Desalination Of Salty Water Research Articles

Study the effect of solar power on the efficiency of desalinating saline water: Case studies Al-Khafji and Gulf of Aqaba areas

The desalination of salty water has become a necessary industrial process to overcome the next global shortage in freshwater. In this study, adding a Reheat Solar Collector Cycle (RSCC) to a multi-stage flash plant is used to increase the optimization of the desalination process, improving efficiencies, reducing energy, and increasing the production of freshwater demands to overcome the global crisis of shortage in freshwater. Two projects employ this numerical technique. The first project is conducted in the Al-Khafji multi-stage flash plant in Saudi Arabia with an input mass flow rate of 1 Mkg/h (277.78 kg/s), TDS of 35,000 ppm, and wind velocity of 1 m/s. The second project is conducted in the Gulf of Aqaba in Jordan with an input mass flow rate of 1 Mkg/h (277.78 kg/s), TDS of 40,000 ppm, and wind velocity of 1 m/s. The module of the LS-2 Parabolic Trough Collector (PTC) is used to gain the required energy to heat seawater. The results show that in the Al-Khafji project, an increase of 7.1% in the plant capacity per day and an increase in efficiency from 7.8 to 8.4 were observed. While, in the Gulf of Aqaba, an increase of 7.7% in the plant capacity per day and an increase in efficiency from 7.8 to 8.4 are observed.

Research progress of sodium super ionic conductor electrode materials for capacitive deionization

The world is suffering from water shortage and the hope relies on the desalination of salty water. Several technologies are available for desalination such as reverse osmosis and electrodialysis. However, the application of these technologies in desalination is limited by the higher energy consumption, high investment and maintenance costs. Capacitive deionization (CDI), an up-coming technology at an infant stage is able to supplement the dwindling freshwater resources and provide water to the population. The performance of CDI is directly affected by the electrode materials. Since its inception carbon has been the principal electrode materials for CDI technology. However, low salt removal capacity due to inaccessibility of nanopores and ejection of co-ions hinder the application of carbon materials. Battery materials have been developed as an alternative to accompany carbon materials. Specifically, sodium superionic conductor (NASICON) materials have been used in brackish water desalination by CDI due to having the diffusion channels forming a three dimensional open structure and availability at low cost. However, the NASICON materials have not yet applied in the desalination of water with high salinity such as sea water. This paper reviews the present status of NASICON materials as CDI electrode materials and fairly compares it with carbon materials. It further compares the cost of NASICON and carbon materials, highlights the possibility of NASICON to desalinate high ionic strength solutions such as seawater. Moreover, the paper, discuss the methods which can be used to enhance the salt removal capacity of NASICON materials and provide examples of NASICON materials in the field of energy storage that can be borrowed and used in CDI. From the analysis of this work, NASICON materials are great companion of the carbon materials, are cost effective and are promising for the desalination of sea water.

Charged functional groups modified porous spherical hollow carbon material as CDI electrode for salty water desalination

As a new electrochemical technology, capacitive deionization (CDI) has been increasingly applied in environmental water treatment and seawater desalination. In this study, functional groups modified porous hollow carbon (HC) were synthesized as CDI electrode material for removing Na+ and Cl− in salty water. Results showed that the average diameter of HC was approximately 180 nm, and the infrared spectrum showed that its surface was successfully modified with sulfonic and amino groups, respectively. The sulfonic acid functionalized HC (HC-S) showed better electrochemical and desalting performance than the amino-functionalized HC (HCN), with a maximum Faradic capacity of 287.4 F/g and an adsorptive capacity of 112.97 mg/g for NaCl. Additionally, 92.63% capacity retention after 100 adsorption/desorption cycles demonstrates the excellent stability of HC-S. The main findings prove that HC-S is viable as an electrode material for desalination by high-performance CDI applications.

