Desalination Capability Research Articles

Dual redox centers in MnCo2O4 nanorod cathode for highly efficient capacitive deionization

Capacitive deionization (CDI) technology via faradic electrodes with active redox pairs has achieved tremendous success in desalination. However, the inner collaborative mechanisms of multi-redox centers in electrodes are rarely deep-analyzed. Thus, this work intensively investigated the inner enhanced mechanisms of multi-redox centers, starting from the dual-redox-based MnCo2O4 nanorod (MCO-NR) cathode in capacitive desalination. The electrochemical tests indicated a surface capacitive ratio of MCO-NR as high as 86 % when the scan rate was 100 mV s−1. Multi-dimensional CDI tests demonstrated that the highest capacity of MCO-NR could reach 61.78 mg g−1, with four theory models elaborating the electrosorption kinetics and maximum desalination capability. The refined ex-situ XPS measurements, carefully designed comparative experiments, and DFT calculations were used to analyze the Na+ (de)intercalation characteristics, the inner enhanced electrosorption mechanisms of dual redox centers, and the effects that the Mn redox center exerts on the MnCo2O4 structure. These results showed the superiority of dual- or multi-redox-center-based faradic capacitive desalination, providing a new perspective for designing high-property faradic electrode materials.

Selective Lithium separation from Li/Co/Ni mixtures using optimized flow-electrode capacitive deionization

The increasing need for lithium has heightened its significance as a crucial resource in numerous sectors, particularly in realms of portable electronics, electric vehicles (EVs), and large-scale energy storage systems. However, the finite availability of lithium resources and environmental concerns associated with its extraction underscore the significance of developing an efficient recycling method. In this study, we explored the potential of recovering lithium from waste battery leachate using an emerging technology known as flow-electrode capacitive deionization (FCDI). Unlike traditional capacitive deionization (CDI), FCDI offers continuous desalination capabilities, making it particularly suitable for recycling industries. While FCDI exhibits promise in recovering waste battery leachate, its inherent lack of selectivity presents a challenge. To address this issue, we tried to tune its selectivity towards lithium by employing a layer-by-layer deposition method to modify a cation exchange membrane (CEM) with poly(allylamine hydrochloride) (PAH) and poly(styrene sulfonate) (PSS) functional multilayers. This strategic modification of CEM was performed by alternatively depositing positively charged PAH and negatively charged PSS multilayers, which switched an innate divalent cation preference of CEM into a monovalent cation preference based on differences in ion sizes and charge densities. The membrane was used to treat a synthetic leachate mixture from wasted batteries, with a molar ratio of 30 mM:44 mM:4 mM for Li:Co:Ni, demonstrating a Li selectivity of 12.88 over Co and Ni with an exceptionally low energy consumption of 0.57 Wh/molLi. We believe our approach can lead to new technologies that address shortcomings of existing lithium recycling method and expand the application not only to lithium recycling, but also to future lithium production technologies and removal of specific ions such as for toxin removal.

Seed strategy synthesis of porous NASICON structured NaTi2(PO4)3/carbon aerogel nanocomposites for high-performance hybrid capacitive deionization

The limited capacity of conventional carbon electrode materials hinders the practical application of capacitive deionization (CDI). Hence, it is imperative to develop electrode materials with high sodium ion adsorption and reliable stability to facilitate the construction of hybrid CDI (HCDI) systems. Notably, NaTi2(PO4)3 (NTP) has received significant attention due to its high capacity and rapid transportation ability of sodium ions. However, the poor electrical conductivity and limited electrolyte contact area of NTP have prevented further improvement in its deionization capacity. Herein, we report a seed strategy to synthesize NTP/carbon aerogel (CA). P25 was used as a seed crystal to prepare TiO2/CA via the sol–gel method and supercritical CO2 drying. NTP/CA was then obtained from TiO2/CA by hydrothermal synthesis and calcination. This strategy preserved the rational network skeleton of CA and endowed NTP/CA with a high specific surface area of 420 m2/g. The enhanced electrical conductivity provided by CA yielded a remarkable salt adsorption capacity of 43.3 mg/g in a 500 mg/L NaCl solution and a stable cycle desalination capability. This work provides a new perspective for constructing three-dimensional, highly efficient and stable HCDI electrode materials.

