Seawater Desalination Research Articles

Experimental Study on Corrosion of Stainless Steel in Low Temperature Multi effect Seawater Desalination

Starting from the corrosion mechanism, this paper analyzes the characteristics of various types of stainless steel and selects the best performance composite plate composite plate stainless steel. Analyze and select the most suitable corrosion detection method based on specific practical multi working conditions, discuss the interference factors that affect metal corrosion during experimental simulation, and the advantages of newly developed sheet metal. The new development of composite board panels, with the substrate and composite materials applying their respective capabilities for MED, will bring breakthrough progress to the scientific research and engineering application of composite boards.

Robust and comprehensive predictive models for methane hydrate formation condition in the presence of brines using black-box and white-box intelligent techniques

Accurate estimation of gas hydrate formation condition is crucial for many reasons. In one hand, the gas hydrate formation is a promising approach for gas separation, cold energy storage, seawater desalination, etc. On the other hand, in some industries, this phenomenon may cause some challenges, such as pipelines blockage. The current study was undertaken to develop trustworthy predictive tools for methane hydrate formation temperature (MHFT) in the presence of brines. To achieve this target, 1051 experimental data pertinent to the methane hydrate equilibrium in 26 single and multiple brines over an extensive range of operating conditions were amassed from published studies. Four simple factors, including pressure, brine concentration, salt molecular weight and salt melting temperature were defined as the input variables, and the black-box intelligent techniques, including gaussian process regression (GPR), multilayer perceptron (MLP) and radial basis function (RBF) were employed to link MHFT to the mentioned factors. A plethora of graphical and statistically-based assessments were performed to determine the accuracy level of the proposed models. While all intelligent models had excellent performances, the one established by the GPR method showed the best agreements with experimental data, and gave the AARE and R2 values of 0.14% and 99.17%, respectively, in the testing step. The foregoing model was capable of predicting MHFT over a broad range of conditions with relative deviations mostly below 0.10%. Additionally, it showed an excellent performance in describing the physical variations of MHFT versus operating factors. The authority of the analyzed databank and the presented model was asserted via the William's plot investigation. Moreover, a sensitivity analysis was undertaken in order to determine the most fundamental factors in controlling MHFT. Eventually, a simple mathematical correlation was also derived based on the white-box intelligent approach of gene expression programming (GEP), which allowed the accurate estimation of MHFT with an AARE of 0.56%.

Polar bear hair inspired 3D photothermal evaporator for efficient solar steam desalination and electricity generation

While solar steam generation for desalination and electricity production is a burgeoning field, traditional systems often face challenges with rapid heat loss and salt buildup. To address these issues, we introduce a biomimetic approach, inspired by the unique thermal properties of polar bear hair. Our study presents a photothermal 3D hierarchical hollow Ppy@CuO nanorod array system, featuring a dual-structured design: a cone-shaped 3D topological structure for improved light absorption and a hollow structure for enhanced thermal insulation. This innovative approach effectively maximizes solar energy capture and reduces thermal losses, particularly in marine environments. Our system exhibits outstanding performance in solar steam generation, achieving high water evaporation rates and maintaining stability and efficiency in high-salinity settings. Under one solar illumination at a 75° tilt angle, the Ppy@CuO-3 NAs demonstrated an evaporation rate of 3.3 kg m−2 h−1 and an energy efficiency of 97.5 %. Additionally, the synergistic effect of released Cu2+ and Ppy resulted in a 99.9 % antibacterial rate against E. coli and S. aureus. This significant advancement in simultaneous, effective seawater desalination and efficient evaporation-driven electricity generation marks a crucial step toward future sustainable resource utilization.

