Saline Water Desalination Research Articles

An effective solar assisted semi-cylindrical saline water desalination system with direct atomizer and energy storage materials for domestic use: an experimental investigation.

Solar still is the easiest method to purifying the saline water for domestic usage, but this method needs much improvement for better performance since it has lower productivity. In this paper, an experimental investigation is completed to analyse the semi cylindrical solar productivity still. The semi-cylindrical still is incorporated with direct atomizer and scrap used as an energy storage medium. Experiments are carried out during March 2020 in Kovilpatti, the southern part of India, with a depth of 2 and 4 cm saline water. Comparative performance analysis is made for conventional semi-cylindrical still, semi-cylindrical still with an atomizer, and semi-cylindrical still with atomizer and storage materials. The experimental study shows that the productivity of still increases while decreasing the water depth. Compared with 2-cm and 4-cm depth, solar still with 2-cm depth gives promising distillate productivity. The solar productivity still having 4-cm depth of water without atomizer gives only 2670 ml; on the other side, 2-cm water depth without atomizer gives 3100-ml productivity. The maximum productivity of solar still is found on a semi-cylindrical solar still combined with atomizer and energy storage medium having 2-cm water depth. Results revealed a higher freshwater production rate of 3610 ml found while incorporating atomizer and energy storage with the solar still. The system efficiency improved up to 35.20% compared to conventional semi-cylindrical still with 4 cm of saline water depth.

Integration of Geophysical and Geospatial Techniques to Evaluate Geothermal Energy at Siwa Oasis, Western Desert, Egypt

Environmental degradation is reducing crop productivity in many regions of Egypt. Moreover, unsustainable surface water drainage contributes to salinized soil conditions, which negatively impact crops. Egypt is seeking solutions to mitigate the problem of surface water drawdown and its consequences by exploring renewable and sustainable sources of energy. Geothermal energy and the desalination of saline water represent the only solutions to overcoming the fresh water shortage in agricultural industry and to providing sustainable fresh water and electricity to villages and the Bedouin livelihood. In Egypt, the Siwa Oasis contains a cluster of thermal springs, making the area an ideal location for geothermal exploration. Some of these thermal springs are characterized by high surface temperatures reaching 20 °C to 40 °C, and the bottom-hole temperatures (BHT) range from 21 °C to 121.7 °C. Pre-Cambrian basement rocks are usually more than 440 m deep, ranging from 440 m to 4724.4 m deep. It is this feature that makes the Siwa Oasis locality sufficient for geothermal power production and industrial processes. This study utilized both the Horner and the Gulf of Mexico correction methods to determine the formation temperatures from BHT data acquired from 27 deep oil wells. The present study revealed a geothermal gradient ranging from 18 to 42 °C/km, a heat flux of 24.7–111.3 mW/m2, and a thermal conductivity of 1.3–2.65 W/m/k. The derived geothermal, geophysical, and geological layers were combined together with space data and the topographic layer to map relevant physiographic variables including land surface elevation, depth to basement, lineament density, land surface temperature, and geologic rock units. The ten produced variables were integrated in GIS to model the geothermal potential map (GTP) for the Siwa Oasis region. According to the model, both the eastern side and north and northeastern portions of the study region contain high and very high geothermal potential energy. Combining bottom-hole temperature measurements with satellite remote sensing and geospatial analysis can considerably enhance geothermal prospecting in Egypt and other East African areas that have geologically and tectonically similar settings. In addition to identifying sustainable resources needed for food production, this research has implications for renewable energy resources as well.

Environmental-friendly biomass-based Janus ink/urushiol modified cotton fabric for efficient solar-driven interfacial evaporation

