Entropy Generation and Natural Convection Heat Transfer of (MWCNT/SWCNT) Nanoparticles around Two Spaced Spheres over Inclined Plates: Numerical Study

A numerical study is conducted to evaluate the steady natural convective heat transfer problem and entropy generation of both single wall (SWCNT) and multi wall (MWCNT) nanoparticles with water as a base liquid over two spaced spheres. The isothermally heated spheres are located between two plates of short length. The cooled plates are maintained at different inclination angles. A numerical approach based on the finite volume method and multigrid acceleration was used to solve the governing equations. The effects of nanoparticle type, volume fraction, the inclination angle of the plates and the Rayleigh numbers are well-considered. Results reveal that there is a remarkable enhancement of the average Nusselt number over the plates for MWCNT nanoparticles with 63.15% from the inclination angle 0° to 30°. Furthermore, optimal heat transfer rates over the plates for MWCNT nanoparticles equates to 1.9, which is obtained for the inclination 30° and a Rayleigh number of 10$^{6}$. However, for SWCNT nanoparticles, the same equates 0.9, which is obtained for the inclination 90° and a Rayleigh number of 10$^{6}$. The comprehensive analysis is presented under some well-defined assumptions which show the reliability of the present investigation

Natural and recycled materials for sustainable membrane modification: Recent trends and prospects

Despite water being critical for human survival, its uneven distribution, and exposure to countless sources of pollution make water shortages increasingly urgent. Membrane technology offers an efficient solution for alleviating the water shortage impact. The selectivity and permeability of membranes can be improved by incorporating additives of different nature and size scales. However, with the vast debate about the environmental and economic feasibility of the common nanoscale materials in water treatment applications, we can infer that there is a long way before the first industrial nanocomposite membrane is commercialized. This stumbling block has motivated the scientific community to search for alternative modification routes and/or materials with sustainable features. Herein, we present a pragmatic review merging the concept of sustainability, nanotechnology, and membrane technology through the application of natural additives (e.g., Clays, Arabic Gum, zeolite, lignin, Aquaporin), recycled additives (e.g., Biochar, fly ash), and recycled waste (e.g., Polyethylene Terephthalate, recycled polystyrene) for polymeric membrane synthesis and modification. Imparted features on polymeric membranes, induced by the presence of sustainable natural and waste-based materials, are scrutinized. In addition, the strategies harnessed to eliminate the hurdles associated with the application of these nano and micro size additives for composite membranes modification are elaborated. The expanding research efforts devoted recently to membrane sustainability and the prospects for these materials are discussed. The findings of the investigations reported in this work indicate that the application of natural and waste-based additives for composite membrane fabrication/modification is a nascent research area that deserves the attention of both research and industry

Role of copper and alumina for heat transfer in hybrid nanofluid by using Fourier sine transform

The convection, thermal conductivity, and heat transfer of hybrid nanofluid through nanoparticles has become integral part of several natural and industrial processes. In this manuscript, a new fractionalized model based on hybrid nanofluid is proposed and investigated by employing singular verses and non-singular kernels. The mathematical modeling of hybrid nanofluid is handled via modern fractional definitions of differentiations. The combined Laplace and Fourier Sine transforms have been configurated on the governing equations of hybrid nanofluid. The analytical expression of the governing temperature and velocity equations of hybrid nanofluid have been solved via special functions. For the sake of thermal performance, dimensional analysis of governing equations and suitable boundary conditions based on Mittage-Leffler function have been invoked for the first time in literature. The comparative analysis of heat transfer from hybrid nanofluid has been observed through Caputo-Fabrizio and Atangana-Baleanu differential operators. Finally, our results suggest that volume fraction has the decelerated and accelerated trends of temperature distribution and inclined and declined profile of heat transfer is observed copper and alumina nanoparticles

Fundamentals of membrane bioreactors: materials, systems and membrane fouling

This book provides a critical, carefully researched, up-to-date summary of membranes for membrane bioreactors. It presents a comprehensive and self-contained outline of the fundamentals of membrane bioreactors, especially their relevance as an advanced water treatment technology. This outline helps to bring the technology to the readers’ attention, and positions the critical topic of membrane fouling as one of the key impediments to its more widescale adoption. The target readership includes researchers and industrial practitioners with an interest in membrane bioreactors