Hollow carbon fiber wrapped by regular rGO wave-like folds for efficient solar driven interfacial water steam generation

Efficient seawater desalination is an effective way to solve the shortages of fresh water and energy but with limitations of the low fresh water production rate and high cost. Here, a hollow carbon fiber (HCF) wrapped by regular reduced graphene oxide (rGO) wave-like folds (rGO@HCF) is prepared on account of the differences in thermal shrinkage performance between graphene oxide (GO) and willow catkins fiber. Under one sun irradiation (1 kW m−2), the dry and wet surface temperature of the resulting evaporator reached up to 119.1 °C and 61.7 °C, respectively, and the water steam production rate reached 3.42 kg m−2 h−1. Also, for the outdoor experiment, the rGO@HCF exhibits good evaporator performance which reach up 27.8 kg m−2 day−1. Additionally, rGO@HCF also shows good seawater desalination performance and excellent durability for longtime work. DSC results indicate that the evaporation enthalpy of bulk water and adsorbed water decreased from 2503.92 to 1020.54 J g−1. The excellent evaporating performance is mainly attributed to the regular wave-like microstructure surface of the HCF, which can enhance the light absorption, reduced the vaporization enthalpy of the adsorption water. The findings not only introduce a novel approach for agricultural utilization, but also establish a crucial theoretical foundation for the design of regular wave-like microstructures.

Putting stored hydrogen to work without consuming it: A flexible system for energy conversion and water desalination

We report a flow battery that utilises hydrogen as a charge carrier in both the cathode and anode and makes use of the energy released in acid-base neutralisation to desalinate seawater and generate electricity, based on cheap and relatively safe electrolytes stored externally. We demonstrate desalination of simulated seawater from 0.6 to 0.009 ± 0.005 M NaCl and successful removal of Na+, K+, Mg2+, and Ca2+ from real seawater to potable levels. The battery can also be used for osmotic energy conversion through reverse electrodialysis (RED) if the acid and base are substituted by neutral diluted aqueous solution (e.g., freshwater), reaching power densities similar to state-of-the-art systems while using a much more environmentally friendly redox charge carrier, namely hydrogen, than those common in RED systems. The most important characteristics of the reported system are (i) its flexibility, which allows easy tuning to favour either energy generation or degree of desalination by changing the flow rates and volumes of each individual channel and/or the discharge current and (ii) the possibility of putting hydrogen to work without consuming it while stored for later shipment, thereby producing a profit that can contribute to decreasing the cost of green hydrogen.

Integrated water quality and performance assessment of seawater desalination plants along two coasts in Egypt

This study aims to assess feedwater, brine, and drinking water quality related to eight full-scale Egyptian seawater desalination plants. Collected water quality records from plants on the Mediterranean and Red Seas were monthly analyzed to identify different physical, chemical, and biological parameters during 2022. Statistical analysis and water quality indices (WQIs) approaches were applied to evaluate the various water quality states based on the available international and Egyptian guidelines. Analyzed seawater quality properties showed compliance with the most operating permissible limits except for high concentrations of turbidity, fats, oils, and greases, total bacteria in one plant, and iron, manganese, and silica in another plant. The monthly measured Weighted Arithmetic WQI classified 71 % and 100 % of desalination plants as having “Excellent” water rank according to the standard limits of the World Health Organization and the Egyptian Water Quality Standard, respectively. However, 65 % and 52 % of desalination plants were projected into the “good” water quality rank based on the Canadian Council of Ministers of the Environment WQI for the same guidelines. The results indicate that the feed intake type and the location of a desalination plant can optimize its performance efficiency, minimize contamination sources, and mitigate the potential environmental impacts of brine.

Research on the application of hydrophilic modified covalent organic framework membranes in seawater desalination

Given the global challenge of freshwater scarcity, the importance of seawater desalination technology has grown. This study examines the efficiency and role of hydrophilic-modified covalent organic framework (COF) membranes in seawater desalination through molecular simulations. Incorporating hydrophilic groups like -SO3H into N2COF membranes and optimizing their structure significantly improved water permeability and salt ion retention. Non-equilibrium molecular dynamics (NEMD) simulations showed that hydrophilic modifications enhance water permeability while preserving salt ion interception efficacy. Furthermore, adjusting the membrane's stacking method could further enhance its seawater desalination performance. The simulations confirm the high-efficiency desalination capability of hydrophilic-modified COF membranes and offer crucial theoretical guidance for designing and preparing high-performance desalination materials.