Much attention has been paid to the interfacial solar-thermal conversion method for water resource purification. According to the hydrophilicity of ink carbon particles and the amphiphilicity of urushiol molecules (the main compound of Chinese lacquer), a novel environmentally friendly biomass Janus ink/urushiol modified cotton fabric was successfully prepared and exhibited one hydrophilic side and one hydrophobic side through simple immersion and spraying treatments. The Janus fabric displayed excellent water transport behavior, mechanical stability, thermal conductivity, and photothermal conversion performance. Under one stimulated solar radiation, the temperature of the Janus fabric increased to 85 °C in 2 min. Additionally, a photothermal vapor device prepared using a polyethylene ring and the Janus fabric demonstrated a high conversion efficiency of 94.3% with an impressive evaporation rate of 1.64 kg m−2h−1, which was 3.35 times the rate of water evaporation in the absence of the modified fabric. The Janus fabric showed satisfactory resistance to ultraviolet radiation and pH values. After 8 cycles (every 10 h) of exposure to outdoor sunlight, the modified fabric showed a slightly decreased evaporation rate, which could be restored to the previous level by re-spraying ink on the modified fabric. In the concentrated salt solutions, the solar-driven evaporator displayed excellent salt rejection capacity. During the desalination of high-concentration saline water, the Janus fabric showed acceptable diurnal correspondence. After desalination, the water quality reached the required standards for drinking water. In particular, the B3+ content droppingto 0.33 mg L−1(below the thresholdof 0.5 mg L−1). The solar steam generator also showed remarkable purifying capabilities for wastewater containing heavy metals and organic dyes. The Janus ink/urushiol fabric, prepared in an easy way, has a wide range of applications in seawater desalination and sewage treatment, which can be applied for mitigation of freshwater crises and environmental remediation.

Integrated solar evaporator based on photothermal Cu-CuOx/NC with heat-insulated polyurethane foam enabling highly efficient salt-tolerant desalination and water purification

Renewable solar energy meeting photothermal materials provides a promising approach for freshwater production via interfacial steam generation. The design and manufacture of high-performance evaporators are still highly anticipated for practical applications. Herein, the robust and durable solar evaporator is proposed and fabricated by integration of photothermal Cu-CuOx/NC (CNC) and three-dimensional porous structure heat-insulated polyurethane (PU) foam with polyvinyl alcohol (PVA)/sodium alginate (SA) modifications. The designed PVA-SA-CNC/PU simultaneously possesses fast water transmission, broadband light trapping, satisfactory mechanical robustness and effective heat confinement. When applied as a solar evaporator, the PVA-SA-CNC/PU exhibits a high evaporation rate of 1.99 kg m−2 h−1 and operates stably within ten consecutive cycles under one-sun illumination, which can also handle salt tolerant desalination of seawater and saline water to sustainably produce freshwater. In addition, the functional versatility of the fabricated evaporator is explored to purify various wastewater. This study establishes a highly efficient integrated evaporator with multitasking water purification towards the solution of water shortage.

Mesopore-enhanced graphene electrodes with modified hydrophilicity for ultrahigh capacitive deionization

Capacitive deionization (CDI) technology represents a potent approach towards energy-efficient and sustainable access to potable water, with minimal environmental impact. However, the ion removal capacity of CDI systems remains inadequate for desalination of saline water. Herein, mesopore-enhanced graphene foam with modified hydrophilicity via O2-plasma treatment (MGFP) is proposed for ultrahigh CDI. This developed MGFP encompasses abundant mesopores, outstanding electrical conductivity and good hydrophilicity, enabling fast ions migration, efficient solution/pores contact and high adsorption capacity. As such, MGEP delivers a high specific capacitance of 156.64 F g−1 at 1 mV s−1, and a maximum salt adsorption capacity (SAC) up to 40.76 mg g−1 (1000 mg L−1, 1.2 V), much higher than most of the CDI systems leveraging the carbon-based materials. What's more, MGFP can be employed in the treatment of wastewaters containing various heavy metals, with the SAC of 89.96, 83.38, and 91.80 mg g−1, as for CuCl2, CoCl2, and NiCl2 (1000 mg L−1, 1.6 V), respectively. This well-developed MGFP undoubtedly presents a promising material platform within the CDI system, effectively tackling the pressing concern of water scarcity.

Novel hexa-fluorinated intrinsically porous polyimide membranes for the desalination of high saline water by air-gap membrane distillation

Hexa-fluorinated porous membranes were prepared from 4,4′-(hexafluoroisopropylidene) diphtalic anhydride (6FDA)- 2,3,5,6- tetramethyl-p-phenylenediamine (TMPD) (6FDA-TMPD), which prepared by a polycondensation reaction between the dianhydride 6FDA and the diamine TMPD at 200 °C, by nonsolvent induced phase inversion process for the desalination of highly saline water (70,000 mg L−1) via membrane distillation (MD) technology. Here, for the first time, we demonstrate the significance of the intrinsic porosity of 6FDA-TMPD polyimide membranes, that not only result in an excellent performance in MD without the addition of porogen chemicals but also outperform other membranes including commercially available membranes. The membrane characteristics were optimized by varying the coagulation bath, dope solution concentration, and thickness. Notably, the developed membranes possess high porosity which can be attributed to the high BET surface area (550 m2 g−1) of 6FDA-TMPD. Membranes developed from an ethanol-based coagulation bath resulted in spongy-like morphology and demonstrated excellent desalination performance with a high flux (∼ 18.20 kg m−2 h−1) and stable salt rejection (> 99.96 %). The reported fabrication approach can be used to delineate the key design parameters for the fabrication of highly efficient intrinsically porous polyimide-based membranes which may pave the way for the practical application of MD for the desalination of highly saline water.Graphical abstract.