Utilization of recycled materials for low-cost MXene synthesis and fabrication of graphite/MXene composite for enhanced water desalination performance

Access to clean and safe drinking water is essential to human health, economic progress, and ecological stability. Advanced materials have emerged to advance water treatment processes, particularly desalination, but are associated with the major challenge of being fabricated through environmentally taxing mining processes, which contributes to the carbon footprint. This study explores an innovative approach of using a renewable carbon-rich material derived from waste to create MXene nanocomposites that are applied to improve water thermal desalination. The synthesis of MXenes from recycled materials involves a series of chemical and exfoliation procedures, resulting in the production of two-dimensional nanosheets with exceptional electrical and mechanical properties. The integration of biomass offers a sustainable alternative to traditional precursors used for MXene preparation and introduces unique functional groups onto the MXene surface, which enhances its ability to absorb substances. This nanocomposite successfully produced solar evaporation rates of up to 3.0 kg m−2h−1 with 96.03 % solar steam conversion efficiency under single solar irradiation (1 sun). Through extensive characterization of SEM, FESEM, EDX, XRD, BET, contact angle, and performance assessments of desalination and water quality by ICP-OES, this study sheds light on the underlying mechanisms driving the improved water desalination capabilities of MXene composites. The composite materials show great mechanical properties, thermal stability, and chemical stability against acidic, alkali, and concentrated salty conditions. Mechanical robustness is the key advantage of this work. The findings underscore the importance of sustainable material utilization and highlight the potential of MXene composites as next-generation solutions for energy-efficient and environmentally friendly water desalination technologies.

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.

Tuning polyamide membrane chemistry for enhanced desalination using Boc-protected ethylenediamine and its in situ Boc-deprotection

The scarcity of freshwater resources, driven by rapid population growth and industrialization, underscores the urgent need for advanced desalination technologies. This research aims to meet this critical demand by enhancing the performance of polyamide membranes through innovative chemical tuning of the active layer. By strategically using Boc-protected ethylenediamine (EDA), we can precisely control the membrane’s surface properties. One amino group in EDA is protected with a Boc group, allowing the other to participate in the interfacial polymerization (IP) reaction with meta-phenylenediamine (MPD) and trimesoyl chloride (TMC). This inclusion of Boc-protected EDA enables in situ tuning of the active layer chemistry during polymerization. Subsequent removal of the Boc protection generates hydrophilic ammonium groups on the membrane surface, enhancing its desalination capabilities. As a result, three distinct membranes were fabricated and thoroughly characterized: MPD-TMC (control), MPD-TMC-EDA-Boc, and MPD-TMC-EDA-Deboc. At 20 bar and 2000 ppm NaCl feed, the MPD-TMC-EDA-Deboc membrane demonstrated superior desalination performance with a salt rejection of 98 ± 0.5% and a permeate flux of 25 L m−2 h−1; an increase of 25% compared to the control membrane. For the seawater nanofiltration (NF) permeate with a TDS of 33,700 ppm, a salt rejection of 97% and a permeate flux of 23 L m−2 h−1 was recorded at 20 bar. The MPD-TMC-EDA-Deboc membrane showed enhanced antifouling performance (95 ± 1% flux recovery) compared to the control MPD-TMC membrane with 93 ± 1% flux recovery. The Boc-protection/deprotection strategy demonstrated the high potential of this approach to significantly enhance the performance of polyamide membranes for desalination applications.

Study on preparation and performance of TiN modified vertically aligned carbon fiber evaporator

The application of solar photothermal conversion is currently one of the main ways to utilize solar energy, therefore it is crucial to find effective materials for photothermal conversion. In this study, carbon fiber evaporators (C-EVAP and R-EVAP) with vertically aligned carbon fiber structure were prepared from ramie and cotton using fiber bundling and carbonization, and then TiN-C-EVAP and TiN-R-EVAP were further obtained by modifying with TiN. The effects of precursor materials and TiN modification on the performance of the evaporators were discussed. The vertically aligned carbon fiber structure facilitates rapid moisture transport similar to the tree stem, enhances the internal reflection of light and improves light absorption. Compared to the short carbon fibers of cotton evaporators, ramie evaporators (R-EVAP and TiN-R-EVAP) with the long vertically aligned carbon fibers and multi-stage hollow structure have better photothermal conversion efficiency. Owing to the wide plasma resonance absorption spectrum and high absorbance of TiN, the TiN modification improves photothermal conversion efficiency of the carbon evaporators. The combination of long vertically aligned carbon fiber structure and TiN modification gives the ramie evaporator efficient photothermal conversion performance. The prepared TiN-R-EVAP has the best photothermal conversion efficiency with an evaporation rate of 1.96 kg·m−2h−1 and an evaporation efficiency of 91.29 % under 1 sunlight. It also has seawater desalination capability and excellent cycling stability, and the typical ion content of the TiN-R-EVAP desalinated condensate can meet the World Health Organization (WHO) standard for usable freshwater salinity. The vertically aligned ramie evaporators similar to the tree stem can be applied to the fields of photothermal conversion and seawater desalination.