Construction of PPS based carbon fiber photothermal foam for crude oil absorption and seawater desalination

Efficient and clean solar energy conversion through photothermal materials has garnered significant attention, finding applications across energy, environmental protection, and healthcare sectors. This project focused on developing waste PPS-based carbon fiber (PCF) foam, emphasizing the high-value utilization of waste fibers in solar photothermal oil-absorption and photothermal evaporation applications. With exceptional light-absorption capabilities exceeding 97 %, the PCF@PDMS foam demonstrated superior photothermal conversion efficiency alongside impressive mechanical properties, facilitating effective absorption of highly viscous crude oil. Through PVA/CNF hydrophilic modification, internal water supply channels were integrated into the mPCF@PDMS foam, optimizing the evaporation surface area by retaining hydrophobic regions. This design not only enhanced thermal insulation but also significantly increased the evaporation rate to 2.00 kg·m−2·h−1 with an efficiency of 89.89 % under 1.0 sun irradiation. The presence of hydrophobic regions endowed the evaporator with self-floating ability, enhancing its practicality. During simulations of seawater desalination, the prepared evaporator exhibited remarkable salt crystallization resistance attributed to the strong water supply capacity and Marangoni effect induced during saltwater evaporation, facilitating salt diffusion and water evaporation. Overall, the foams developed in this project hold substantial application potential in the realm of photothermal technology.

Design, economic analysis, and environmental assessment of an innovative municipal solid waste-based multigeneration system integrating LNG cold utilization and seawater desalination

This paper presents a novel integrated solution for harnessing energy from biomass alongside liquefied natural gas cooling. The process is investigated and evaluated in various scenarios. This integrated system yields electricity, hydrogen, cold water, hot water, and fresh water. Thermodynamic analysis of the process is conducted under different scenarios. Moreover, the overall environmental damage effectiveness factor is calculated using exergo-environmental evaluation, revealing that heat exchanger E-103 exhibits the highest effectiveness factor of environmental damage, with an exergy efficiency of 37.3 %. Simulation results indicate an overall energy efficiency and overall exergy efficiency of 58.24 % and 31.97 %, respectively. Energy efficiencies of the process are found to be 32.15 %, 34.85 %, 36.71 %, and 58.24 % in single generation, combined heat and power, combined cooling, heating, and power, and multi-generation scenarios, respectively. The study evaluates the simultaneous effects of pressure and flow rate variations of liquefied natural gas fluid, input flow rate variations of municipal solid waste biomass, and cyclohexane working fluid pressure variations in the organic Rankine cycle on other variables. Finally, an economic evaluation of the new process outlines its annual cost and the levelized energy cost parameter under base design conditions, which amount to 9,383,042 $ and 0.092 $/kWh, respectively.

Dual-functional TFNC polyester membranes utilizing maltitol for dye/salt separation and desalination

To achieve a promising application prospect in nanofiltration (NF) membrane separation, a strategic design tailored to particular functions is crucial. Here, tailor-made thin film nanofibrous composite (TFNC) NF membranes for specific applications were fabricated via interfacial polymerization (IP) between maltitol and trimesoyl chloride (TMC) on PAN nanofibrous substrates. Owing to the moderate reactivity of maltitol, a range of sugar alcohol based polyester membranes with different morphologies and cross-linking degrees were obtained by varying the monomer concentration as well as the reaction time. In this case, the finely tuned loose Mal1-TMC0.2-2 membrane exhibited a prominent permeability (110.34 L m−2 h−1 bar−1) and an extraordinary selectivity for dye/salt mixed solution, with the rejection of Congo Red up to 99.11 % and NaCl retention of only 7.41 %, indicating its suitability for textile wastewater treatment. Further, the dense Mal2-TMC0.4-10 membrane showed an excellent Na2SO4 rejection of 97.40 % with a good permeability of 18.65 L m−2 h−1 bar−1, making it a candidate for seawater and brackish water desalination. In addition, both membranes demonstrated reliable chlorine and pressure resistance along with long-term stability. This study provided new insights and inspiration to the design and preparation of NF membranes for specialized applications.