Book Review Advanced Materials for Wastewater Treatment and Desalination: Fundamentals to Applications

Book Review Advanced Materials for Wastewater Treatment and Desalination: Fundamentals to Applications

UiO-66-NH2 MOF/organosilica mixed-matrix membrane for water desalination

A new amine-functionalized UiO-66/organosilica mixed-matrix membrane was fabricated and explored for pervaporation (PV) water desalination. The incorporation of amine-functionalized UiO-66 (UiO-66-NH2) into the BTESE-derived organosilica networks endowed the membrane with enhanced hydrophilicity and dense network structure, leading to an improvement in water flux and NaCl rejection. The UiO-66-NH2/BTESE mixed-matrix membrane was proved to be highly effective for desalination of saline water in concentrations from 1 to 13 wt% of dissolved NaCl. Moreover, the membrane exhibited superior structural stability under a continuous PV desalination operation up to 100 h, delivering water permeance of >3.1 × 10−6 mol m−2 s−1 Pa−1 combined with NaCl rejection of >99.9%. The high water permeance was mainly ascribed to the specific pore structure and the preferential interactions between pore channels and water molecules, and the excellent salt rejection was primarily based on the sieving effect. The proposed UiO-66-NH2/BTESE mixed-matrix membranes show great prospects as an alternative for concentrated brine desalination.

Fabrication of hydrophobic bi-layer fiber-aligned PVDF/PVDF-PSF membranes using green solvent for membrane distillation

Green high-flux poly(vinylidene fluoride) (PVDF) membranes with hydrophobic properties are beneficial for membrane distillation (MD). In this study, PVDF and polysulfone (PSF) polymer powders were dissolved in PolarClean to form immiscible polymer solutions. After casting the PVDF-PSF membranes and inducing a phase inversion procedure in water, a high-porosity fiber aligned PVDF-PSF membrane was obtained. The PVDF-PSF membranes also exhibited high tensile strength and satisfactory vapor flux. However, the surface hydrophobic properties were relatively poor and the surface pore sizes were large. Therefore, a PVDF/PolarClean/propylene glycol (PG) solution was used to construct rough PVDF nanoparticles (NPs) on the PVDF-PSF membrane surface. The PVDF NPs decreased the membrane pore size and increased the surface roughness. The resulting membrane exhibited a highly hydrophobic membrane surface and a higher liquid entry pressure than the pristine PVDF-PSF membrane. In addition, the whole process did not contain any toxic solvents and the stability of the PVDF/PVDF-PSF membrane was satisfactory after ultrasonic treatment. In the desalination of saline water containing 3.5 wt% and 12 wt% NaCl solutions, the resulting membrane showed a high water flux, with a rejection rate higher than 99.99 % after 120 h. This study provides important guidance for polymer membranes for MD.

Step-by-Step Fabrication of PVDF-TiO2 Hollow Fiber Membrane and Its Application Desalination of Wetland Saline Water via Pervaporation

Wetland water is opted as the source of domestic water supply when the availability of clean fresh water is scarce. Wetland water requires proper treatment due to the high concentration of organic matter and high salinity, particularly in the dry season. This research aims to synthesize, characterize, and investigate the performance of polyvinylidene fluoride (PVDF)-TiO2 hollow fiber membrane for wetland saline water desalination via pervaporation. The PVDF-TiO2 hollow fiber membranes were fabricated through the dry wet spinning method under various air gaps (10, 15, and 20 cm). Then, the resulting membranes were tested in a pervaporation process at temperatures of 25, 40, and 60°C. Results show that the incorporation of TiO2 into the PVDF matrix imparted hydrophilicity properties into the resultant membranes. The presence of TiO2 was confirmed by the TiO2 stretching vibration at 1640 cm-1 (FTIR) and the TiO2 phase at diffraction peaks at 25.5 and 37°. The membranes exhibited the highest water flux (7.48 kg/m2.h) and salt rejection ( 99.5%) at 40°C. Overall, the developed PVDF-TiO2 hollow fiber membranes showed encouraging results and demonstrated their effectiveness for the desalination of wetland saline water.