Encapsulation hierarchical bimetallic oxide with flexible electrospinning carbon nanofibers for efficient capacitive deionization

Water scarcity, an intensifying issue, has spurred extensive research into the development of sophisticated freestanding pseudocapacitive electrode materials. Characterized by their precise morphology, intricate mechanics, and superior desalination capabilities, these materials are revolutionizing water treatment technologies. However, their broad adoption is hampered by complex fabrication processes and the necessity for various unique components. Herein, the paper introduces a streamlined method combining electrospinning and carbonization to produce a freestanding nitrogen-doped carbon nanofiber encapsulating manganese cobalt oxide (MCO) nanoparticles for desalination purposes. The approach significantly enhances interfacial interactions, mitigates volume shifts during sodium ion adsorption and desorption, and strengthens interfacial stability. Benefiting from its structural and compositional merits, the optimal MCO-1.0 electrode showcases exceptional electrochemical attributes. It achieves an impressive desalination efficiency (34.68 mg g−1), swift capacitive deionization rate (0.58 mg g−1 min−1), and superior cyclic durability. The study enhances our understanding of freestanding carbon fibers encapsulated with metal oxide nanoparticles, a key step toward developing robust electrodes for industrial applications.

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.

The role of ionic concentration polarization on the behavior of nanofluidic membranes

Water, the elixir of life, faces a pressing challenge—salinity. As humanity's demand for freshwater intensifies, the significance of efficient desalination processes becomes paramount. The promising prospects of nanofluidic membranes and unique electrokinetic phenomena like ion concentration polarization (ICP) signal optimistic strides in enhancing salt removal processes. This study is dedicated to elucidating the transport mechanism of buffer ions at interfaces between micro and nanochannels. To achieve this, we introduce a multiphysics coupling model that incorporates a boundary condition for the fixed surface voltage, offering a comprehensive description of the impact of nanochannel arrays. In this context, it is important to note that the nanochannel array is characterized by a positive charge density, akin to a cation exchange membrane (CEM), seamlessly integrated into the microchannel wall to serve as a cationic half-cell. The analysis involved solving governing equations, including the Poisson-Nernst-Planck, continuity, and Navier-Stokes equations, numerically using the finite element method in an unsteady state. Employing cylindrical nanochannel array configurations—single, dual, and triple—we scrutinized their impact on salt species concentration and removal efficiency under specified conditions (c0=1mM, ρv=2C/m3, LN=10μm, VT=26mV, Vsurr=4VT, VL/VR=8,t≥0.5 and ζ=−60mV). The single nanochannel array configuration demonstrated a relatively uniform salt distribution, achieving a removal efficiency of approximately 58%. The introduction of two nanochannel arrays at distinct locations resulted in a notable increase in removal efficiency, reaching 72%, particularly in the "down first" configuration, emphasizing a synergistic effect. The presence of three nanochannel arrays, each with varying lengths, produced intricate patterns, with the highest removal efficiency observed at 91% in the "different length" condition. This study emphasizes the superior desalination capabilities achievable through multiple nanochannel arrays, advancing our understanding of nanofluidic membrane applications for efficient water desalination. In conclusion, emulating electrodialysis membrane procedures, particularly by integrating an anionic half-cell, holds promise for further advancing desalination processes, offering a potential avenue to enhance efficiency.

