Seawater Desalination Research Articles

Brine treatment using fluidized bed homogeneous crystallization technology for the simultaneous recovery of calcium and magnesium as dolomite-like granules

Fluidized bed homogeneous crystallization (FBHC) technology is an effective method to treat metal-contained wastewater at ambient temperature and pressure. Seawater desalination is common to produce fresh water and concentrated brine. This highly hardness-contained brine decreases the lifetime of membranes by fouling during desalination process. This study recovers calcium and magnesium by carbonate reagent from synthetic brine wastewater to be dolomite-like particles. The greatest total removal is 90.7 % for calcium and 76.0 % for magnesium, with a crystallization ratio of 89.5 % for Ca and 75.7 % for Mg, using a 40 min of hydraulic retention time, 9.5 of effluent pH, 2.0 of molar ratio, and 24 of reflux ratio. The effluent from the fluidized bed reactor (FBR) is aged in a sedimentation tank for 24 h to increase removal efficiency to 99.98 % for Ca and 84.7 % for Mg. XRD, SEM, FTIR, and Raman analysis reveal that particles are composed of CaCO3·H2O and MgCO3·3H2O with a dolomite-like structure and a core-shell morphology. In a real brine wastewater treatment by FBHC system, 86 % of Ca and 74 % of Mg are crystallized, so disposal costs are 75 % less than those for chemical precipitation, a conventional treating method. Therefore, FBHC technology has high potential to treat hardness-contained brine by reclaiming as dolomite-like granules.

Efficient Solar Steam Generation by Multiscale Photothermal Structures Derived from Cactus Stems.

Solar steam generation (SSG) is a promising technique that may find applications in seawater desalination, sewage treatment, etc. The core component for SSG devices is photothermal materials, among which biomass-derived carbon materials have been extensively attempted due to their low cost, wide availability, and diversified microstructures. However, the practical performance of these materials is not satisfactory because of the multifaceted structural requirements for photothermal materials in SSG scenarios. In this work, cactus stems, which possess abundant and multiscaled pores for simultaneous sunlight gathering and water evaporation, are applied as the photothermal structure for SSG devices after mild heat treatment. Consequently, the SSG device based on the carbonized cactus stems delivers high performance (an absorption rate of 93.7% of the solar spectrum, an evaporation rate of 2.02 kg m-2 h-1, and an efficiency of 91.4% under one solar irradiation). We anticipate that the material can be a potential candidate for efficient SSG devices and may shed light on the sustainable supply of water.

Assessment of the economic viability, environmental, and social impacts of green hydrogen production: an Algerian case study

The impacts of climate change are real and in many parts of the world testify to its harsh reality, including rampant extreme weather events, droughts, heat, wildfires, and flooding which have recorded in places which have not experienced them in recent memory. In the quest to avert such events, there is a growing awareness and demand for sustainable processes and operations. Today, sustainability encompasses a balance between ecological footprint and human development index, taking into consideration economics, the green environment, safety, quality, ethics, diversity and inclusion (D&I), and communities. This article presents some steps that have been taken by Algeria to balance energetic autonomy and sustainable development, and a case study on green hydrogen production employing membrane processes. Algeria’s objective to join the global fight against climate change is to develop its green hydrogen base. Given its resources, including available solar and wind power, seawater desalination plants, building capacity, and its favorable location, it is developing its green hydrogen economy to supply hydrogen, especially to Europe. This presents an opportunity for other developing nations, especially in Africa, to gain from this experience.

