Nidal Hilal

• DSc PhD EurIng CEng FIChemE FLSW FRSC
• Professor (Full) at New York University Abu Dhabi

Over the last decades, the tightening of water quality regulations and the increased attention given to trace contaminants in water has been favouring the emergence of novel treatment technologies in order to upgrade or improve conventional water treatment processes. This review surveys recent studies on using combined ion exchange (IX) and pressur...

This paper presents an overview on recent developments in surface modification of polymer membranes for reduction of their fouling with biocolloids and organic colloids in pressure driven membrane processes. First, colloidal interactions such as London-van der Waals, electrical, hydration, hydrophobic, steric forces and membrane surface properties...

With the rapid advancement of effective photothermal materials, photothermal membrane distillation (P-MD) has emerged as a new technology for water treatment using solar energy. This technology captures large amounts of solar energy and localizes heating on the membrane-feed water interface using photothermal effects. This research analyses P-MD me...

Feed spacers are crucial for enhancing the performance and efficiency of membrane-based technologies. Researchers have long focused on optimizing feed spacer designs and materials to improve fluid mixing and mass/heat transfer across membranes. However, these improvements often increase pressure drops, raising energy requirements. Therefore, innova...

Membrane engineering is a complex field involving the development of the most suitable membrane process for specific purposes and dealing with the design and operation of membrane technologies. This study analyzed 1424 articles on reverse osmosis (RO) membrane engineering from the Scopus database to provide guidance for future studies. The results...

Membrane technologies play a crucial role in hydrogen generation and recovery processes, offering significant advantages in terms of efficiency, selectivity, and environmental sustainability. Membrane-based hydrogen generation technologies, such as water electrolysis and reforming processes, have gained considerable attention due to their ability t...

The Grand Ethiopian Renaissance Dam (GERD) on the Nile River has become a focal point in the fields of water diplomacy, economics, and environmental considerations in the Nile Basin. Announced during the Arab Spring in 2011, the GERD aims to address Ethiopia’s significant energy shortfall and foster regional economic growth by potentially doubling...

Limitations in existing anion exchange membranes deter their use in the efficient treatment of industrial wastewater effluent. This work presents an approach to fabricating novel anion-conducting membranes using epoxy resin monomers like hydrophobic or hydrophilic diglycidyl ether and quaternized polyethyleneimine (PEI). Manipulating the diglycidyl...

Membrane distillation (MD) is a versatile low-temperature separation process used for desalinating saline solutions with high salt rejection rates. Its current drawbacks include low flux and high energy demand. This study presents localized electrically induced heating using ceramic-coated metallic spacers to improve MD performance. We coated Ni-Cr...

Water and energy are two strategic drivers of sustainable development, intimately interlaced and vital for a secure future of humanity. Given that water resources are limited, whereas global population and energy demand are exponentially growing, the competitive balance between these resources, referred to as the water-energy nexus, is receiving re...

Feedwater heating represents a pivotal and energy-intensive step in membrane distillation (MD), contributing significantly to the total energy costs. Thus, elevating the thermal efficiency of the MD process is vital for its broader energy optimization. Recent years have witnessed an uptick in research targeting the enhancement of thermal efficiency...

Membrane technology has shown a promising role in combating water scarcity, a globally faced challenge. However, the disposal of end-of-life membrane modules is problematic as the current practices include incineration and landfills as their final fate. In addition, the increase in population and lifestyle advancement have significantly enhanced wa...

Surface patterning of membranes has emerged as a nonchemical approach to improving the performance of water separation and ion exchange membranes. These patterns reduce the interactions between foulants and the membrane, which ultimately hinder foulant adsorption and deposition. Therefore, in water separation membranes, such surface patterns can be...

This study investigates the potential of surface-patterned membranes in replacing the conventional feed spacer-assisted filtration process. Two types of surface patterns, namely diamond (D) and honeycomb (HC), were utilized in the fabrication of the surface-patterned membranes. These membranes showed larger effective membrane area and higher averag...

This book provides a novel exploration of the application of nanofiltration membrane technology for sustainability in various industries, situated in view of recent breakthroughs and the use of reuse, recycle and resource recovery approaches. Moving from a comprehensive discussion of nanofiltration membrane processes to case studies and real-world...

The use of reverse osmosis (RO) for water reclamation has become an essential part of the water supply owing to the ever-increasing water demand and the utmost performance of the RO membranes. Despite the global RO implementation, its inferior rejection against low molecular weight contaminants of emerging concerns (CECs) (i.e., N-nitrosodimethylam...

Obtaining fresh drinking water is a challenge directly related to the change in agricultural, industrial, and societal demands and pressure. Therefore, the sustainable treatment of saline water to get clean water is a major requirement for human survival. In this review, we have detailed the use of electrospun nanofiber-based membranes (ENMs) for w...

In this study, an electrohydrodynamic atomization or electrospraying technique is used for the uniform deposition of carbon nanotubes (CNT) on a commercially available PTFE membrane and employed for Membrane Distillation (MD) process. Modified PTFE-CNT membrane was characterized for water contact angle, liquid entry pressure (LEP), pore size distri...