Laser‐Induced Porous Graphene/CuO Composite for Efficient Interfacial Solar Steam Generation

AbstractInterfacial solar steam generation can produce clean water in an environmentally friendly and efficient way. The evaporator employing graphene as a photothermal conversion material represents an excellent paradigm within the realm of interfacial evaporators. However, existing graphene materials exhibit a certain degree of hydrophobicity and are associated with intricate manufacturing processes. Hence, the study proposes a hydrophilic composite graphene‐based material incorporating CuO, which is fabricated through a straightforward laser‐induced graphene synthesis method directly onto a polyimide film coated with CuCl2. Due to the fast capillary performance endowed by the enhanced hydrophilicity and hierarchical structural morphology, the assembled laser‐induced‐graphene evaporator achieves an evaporation rate of 2.54 kg m−2 h−1 under 1 sun irradiation with an evaporation efficiency of 91.1%, while also demonstrating excellent desalination capabilities. The as‐prepared graphene‐based evaporator has significant potential for desalination and wastewater treatment applications, offering an effective solution to address clean water challenges in remote areas.

Desalination Performance of MoS2 Membranes with Different Single-Pore Sizes: A Molecular Dynamics Simulation Study.

Utilizing molecular dynamics simulations, we examined how varying pore sizes affect the desalination capabilities of MoS2 membranes while keeping the total pore area constant. The total pore area within a MoS2 nanosheet was maintained at 200 Å2, and the single-pore areas were varied, approximately 20, 30, 40, 50, and 60 Å2. By comparing the water flux and ion rejection rates, we identified the optimal single-pore area for MoS2 membrane desalination. Our simulation results revealed that as the single-pore area expanded, the water flux increased, the velocity of water molecules passing the pores accelerated, the energy barrier decreased, and the number of water molecules within the pores rose, particularly between 30 and 40 Å2. Balancing water flux and rejection rates, we found that a MoS2 membrane with a single-pore area of 40 Å2 offered the most effective water treatment performance. Furthermore, the ion rejection rate of MoS2 membranes was lower for ions with lower valences. This was attributed to the fact that higher-valence ions possess greater masses and radii, leading to slower transmembrane rates and higher transmembrane energy barriers. These insights may serve as theoretical guidance for future applications of MoS2 membranes in water treatment.

Scalable NH4V4O10 clusters as functional network nodes on toughened porous carbon nanofibers for hybrid capacitive deionization

Layered vanadium-based compound (e.g., NH4V4O10) is acknowledged as an outstanding candidate for intercalation pseudocapacitance electrode of capacitive deionization (CDI) cells. However, the directed production of high-efficiency NH4V4O10-based self-supporting CDI electrodes and their structure–activity connection warrant more in-depth study. Herein, the delicate design and controllable construction of NH4V4O10 clusters on the freestanding porous carbon nanofiber (PCNF) scaffolds (the composite PCNFs/NH4V4O10 is defined as CNVO) using a new organic reducing agent of citric acid is proposed, where NH4V4O10 clusters as functional network nodes can improve the mechanical toughness, electrochemical capacitive performance, and desalination capability of the CNVO hybrid. The Na+ adsorption mechanism on CNVO is confirmed by ex-situ experimental characterizations and density functional theory (DFT) calculations. The hybrid CDI (HCDI) cell composed of the optimized CNVO cathode and PCNFs anode shows a desirable desalination capacity (45.07 mg g−1), a superior salt removal rate (16.4 mg g−1 min−1), an excellent energy utilization, and an acceptable cyclic regeneration ability in 500 mg L-1 NaCl solution. More importantly, the assembled HCDI system is promising for the desalination of reclaimed water from the printing and dyeing enterprise. This work highlights a scalable strategy that is experimentally and theoretically feasible to design and fabricate high-efficiency CDI electrodes.

Bio-inspired co-deposition of dopamine and N-oxide zwitterionic polyethyleneimine to fabricate anti-fouling loose nanofiltration membranes for dye desalination