N, S-carbon quantum dots as inhibitor in pickling process of heat exchangers for enhanced performance in multi-stage flash seawater desalination

The heat exchanger in multi-stage flash seawater desalination needs to be pickled during long-term service to remove oxidation products on the copper surface. In this paper, we introduce a method for preparing carbon quantum dots from biowaste, and explore their ability to inhibit the corrosion of copper in sulfuric acid and its corrosion inhibition mechanism. Firstly, the UV–vis spectra, microstructure, tissue composition of N, S-CDs were tested by Ultraviolet-visible spectrophotometer, TEM and Fourier transform infrared. Secondly, the effectiveness of N, S-CDs in preventing corrosion was analyzed by electrochemical testing. The electrochemical test results showed that the impedance value of the solution of 200 mg/L N, S-CDs was 94,440 Ω cm2 at 298 K， with corrosion inhibition efficiencies (η) of 99.89 %, 99.77 % and 99.72 % at 298 K, 308 K, and 318 K, respectively. Moreover, SEM, XPS and AFM were used to characterize the micro-morphology and composition both before and after corrosion. It is worth noting that we used the fluorescence properties of carbon quantum dots as fluorescent probes to deeply verify the corrosion inhibition mechanism of N, S-CDs on copper.

Effect of electron acceptors on electricity production and desalination of caspian sea water using microbial desalination cells

ABSTRACT The Microbial Desalination Cell (MDC) stands out as an innovative and a sustainable technology for both renewable energy generation and water treatment. The choice of electron acceptor significantly influences the efficiency of electricity flow. This study focuses on exploring the MDC performance under different conditions, including variations in cathode electron acceptors, initial pH levels, and hydraulic retention time (HRT). The investigation assesses simultaneous reduction of TDS and power generation from Caspian Sea water, a prominent saline water source in northern Iran, in both open-circuit (OC) and closed-circuit (CC) modes. The findings reveal that sodium hypochlorite, potassium permanganate, and potassium bromate as catholyte achieved TDS reduction rates of 84%, 77%, and 72%, respectively, under CC conditions at pH 5. Furthermore, it was observed that increasing HRT and pH levels lead to a decrease in desalination efficiency and power generation. Notably, the study highlights that the maximum power density was attained using permanganate, hypochlorite, and bromate as catholyte in both OC and CC configurations. By showcasing the adaptability of MDC performance with different cathode electron acceptors under varying conditions, this research offers valuable insights for optimizing MDC efficiency when treating real saline water sources.

Functional of thin-film composite Janus membrane with sacrificial layer for inorganic scaling control in membrane distillation

Membrane distillation technology, utilized for treating hypersaline wastewater from seawater desalination, often encounters challenges related to inorganic scaling, adversely affecting membrane performance. Herein, we introduce a innovative approach employing a sacrificial layer on the surface of Thin Film Composite (TFC) membranes to concurrently enhance inorganic scaling resistance and facilitate membrane reusability. The sacrificial layer (Fe3+-TA) consisted of tannic acid (TA) complexed with iron ions (Fe3+) and could be removed and regenerated in situ. The results demonstrated that the Fe3+-TA layer significantly improved the membrane's surface smoothness and densification, maintaining superior anti-scaling performance. The modified membrane exhibited remarkable durability, sustaining six reuse cycles with a flux recovery exceeding 97 % in gypsum scaling tests. Furthermore, the formation of new complexes during gypsum scaling tests confirmed the membrane's augmented scaling retardation capabilities. Thus, integrating of a sacrificial layer into TFC membranes presents a promising strategy for advancing membrane distillation processes in hypersaline wastewater treatment.

Large-Scale carbon Fiber-Based Solar-Driven evaporator with 1T MoS2-MXene Heterostructure: Towards reliable mechanical performance and efficient seawater desalination