Membrane Technologies for Nitrogen Recovery from Waste Streams: Scientometrics and Technical Analysis

The concerns regarding the reactive nitrogen levels exceeding the planetary limits are well documented in the literature. A large portion of anthropogenic nitrogen ends in wastewater. Nitrogen removal in typical wastewater treatment processes consumes a considerable amount of energy. Nitrogen recovery can help in saving energy and meeting the regulatory discharge limits. This has motivated researchers and industry professionals alike to devise effective nitrogen recovery systems. Membrane technologies form a fundamental part of these systems. This work presents a thorough overview of the subject using scientometric analysis and presents an evaluation of membrane technologies guided by literature findings. The focus of nitrogen recovery research has shifted over time from nutrient concentration to the production of marketable products using improved membrane materials and designs. A practical approach for selecting hybrid systems based on the recovery goals has been proposed. A comparison between membrane technologies in terms of energy requirements, recovery efficiency, and process scale showed that gas permeable membrane (GPM) and its combination with other technologies are the most promising recovery techniques and they merit further industry attention and investment. Recommendations for potential future search trends based on industry and end users’ needs have also been proposed

Removal of Dyes Using Graphene Oxide (GO) Mixed Matrix Membranes

The application of membrane technology to remove pollutant dyes in industrial wastewater is a significant development today. The modification of membranes to improve their properties has been shown to improve the permeation flux and removal efficiency of the membrane. Therefore, in this work, graphene oxide nanoparticles (GO-NPs) were used to modify the polyethersulfone (PES) membrane and prepare mixed matrix membranes (MMMs). This research is dedicated to using two types of very toxic dyes (Acid Black and Rose Bengal) to study the effect of GO on PES performance. The performance and antifouling properties of the new modified membrane were studied using the following: FTIR, SEM, AFM, water permeation flux, dye removal and fouling, and by investigating the influence of GO-NPs on the structure. After adding 0.5 wt% of GO, the contact angle was the lowest (39.21°) and the permeable flux of the membrane was the highest. The performance of the ultrafiltration (UF) membrane displayed a rejection rate higher than 99% for both dyes. The membranes showed the highest antifouling property at a GO concentration of 0.5 wt%. The long-term operation of the membrane fabricated from 0.5 wt% GO using two dyes improved greatly over 26 d from 14 d for the control membrane, therefore higher flux can be preserved

Natural and recycled materials for sustainable membrane modification : Recent trends and prospects

Funding Information: Nidal Hilal would like to thank Tamkeen for funding the NYUAD Water Research Center under the NYUAD Research Institute Award (project CG007 ). Publisher Copyright: © 2022 The AuthorsDespite water being critical for human survival, its uneven distribution, and exposure to countless sources of pollution make water shortages increasingly urgent. Membrane technology offers an efficient solution for alleviating the water shortage impact. The selectivity and permeability of membranes can be improved by incorporating additives of different nature and size scales. However, with the vast debate about the environmental and economic feasibility of the common nanoscale materials in water treatment applications, we can infer that there is a long way before the first industrial nanocomposite membrane is commercialized. This stumbling block has motivated the scientific community to search for alternative modification routes and/or materials with sustainable features. Herein, we present a pragmatic review merging the concept of sustainability, nanotechnology, and membrane technology through the application of natural additives (e.g., Clays, Arabic Gum, zeolite, lignin, Aquaporin), recycled additives (e.g., Biochar, fly ash), and recycled waste (e.g., Polyethylene Terephthalate, recycled polystyrene) for polymeric membrane synthesis and modification. Imparted features on polymeric membranes, induced by the presence of sustainable natural and waste-based materials, are scrutinized. In addition, the strategies harnessed to eliminate the hurdles associated with the application of these nano and micro size additives for composite membranes modification are elaborated. The expanding research efforts devoted recently to membrane sustainability and the prospects for these materials are discussed. The findings of the investigations reported in this work indicate that the application of natural and waste-based additives for composite membrane fabrication/modification is a nascent research area that deserves the attention of both research and industry.Peer reviewe

Long-Term Stable Metal Organic Framework (MOF) Based Mixed Matrix Membranes for Ultrafiltration

