillation (MD) is of the utmost importance. Enhancing the efficiency of MD by adding nanoparticles to or onto a membrane's surface has drawn considerable attention from the scientific community. It is crucial to thoroughly examine state-of-the-art nanomaterials-enabled MD membranes with desirable properties, as they greatly enhance the efficiency and reliability of the MD process. This, in turn, opens up opportunities for achieving a sustainable water-energy-environment nexus. By introducing carbon-based nanomaterials into the membrane's structure, the membrane gains excellent separation abilities, resistance to various feed waters, and a longer lifespan. Additionally, the use of carbon-based nanomaterials in MD has led to improved membrane performance characteristics such as increased permeability and a reduced fouling propensity. These nanomaterials have also enabled novel membrane capabilities like in situ foulant degradation and localized heat generation. Therefore, this review offers an overview of how the utilization of different carbon-based nanomaterials in membrane synthesis impacts the membrane characteristics, particularly the liquid entry pressure (LEP), hydrophobicity, porosity, and membrane permeability, as well as reduced fouling, thereby advancing the MD technology for water treatment processes. Furthermore, this review also discusses the development, challenges, and research opportunities that arise from these findings.

Progress in membrane distillation processes for dye wastewater treatment: A review

Textile and cosmetic industries generate large amounts of dye effluents requiring treatment before discharge. This wastewater contains high levels of reactive dyes, low to none-biodegradable materials and chemical residues. Technically, dye wastewater is characterised by high chemical and biological oxygen demand. Biological, physical and pressure-driven membrane processes have been extensively used in textile wastewater treatment plants. However, these technologies are characterised by process complexity and are often costly. Also, process efficiency is not achieved in cost-effective biochemical and physical treatment processes. Membrane distillation (MD) emerged as a promising technology harnessing challenges faced by pressure-driven membrane processes. To ensure high cost-effectiveness, the MD can be operated by solar energy or low-grade waste heat. Herein, the MD purification of dye wastewater is comprehensively and yet concisely discussed. This involved research advancement in MD processes towards removal of dyes from industrial effluents. Also, challenges faced by this process with a specific focus on fouling are reviewed. Current literature mainly tested MD setups in the laboratory scale suggesting a deep need of further optimization of membrane and module designs in near future, especially for textile wastewater treatment. There is a need to deliver customized high-porosity hydrophobic membrane design with the appropriate thickness and module configuration to reduce concentration and temperature polarization (CP and TP). Also, energy loss should be minimized while increasing dye rejection and permeate flux. Although laboratory experiments remain pivotal in optimizing the MD process for treating dye wastewater, the nature of their time intensity poses a challenge. Given the multitude of parameters involved in MD process optimization, artificial intelligence (AI) methodologies present a promising avenue for assistance. Thus, AI-driven algorithms have the potential to enhance overall process efficiency, cutting down on time, fine-tuning parameters, and driving cost reductions. However, achieving an optimal balance between efficiency enhancements and financial outlays is a complex process. Finally, this paper suggests a research direction for the development of effective synthetic and natural dye removal from industrially discharged wastewater.

Breakthrough applications of porous organic materials for membrane-based CO2 separation: a review

Over the last decades, porous organic materials (POMs) have been extensively employed in various industrial approaches including gas separation, catalysis and energy production due to possessing indisputable advantages like great surface area, high permeability, controllable pore size, appropriate functionalization and excellent processability compared to traditional substances like zeolites, Alumina and polymers. This review presents the recent breakthroughs in the multifunctional POMs for potential use in the membrane-based CO2 separation. Some examples of highly-selective membranes using multifunctional POMs are described. Moreover, various classifications of POMs following with their advantages and disadvantages in CO2 separation processes are explained. Apart from reviewing the state-of-the-art POMs in CO2 separation, the challenges/limitations of POMs with tailored structures for reasonable application are discussed.

Numerical evaluation of sweeping gas membrane distillation for desalination of water towards water sustainability and environmental protection

Sweeping gas membrane distillation (SGMD) is considered a membrane distillation configuration. It uses an air stream to collect the water vapour. A 2D mathematical model is prepared in the current study to predict the effect of various operating parameters on the SGMD performance. Also, the temperature distribution in the SGMD was obtained. The effect of air inlet temperature, salt concentration, feed and air flowrate on air and salted solution outlet temperature and vapour flux through the membrane is investigated. There was good agreement between experimental data and modelling outputs. It was found that increase in air inlet temperature from 40 to 72 °C was increased the outlet temperature of air stream and cold solution from 37 to 63 °C and 38 to 65 °C respectively. Furthermore, increase in air inlet temperature led to the enhancement of vapour flux in the membrane distillation. Also, the salt concentration and feed flow rate did not have meaningful influence on the outlet temperatures, however, the flux was increased by increasing feed flowrate.