Solar-driven interfacial water evaporation is often regarded as a promising method for producing fresh water from seawater. However, developing an evaporator with an ideal evaporation rate and efficient seawater desalination capabilities remains a significant challenge, especially when considering the mechanical performance requirements in large-scale practical use. Based on this, this work proposed a Janus-structured 3D carbon fiber (CF)-reinforced solar-driven evaporator fabricated through a vacuum-assisted infusion process (VAIP). A heterogeneous structure of 1 T MoS2-MXene, formed through ion embedding, was adorned on the surface to serve as an efficient photothermal conversion material. Due to the synergistic advantages, the Janus 1 T MoS2-MXene/ CSA/CF (JMMC) evaporator achieved excellent solar absorption efficiency of 94 % in the range of 200–2500 nm. The evaporator exhibited an evaporation enthalpy as low as 1556.4 kJ·kg−1, which facilitated the escape of water molecules at the interface. The JMMC evaporator delivered a high evaporation rate of 2.29 kg m-2h−1 and an efficiency of 93.8 % under the irradiation of 1 sun (1.0 kW/m−2(−|-)). The influence of the heterogeneous structure of 1 T MoS₂-MXene on the water evaporation rate was thoroughly assessed through molecular dynamics simulations. Besides, the mechanical performance of this evaporator was highly satisfactory, rendering it suitable for application in demanding and complex usage environments. Furthermore, its remarkable conductivity facilitated an excellent Joule heating effect even at low voltages, enabling water evaporation under challenging circumstances such as overcast skies or indoor settings. The versatility of this scalable evaporator holds great promise for addressing the issue of freshwater scarcity.

Enhanced hydrophilicity and stability of carbon-based aerogel with assembling of halloysite nanotubes and silica fibers for efficient solar seawater evaporation and desalination

Solar vapor generation has emerged as a sustainable technique for seawater evaporation and desalination. Integrating high hydrophilicity, strong light absorbance, good salt resistance, fast water transfer and good structural stability simultaneously in one evaporator at low cost for achieving cost-effective evaporation and long-term utilization is highly desirable but still challenging. Herein, an eco-friendly and low-cost aerogel (CSH) with natural chitosan, halloysite nanotubes and silica fibers was prepared by freeze-casting, which was then carbonized to construct a robust aerogel (cCSH) as evaporator. The cellular structure of cCSH aerogel with microchannels enables fast water transfer and rapid salt dissolution, the carbonized chitosan favors enhanced light absorption, the halloysite assembled on the walls endows the aerogel with excellent hydrophilicity, and the silica fibers penetrating the multilayer guarantee good structural stability. As expected, the prepared evaporator (cCSH200) exhibits remarkable evaporation rates of 2.49/7.20 kg·m−2·h−1 under one/four sun, respectively, exceeding most biomacromolecule-derived aerogels. Besides, it displays outstanding salt resistance, wastewater purification ability and long-term cycle stability. Outdoor test further substantiates the admirable evaporation performance, long-term durability and enormous application prospect of the cCSH200. This work affords a low-cost tactic for the development of efficient evaporator for solar-driven seawater desalination and wastewater treatment.

Study on the Preparation and PEC-Type Photodetection Performance of β-Bi2O3 Thin Films.

Bismuth-based compounds have been regarded as a kind of promising material due to their narrow bandgap, high carrier mobility, low toxicity, and strong oxidation ability, showing potential applications in the field of photoelectrochemical (PEC) activities. They can be applied in sustainable energy production, seawater desalination and treatment, optical detection and communication, and other fields. As a member of the broader family of bismuth-based materials, β-Bi2O3 exhibits significant advantages for applications in engineering, including high photoelectric response, stability in harsh environments, and excellent corrosion resistance. This paper presents the synthesis of β-Bi2O3 thin films utilizing the mist chemical vapor deposition (CVD) method at the optimal temperature of 400 °C. Based on the β-Bi2O3 thin film synthesized at optimal temperature, a PEC-type photodetector was constructed with the highest responsivity R of 2.84 mA/W and detectivity D of 6.01 × 1010 Jones, respectively. The photodetection performance was investigated from various points like illumination light wavelength, power density, and long-term stability. This study would broaden the horizontal and practical applications of β-Bi2O3.