Effects of the Spacer Obstacles on the Capacitive Deionization Performance

The capacitive deionization (CDI) process uses porous electrodes to adsorb electrostatic ions, offering the possibility of efficient desalination of salty water. The purpose of this study is to investigate the effects of obstacles in CDI spacers on charge transfer and adsorption. The results reveal that the adsorption rate of the CDI cells increases remarkably for the obstacle height ratios of h = 0.8 and 0.9 in comparison with the original channel. In contrast, the performance deteriorates for the cells with height ratios of h = 0.3 and 0.6. For desalination operations that end at half the equilibrium salt adsorption capacity (SAC), the CDI channel containing rectangular obstacles covering 80% of the channel, improves the ASAR (0.13 mg g−1 min−1) by 8% compared to the same situation with the original spacer (0.12 mg g−1 min−1). This gain increases to 25% for the barriers covering 90% of the channel height. The results show that as the barrier height is modest, it prevents salt from entering the electrodes, allowing a low concentration zone to be identified adjacent to the barrier inside the electrode. Interestingly, if the barrier height ratio is as high as h = 0.8 and 0.9, the strong vortices facilitate the ions transfer towards the electrode and consequently, more adsorption occurs.

Utilization of Unconventional Water Resources (UWRs) for Aquaculture Development in Arid and Semi-Arid Regions – A Review

Abstract Today, the increase of the world’s population and climate change has resulted in the reduction of fresh water resources and the increase of arid and semi-arid areas, and thus, it is necessary to find a new solution to increase the production of food resources. Aquaculture is one of the sources of food production, which can play a key role in fighting poverty and hunger. Sustainable aquaculture is strongly dependent on water quantity and quality, and also, optimal fish production can be determined by the physical, chemical and biological quality of water. Due to the current restrictions and the global increase in demand for aquatic products, unconventional waters (UWs) have been used in aquaculture. UWs include: recycled water, sewage, saline water, agricultural drains and water resulting from the process of sweetening and desalination of salty water. Today, these water resources have been used to grow all kinds of aquatic animals to provide food and protein. Considering the limited water resources in the world, the use of UWs is very effective and efficient in managing drought, and is considered as one of the ways to develop food production for humans. Due to its importance in areas facing water scarcity, the use of unconventional water resources (UWRs) to supplement or replace the use of conventional fresh water sources has been considered. In this review study, the importance of UWs and their sources, aquaculture products and aquatics that can be cultivated with the help of UWs are discussed.

Janus aramid nanofiber aerogel incorporating plasmonic nanoparticles for high-efficiency interfacial solar steam generation

Interfacial solar steam generation (ISSG) is a novel and potential solution to global freshwater crisis. Here, based on a facile sol-gel fabrication process, we demonstrate a highly scalable Janus aramid nanofiber aerogel (JANA) as a high-efficiency ISSG device. JANA performs near-perfect broadband optical absorption, rapid photothermal conversion and effective water transportation. Owning to these features, efficient desalination of salty water and purification of municipal sewage are successfully demonstrated using JANA. In addition, benefiting from the mechanical property and chemical stability of constituent aramid nanofibers, JANA not only possess outstanding flexibility and fire-resistance properties, but its solar steaming efficiency is also free from the influences of elastic deformations and fire treatments. We envision JANA provides a promising platform for mass-production of high-efficiency ISSG devices with supplementary capabilities of convenient transportation and long-term storage, which could further promote the realistic applications of ISSG technology.

Water Desalination Driven by Solar Energy

The abundance of drinking water is necessary for daily needs, but recently it has become a worrying obsession worldwide, as it requires the use of fossil fuels for its production, and since the whole world is moving to reduce greenhouse gases emissions, it was necessary to think about using alternative renewable energy in the production of drinking water and that was through desalination of salty water. Solar energy has been widely used. The methods that use solar power are divided into direct and indirect, which include several steps, and the solar energy systems used are varied. In the present study, desalination methods and some types of solar energy systems used are mentioned with a comparison of the amount of production and costs, in addition to the improvement resulting from the use of PCM. It was found that the solar Fresnel lens system is the most effective in producing fresh water compared with its cost. The solar desalination stations in Jordan are 29 and only 1 solar-powered desalination plant out of them, but the universities and independent factories have their solar deamination systems.