Enzymatic synthesis of branched chain fatty acid-enriched structured triacylglycerols via esterification with glycerol

While branched-chain fatty acids (BCFA)-enriched triacylglycerols (TAG) has various health benefits, its preparation has not been reported. This study aimed to synthesize high-purity BCFA-enriched structured TAG. First, BCFA was enriched from lanolin through saponification, calcification, and urea complexation. Next, BCFA-enriched TAG was synthesized by enzymatic esterification of BCFA and glycerol. Then, lipases were screened by molecular docking and practical experiments, which suggested that Lipozyme 435 was the best lipase for esterification since it had the lowest binding energy. Structured TAG containing 92.23% BCFA was synthesized under conditions optimized by single-factor experiments. Furthermore, molecular distillation was adapted to remove excess fatty acids and small molecule impurities. Finally, high-purity BCFA-enriched structured lipid containing 70.26% TAG was obtained. Overall, this study successfully developed a method for synthesizing BCFA-enriched structured TAG, which holds great promise for applications in value-added foods.

The roles of artificial intelligence techniques for increasing the prediction performance of important parameters and their optimization in membrane processes: A systematic review

Membrane-based separation processes has been recently of significant global interest compared to other conventional separation approaches due to possessing undeniable advantages like superior performance, environmentally-benign nature and simplicity of application. Computational simulation of fluids has shown its undeniable role in modeling and simulation of numerous physical/chemical phenomena including chemical engineering, chemical reaction, aerodynamics, drug delivery and plasma physics. Definition of fluids can be occurred using the Navier-Stokes equations, but solving the equations remains an important challenge. In membrane-based separation processes, true perception of fluid's manner through disparate membrane modules is an important concern, which has been significantly limited applying numerical/computational procedures such s computational fluid dynamics (CFD). Despite this noteworthy advantage, the optimization of membrane processes using CFD is time-consuming and expensive. Therefore, combination of artificial intelligence (AI) and CFD can result in the creation of a promising hybrid model to accurately predict the model results and appropriately optimize membrane processes and phase separation. This paper aims to provide a comprehensive overview about the advantages of commonly-employed ML-based techniques in combination with the CFD to intelligently increase the optimization accuracy and predict mass transfer and the unfavorable events (i.e., fouling) in various membrane processes. To reach this objective, four principal strategies of AI including SL, USL, SSL and ANN were explained and their advantages/disadvantages were discussed. Then after, prevalent ML-based algorithm for membrane-based separation processes. Finally, the application potential of AI techniques in different membrane processes (i.e., fouling control, desalination and wastewater treatment) were presented.

Molecular modeling for sensing of cisplatin drug by graphdiyne: electronic study via DFT

CONTEXT

By utilizing first-principles calculations, we studied the electronic properties of graphdiyne nanosheet (GDY) and its Si-doped counterpart, Si-GDY. Both GDY and Si-GDY sheet surfaces were examined for the drug cisplatin (CP) adsorption using adsorption energy, charge transfer, and changes in electrical conductivity as indicators. Pure GDY has little affinity for CP, according to this study. Only 7.83% of the GDY surface's bandwidth energy changed after CP adsorption. CP on Si-GDY has a gaseous energy value of -18.75 kcal/mol and an aqueous energy value of - 49.39 kcal/mol.

METHODS

The prescribed medications' water-phase solubility is determined by their solvation energy value. These charges are transferred between CP and the Si-GDY sheet, which is extremely positively charged, and this gives CP the necessary binding energy. After CP adsorption, electrical conductivity of Si-GDY increased by approximately 19.01%.