Pilot-scale testing of a multi-tube type falling film distillation column equipped with a biphasic thermosyphon as a new alternative for the desalination of brackish water and seawater

This paper proposes an innovative technology for desalinating brackish water and seawater using a multi-tube type falling film distillation column integrated with a biphasic thermosyphon. Based on the literature survey, this proposal has not been previously explored. In this study, the viability of the pilot-scale application of this technology for desalination was tested, and the process performance was evaluated in terms of distillate flow rate, salinity removal, and energy consumption, considering different experimental conditions. Synthetic solutions containing 10.0 and 35.0 g/L of sodium chloride were used to simulate brackish water and seawater salinities, respectively. The thermal desalination pilot plant integrating a compact falling film distillation column and a biphasic thermosyphon demonstrated high effectiveness, consistently producing desalinated water with a conductivity below 10 μS cm−1. Considering both concentrations, the optimal condition for desalinated water production was a feed temperature of 85 °C, a vapor chamber temperature of 121 °C, and an energy consumption of 16 kW. This new technological option’s energy consumption is approximately 33 % lower than that of a simulated flash distillation column operating under similar conditions. In conclusion, this study presents promising results, establishing falling film distillation technology as a viable alternative for desalinating brackish water and seawater.

Scaling in reverse osmosis seawater desalination: Mechanism and prevention—A literature review

Scaling in reverse osmosis seawater desalination: Mechanism and prevention—A literature review

MnO2-modified PEEK membrane for efficient oil-water separation and solar-assisted seawater desalination

Economic and efficient routes to achieve clean freshwater from oil-water mixtures and seawater have gained special attention to reduce the current water crisis, but still a challenge unsolved. Herein, poly (ether ether ketone) (PEEK) membrane, modified with MnO2 layer, has been prepared by facile hydrothermal method to address this issue aforementioned. Given the existence of PEEK and underwater superoleophobicity/underoil superhydrophilicity of MnO2, the composite membrane exhibits strong mechanic properties (tensile stress: 110.2 MPa) and high separation efficiencies (99.9 %) for different oil–water mixtures under gravity. Additionally, our membrane could also effectively separate immiscible oil mixtures according to the dipole–dipole interaction. Furthermore, firm chemical stability against dichloromethane, N, N-Dimethylformamide, 1 M NaOH, 1 M HCl, and 1 M NaCl has been achieved. Most importantly, our membrane displays durable evaporation efficiency (2.63 kg m-2h−1), high energy efficiency (85.9 %), and super salt tolerance under 1 sun irradiation, for solar-assisted seawater desalination.

Evaluation of suitable sites for concentrated solar power desalination systems: case study of Mauritania

It is imperative to address the critical problem of water scarcity in sub-Saharan Africa, especially in light of the aggravating effects of climate change brought on by the extraction of fossil fuels. In order to ensure the availability of drinkable water in these places, this research proposes integrating concentrated solar power (CSP) with desalination systems (DS). Present research is focused on identifying and evaluating potential locations for DS/CSP implementation within Mauritania by employing a comprehensive, multi-criteria decision-making framework. This framework synthesizes mathematical approaches from multi-criteria analysis with geospatial analysis techniques, considering a range of factors including environmental impact, economic viability, demographic demands, and climatic conditions. Research findings reveal that 10% of the Mauritanian, approximately 103070 km2, presents optimal conditions for the deployment of DS/CSP facilities. The study delineates the coastal regions as prime candidates for seawater desalination plants, while the densely populated southeastern areas are identified as suitable for brackish water desalination systems. Conversely, the less inhabited northern territories hold the potential for decentralized brackish water desalination plants. Hence this study provides a holistic approach for DS/CSP systems installation to manage water scarcity as well as energy security issues in Mauritania. And also provides basis for formulating future policies in the region.

A sustainable MXene/PVA/CNFs@Fabric roll-based 3D photothermal evaporator integrating efficient evaporation and anti-pollution design

