Desalination Research Articles

Flexible beads-on-string hierarchically porous carbon nanofiber/nanotube composites for enhanced capacitive deionization performance in water desalination

Capacitive deionization (CDI) has garnered significant interest for desalinating water and wastewater. However, electrode materials have remained a primary constraint in CDI technology. This study incorporated carbon nanotubes (CNTs) into a polyacrylonitrile (PAN) solution to synthesize a hierarchically porous activated carbon nanofiber (ACNF)/CNT composite. The ACNF/CNT composite possesses a highly flexible structure characterized by a distinctive beads-on-string morphology. It exhibits a specific surface area of 699 m2/g, a specific pore volume of 0.448 cm3/g, and an average pore width of 3.38 nm. The composite is composed of micropores (38 %), mesopores (59 %), and macropores, creating a multi-scale porous architecture. The surface capacitance of the ACNF/CNT composite is six times greater than that of the ACNF alone, and its charge transfer resistance is reduced to one-tenth. Furthermore, the electrosorption capacity of the ACNF/CNT composite as CDI electrodes was found to be 17.3 mg/g for a 500 mg/L NaCl solution, demonstrating stability over 30 cycles. Kinetic studies suggest that the mesopore-rich beads-on-string structure enhances intraparticle diffusion and the electrosorption process. The ACNF/CNT composite also demonstrates exceptional flexibility and mechanical stability, which are crucial for its application at a pilot scale. This study introduces a novel hierarchically porous electrode material for CDI desalination.

Metal plate-based promotion on methane hydrate nucleation: Insights into the influence of metal type and surface properties

Hydrate-based technologies hold significant promise in the fields of gas storage, water desalination and gas separation, but their application is restricted by the long induction time and high degree of randomness associated with hydrate nucleation. In this study, we conducted experimental investigations to access the influence of metal plates (Mg, Al and Zn) on methane hydrate nucleation under both pure water and acidic conditions. The results demonstrated that Mg plate exhibited the strongest promotion effect on methane hydrate nucleation. The presence of acid significantly accelerated hydrate nucleation in the Zn plate system, but conversely reduced the promotion effect of Al plate. In conjunction with the in-situ morphology evolution of hydrate nucleation, methane-liquid–metal interface was found to play a crucial role in the metal-induced promotion effect. Two nucleation modes were proposed accordingly: (i) in pure water, hydrate nucleation initiated exclusively at the methane-liquid–metal interface without extra nucleation site (Mode 1), and (ii) in acidic condition, hydrate nucleation occurred with evident multiple nucleation sites (Mode 2). Furthermore, SEM imaging, AFM and contact angle characterization revealed that the surface properties of metal plate (e.g., hydrophilicity and roughness) were the key factors in determining the effectiveness of the promotion effect. Liquid climbing upward along the metal plate surface was vital for metal plates to promote gas hydrate formation. Overall, this study provides new insights into hydrate nucleation promotion and suggests a straightforward way to enhance hydrate nucleation by modifying surface properties

Hierarchical Ti3C2Tx MXene@Honeycomb nanocomposite with high energy efficiency for solar water desalination

The utilization of solar-driven interfacial evaporation holds immense promise in enhancing energy efficiency and establishing sustainable methods for seawater desalination and water purification. While designing the materials to achieve high evaporation efficiency, the tuning of materials with porosity and surface chemistry is very crucial. Novel sustainable materials are of great importance for solar water desalination applications since clean water production is utmost important in the current era. There exists a lack of exploration in modifying the surface wettability states of solar evaporators to expedite the vapor generation rates. In this study, we showcase a hydrophilic Ti3C2Tx MXene-coated carbonized honeycomb (CHC) (Ti3C2Tx MXene@CHC) nanocomposite-based hexagonal-shaped evaporator surface. This is the first-time report on the effective utilization of hierarchical CHC for the preparation of solar absorber comprising of Ti3C2Tx MXene@CHC nanocomposite, particularly for the solar water desalination. The Ti3C2Tx MXene@CHC nanocomposite evaporator achieves an impressive water evaporation rate of 1.6 kg m−2 h−1 with 90% efficiency under 1 sun illumination. The augmented thickness of the water layer in the hydrophilic surface of the Ti3C2Tx MXene@CHC nanocomposite helps in facilitating the rapid escape of water molecules. The relatively elongated contact lines in the hydrophobic region simultaneously ensure substantial water evaporation, significantly enhancing the water desalination process. The Ti3C2Tx MXene@CHC nanocomposite exceeds stringent quality benchmarks, signaling its potential for solar water desalination.