Poly(vinyl alcohol)/carbon nanotube (CNT) membranes for pervaporation dehydration: The effect of functionalization agents for CNT on pervaporation performance

Polymeric membrane-based pervaporation separation for desalination of salty water and dehydration from water/organic solvent mixtures is studied. In this work surface-functionalized carbon nanotubes (CNTs) are used to build up water-conduction pathways in poly(vinyl alcohol) (PVA) membranes. For probing the effect of functionalization agents for CNT on pervaporation separation performance, 4 agents, including PVA, polyethylenimine, lignin, and cellulose nanocrystal, have been included in the studies. The hydrophilicity of the functionalization agents, providing strong interaction between the functionalized CNT surfaces and water molecules, plays a critical role on construction of water-conduction pathways in the PVA/functionalized CNT membranes. Small amount of functionalized-CNTs (about 0.03 wt%) have exhibited significant effects on enhancing the permeation fluxes of the membranes. Among the functionalized CNTs, PVA-CNT shows the highest performance on enhancing the permeation fluxes of the corresponding membranes for desalination on a feeding solution of 3.5 wt% NaCl(aq). On the other hand, for dehydration on water/alcohol mixtures, ozonized lignin-functionalized CNTs are most effective for membrane modification. For a 70 wt% ethanol aqueous solution at 25 °C, the PVA/lignin-CNT membrane possessing 0.03 wt% of lignin-CNT exhibits a flux of 880 g m−2 h−1, compared to the value of 565 g m−2 h−1 found with the neat PVA membrane. The water concentrations of the permeated liquids for both membranes are above 99.95 wt%, corresponding to water separation factors above 4464. The increased fluxes could be attributed to the enhanced molecule mobility associating to the CNT-based water conduction pathways.

A novel highly osmotic K/Fe3O4/CNF magnetic draw solution for salty water desalination

Forward osmosis (FO) is increasingly being studied as an alternative desalination technique to the other conventional desalination technologies, owing primarily to its low energy potential. However, the co-opted energy limitations in the draw solution (DS) regeneration stage in FO desalination processes and the lack of effective DS have hampered FO's implementation for potable water application on an industrial scale. In this work, we explored the Donnan principle to engineer a DS material having the duality of magnetic and solar-thermal separability functionalities from a sustainability viewpoint whilst exploiting a careful selection of material properties. A novel potassium functionalised iron oxide doped carbon nanofibres (K/Fe3O4/CNF) magnetic nanoparticles (MNPs) was successfully synthesised for FO desalination applications, utilising an eco-friendly strategy that improves hydrophilicity of DS without polymers. The novel DS obtained a significant osmotic pressure (86.1 bar), whilst it FO performance showed a small reverse salt flux (RSF) and specific reverse salt flux (SRSF) values of 0.10 gMH and 0.004 g/L, respectively. These values compare to at least <10 % of most RSF and SRSF values reported in the literature. The facile DS synthesis strategy adopted herein will potentially open a new route to preparing other DS nanomaterials with unique multi functionalities and enhanced hydrophilicity devoid of polymers. Whilst magnetic DS re-concentration may be achievable, additional research is required to appraise this methodology's overall energy implications and economic advantages over existing DS recovery methods.

The underlying mechanism insights into support polydopamine decoration toward ultrathin polyamide membranes for high-performance reverse osmosis

The development of ultrathin polyamide (PA) nanofilms with desirable water permeance and high selectivity has been recognized as crucial for energy-efficient desalination of salty water and wastewater reclamation. In this study, an ultrathin PA reverse osmosis membrane (∼25 nm) was fabricated via polydopamine (PDA) interlayer-mediated interfacial polymerization onto a polyethersulfone (PES) substrate. The ultrathin PDA interlayer was soldered in situ onto PES substrates by precisely controlling the ammonia-initiated self-assembly process. Furthermore, the PDA interlayer conferred a high-density uptake toward aqueous amine monomers and served as a quasi-molecular-scale regulator that mediated their diffusion into the organic phase to polymerize with the acyl chloride of 1, 3, 5-benzenetricarbonyl trichloride (TMC). The synergistic effects triggered self-sealing and inhibited membrane growth, promoting the formation of an ultrathin and defect-free PA nanofilm with a hierarchical nanostripe surface. The newly developed membranes exhibited a desirable water permeance of up to 1.44 L m−2 h−1·bar−1, almost triple that of the pristine PA membrane (0.44 L m−2 h−1·bar−1), and a simultaneously enhanced rejection ratio of 99.2% toward NaCl. This work sheds light on strategies to develop ultrathin PA-based membranes with high water permselectivity for environmental- and energy-relevant applications.