Solar-driven interface evaporation is an effective approach towards achieving clean seawater desalination. The focus of research in this field lies in attaining sustained, stable, and efficient steam generation during the photothermal evaporation process. In this study, the proposed MPFR evaporator featured a 3D spiral conical groove design combined with a hydrophilic MXene/PVA/CNFs functional layer, which effectively enhanced light absorption (>97 %) through multistage reflection and absorption. This facilitated a body-phase absorption/body-phase heating process that effectively reduced the surface temperature of the illuminated area compared to a flat evaporator. Consequently, this was conducive to the absorption of environmental heat to supply water evaporation. Under 1.0 sun illumination, the evaporation rate and evaporation efficiency of MPFR-4 evaporator reached 3.84 kg m−2·h−1 and 156.29 % respectively. The introduction of the hydrophilic functional layer not only enabled water activation but also enhanced the water supply capacity of both yarn and fabric on the evaporator surface, forming a water layer that promoted high-salinity water diffusion and salt crystal dissolution while effectively inhibiting salt crystal pollution. Moreover, this water layer imparted oil-repellent characteristics to the evaporator, enabling it to resist oil-pollution from sea surfaces as well. Thus, this work provided novel insights into designing highly efficient and anti-pollution solar thermal evaporators that drove advancements within green and sustainable water generation.

Solar evaporation of liquid marbles with Fe3O4/CNT hybrid nanostructures

HypothesisThrough the rational design of nanomaterial composites, broadband light harvesting and good thermal insulation can be achieved simultaneously to improve the efficiency of water evaporation. ExperimentSolar evaporation experiments were carried out on liquid marbles (LMs) coated with Fe3O4 nanoparticles, carbon nanotubes (CNTs) and hybrid nanomaterials (Fe3O4/CNTs) with different mass ratios of 2:1, 1:1 and 1:2. FindingThe results showed that the mixture of Fe3O4/CNTs enhances the light harvesting ability and solar interfacial evaporation performance. Fe3O4/CNT-LM at the mass ratio of 2:1 case provides the highest evaporation rate of 11.03 μg/s, which is about 1.22 and 1.34 times higher than that of Fe3O4 and CNT, respectively. This high performance is mainly due to the synergistic effect between Fe3O4 nanoparticles and CNTs, as the hybrid nanostructure significantly improves the both photothermal conversion and heat localization capability. Numerical simulation further supports that the composite can concentrate the electromagnetic field and heat at the phase-change interface. This leads to a rapid evaporation of the boundary region. This study provides a novel approach to a three-dimensional interface by assembling nanomaterials on the drop surface to enhance evaporation, which may have far-reaching implications for seawater desalination.

Multiscale MXene Engineering for Enhanced Capacitive Deionization via Adaptive Surface Charge Tailoring.

Capacitive deionization (CDI), renowned for its eco-friendly and low-energy approach to water treatment, encounters challenges in achieving optimal deionization efficiency and cycle stability despite recent advancements. In this study, the CDI electrodes were crafted with multilevel pore structures using modified cellulose (MCNF) and porous activated MXene (PAMX), aiming to the impact of surface modification on adsorption efficiency, stability, and overall performance. The experimental results demonstrated the superiority of the electrode, specifically the formulation integrating sulfonic acid-treated cellulose and PAMX (SCNF@PAMX). This configuration exhibited remarkably a higher desalination rate (3.91 mg·g-1·min-1) and enhanced desalination capacity (31.24 mg·g-1), with cycling performance exceeding 90%. Density functional theory calculations underscored the formidable adsorption energy of SCNF for Na+ (2.15 eV), surpassing that of other modified electrodes. The enhancement of deionization performance and efficiency through surface charge modification, altering Na+ electrostatic adsorption, lays a solid foundation for advancing more efficient and durable seawater desalination technologies.

A 3D self-floating solar vapor generator based on a novel self-healing aero-hydrogel containing peach gum polysaccharide with durability and continuous operation

Solar energy interfacial evaporation represents a promising and sustainable approach with considerable potential for seawater desalination and wastewater treatment. Nonetheless, creating durable evaporators for continuous operation presents a challenge. Motivated by natural self-healing mechanisms, this study developed a novel 3D hybrid aero-hydrogel, which exhibited a self-healing efficiency of 89.4 % and an elongation at break post-healing of 637.7 %, featuring self-healing capabilities and continuous operation potential. Especially, the incorporation of hyperbranched water-soluble polymers (peach gum polysaccharide) endow the final solar water evaporators with a lower evaporation enthalpy of water, resulting in that the refined SVG3, with a notable water surface architecture and an expanded evaporation area, achieved a steam generation rate of 2.13 kg m−2 h−1 under 1 Sun. Notably, SVG2 achieved a high evaporation rate of 2.43 kg m−2 h−1 with the combined energy input of 1 Sun and 6 V, significantly surpassing the rate of 1.96 kg m−2 h−1 without voltage input. The results indicate that electrical energy significantly enhances and synergizes with SVG, facilitating continuous operation both day and night through the combined use of solar energy and electrical input. This study offers insightful perspectives for the strategic design of multifunctional hydrogels for solar water evaporation.