Design of wastewater treatment unit using End-of-Life (EoL) Reverse Osmosis membrane

Abstract Sultanate of Oman is facing severe challenges due to water scarcity, shortage of rainfall, and limited freshwater resources. Over the past few decades, 90% of the natural water resources are consumed by agriculture. Hence, there is an urgent need to find an alternative to obtain fresh water. Water desalination by Reverse Osmosis (RO) is currently practiced in Oman as freshwater source, since it contributes 80% of the total desalination plants installed worldwide. The RO process results in environmental concerns triggered by emission of gases, and discharge of Reverse Osmosis (RO) membranes. The lifespan of membranes depends on the water quality and the operating conditions, and the membrane life is estimated as 5 to 10 years. In order to mitigate the environmental impact for a sustainable desalination output, reuse of discarded end-of-life (EoL) RO membrane is a feasible solution to enhance the water quality. The efficiency of RO membranes is affected by the fouling, scaling, and chemical cleaning for the yearlong operation which lead to reduced salt rejection rate. Hence, this research aimed to reuse the old RO elements by transforming them into Ultrafiltration unit (UF) by removing the active layer and increasing the pore size of membrane. Additionally, modifying the membrane by open configuration and separating all 28 membrane sheets from the permeating tubes are designed as RO-MBR panels. The study shows that, after 5 weeks of operation, the average turbidity rejection rate was 94%, and the average permeated flux per unit was 6.9 LMH. The new configuration shows the permeate flux stability and acceptable BOD, and COD reduction.

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.

Efisiensi desalinasi air laut dengan menggunakan konsentrasi reflektor parabolik

Water is very important for the life of living things, many countries in the world are experiencing a clean water crisis. The total global water reserve is less than 1.4 billion km3, of which about 97.5% is in the oceans and the remaining 2.5% is fresh water contained in the atmosphere, ice mountains and groundwater. Desalination is generally the process of removing salt from seawater or saltwater. Desalination of seawater and brackish water can be utilized to increase the availability of clean water. Two types of desalination techniques used can be classified into phase change (heat) and membrane. desalination techniques with phase change processes are processes that utilize changes in a substance under certain temperature conditions. While desalination techniques with membrane processes are processes that focus on filtering a substance accurately. Comparison of desalination efficiency between the three materials in different days is the flanel sheet material, the goni and the combination of flanels and goni. Flanel leaf material has the highest efficiency value on the 1st day with a presentation of 57,71% while the lowest one has a value of 32,24%. Then on the 2nd day the most efficient value is 45,32%, while the least value is 0%. In the first day goni material has a highest efficacy value with a presentation of 34,56%, and a lowest value with 0%. Then the second day trial with the same material has its highest effectiveness value with the presentation of 41,44%, and the lower value with 0%.

304L Austenitic Stainless Steel Corrosion Studies in Neutral Environment in Presence of Sulfite Ions

Abstract This paper examined the influence of the sulfite concentration introduced in the electrolyte added to the neutral solution (1 mol L-1 Na2SO4) on the corrosion process of 304L stainless steel material. 304L. The accelerated effect of sulfite ions under corrosion rate of 304L austenitic stainless steel was demonstrated using electrochemical techniques such as linear sweep voltammetry at a low scan rate −1 mV s−1, the Tafel slope method, chronoamperometry, and electrochemical impedance spectroscopy. Electrochemical studies were conducted using a BioLogic SP150 potentiostat/galvanostat. Stainless steels are the most varied and intricate group among all steels. Among them, 304L austenitic stainless steel is one of the most commonly utilized alloys, prized for its excellent corrosion resistance and strength, hygienic and aesthetic properties, affordability, good formability, and effective weldability. [1-3]. In modern industry, the amount of austenitic stainless steel represents only about 2% of the total steel production manufactured globally. This type of steel is commonly employed in chemical engineering, metal extraction, desalination and wastewater treatment plants, the oil and gas sector, transportation and aerospace industries, the food and beverage sector, as well as in architecture and construction engineering. [1].