Comprehensive Electrochemical Impedance Spectroscopy Study of Flow-Electrode Capacitive Deionization Cells.

Flow-electrode capacitive deionization (FCDI) offers infinite ion adsorption for continuous desalination of high-concentration saline water by supplying a flow-electrode to the cell. Although extensive efforts have been made to maximize the desalination rate and efficiency of FCDI cells, the electrochemical properties of these cells are not fully understood. This study investigated the factors affecting the electrochemical properties of FCDI cells containing activated carbon (AC; 1-20 wt %) and various flow rates (6-24 mL/min) for the flow-electrode using electrochemical impedance spectroscopy before and after desalination. Examination of the impedance spectra using the distribution of relaxation time and equivalent circuit fitting analysis revealed three distinctive resistances such as internal, charge transfer, and ion adsorption resistances. The overall impedance decreased significantly after the desalination experiment due to increased ion concentrations in the flow-electrode. The three resistances decreased with increasing concentrations of AC in the flow-electrode due to the extension of electrically connected AC particles that participated in the electrochemical desalination reaction. The ion adsorption resistance decreased significantly due to the flow rate dependence of the impedance spectra. In contrast, the internal and charge transfer resistances were invariant.

Development of Hydrophobic Coal-Fly-Ash-Based Ceramic Membrane for Vacuum Membrane Distillation.

Membrane distillation is an emerging separation technology with a high separation factor in water desalination. Ceramic membranes are increasingly used in membrane distillation because of high thermal and chemical stabilities. Coal fly ash is a promising ceramic membrane material with low thermal conductivity. In this study, three hydrophobic coal-fly-ash-based ceramic membranes were prepared for saline water desalination. The performances of different membranes in membrane distillation were compared. The effects of membrane pore size on permeate flux and salt rejection were researched. The coal-fly-ash-based membrane showed both a higher permeate flux and a higher salt rejection than the alumina membrane. As a result, using coal fly ash as the material for membrane fabrication can effectively increase the performance when applied to MD. Increasing the membrane pore size improved the permeate flux, but reduced the salt rejection. When the mean pore size increased from 0.15 μm to 1.57 μm, the water flux rose from 5.15 L·m-2·h-1 to 19.72 L·m-2·h-1, but the initial salt rejection was reduced from 99.95% to 99.87%. The hydrophobic coal-fly-ash-based membrane with a mean pore size of 0.18 μm exhibited a water flux of 9.54 L·m-2·h-1 and a salt rejection of higher than 98.36% in membrane distillation.

Desalination of produced water via CO2 + C3H8 hydrate formation

Recent years have seen increased interest in gas hydrate production as a viable saline water desalination technique. Produced water is the liquid that is extracted from oil and gas fields and is typically salty. The management of produced water is a significant aspect of the petroleum industry because of its potential to serve as a source of fresh water for oil-producing nations with limited access to clean water, growing environmental concerns, and the strict laws governing the discharge of produced water into the environment. In this study, the effect of mixed gas (CO2 + C3H8 (70:30)) hydrate formation in treating produced water and kinetic studies on induction time, moles of gas consumed, rate, water recovery, and water-to-hydrate conversion were experimentally investigated. An aqueous solution with the same ion concentrations was prepared and experiments were performed at 275.15 K/277.15 K, 2.0 MPa, and 450 rpm. The findings unveiled that with an increase in salinity, the water recovery decreased showing the hindering effect of salts on mixed hydrate formation by reducing the solubility of mixed gas due to the strong electrostatic force of attraction between salt ions and water. A maximum of 67.3% water recovery was observed in 2.8 wt% produced water solution at 275.15 K, 2.0 MPa, and 450 rpm. Furthermore, the induction time increased by 52.64% in treating 2.8 wt% and a decrease in moles of gas consumed, water recovery, and water-to-hydrate conversion by 6.99%, 2.08%, and 9.69% compared to the deionized water system at 275.15 K. A removal efficiency of 47%-63% is achieved by using CO2 + C3H8 and the sequence of metal cation removal is in the order K+ > Na+ > Mg2+ > Ca2+ and anions SO42− > Cl− at 275.15 K. The results also showed that with a rise in the experimental temperature to 277.15 K the removal efficiency increased though the amount of hydrate formed is less. This study illustrates that the formation of mixed gas (CO2 + C3H8) hydrate can be used for treating produced water based on the water recovery, removal efficiency, electrical conductivity, and total dissolved solids results with lower energy consumption.