Development of Solar Desalination Units Using Solar Concentrators or/and Internal Reflectors

Solar distillation is one of the oldest and simplest technologies for desalination of salty water using renewable energy, namely solar energy, and the main problem of solar distillers is the low freshwater yield in contrast to the amount of energy input from the sun. To overcome the problem, this study develops three solar desalination units by using solar concentrators or/and internal reflectors, and compares the performance of three developed systems with the one of a conventional solar distiller under the climatic conditions of the Rabat region of Morocco. The three systems are: the solar distiller with a solar concentrator, the solar distiller with internal reflectors, and the solar distiller with a solar concentrator and internal reflectors. The energy balance equations of the systems are numerically resolved to utilize MATLAB software. The findings indicate that the utilization of the internal reflectors, the solar concentrator, and the solar concentrator and internal reflectors give better performance compared to the conventional solar distiller.

INNOVATIVE POTENTIAL OF FRESHWATER RESOURCES OF UKRAINE: STATE, REGIONAL FEATURES AND DEVELOPMENT PROSPECTS

Introduction. Restoration and cleaning of freshwater resources remains a fairly relevant issue both at the national level and in the world. The strategic goals of sustainable development remain providing clean water to all the population. There is water pollution, which is quite acutely puts in prior to humanity. The study of the current state of the innovative potential of freshwater resources and prospects of technological development in world trends are quite relevant and important. The purpose of the article is the process of studying the current state, regional features and prospects for the development of innovative potential of freshwater resources of Ukraine. The results. Analyzed, the current state of expenditures for innovation in the protection and rational use of freshwater resources. It is determined that the structure of protection costs and rational use of freshwater resources is divided into the costs of protection and rehabilitation of soil, underground and surface water, cleaning of reciprocal water and research work of environmental orientation. Analysis show that the largest share in 2020 in the structure of expenses occupy current expenses – 75,02%, with capital investments – 24,97%. The structure of capital investments amounted to 61,83% in defense and rehabilitation of soil, underground and surface water, 12,80% for the purification of reciprocal waters and 7.67% on research and research activities of environmental orientation. It is determined that the largest amount of capital investment was aimed at protecting and rehabilitation of soil, underground and surface waters – 2554224,5 thousand UAH and to clean reciprocity – 1578201,4 thousand UAH. Conclusions. It is substantiated that the costs are aimed at scientific research of environmental protection unreasonably insignificant in volumes. The analysis showed that during the last three years they did not exceed 0.3% of the total environmental expenses in Ukraine, this negatively affects the development and implementation of advanced innovation technologies in the sphere of resource conservation. It is determined that modern trends of technological development in the water and its purification can be: reverse osmosis (RO) of sea, brackish and river water – for the desalination of salty water; Nanofiltration, reverse osmosis, membrane bioreactors, microfiltration and disinfection – for water and sewage treatment. Keywords: freshwater resources, innovations, expenses, capital investments.