While phenomenal strides are being made on the technological front, the water industry lags behind other sectors in the adoption of innovative techniques. Contributing factors include long lifetimes and costs of previous water infrastructure, risk aversion due to public health concerns surrounding water access, and low financing for innovation. Whi...

Membrane-based separation technologies play a pivotal role in attenuating the freshwater shortage worldwide. Spiral wound membrane (SWM) modules which involve several membrane envelopes glued together and separated by feed spacers have been used widely in these technologies. The primary role of feed spacers in the SWM module is to create the flow c...

Membrane technology has become increasingly popular and important for separation processes in industries, as well as for desalination and wastewater treatment. Over the last decade, the merger of nanotechnology and membrane technology in the development of nanocomposite membranes has emerged as a rapidly expanding research area. The key motivation...

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 regul...

In this investigation, the electrospraying of CNTs on an electrospun PVDF-Co-HFP membrane was carried out to fabricate robust membranes for the membrane distillation (MD) process. A CNT-modified PVDF-Co-HFP membrane was heat pressed and characterized for water contact angle, liquid entry pressure (LEP), pore size distribution, tensile strength, and...

Ceramic membranes are gaining importance in several mainstream membrane applications. Their high chemical and thermal resistance stability make them ideal candidates for oil/water separation, dye rejections, in dairy production, catalyst recovery and in treating a variety of wastewater effluents. Although ceramic microfiltration and ultrafiltration...

Feed spacers are an important component of membrane‐based filtration systems as they promote turbulence and mass transfer during the filtration process—thereby, reducing the membrane fouling and improving the flux. Whereas spacers are used as a separate component in conjunction with membranes, herein, we demonstrate that membrane‐integrated spacers...

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 dif...

Brine, in the form of seawater, salt lakes and geothermal water, holds massive amounts of valuable minerals. Among the variety of metallic and non-metallic elements that are recovered from brine at varying scales, Lithium (Li) has received immense interest in recent years due to its exponentially rising demand. Concentrated brine, which is the by-p...

Electrospinning is a versatile technique for the fabrication of nanofibrous, nanostructured composite membranes for a large number of applications. This mini-review focuses on electrospun membranes for various MD configurations. We provide a background to the electrospinning process, recent developments, and the potential of the electrospinning tec...

Membrane fouling is one of the challenging issues surrounding membrane‐based separation. Here in, we demonstrate direct 3D printing of electrically conductive interdigitated spacer on an ultrafiltration membrane for membrane cleaning and chlorination via periodic electrolysis. The spacers were 3D printed on the membrane surface via material extrusi...

Much research has been carried out in recent years to investigate the use of nanomaterials as fillers in polymeric nanofiltration membranes, to improve water transport and fouling resistance whilst preserving, where possible, selectivity. This review paper considers the background to this research, including membrane fabrication and incorporation o...

Nanofiltration (NF) membrane has been applied for the treatment of wastewater owing to its unique features such as higher selectivity towards divalent/polyvalent ions while allowing permeation for monovalent ions and small molecules of less than 100 Da. Thus, the use of NF in wastewater treatment is promising for water recycling, reuse, and recover...

Air gap membrane distillation (AGMD) is a low-temperature separation process applied commonly to desalination of (hyper)saline feeds. The low energy efficiency of heating the bulk feed solution to drive vapor transport in MD must be addressed through novel materials and techniques. In this work, we introduce the concept of intermittent electrical h...

The implementation of membrane surface modification to enhance the performance of membrane-based separation has become a favored strategy due to its promise to address the trade-off between water permeability and salt rejection as well as to improve the durability of the membranes. Tremendous work has been committed to modifying polymeric membranes...

Membrane Distillation (MD) is a membrane-based, temperature-driven water reclamation process. While research emphasis has been largely on membrane design, upscaling of MD has prompted advancements in energy-efficient module design and configurations. Apart from the four conventional configurations, researchers have come up with novel MD membrane mo...

The saline wastewater from various sources including agriculture and industrial activities, appears to have high salt concentration, organic content and other pollutants which can harm the environment. Thus, saline waste-water treatment has become one of the major concerns in many countries. Membrane technology offers great potential in saline wast...

Surface modification of membranes is an effective approach for imparting unique characteristics and additional functionalities to the membranes. Chemical grafting is a commonly used membrane modification technique due to its versatility in tailoring and optimizing the membrane surface with desired functionalities. Various types of polymers can be p...

Inorganic membranes hold great potential for various mainstream applications such as in wastewater treatment, drug manufacturing, food and beverage production, and dairy purification. There are numerous commercially available ceramic membranes which possess high corrosion resistance, high strength, and good heat resistance. However, these membranes...

Zeolites, in the form of monolithic and well-defined structures, offer great opportunity as potential adsorbents to remediate various environmental pollutants. In this work, zeolite-Y structures were fabricated via 3D printing technique and their potential was demonstrated for removing toxic heavy metals from wastewater. Using a lab-scale column-ty...

Water scarcity is a grand challenge that requires continuous exploration of new desalination technologies in order to augment the global supply of fresh water. In this context, membrane distillation (MD) is a promising technology that operates based on a thermal gradient to transfer vapor molecules across a porous hydrophobic membrane. Lack of suit...