A novel photovoltaic-thermal system based on spectral splitting of nanoparticle suspensions for simultaneous hydrogen production and seawater desalination

Traditional photovoltaic-thermal systems achieve full-spectrum sunlight utilization while producing only low-grade heat. This study reports an efficient PVT system designed for simultaneous hydrogen production and seawater desalination, in addition to high-efficiency electrical output. Specifically, Ag@SiO2/CoSO4-PG nanoparticle suspensions with varied loadings were prepared for photothermal and photoelectric conversion. Here, desalinated seawater can be directly utilized for electrolytic hydrogen production driven by photoelectric conversion module. System performance was evaluated across a broad range of conditions. The system exhibits peak photothermal and photoelectric conversion efficiencies of 45.57 % and 15.39 % respectively, when the nanoparticle loading is 80.00 mg/L. Using an 80.00 mg/L nanoparticle suspension filter, the system achieves a peak exergy efficiency of 60.71 % and an economic value enhancement of 75.9 % compared to a PV only system, when the worth factor w is 3. Under optimal operational conditions, the photo-hydrogen conversion efficiency reached 7.82 %. This study demonstrates an effective strategy for full spectrum solar energy conversion to hydrogen using sea water and provides a valuable guidance for future study.

Real options analysis of seawater desalination with solar photovoltaic energy systems: A least-squares stochastic perspective

Real Options Analysis (ROA) offers a modern theoretical framework to evaluate the impact of managerial flexibilities and uncertainties on the intrinsic investment value of renewable-powered desalination projects. This study analyzes Photovoltaic-powered Reverse Osmosis (PV-RO) desalination plants using a novel Least Square Monte-Carlo Real Options Analysis (LSMC-ROA) to assess the deferral of investment decisions. Three scenarios for powering RO are explored: reliance on the national grid with a subsidized electricity tariff for of $0.085/kWh, which applicable only to governmental sections in Saudi Arabia, full PV power with grid balancing ($0.083/kWh), and PV with a battery storage system (average electricity cost of $0.138/kWh). The presented modeling results reveal that considering the flexibility to defer and wait for new information, the total investment values would be $43.9 million, $59.6 million, and $30.5 million, respectively. Therefore, the optimal investment timing might be to defer investment to the second year. Additionally, the analysis reveals an unexpected outcome: a threshold salinity level for feedwater exists that can affect the economic viability of renewable-powered desalination. The proposed LSMC-ROA framework emerges as a robust tool for addressing uncertainties and assessing economic feasibility in the context of PV-RO desalination projects.

One-step facile fabrication of PDA@MCE for high efficiency seawater desalination

A variety of photothermal materials have been developed and applied in photothermal seawater desalination. As a conjugated polymer, Polydopamine (PDA) has excellent light absorption properties in the UV–visible region, and is widely used as a solar energy material. In this work, Polydopamine-mixed cellulose membrane (PDA@MCE) with Janus structure was prepared by a one-step method for water evaporation at the interface between PDA and mixed cellulose membrane (MCE). PDA@MCE has good thermal stability. When the reaction time is 6 h, the evaporation rate of the composite is twice that of MCE, and the photothermal conversion efficiency is about 62 %. PDA@MCE, as a kind of photothermal material with simple preparation method and friendly to the environment, has excellent application potential in solar driven interfacial water evaporation.