Developing anti-fouling loose nanofiltration membranes (LNMs) that can achieve dye desalination of saline textile wastewater through dye retention and salt permeation for resource utilization remains an urgent challenge that needs to be addressed. Inspired by the biomimetic adhesion of mussels and the excellent fouling resistance of saltwater fish surfaces, novel LNMs were prepared through co-deposition strategy using dopamine (DA) and N-oxide zwitterionic polyethyleneimine (ZPEI) as biomimetic functional materials. There are multiple interactions between them, including Schiff base reaction, Michael addition reaction, cation-π interaction and covalent polymerization. Compared with PEI-LNM prepared under the similar method, the optimized ZPEI-LNM displays more uniform surface, smaller average roughness (6 nm vs 22 nm), and denser pore size (0.69 nm vs 0.79 nm), indicating the zwitterionic N-oxide moieties in ZPEI regulate the deposition process and the cross-linking structure of the selective layer. ZPEI-LNM exhibits a high pure water flux of 203.0 L m−2h−1 under 0.6 MPa. Importantly, ZPEI-LNM shows high retention towards different dyes, including Congo red (CR, negative, 696.8 g/mol) of 100.0 %, Acid fuchsin (AF, negative, 585.5 g/mol) of 99.5 %, Crystalline violet (CV, positive, 408.0 g/mol) of 98.2 %, and Indigo carmine (negative, 466.4 g/mol) of 96.0 %, while the rejection of NaCl (8.7 %) and Na2SO4 (12.7 %) are both lower. As expected, for the mixture solution of AF/NaCl, the dyes are efficiently rejected, while salts can pass through, indicating that ZPEI-LNM displays an excellent dye desalination capability. Furthermore, multiple-cycle antifouling tests for bovine serum albumin (BSA) and sodium alginate (SA) reveal that the flux recovery ratios are higher than those of PEI-LNM (BSA: 90.4 % vs 81.9 %; SA: 86.6 % vs 80.5 %), indicating ZPEI-LNM exhibits better anti-fouling performance towards different model foulants owing to the outstanding hydration layer caused by zwitterionic N-oxide moieties and lower surface roughness. Consequently, the work offers a new viewpoint for the fabrication of anti-fouling LNMs via biomimetic strategy for dye desalination.

Asymmetric capacitive deionization based on pore structures of biochar

Biochar is an affordable and sustainable material for the application of capacitive deionization. Although the desalination capability of biochar is significantly impacted by its pore size distribution, the correlation between them is challenging to explore due to the uncontrollable pore size. This study exclusively utilizes different activation mechanisms to regulate the pore size distribution of carbon derived from the same biomass precursor, and explores the role of pore structures in capacitive deionization. The specific capacitance of microporous biochar (MiB) can reach up to 319.1 F/g (0.2 A/g), with an Epzc of 0.11 V and high oxygen content, while mesoporous biochar (MeB) has a specific capacitance of only 170.4 F/g, an Epzc of 0 V, and a small charge transfer impedance. The MeB//MiB desalination cell is designed based on these characteristics and demonstrates a higher salt adsorption capacity of 17.04 mg/g at 1.2 V, compared to MiB//MiB (15.72 mg/g) and MeB//MeB (6.07 mg/g), alongside a stability of 81 % after 50 cycles. These capabilities can be attributed to the expanded voltage range resulting from the different Epzc, and the high ion storage capacity of MiB, as well as the fast ion transport capability of MeB. The oxygen/carbon ratio of the anode in MeB//MiB increased by only 42 %, whereas that in MiB//MiB increased by 370 %, confirming the oxidation inhabitation ability of the asymmetric structure and the oxidation resistance of MeB. Therefore, constructing ideal pore structures and more importantly reasonable deployment is an effective strategy for improving desalination capacity and stability.

Unveiling the role of Atomic-Level “Pump-Driven” effect in MoS2/MnO2 for facilitating directional charge transfer in hybrid capacitive deionization

In addressing the limitations imposed by the inherently low electronic conductivity and substantial ion transfer resistance of transition metal oxides (TMOs) in hybrid capacitive deionization (HCDI) applications, this study delineates a pioneering approach through the fabrication of a MoS2/MnO2 heterostructure, leveraging manganese dioxide (MnO2) as a model system. The investigation underscores the essentiality of constructing high-quality interfaces to act as conduits for directional charge flow, a critical but formidable challenge for enhancing desalination efficacy in electrode materials. By harnessing an atomistic “pump-driven” mechanism, the MoS2/MnO2 heterostructure demonstrably facilitates the promotion of desalination processes, underscored by the establishment of a potent local electric field (IEF) aimed at commanding charge dynamics. Empirical and computational analyses coalesce to unveil the preferential electron transfer from MoS2 to MnO2, a phenomenon precipitated by charge redistribution. This orchestrated charge flow not only augments electronic and ionic transfer efficiencies but also emboldens the MoS2/MnO2 heterostructure with enhanced desalination capabilities. The results show that MoS2/MnO2 demonstrates superior HCDI performance compared to MnO2 in a 500 mg L-1 NaCl solution at 1.2 V, with SRC of 33.21 mg g-1 and SRR of 1.50 mg g-1 min-1. The elucidation of this charge-guided dynamic, achieved through meticulous manipulation of the electronic microstructure and the IEF at the atomic scale, presents a novel paradigm for material science. This research presents an innovative approach for realizing robust charge-guided dynamics through the deliberate manipulation of the electronic microstructure and IEF of materials, employing an atomic-level “pump-driven” effect. This strategy opens new avenues for extending these principles to a broad array of advanced materials.