The evolutive role of shoot apical meristems in the adaptation of angiosperms to life at sea and the jump to potential environmental biotechnology applications

Seagrasses have adapted to a submerged lifestyle in seawater through a complex set of evolutionary processes. However, they show sensitivity to increases in natural salinity levels such as those commonly found in discharges of desalination plants, which have exponentially grown due to water scarcity in highly populated temperate areas, such as the Mediterranean basin. This study assessed the effects of brine-derived hypersalinity on the Mediterranean seagrass Posidonia oceanica, focusing on the metabolic responses of shoot apical meristems (SAMs). Although most physiological and genetic studies have used leaves, SAMs are more directly correlated with plant survival and might be more responsive to salinity stress. The experiments were: a controlled mesocosm of more than six practical salinity units (psu) over natural levels using either artificial salts or desalination brine and field transplantation experiments comparing two sites following the dilution plume of the brine (+5 and + 2 psu) with control. Hydrogen peroxide (H2O2), thiobarbituric acid reactive substances (TBARS), and ascorbate were measured to determine oxidative stress and damage, as well as relative expression of genes related to osmotic regulation and oxidative responses. Overall, relative expression of genes related to osmotic regulation (SOS1, SOS3, AKT 2/3) and oxidative stress (STRK1, CAT, MnSOD, FeSOD, APX, GR) was higher in SAMs at higher brine exposures, indicating a more active metabolic response in this organ. Similarly, reactive oxygen species (ROS) production and lipid peroxidation were higher closer to brine discharge and total ascorbate lower, indicating a correlative response with stressor intensity. These findings confirm that SAMs play an essential role in P. oceanica hypersalinity responses and its adaptation to life in the marine environment. Finally, the use of P. oceanica SAMs in this study is highly recommended for an early detection of threats caused by desalination brines that may cause physiological damage and meadow regression.

Oil removal using agricultural wastes adsorbents in a fixed bed column as a pretreatment in RO systems

Oil removal from seawater is an essential pre-treatment in Reverse Osmosis desalination plants to mitigate membrane fouling. The present paper investigates the feasibility of oil removal from water using agricultural wastes as low-cost adsorbents. Three wastes, rice husk, sugarcane bagasse, and sawdust were tested using two types of water, oily seawater and oily distilled water. For comparison, activated carbon adsorbent was included in the tests as a reference case. The experiments were conducted in a fixed bed column (10 cm diameter and 55 cm height), at an initial oil concentration of 1000, 3000, and 5000 mg/L, bed height of 10, 15, and 20 cm, and flow rate of 75, 145, and 290 mL/min. The parametric study indicated that the breakthrough time and the percentage of oil removal increased with the decrease in initial oil concentration and flow rate, but the breakthrough time increases with increasing the bed height. The oil removal percentage using rice husk was higher than sawdust and sugar cane bagasse and it was 18.9 % lower than that of activated carbon. Thus, rice husk can be a cheap alternative to activated carbon. The effect of oil type and water type was not significant. Additionally, the 50 % breakthrough time was 1388 min for activated carbon, 912 min for rice husk, 580 min for sawdust and 421 min for sugar cane bagasse. Assessing the dynamics models indicated that the non-linear forms of the Thomas, Bohart-Adams, and Yoon-and-Nelson kinetic models perform better than their linear forms, and the difference in performance among these models was not so big, i.e., any of these models can be used to predict the breakthrough curve.