Exploring mass transfer mechanisms in reverse osmosis membranes: A comparative study of SDM and DSPM-DE models

Thin-film composite reverse osmosis (RO) membranes have dominated desalination technology for decades, with the solution diffusion model (SDM) serving as the gold standard for interpreting mass transfer phenomena since its inception. However, debates still persist regarding the effect of charge on separation performance, owing to the SDM's inability to explore membrane charge. In this study, polyethyleneimine (PEI) was utilized to modify the surface of a commercial seawater desalination membrane (SW30, Dupont Company), imparting regulatable charge properties based on the solution pH. The separation performance of the modified RO membrane was experimentally validated under varying NaCl feed salinities. Specifically, the Donnan-steric pore model with dielectric exclusion (DSPM-DE), known as a charge-responsive model, was employed and juxtaposed with SDM to authenticate the experimental findings. The results indicated that the dielectric effect primarily governed ion distribution (Na+ and Cl−) within the membrane, followed by the steric effect, and ultimately, the Donnan effect. Consequently, DSPM-DE aligned well with the observed salt rejection only when the membrane was strongly charged (that is, under acidic or alkaline conditions), but performed poorly in the neutral state. This observation, rarely revealed in previous research, stems from conventional desalination membranes being negatively charged in most natural water environments. Conversely, the SDM aligned well with the experimental data because it solely considered the solutes' solubility parameters and diffusion coefficient, independently of the surface charge of the desalination membranes. Given the extensive research on surface modification, our study demonstrates the limited influence of charge effects on the selective enhancement of RO membranes.

Full-length 16S rRNA gene sequencing reveals the operating mode and chlorination-aggravated SWRO biofouling at a nuclear power plant.

Reverse osmosis (RO) membrane fouling and biological contamination problems faced by seawater desalination systems are microbiologically related. We used full-length 16S rRNA gene sequencing to assess the bacterial community structure and chlorine-resistant bacteria (CRB) associated with biofilm growth in different treatment processes under the winter mode of a chlorinated seawater desalination system in China. At the outset of the winter mode, certain CRB, such as Acinetobacter, Pseudomonas, and Bacillus held sway over the bacterial community structure, playing a pivotal role in biofouling. At the mode's end, Deinococcus and Paracoccus predominated, with Pseudomonas and Roseovarius following suit, while certain CRB genera still maintained their dominance. RO and chlorination are pivotal factors in shaping the bacterial community structure and diversity, and increases in total heterotrophic bacterial counts and community diversity in safety filters may adversely affect the effectiveness of subsequent RO systems. Besides, the bacterial diversity and culturable biomass in the water produced by the RO system remain high, and some conditionally pathogenic CRBs pose a certain microbial risk as a source of drinking water. Targeted removal of these CRBs will be an important area of research for advancing control over membrane clogging and ensuring water quality safety in the future.

MnO2/Poly-L-lysine Co-decorated Carbon Fiber Cloth with Decreased Evaporation Enthalpy and Enhanced Photoabsorption/Antibacterial Performance for Solar-Enabled Anti-fouling Seawater Desalination

MnO2/Poly-L-lysine Co-decorated Carbon Fiber Cloth with Decreased Evaporation Enthalpy and Enhanced Photoabsorption/Antibacterial Performance for Solar-Enabled Anti-fouling Seawater Desalination

Construction of magnetic and photothermal wood membrane with asymmetric wettabilities and wind drift resistance for solar-driven seawater desalination and purification

To generate clean freshwater controllably and efficiently, Fe3O4/CNT nanomaterials and hydrophobic PVDF were introduced to delignified wood with man-made-cutting structure (D-Wood) in simple brushing method for constructing the magnetic and photothermal wood evaporator with asymmetric wettabilities and wind drift resistance. Such method could endow wood with various shapes design, outstanding magnetically sensitivity, remarkable photothermal conversion efficiency (129.08 %), high evaporation rate (1.92 kg·m−2·h−1), good dye degradability (97.23 %), and excellent wind resistance (6.6 m/s). The superhydrophilic and underwater superoleophobic bottom of Fe3O4/CNT/PVDF@D-Wood evaporator accelerated the bulk seawater transport during its evaporation procedure, but prevented the oil pollutants blocking the microchannels of evaporator during the long periods of flotation at sea. Meantime, its hydrophobic top could effectively reduce the downward diffusion of heat, and improve the salt tolerance. After 10 cycles of acid-base, ultrasound treatments and evaporating experiments, Fe3O4/CNT/PVDF@D-Wood evaporator still exhibited excellent evaporation rate and conversion efficiency, displaying remarkable repeatability and long-term durability. In weak magnetic field (3 V), its furthest response displacement and time were 5 cm and 41 s, respectively. After prolonged evaporation procedure, the magnetic responsivity of Fe3O4/CNT/PVDF@D-Wood evaporator could be in almost constant level, which offers a promising biomass product for seawater desalination and polluted-water purification.