In this study, novel mixed matrix polyethersulfone (PES) membranes were synthesized by using two different kinds of metal organic frameworks (MOFs), namely UiO-66 and UiO-66-NH2. The composite membranes were characterised by SEM, EDX, FTIR, PXRD, water contact angle, porosity, pore size, etc. Membrane performance was investigated by water permeation flux, flux recovery ratio, fouling resistance and anti-fouling performance. The stability test was also conducted for the prepared mixed matrix membranes. A higher reduction in the water contact angle was observed after adding both MOFs to the PES and sulfonated PES membranes compared to pristine PES membranes. An enhancement in membrane performance was observed by embedding the MOF into PES membrane matrix, which may be attributed to the super-hydrophilic porous structure of UiO-66-NH2 nanoparticles and hydrophilic structure of UiO-66 nanoparticles that could accelerate the exchange rate between solvent and non-solvent during the phase inversion process. By adding the MOFs into PES matrix, the flux recovery ratio was increased greatly (more than 99% for most mixed matrix membranes). The mixed matrix membranes showed higher resistance to protein adsorption compared to pristine PES membranes. After immersing the membranes in water for 3 months, 6 months and 12 months, both MOFs were stable and retained their structure. This study indicates that UiO-66 and UiO-66-NH2 are great candidates for designing long-term stable mixed matrix membranes with higher anti-fouling performance.</p

Anti-Fouling Performance of Mixed Matrix PVDF Membranes with Mono-Hydroxyl Poly(dimethylsiloxane) (PDMS-OH) Grafted Silica Nanoparticles

In this study, we investigate the use of surface-modified silica nanoparticles to improve the anti-fouling performance of PVDF ultrafiltration membranes. Here, fouling resistant nanoparticles were prepared by grafting monohydroxy-polydimethylsiloxane onto the surface of silica nanoparticles using Steglich esterification. The mixed matrix PVDF membranes were prepared at a range of nanoparticle concentrations (0, 1.6, 3.2, 6.3, and 11.8%) to understand how PDMS modified silica content affected membrane performance. The resulting hybrid membranes were characterised using a range of techniques including scanning electron microscopy (SEM), water contact angle (CA), porosity, and pore size measurements, in order to determine how morphological features of the nanocomposite membranes affected fouling and pure water flux. Embedding silica nanoparticles resulted in a significant reduction in membrane fouling, including lower protein adsorption and a flux recovery ratio of 97 %. Although water flux was reduced by the addition of nanoparticles, the change in the porosity, mean pore size and the hydrophilicity of the membrane caused the rejection rate to be increased significantly. Together, these results are of particular benefit to the ultrafiltration industry, where improved antifouling and flux recovery can help reduce operating and maintenance costs in these membrane processes.<br /

Potential application of hybrid forward osmosis – Membrane distillation (FO-MD) system for various water treatment processes

peer reviewedDifferent membrane processes have been used to address water scarcity issues. Among them, membrane distillation (MD) is a promising technology due to its capacity to treat hypersaline water. Forward osmosis (FO) is another innovative technology that has the advantage of low operational energy. A hybrid system of these two technologies has proven to be an effective technique for the water treatment industry particularly for water reclamation and resource recovery. Understanding the fundamentals of this amalgamation and the challenges that brings with it is an important topic for the scientific and research community. This work presents a detailed review of the FO-MD systems enriched with the recent advances in this system. The opportunities and challenges for the individual technologies and the system overall were critically addressed. Successful pilot designs for the hybrid system were illustrated. Mathematical modeling for the water transfer in the hybrid system was also elaborated to identify the key points and boundaries of the processes. It is apparent that the inherent low energy conversion in MD and the need for draw solution regeneration are the prominent challenges of this system. Another important aspect to be highlighted is that the water transfer balance between MD and FO is the key requirement for a stable and successful operation. The use of alternative energy is possible but it is only feasible in specific cases such as the existence of seawater and wastewater facilities in a proximity or the case of produced water that contains geothermal heat. Implementing heat recovery in the MD stage, using functionalized particles as a source of osmolarity in the draw solution, and developing membrane materials with unique characteristics such as omniphobic and Janus MD membranes are effective strategies that have just recently shown to improve the systems economics and such strategies should be explored further