Techno-economic investigation of an entirely solar-powered hybrid HDH/RO desalination plant for moderate water demand under various operating conditions

The study presented a scalable, entirely solar-powered hybrid desalination system suitable for moderate demand and valid for various water salinities. The system merged two desalination techniques: HDH (humidification-dehumidification) and RO (reverse osmosis) units. The required power for all components was obtained from a photovoltaic system. The experiments were conducted to evaluate the separate units and hybrid system performances under different conditions, including various sprayed hot water (to the HDH) temperatures, RO feed water temperatures, air velocities, and water salinities. Based on the recorded data, the techno-economic analyses were conducted to assess the gain output ratio (GOR), recovery ratio (RR), specific energy consumption (SEC), the total amount of dissolved solids (TDS), and product cost. As a result, the RO unit's productivity increased almost linearly with feed temperature, showing a maximum hourly yield of 60 L/m2. In contrast, HDH productivity showed exponential growth with feed temperature, achieving a maximum hourly yield of 18 L/m2. The SEC of the RO unit decreased from 1.1 kWh/m³ to 0.63 kWh/m³ when using the rejected HDH's hot brine. The hybrid system's accumulated productivity reached 535 L/m2, significantly higher than the standalone HDH (58.5 L/m2) and standalone RO (368 L/m2). Additionally, the hybrid system demonstrated substantial improvements in GOR and RR, with daily values of 11.15 and 55.73%, respectively. Economically, the distillate water cost was significantly lower, at 0.63 $/m³ for the HDH/RO system compared to 3.51 $/m³ for the standalone HDH.

Hydrate technology for water desalination in the Mekong Delta, Vietnam

Freshwater scarcity is a critical issue in Vietnam, particularly in the Mekong Delta, a densely populated region with an agriculture-based economy. This scarcity is largely driven by saltwater intrusion during the dry season, severely affecting both agriculture and the local economy. In response, advanced desalination technologies have been proposed. In this study, we investigated the use of cyclopentane (CP), a liquid guest molecule, and 1,1,1,2-tetrafluoroethane (R134a), a gaseous guest molecule, as hydrate formers to desalinate saline water from the Mekong Delta. This study aimed to evaluate and compare the freshwater recovery efficiencies of these hydrate formers and assess the potential of hydrate technology for practical application in the region. We performed thermodynamic and kinetic investigations on sodium chloride solutions (1.0–3.5 wt%), representing the salinity levels of seawater in the Mekong Delta, to establish a laboratory-scale desalination system. The results showed a consistent thermodynamic trend: the higher concentration of samples leads to the longer time of hydrate formation to achieve the conversion of water into hydrates exceeding 60 %. Additionally, the CP and R134a hydrate structures were characterized using Raman spectroscopy, which revealed significant changes in the water peak and C–H band signal during the hydrate formation process. After a single-stage hydrate treatment using CP and R134a, the removal efficiencies for ions and total dissolved solids in saline water samples from the Mekong Delta exceeded 75 % and 70 %, respectively. These findings serve as a reference for developing a larger-scale hydrate-based desalination technology to address the challenges of saltwater intrusion in the Mekong Delta region.

Synthesis of CuO/Fe3O4 Nanocomposite for enhanced solar thermal desalination

Nanoparticle (NPs) have attracted the attention of scientists and researchers in water remediation due to the improvement in its processability, and its cost effectiveness. The present work analyzed the synergistic effect of CuO (NPs) with different ratios (0, 0.5, 0.6, 0.7, 0.8, 0.9 and 1 wt %) on the structural, and optical properties of Fe3O4 (NPs), that can be used in water desalination process. The general methodology for preparation and structural properties of CuO (NPs), Fe3O4 (NPs) and CuO/Fe3O4 (NCs) were analyzed by (XRD) and (TEM) measurements. The morphological combination of (SEM) with (EDX), were used for determining the elemental identification of CuO/Fe3O4 (NCs). The characterization topography was found to be strongly affected by the change of the CuO concentration. Furthermore, the Urbach energy (EU), steepness parameter (σ), electron-phonon interaction (Ee-p), optical band gap (Eg), refractive index (n) and optical conductivity (σopt) were calculated. The optical absorption studies in the UV–Visible region, revealed that the CuO/Fe3O4 (NCs) was found to be direct allowed transition, and the energy bandgap value decreased from 2.52 eV to 2.15 eV based on the percentage change of CuO (NPs) in CuO/Fe3O4 (NCs). Moreover, the value of thermal conductivity (k), and thermal efficiency (η), showed an increase with the increase of the ratio of CuO (NPs), which may be an indication for opening an innovation way that can satisfy the need of seawater desalination technology.