Simultaneous efficient evaporation and stable electricity generation enabled by a wooden evaporator based on composite photothermal effect

The current solar interfacial evaporators have limited evaporation performance due to their single photothermal mechanism, insufficient light utilization, and improper heat management. Therefore, a novel approach involving polypyrrole (PPy) and Ag nanoparticles (AgNPs) modified wooden evaporator (AgPW) using an in-situ polymerization and growth method was proposed for efficient and sustainable freshwater purification. The composite photothermal effect of PPy and AgNPs led to a significantly enhanced light absorption capacity and superior photothermal conversion efficiency in a wide spectrum range, which coupled with the rapid water transport capacity conferred by the regular vertical channels and superior hydrophilicity of the delignified wood, resulted in remarkable evaporation performance through the coordinated regulation of thermal and water management. The optimized AgPW50 achieved an evaporation rate of up to 2.04 kg m−2 h−1 and an evaporation efficiency of 90.7 % under 1 kW m−2 irradiation. Importantly, this evaporator was highly salt resistant and long-term desalination stability, and can also be extended to the purification of various types of wastewaters while converting the released waste heat into stable electricity generation. The innovative Ag/PPy wooden evaporator integrates biomass resources with solar energy utilization, demonstrating an environmentally friendly, efficient and cost-effective strategy for seawater desalination and energy production, providing a new sustainable development pathway to solve the challenge of balancing water security and energy consumption.

Primarily experimental study of the energy performances of a humidification-dehumidification seawater desalination system coupled with a heat pump

The study presented in this article explores a comprehensive analysis of a humidification-dehumidification (HDH) seawater desalination system integrating a heat pump for heating seawater intended for distillation, and incorporates additional condensation plates supplied with cold seawater. This system was the subject of an experimental investigation to simultaneously evaluate the energy performance of the heat pump and the thermal behavior of the desalination unit, focusing on seawater and condensation wall temperatures, as well as the stratification of temperatures of humid air inside the unit compared to the evaporation surface. Experimental results showed an average daily production of distilled water of approximately 32.75 kg/m² per day, with an electrical consumption of 37.68 kWh/day, which was reduced to 26.72 kWh/day through the integration of photovoltaic solar energy. Based on heat and mass balance equations of all the system’s components, the study used a detailed thermodynamic model. The system's energy performance was analyzed by calculating the coefficient of performance (COP), the specific energy consumption (SEEC), and the gain output ratio (GOR), reflecting the overall energy efficiency of the HDH system coupled with the heat pump, as well as the recovery ratio (RR), indicating the proportion of the recovered water compared to the input water.

A novel nanoplastic removal method based on solar interface evaporation technology

The widespread presence of nanoplastics in water environment has become a prominent threat to human health, and it is urgent to develop low-carbon and efficient nanoplastic removal methods. In this work, a novel nanoplastic removal method based on solar interface evaporation technology was successfully developed. The solar interface evaporator was constructed by modifying the surface of sorghum straw with polypyrrole, which exhibited satisfactory evaporation rate (2.946 kg·m−2·h−1) with a solar steam conversion efficiency up to 95.4 %. The proposed evaporator was successfully applied to the removal of nanoplastics obtained from take-out lunch boxes, mineral water bottles and plastic bags. The device also showed potential application in seawater desalination and sewage treatment. The water transport and heat transfer during the evaporation process were simulated by finite element simulation. This work sheds new light on nanoplastic removal and expands the application of solar interface evaporation techniques.