In-situ desalination-coupled electrolysis with concurrent one-step-synthesis of value-added chemicals

An efficient multi-functional electrolyzer with a Ni- and Fe-layered double hydroxide (NiFe-LDH) anode and a binary NiMo cathode is designed for overall water splitting coupled with the desalination of saline water and production of value-added chemicals. The NiFe-LDH and NiMo pairs separated by a bipolar membrane (BPM) show overpotentials as low as those of noble metal catalysts for oxygen and hydrogen evolution reactions in 1 M KOH and 1 M H2SO4 solutions, respectively. Arraying anion and cation-exchange membranes (AEMs and CEMs, respectively) with BPMs (NiFe-LDH/BPM/[AEM/CEM]n/BPM/NiMo; n = 1 or 5) further enables the desalination of brackish water and seawater at specific energy consumption of 1.8 kWh m−3, with concurrent production of HCl and NaOH. The Faradaic efficiencies of the device for O2 and H2 production are >95 % at J = 100 mA cm−2 over 20 h, while the initial pH values of the anolyte and catholyte remain unchanged. Detailed surface characterization of the electrocatalysts is performed, and various electrolyzer configurations are compared in terms of desalination efficiency.

Synergetic pseudocapacitive sodium capture for efficient saline water desalination by iron oxide Hydroxide-Decorated palladium nanoparticle anchored 3D flowerlike molybdenum sulfide

Capacitive deionization (CDI)-based saline water desalination presents an admirable alternative for sustainable freshwater production. However, the lack of robust electrode materials impedes its wide application. Herein, a three-dimension (3D) heterostructured iron oxide-hydroxide-incorporated palladium nanoparticle-anchored molybdenum disulphide (FeOOH/Pd/MoS2) hybrid constructed by the two-step spontaneous interfacial redox reactions is reported as efficient Faradaic CDI electrode materials for desalination application. The FeOOH/Pd/MoS2 hybrid electrode delivers a superior desalination capacity of 41.1 mg g−1 in a 500 mg L-1 NaCl solution, along with impressive cycling stability and a high capacitive contribution of 80 % at a rate of 1 mV s−1. The synergetic pseudocapacitive removal process is thoroughly clarified by ex-situ XPS characterizations. Experimental analysis and density functional theory calculations reveal that the bi-component participation of FeOOH and Pd can efficiently tailor the electronic structure of MoS2, leading to the reinforcing electronic conductivity toward the promoted Na+ capture feature. Moreover, the hybrid electrode manifests outstanding removal efficiencies up to 91.25 % for diverse heavy metal ions (i.e., Pb2+, Cd2+, Cu2+, Ni2+, and Cr3+), demonstrating its great prospects for low-concentration wastewater purification. This work supplies an ingenious avenue for the rational design of heterostructured MoS2 Faradaic electrodes for advanced CDI desalination.

Porous functional materials with excellent solar-thermal and electro-thermal properties for desalination of saline water

Desalination of saline water is a key technology to produce safe drinking water. Here, we report a novel type of reduced graphene oxide (GO) nanosheets modified porous functional materials (rGS) with both excellent solar-thermal and electro-thermal properties for efficient, portable, and continuous desalination of saline water. The rGS porous materials are prepared by modifying porous melamine sponges with GO nanosheets, and then reducing GO nanosheets into reduced GO (rGO) nanosheets. With sufficient rGO nanosheets coated on rGS porous materials, water evaporation fluxes of rGS-5 porous materials are > 1100 g m-2h−1 in solar-thermal desalination under 1000 W m−2 and > 3600 g m-2h−1 in electro-thermal desalination under direct voltage of 20 V due to the excellent solar-thermal property and Joule effect of rGS. The salt rejection values are always higher than 99.95% towards different saline waters including hypersaline water, and the salinities of distilled waters are always far lower than the WHO standard for safe drinking water. The strategy and results in this work provide valuable guidance for designing portable desalination systems to produce safe drinking water by simply using solar energy and/or direct-current power supply in certain applications with special needs such as remote regions and disaster situations.

Fabrication of Activated Carbon Decorated with ZnO Nanorod-Based Electrodes for Desalination of Brackish Water Using Capacitive Deionization Technology.