Process intensification in the direct contact membrane distillation (DCMD) desalination by patterning membrane surface: A CFD study

In this research, the impact of pattern geometry on the intensification of the performance of surface patterned membranes for saline water desalination by direct contact membrane distillation (DCMD) is investigated by computational fluid dynamics (CFD) simulation. The Comsol Multiphysics software was applied to solve the governing transport equations for heat, momentum, and mass transfer. The result of the model was validated by the published experimental data, and the maximum deviation was less than 10%. The target was to maximize the permeate flux by altering surface pattern geometry and dimensions. Based on the previous studies, a prism pattern was chosen in this work, and the influences of pattern type (3 types), pattern dimension (25-150 µm valley depth), and the distance between the valleys (0-400 µm) were studied on the temperature polarization coefficient (TPC) and DCMD permeate flux. The results showed that the pattern with a valley depth of 25 µm and a distance between the valleys of 300 µm had the best performance in DCMD operation. In this situation and feed temperature of 80°C, a TPC of 0.78 and a water flux of 49.3 kg/m2.h were attained. The characteristics of flow close to the patterned membrane surface were also investigated, and it was observed that there are weak shear stresses in the lower zone of the valleys, while stronger shear stresses are created in the upper regions that are responsible for improving the TPC and water flux in the patterned membranes.

ZnO/nZVI nanoparticle-enhanced double-slope U-shaped solar distillation: A thermodynamic investigation of cephalexin adsorption

The increasing need for sustainable methods to remove pharmaceutical contaminants like cephalexin and improve water desalination is critical. This study explores ZnO/nZVI nanoparticles synthesized with Jackfruit peel extracts as eco-friendly, cost-effective adsorbents, enhancing water purification in solar desalination systems. This work used a matte black paint coating within a double slope U-shaped solar distiller (DSUD) in a discontinuous experimental setting to examine potential improvements in solar distillation performance. Activated carbon (AC) and bioactive powdered nanoparticles of ZnO/nZVI (nano zerovalent iron), produced from jackfruit peel extracts (JP) were combined in a synergistic way. The effectiveness of cephalexin removal was assessed taking into account the JPAC solution parameters, reaction duration, ZnO/nZVI concentrations in the nanocomposite dosage, and initial nanocomposite concentration. The best conditions for cephalexin adsorption were found to be pH 5 and reaction time of 50 min, which resulted in high absorption efficiencies of 94.74% (nZVI) and 97.53% (ZnO) at room temperature with a JPAC dose of 2.50 g L⁻1. The efficiency of the eco-friendly adsorbent in getting rid of cephalexin was calculated using “pseudo-second-order kinetics” for nanocomposites, which is consistent with the “Langmuir” isothermal absorption process. The nanocomposites as absorbent materials in solar thermal desalination processes, efficient heat transmission and energy storage have been established. JPAC and the addition of steel balls (S) with a silver hue to the DSUD improved the internal heat transfer mechanisms. Thermodynamic of Gibbs free energy and the Laplacian method (TGL), two thermodynamic concepts, were used to extensively study the temperature dynamics of the DSUD with SJPAC components. For ZnO/JPAC, an exceptional distillate production rate was noted from 8:00 to 18:00, with a noteworthy 4.932 L/m2 output in winter and 5.833 L/m2 per day in summer. Using silver balls, ZnO/JPAC generated significant yields over a 24-h period: 8.957 L/m2 in summer and 7.253 L/m2 in winter, with an ideal energy efficiency of 51.05%. The unique advancements in TGL procedures and their environmental consequences are presented in this paper. The field of thermal energy transduction will advance if silver balls are used in DSUD for the synthesis of JPAC, ZnO/JPAC, and nZVI/JPAC, as supported by the theoretical insights presented here.