Membrane Fabrication and Modification by Atomic Layer Deposition: Processes and Applications in Water Treatment and Gas Separation

Membrane-based separation processes are part of most water purification plants worldwide. Industrial separation applications, primarily water purification and gas separation, can be improved with novel membranes or modification to existing ones. Atomic layer deposition (ALD) is an emerging technique that is proposed to upgrade certain kinds of membranes independent of their chemistry and morphology. ALD deposits thin, defect-free, angstrom-scale, and uniform coating layers on a substrate's surface by reacting with gaseous precursors. The surface-modifying effects of ALD are described in the present review, followed by a description of various types of inorganic and organic barrier films and how these can be used in combination with ALD. The role of ALD in membrane fabrication and modification is categorized into different membrane-based groups according to the treated medium, i.e., water or gas. In all membrane types, the ALD-based direct deposition of inorganic materials, mainly metal oxides, on the membrane surface can improve antifouling, selectivity, permeability, and hydrophilicity. Therefore, the ALD technique can broaden the applications of membranes to the treatment of emerging contaminants in water and air. Finally, the advancement, limitations, and challenges of ALD-based membrane fabrication and modification are compared to provide a comprehensive guideline for developing next-generation membranes with improved filtration and separation performance.

Sensing of Acetaminophen Drug Using Silicon-Doped Graphdiyne: a DFT Inspection

Using first-principles calculations, we studied the electronic properties of graphdiyne (GDY) nanosheet and its Si-doped counterpart, SiGDY. Both GDY and SiGDY sheet surfaces were examined for acetaminophen (AP) drug adsorption using adsorption energy, charge transfer, and change in electrical conductivity (as indicators). As shown in this study, pure GDY has little affinity for AP. In specific, only 7.83 percent of the GDY surface's bandwidth energy changed after AP adsorption. On SiGDY, AP has a gaseous energy value of - 18.75 kcal/mol, as well as an aqueous energy value of - 49.39 kcal/mol. The water-phase solubility of the prescribed medications is determined using their solvation energy value. These charges are transferred between AP and the SiGDY sheet, which is extremely positively charged, giving AP the necessary binding energy. After AP adsorption, the electrical conductivity of SiGDY was increased by approximately 19.01 percent.

The Impact of Operational Parameters on Polypropylene Membrane Performance during the Separation of Oily Saline Wastewaters by the Membrane Distillation Process

In the present study, membrane distillation (MD) was applied for the treatment of oily saline wastewaters produced on ships sailing the Baltic Sea. For comparison purposes, experiments were also carried out with model NaCl solutions, the Baltic Seawater and oil in water emulsions. The commercial Accurel PP V8/2 membranes (Membrana GmbH, Germany) were used. In order to investigate the impact of the operational parameters on the process performance, the experiments were conducted under various values of the feed flow velocity (from 0.03 to 0.12 m/s) and the feed temperature (from 323 to 343 K). The obtained results highlight the potential of PP membranes application for a stable and reliable long-term treatment of oily wastewater. It was demonstrated that the permeate flux increased significantly with increasing feed temperature. However, the lower temperature ensured the limited scaling phenomenon during the treatment of oily wastewaters. Likewise, increasing the feed flow velocity was beneficial to the increase in the flux. Moreover, it was found that performing a cyclic rinsing of the module with a 3% HCl solution is an effective method to maintain a satisfactory module performance. The present study sheds light on improving the MD for the treatment of oily wastewaters.

Numerical assessment of the influence of helical baffle on the hydrothermal aspects of nanofluid turbulent forced convection inside a heat exchanger

This study is devoted to the numerical assessment of the influence of helical baffle on the hydrothermal aspects and irreversibility behavior of the turbulent forced convection flow of water-CuO nanofluid (NF) inside a hairpin heat exchanger with 100 mm length, 10 mm inner tube internal diameter, and 15 mm outer diameter internal diameter. The variations of the first-law and second-law performance metrics are investigated in terms of Reynolds number (Re = 5000-10,000), volume concentration of NF ([Formula: see text]) and baffle pitch (B = 25-100 mm). The results show that the NF Nusselt number grows with the rise of both the Re and [Formula: see text] whereas it declines with the rise of B. In addition, the outcomes depicted that the rise of both Re and [Formula: see text] results in the rise of pressure drop, while it declines with the increase of B. Moreover, it was found that the best thermal performance of NF is equal to 1.067, which belongs to the case B = 33.3 mm, [Formula: see text]=2%, and Re = 10,000. Furthermore, it was shown that irreversibilities due to fluid friction and heat transfer augment with the rise of Re while the rise of B results in the decrease of frictional irreversibilities. Finally, the outcomes revealed that with the rise of B, the heat transfer irreversibilities first intensify and then diminish.