Capacitive deionization (CDI) is a promising and cost-effective technology that is currently being widely explored for removing dissolved ions from saline water. This research developed materials based on activated carbon (AC) materials modified with zinc oxide (ZnO) nanorods and used them as high-performance CDI electrodes for water desalination. The as-prepared electrodes were characterized by cyclic voltammetry, and their physical properties were studied through SEM and XRD. ZnO-coated AC electrodes revealed a better specific absorption capacity (SAC) and an average salt adsorption rate (ASAR) compared to pristine AC, specifically with values of 123.66 mg/g and 5.06 mg/g/min, respectively. The desalination process was conducted using a 0.4 M sodium chloride (NaCl) solution with flow rates from 45 mL/min to 105 mL/min under an applied potential of 1.2 V. Furthermore, the energy efficiency of the desalination process, the specific energy consumption (SEC), and the maximum and minimum of the effluent solution concentration were quantified using thermodynamic energy efficiency (TEE). Finally, this work suggested that AC/ZnO material has the potential to be utilized as a CDI electrode for the desalination of saline water.

Achieving Energy-Saving, Continuous Redox Flow Desalination with Iron Chelate Redoxmers

Desalination of saline water is becoming an increasingly critical strategy to overcome the global challenge of drinkable water shortage, but current desalination methods are often plagued with major drawbacks of high energy consumption, high capital cost, or low desalination capacity. To address these drawbacks, we have developed a unique continuous-mode redox flow desalination approach capitalizing on the characteristics of redox flow batteries. The operation is based on shuttled redox cycles of very dilute Fe 2+ /Fe 3+ chelate redoxmers with ultralow cell overpotentials. The air instability of Fe 2+ chelate is naturally compensated for by its in situ electrochemical generation, making the desalination system capable of operations with electrolytes at any specified state of charge. Under unoptimized conditions, fast desalination rates up to 404.4 mmol·m −2 ·h −1 and specific energy consumptions as low as 7.9 Wh·mol NaCl −1 have been successfully achieved. Interestingly, this desalination method has offered an opportunity of sustainable, distributed drinkable water supplies through direct integration with renewable energy sources such as solar power. Therefore, our redox flow desalination design has demonstrated competitive desalination performance, promising to provide an energy-saving, high-capacity, robust, cost-effective desalination solution.

Synthesis and application of NiO-ZrO2@g-C3N4 nanocomposite for high-performance hybrid capacitive deionisation

The desalination of saline water from the ocean and estuaries provides about 65 % of the global freshwater supply. Desalination technology development is dependent on a reliable and cost-effective electrode material. This research is focused on the synthesis and application of NiO-ZrO2@g-C3N4 nanocomposite for the desalination of saline water by the hybrid capacitive method. NiO-ZrO2@g-C3N4 was synthesized by a solid-state reaction. It was then used to modify the activated carbon electrode. This was applied as an electrode in a CDI cell for the desalination of saline water. The highest ion adsorption capacity recorded is 24.45 mg/g at 1.2 V applied voltage and an electrolyte concentration of 800 mg/L, while the optimum salt recovery efficiency was recorded at 42.7 % with the 300mb/L solution. The specific capacitance of the NiO-ZrO2@g-C3N4 composite is 550F/g at a scan rate of 10 mV/s in a 1.0 M KCl solution, and that of g-C3N4 is 300F/g at a scan rate of 10 mV/s, in a 1.0 M KCl solution. The NiO-ZrO2@g-C3N4 composite also displayed excellent electrochemical stability after nine cycles of adsorption/desorption measurements. The result implies that NiO-ZrO2@g-C3N4 is an ideal electrode material for application in desalination by the hybrid capacitive deionisation method.

Effect of cyclopentane on hydrate-based desalination efficiency at different operating condition

BackgroundHydrate based Desalination (HBD) is a new method for desalination of saline water that has been proposed in recent decades. Despite the advantages of this method, researchers are still continuing research in various fields, including the use of suitable additives to increase the rate of hydrate formation and perform the process in more suitable operating conditions. MethodThe effect of temperature, pressure, sodium chloride and cyclopentane concentration on desalination efficiency has been investigated. The experiments were performed at 274.15 and 276.15 K and 6.5, 8 and 9 MPa in a stirrer reactor. Significant findingsThe experimental results indicated that increasing the pressure increases desalination efficiency and increasing temperature has negative effect on desalination efficiency. With three stages of desalination, the highest removal efficiency was 83.13% for a 1 wt% NaCl solution in the presence of cyclopentane while the lowest desalination efficiency was 56% for a 3.5 wt% NaCl solution in the absence of cyclopentane. All experiments indicated the beneficial effect of cyclopentane on desalination efficiency, especially in higher concentrations, while higher NaCl concentration had more negative effect.