Comparative thermoeconomic analysis of integrated hybrid multigeneration systems with hydrogen production for waste heat recovery in cement plants

The cement industry is a widely used and energy-consuming sector, making it one of the largest CO2 emitters, primarily to meet its energy demands. Therefore, this research aims to evaluate the waste heat recovery process from a cement factory to fulfill a portion of its energy requirements. In this study, four scenarios have been evaluated, including power production scenarios, hydrogen production scenarios, methanation production process evaluation scenarios, blending hydrogen with natural gas, oxy-fuel combustion scenarios, and scenarios for producing the required freshwater for the factory and the water electrolysis process. The results show that the steam Rankine cycle with the reheating process and the organic Rankine cycle with methanol working fluid with a production capacity of 24.35 MW, and a payback period of 2.4 years with levelized cost of energy being 0.005809 $/kWh, is the most favorable scenario for the power generation cycle. Also, the process of alkaline electrolysis with a hydrogen production rate of 0.1648 kg/s, and a payback period of 5.816 years, and also with the levelized cost of hydrogen being 1.001 $/kg, happened to be the most suitable hydrogen production scenario compared to other electrolysis scenarios such as PEM and SOEC. Moreover, the process of water desalination by reverse osmosis with the energy consumption of 2.7 MW of power is capable of supplying all the required water of the factory and the water electrolysis process, and it was determined as the most suitable scenario for supplying the required water.

Unlocking desalination’s potential: Harnessing MXene composite for sustainable desalination

Amidst freshwater scarcity, desalination is an effective solution, elevating pure water to a paramount commodity. Researchers actively pursue cost-effective alternatives to traditional desalination methods, with solar steam-based technologies now-a-days. Herein we report the synthesis of hierarchical photothermal absorber consisting of Ti3C2Tx decorated polypropylene fiber (PPF) composite and further used for solar desalination applications. Ensuring system stability amidst temperature fluctuations, pH variations, and mechanical stresses is pivotal for optimal desalination and wastewater treatment performance. Seamless integration of components is imperative to achieve this. Structurally, the Ti3C2Tx MXene@PPF composite evaporator showcases impressive metrics, such as high evaporation rate of 4.63 kg m-2h−1 along with a remarkable solar-evaporation efficiency of 93.48 % when tested under 1 sun illumination. Moreover, the composite absorber exhibits good mechanical stability, exceptional chemical stability even under harsh conditions (such as acid and alkali environments), outstanding salt tolerance and maintained a consistent evaporation rate over extended durations. Also, the absorber achieves good mechanical properties. These findings underscore the Ti3C2Tx MXene@PPF composite evaporator’s potential as a groundbreaking material for solar steam generation, offering high efficiency and cost-effectiveness. Beyond saline water desalination, its salt-preserving attributes and filtration capabilities position it as a promising alternative for wastewater treatment. This study presents an innovative and scalable solar water purification system applicable to a diverse range of water contaminants and manufacture in a cost-effective way.

Thermoeconomic modeling of new energy system based on biogas upgrading to multigenerational purpose

The following article outlines an integrated approach toward the valorization of biogas for energy, chilled water, hot water, freshwater, and liquid carbon dioxide production. The suggested system includes a biogas upgrading unit with a biomethane-fueled burner, a Kalian cycle, an LNG regasification process, and a multi-effect desalination unit that can provide CO2, electricity, cooling, and heating. The new ideas in the proposed system include a cryogenic biogas upgrading process that can be used in many industrial settings, the production of liquid carbon dioxide through biogas upgrading, and the use of biomethane in the integrated combustion process. Furthermore, the grey wolf optimization technique is applied in various multi-objective optimization contexts to achieve optimal operating conditions and preferred performance outcomes. In this simulation, the generation of electricity reaches a value of 755 kW. Attached to it is a cooling load of about 5102 kW, with a heating load of 4725 kW, freshwater capacity about 1.33 kg/s, production rate of liquid CO2 at 0.58 kg/s, and natural gas at 3.1 kg/s. Thermodynamic results reveal that the proposed multigeneration performance scheme providently enhances energy and exergy efficiencies up to 59.82 % and 5.74 %, respectively, compared to the condition of a single product. The performed exergy analysis shows that the overall irreversibility of the suggested configuration is equal to 18,047 kW while about 42.6 % of this value is contributed from the heat exchanger E-104. Moreover, the CO2 emission intensity of the process can be kept as 0.35 kg/kWh. Cryogenic separation can obtain about 88 % of CO2 in biogas and turn it into its liquid phase. The performed economic assessment has resulted in the following total cost rate as well as cost per unit exergy: 321.38 $/h and 83.06 $/GJ, respectively. Under optimal conditions, an exergy efficiency of 13.40 % and a net power output of 2034.39 kW are attained.