Versatile GO/ANFs Aerogel for Highly Efficient Solar-Powered Water Purification in Wide Environments.

Solar-driven interfacial evaporation is a very promising choice for producing clean water. Despite the considerable investigation of pure NaCl brine purification, solar-driven complex water purification, such as real-world seawater desalination as well as domestic and industrial wastewater treatment, has rarely been investigated, mainly due to its compositions being much more complicated than NaCl brine. Herein, we developed a graphene oxide/aramid nanofiber (GO/ANFs) aerogel by a freeze-drying process. The GO/ANFs aerogel combined opened porous microchannels, superhydrophilicity, anti-oil-fouling capacity, enhanced broad-spectrum light absorption (more than 92%), and good solar/heat management. These integrated properties enabled the GO/ANFs aerogel to be an advanced solar interfacial evaporator for efficient freshwater production with the characteristics of localized heat conversion, quick water transport, and salt crystallization inhibition, and the rate of steam production rate was as high as 2.25 kg m-2 h-1 upon exposure to 1 solar irradiation. Importantly, the high-water-vapor generation rate was maintained even under complicated conditions, including real-world seawater, dye water, emulsions, and corrosive liquid environments. Considering its promising adaptability to a wide range of environments, this work hopes to inspire the development of brine desalination, wastewater purification, clean water production, and solar energy utilization.

The perils of building big: Desalination sustainability and brine regulation in the Arab Gulf countries

Seawater desalination has become an accessible option for augmenting freshwater supplies worldwide. In the countries of the Gulf Cooperation Council (GCC), it has been practiced for decades as the main source for domestic water use. Sustainable desalination requires addressing environmental impacts including damage to ecosystems from the high volumes of brine in the Gulf. This paper examines challenges related to environmental regulation of brine management in the Arab Gulf countries using the example of Qatar. It analyzes the brine challenge through infrastructure planning policies and stakeholders’ perceptions. The brine issue has been identified as a major environmental concern that requires action through discharge infrastructure, brine management technologies, and regulatory approaches based on quality thresholds and monitoring systems. Although there is a high level of agreement on the solvability of the brine issue, there are limitations with regard to the high reliance on desalination rendered through large-scale infrastructure. These limitations necessitate complementary water supply infrastructure for storage or the development of other sources through water reuse and storage. While water security considerations require prioritization of protection and supply continuity through desalination, incremental change through a stepwise dual approach of brine management and regulation is still possible.

Long-Term Inhibiting Salt Crystallization on Photothermal Sheet by a Superhydrophobic CNT Composite Coating

Heterogeneous crystallization resulted in low conversion efficiency and short service life has become one of the important challenges of desalination. Here, a fluoro-modified CNT@epoxy composite coating is developed to durably inhibit salt crystallization of photothermal sheet even in highly concentrated salt water. Typically, it can have stable evaporation efficiency of [Formula: see text] without salt crystallization after continuously being operated for 40 cycles under one solar intensity in the 20[Formula: see text]wt.% NaCl solution. That is mainly due to the Cassie state superhydrophobicity that can large increase the heterogeneous nucleation barrier quite close to the homogeneous one in salt water. This study expects to solve the existing problems of complex structure and short service time of seawater desalination units.