Composite reverse osmosis membrane with a selective separation layer of double-layer structure for enhanced desalination, anti-fouling and durability properties

High performance membrane is crucial for energy-efficient desalination of salty water and reclamation of wastewater. Commercially available reverse osmosis membranes manufactured by interfacial polymerization or phase inversion techniques usually face the obstacle of “trade-off” effect between water permeation ability and salt rejection capability. In this work, a novel approach of constructing selective separation layer of double-layer structure was proposed to break through the difficulty of fabrication of reverse osmosis membrane with both high water permeation and salt rejection capabilities. Selective separation layer comprising loose polyamide (PA) sub bulk and dense hydroxypropyl methylcellulose (HPMC)-modified polyvinyl alcohol (PVA) top skin was constructed by the technique of interfacial polymerization followed with surface coating and cross-linking. The double-layer selective separation layer was found to possess an enhanced balance in water and salt permeations and endow the composite membrane with both high water flux and salt rejection. The desired membrane with an optimized selective layer of PA2/PVA + HPMC0.2 achieved 99.4% salt rejection and 37.9 kg/m2 h MPa water permeance to brackish water, which were higher than those of commercial membrane BW30. Furthermore, the desired membrane also exhibited better separation and antifouling performances in reclamation of secondary industry effluent when compared with the state-of-the-art antifouling membrane BW30FR.

Optimal integration of small scale hybrid solar wind RO-MSF desalination system

Solar and wind are two main resources of renewable energies that can supply the energy requirement in the most of world's regions. Iran has desirable condition in terms of solar and wind energy and also is faced with shortage of fresh water resources. Hybrid solar wind RO-MSF desalination system that works with two clean and renewable energy resources of solar and wind, could be a sustainable energy resource for water desalination. Hence, in this paper for evaluating the performance of salty water desalination by hybrid RO-MSF desalination plants, a hybrid system is designed and optimized. Different models of solar wind RO-MSF was considered and analyzed technically and economically. Finally a model which can be used in small scale desalination sites was presented. Design configurations of the hybrid solar-wind RO-MSF desalination systems was done, optimization and sensitivity analysis were done and simulation code of solar wind RO-MSF system for sizing the system were written. Hybridization of RO and MSF systems with two renewable energy resources of wind and solar were led to an increase in reliability and flexibility of system and quality of produced drinking water. The desalinated water price was 1.35–1.84$/m3 depends on different solar wind RO-MSF models. In small scale the solar wind integrated RO-MSF1 was shown the least desalinated water price and most produced desalted water but in large scale the solar wind integrated RO-MSF HR3 was shown the best results. The tests results of manufactured solar wind integrated RO-MSF1 justified the model results.

Zwitterionic Polymer Modified Porous Carbon for High-Performance and Antifouling Capacitive Desalination.

Capacitive deionization (CDI) is an emerging technology for effective brackish water desalination to address fresh water scarcity. It is of great interest due to its high energy efficiency, environmental friendliness, and low-cost operation compared with traditional desalination technologies. However, electrode fouling, caused by dissolved organic matter and resulting in reduction of electrode electrosorption capacity and device lifespan, is an impediment to practical application of CDI. Herein, we report a novel salty water desalination electrode with excellent antifouling properties. The antifouling electrode is prepared by coating zwitterionic polymer brushes, i.e., poly(sulfobetaine methacrylate) (SBMA), on porous carbon (PC) via surface-initiated atom transfer radical polymerization. The successful coating of zwitterionic polymer on PC surface is confirmed by transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, and other characterizations. Coating with polySBMA did not affect the electrosorption capacity of PC electrodes and imparted antifouling properties (versus fouling by model foulant bovine serum albumin) during long-term salt removal tests (100 desalination/regeneration cycles). This is an important step toward practical application of capacitive deionization technology for brackish water desalination.

Synthesis and functionalization of graphene oxide (GO) for salty water desalination as adsorbent

In this article, graphene oxide (GO) was synthesized by the Hummers and the modified Hummers methods and functionalized with chitosan and used as adsorbents for salty water desalination application. The results demonstrated that GO prepared via the modified Hummers method has higher adsorption capacity of sodium ions than GO prepared via the Hummers method. Also, functionalization with chitosan improved sodium ions adsorption capacity of the GO prepared via the modified Hummers method from 770.2 to 830.3mg/g at an initial sodium ion concentration of 40,000mg/l. Langmuir and Freundlich isotherms and two kinetic models were applied to fit the experimental data. Regeneration performance of the prepared adsorbents was also studied. The results demonstrated that both isotherms and the pseudo-second-order kinetic model match the obtained experimental data very well. It was found out that the chitosan functionalized GO with higher adsorption capacity and better regeneration performance can be considered as an effective adsorbent for salty water desalination.