Fertilizer-drawn forward osmosis (FDFO) is a potential alternative to recover and reuse water and nutrients from agricultural wastewater, such as palm oil mill effluent that consists of 95% water and is rich in nutrients. This study investigated the potential of commercial fertilizers as draw solution (DS) in FDFO to treat anaerobic palm oil mill e...

Fouling is major concern in several industries involving separation of heavy oil components such as crude and motor oils. In this work, a novel free-standing, conductive ceramic membrane, made from nanozeolite and carbon nanostructures (CNS) was fabricated. Various nano-zeolite: CNS ratios were studied. The membranes were tested for oil/water separ...

Ultrafiltration (UF) and nanofiltration (NF) membranes have attracted great research interest to treat dye wastewaters. However, UF membranes suffer from low dye rejection and NF membrane have low salt recovery. There is a tradeoff between the dye rejection and salt recovery in the UF and NF membranes. A novel membrane is required for dye rejection...

Water scarcity is a global issue that needs to be urgently addressed to alleviate its adverse impacts on social and economic development. Desalination has been touted as an attractive alternative that can sustainably provide freshwater, particularly when there is no better option to augment water supplies. Tremendous research innovations and evolut...

Emerging technologies present many new possibilities for diversifying the desalination industry, which is currently dominated by thermal desalination, and reverse osmosis. In this review, we highlight recent developments in emerging desalination technologies, focusing on those nearing commercialization i.e. forward osmosis and membrane distillation...

The shortage of clean water sources and increase of demand for fresh water have become as major global challenges not only in industries but also inhuman life. Meanwhile, membrane technology has been extensively noticed due to high separation efficiency, energy-saving and environmentally-friendly characteristic. So, development of new membrane is a...

Unmatched flexibility in terms of material selection, design and scalability, along with gradually decreasing cost, has led 3D printing to gain significant attention in various water treatment and desalination applications. In desalination, 3D printing has been applied to improving the energy efficiency of existing technologies. For thermal desalin...

Water constitutes one of the basic necessities of life. Around 71% of the Earth is covered by water, however, not all of it is readily available as fresh water for daily consumption. Fresh water scarcity is a chronic issue which poses a threat to all living things on Earth. Seawater, as a natural resource abundantly available all around the world,...

Membrane distillation (MD) is a useful technology for water desalination possible at low temperatures using inexpensive membranes offering high salt rejection. Therefore, in the present study, economically and eco-friendly Saudi red clay, tetraethyl orthosilicate, ammonia, and sodium alginate powder as a binder were used to fabricate a ceramic memb...

Membrane fouling in water treatment is a major drawback in membrane-based separation processes. In this work, periodic electrolytic membrane cleaning was used for the first time on ceramic-based electrically conductive membranes. Highly conductive nano zeolite/CNS, hydrophilic microfiltration membranes were fabricated through vacuum filtration, wit...

Nano zeolite-Y ultrafiltration (UF) membrane, with mean pore diameter of 28 nm was fabricated using a simple isostatic pressing technique. Zeolite-Y has preferential water pathways and a unique 3-D microporous structure. The zeolite-Y used in this study has an Al to Si (Al/Si) ratio of 0.07 which renders the membrane superhydrophilic with complete...

Forward osmosis (FO) has been recognized as the preferred alternative membrane-based separation technology for conventional water treatment technologies due to its high energy efficiency and promising separation performances. FO has been widely explored in the fields of wastewater treatment, desalination, food industry and bio-products, and energy...

With limited resources as a driver, the search for novel materials for improved desalination processes has been a major component of water research in recent years. Graphene and its derivatives are one such promising material. Graphene is a 2D material, which exhibits remarkable strength and durability, has a very high specific surface area, is eas...

Pressure retarded osmosis (PRO) has gained attention due to its use as a salinity gradient energy-generating membrane process. This process can convert difference in salinity between two streams into energy as it allows water transport through a semi-permeable membrane against the application of hydraulic pressure. This review provides a comprehens...

Nowadays, integrated microfiltration (MF) membrane systems treatment is becoming widely popular due to its feasibility, process reliability, commercial availability, modularity, relative insensitivity in case of wastewater of various industrial sources as well as raw water treatment and lower operating costs. The well thought out, designed and impl...

Membrane distillation (MD) lags behind other desalination processes such as reverse osmosis due to relatively high energy consumption. Heating in membrane distillation forms a significant component of total energy consumption. This review provides an overview of the various conventional and non-conventional heating methods used in the MD process, f...

Desalinated water is not suitable for direct use as it is prone to corrosion and has adverse effects on human health and the environment. Desalinated water is slightly acidic, lacks minerals and cannot be used un-buffered, thus making remineralization an important component downstream of desalination. We systematically review remineralization requi...

Forward osmosis technology is one of the most rapidly developing processes of desalination and water treatment. The transport of boron in forward osmosis (FO) using various FO membranes was investigated in this study. Three specific membranes — an FTS H2O™ membrane, a PSU membrane and an Aquaporin Inside™ membrane — were applied to study the impact...