Green kaolin-tailored hydrophobic composite membrane for efficient desalination of high-salinity water

This study reports a novel approach to tune the surface and activate ceramic-polymeric based membranes from widely available and naturally occurring kaolin materials for the desalination of highly saline water via membrane distillation. Electrospraying was used to endow the membrane surface with a fine distribution of silica particles to build on roughness and enhance the grafting of long-chain (F21) fluoroalkyl silane (FAS). Interestingly, the adopted approach significantly transformed the surface properties from hydrophilic with water contact angle WCA ∼ 40° to superhydrophobic nature with WCA ∼ 160° along with significant increase in the liquid entry pressure. In air-gap membrane distillation with 70,000 ppm NaCl feed solution, the developed membranes exhibited a stable salt rejection (∼ 99.99 %) and a high water permeate flux of 9.3 kg/m2h. Notably, the membranes developed via the adopted approach outperformed direct FAS-modified kaolin membranes and other reported ceramic-based membranes. Hence, electrosprayed silica and subsequent FAS treatment approach on the membrane surface can effectively activate and make way for actual applications of the ceramic-based membranes for the desalination of highly saline water.

Review on advanced techniques in zero liquid discharge water desalination via humidification-dehumidification within thermally-driven transport reactors

The article examines an advanced zero liquid discharge (ZLD) desalination method focusing on humidification-dehumidification (HDH) in thermally driven transport reactors. The limited availability of water, particularly in dry locations, has prompted the advancement of several desalination techniques. Reverse Osmosis (RO) is a prevalent membrane technology in the market; however, it has restrictions regarding brine disposal. ZLD technologies strive to mitigate environmental consequences by transforming saltwater into drinkable water and precious salts while minimizing waste. Membrane Distillation and Crystallization (MD-C) is notable as a highly efficient Zero Liquid Discharge (ZLD) technique. Despite its high energy consumption, it can combine MD-C with renewable or waste energy sources to improve sustainability. Freeze Desalination (FD) was reviewed for its economic efficiency, especially when utilizing cold energy from liquefied natural gas (LNG). Hybrid systems that combine Forward Osmosis (FO) and membrane distillation with condensation (MD-C) can potentially improve water recovery and decrease energy usage. The HDH desalination process imitates the natural precipitation process, examines its ability to operate at low temperatures, and highlights its potential for integration with renewable energy sources. The review discusses the HDH design, the effect of salinity on its performance, and the different dehumidification technologies. It emphasizes the significance of creative methods in achieving sustainable water management.

Tailoring of Polypyrrole Wrapped Cotton Fiber Sponge for Simultaneous Solar Steam and Solar Thermoelectric Generation

AbstractSolar steam generation (SSG) using floatable evaporators to absorb solar energy and generate heat at the water–air interface has attracted increasing interest in achieving water purification and desalination. Using biodegradable and porous biomass materials as evaporators to fabricate high‐performance SSG devices is a promising route, but the poor efficiency and fussy and energy‐intensive manufacturing process for biomass material‐based evaporators will restrict their practical application. Here, an old commercial cotton quilt is used to prepare porous cotton fiber sponges (CFS) via a simple and scalable mechanical foaming strategy. After being decorated by the polypyrrole (PPy), the CFS@PPy sponge with a hierarchical porous structure shows broadband light absorption capacity, good hydrophilicity, and excellent photothermal capacity. The obtained sponge can be directly used as an evaporator floating on the seawater and shows a high steam‐generation efficiency of 85.07% under 1 sun irradiation. Additionally, it can be used as a photothermal material to construct a solar thermoelectric generation (STG) device and achieve an enhanced open‐circuit voltage (Vout) of 0.4 V and output current (Iout) of ≈59.6 mA under 5 sun irradiations. With the help of a boost converter, the power generation from the STG device can continuously charge the electric bulb and wristband.