The Influence of Synthesis Parameters on Vertically Aligned CNT Sheets: Empirical Modeling and Process Optimization Using Response Surface Methodology.

In the present work, vertically aligned carbon nanotube (VA-CNT) sheets were synthesized via pyrolysis of polybenzimidazole (PBI)-Kapton inside the pores of anodized aluminum oxide (AAO). The synthesized VA-CNT sheets were then evaluated for the desalination of salty water. The results indicated that the VA-CNT sheets were effective for application as an adsorbent for desalination of salty water due to their high adsorption capacity, with no loss of CNTs in the treated water. This study explored the impact of operating time and temperature on liquid adsorption performance through optimization and modeling methods. An empirical model was developed through the evolution of a full factorial design process which considered two significant factors for enhanced antibacterial efficiency and adsorption uptake. The highest antibacterial efficiency was achieved with carbon precursors synthesized at a higher temperature. However, optimal values were obtained for both antibacterial efficiency and adsorption uptake (NaCl) with a combination of CNT membranes. The best conditions for such a membrane were 800°C and 18min. Under these conditions, antibacterial efficiency, contact angle, carbon content, adsorption uptake (NaCl=10,000) and adsorption uptake (NaCl=20,000) were 90.079, 1.69256, 75.213, 76.2352 and 0.997, respectively.

Curious Characteristics of Polar and Nonpolar Molecules Confined within Carbon Nanotubes (CNT) of Varied Diameter: Insights from Molecular Dynamics Simulation

Carbon nanotube (CNT) has emerged as a potential candidate for desalination of salty water as well as for purification of various kinds of gaseous and liquid mixtures which is controlled by the interaction of the fluid molecules within the nanocavity of CNT. It is, therefore, worthwhile to investigate the behavior of both the polar and nonpolar fluid molecules within the nanoconfinement of CNT at the molecular level. In the present study, molecular dynamics simulations have been performed to investigate the structure and dynamics of polar and nonpolar molecules within CNTs. Results show the enhancement of confined density with increase in nanotube diameter. Single file flow of water, methanol, and methane inside CNT(6,6) was diminished with increase in nanotube diameter and converted to layered flow for larger CNTs. Surprisingly, results showed controversial effects of nanotube dimension for dynamics of polar and nonpolar fluids, which has been explained in terms of interaction forces acting between fluid...

Desalination of salty water using vacuum spray dryer driven by solar energy

This paper addresses evaporation under vacuum condition with the aid from solar energy and the recovered waste heat from the vacuum pump. It is a preliminary attempt to design an innovative solar-based evaporation system under vacuum. The design details, equipment required, theoretical background and work methodology are covered in this article. Theoretically, based on the energy provided by the sun during the day, the production rate of pure water can be around 15kg/m2/day. Assumptions were made for the worst case scenario where only 30% of the latent heat of evaporation is recycled and the ability of the dark droplet to absorb sun energy is around 50%. Both the waste heat from the pump and the heat collected from the photovoltaic (PV) panels are proposed to raise the temperature of the inlet water to the system to its boiling point at the selected reduced pressure.

Preparation, characterization, and application of vertically aligned CNT sheets through template assisted pyrolysis of PBI‐Kapton

This article investigates the synthesis of vertically aligned carbon nanotube (CNT) sheets through the pyrolysis of polybenzimidazole (PBI)‐Kapton inside the pores of anodized aluminium oxide (AAO). The nanocomposites of CNT/Alumina obtained were characterized by several techniques. It was found that the resulting carbon structures presented higher crystallinity compared with graphite. All of the CNT sheets had high antibacterial activity that was proportional to degree of CNT crystallinity. Moreover, the desalination of salty water using CNT sheets was performed. The results demonstrated that the vertically aligned CNT sheets could be used as an effective adsorbent for salty water desalination due to their very high adsorption capacity without CNT leakage into water.