Work-function-prompted interfacial charge kinetics in hierarchical heterojunction flexible electrode for efficient capacitive deionization

The growing challenge of water scarcity has spurred extensive research into the development of advanced freestanding pseudocapacitive electrode materials. These electrodes, characterized by their controlled morphology, mechanical complexity, and enhanced desalination capabilities, are advancing water treatment technologies. Additionally, electrodes with interfacially influenced heterostructures demonstrate substantial potential to enhance electrochemical kinetics. However, their widespread adoption is hindered by intricate synthesis procedures and the necessity for multiple discrete components. Herein, the report introduces a cohesive approach that utilizes electrospinning and carbonization to create a freestanding, hierarchically porous nitrogen-doped carbon nanofiber network encapsulating FeNi3 alloy (FeNi3@CNFs) for desalination applications. The method enhances the interfacial effect, mitigates volume changes during sodium ion adsorption and desorption, and improves interfacial stability. By capitalizing on structural and compositional advantages, the novel FeNi3@CNFs electrode delivers outstanding electrochemical properties, including a high desalination capacity (46.47 mg g−1 at 1.2 V), rapid desalination rate (0.77 mg g−1 min−1), and enhanced cyclic durability. Computational analysis via Density Functional Theory shows that the work function prompts a surface charge redistribution at the FeNi3@CNFs heterojunction, optimizing the surface electronic structure and reducing the energy barrier for adsorption. The modification significantly boosts the diffusion kinetics of sodium adsorption. The study delineates a comprehensive methodology for fabricating high-performance heterostructured electrode materials that are effective for capacitive deionization.

RGOs-AgNPs/PVA composite sponges for efficient solar saltwater evaporation

With an increasing demand for seawater desalination, fabricating photothermal materials with low cost, high photothermal conversion efficiency, and excellent mechanical stability is necessary but remains challenging. In this work, reduced graphene oxide nanosheets (RGOs) and silver nanoparticles (AgNPs) doped polyvinyl alcohol (PVA) sponges (RGOs-AgNPs/PVA) are fabricated by the mechanical foaming and impregnation reduction method, which combine the flexible porous structure of PVA sponges with the photothermal properties of RGOs-AgNPs. The incorporation of RGOs-AgNPs enhances the surficial hydrophobicity and reduces the accumulation of water on the surface, and the photothermal synergistic effect of RGOs-AgNPs enhances the water evaporation rate. The results showed that the evaporation rate of RGOs-AgNPs/PVA was 2.09 kg m−2 h−1 and the photothermal conversion efficiency was 94.2 % under standard sunlight intensity of 1 sun (1.0 kW m−2). Furthermore, the long-term stability and effective desalination capability of the RGOs-AgNPs/PVA solar evaporation device offer a potential opportunity for massive seawater desalination. Therefore, this work shows the prospect of combining flexible porous sponges with photothermal materials for practical solar evaporation.

Tailoring hierarchical structures in cellulose carbon aerogels from sugarcane bagasse using different crosslinking agents for enhancing electrochemical desalination capability

Sugarcane bagasse is one of the most common Vietnamese agricultural waste, which possesses a large percentage of cellulose, making it an abundant and environmentally friendly source for the fabrication of cellulose carbon aerogel. Herein, waste sugarcane bagasse was used to synthesize cellulose aerogel using different crosslinking agents such as urea, polyvinyl alcohol (PVA) and sodium alginate (SA). The 3D porous network of cellulose aerogels was constructed by intermolecular hydrogen bonding, which was confirmed by Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and nitrogen adsorption/desorption. Among the three cellulose aerogel samples, cellulose – SA aerogel (SB-CA-SA) has low density of 0.04 g m−3 and high porosity of 97.38%, leading to high surface area of 497.9 m2 g−1 with 55.67% micropores of activated carbon aerogel (SB-ACCA-SA). The salt adsorption capacity was high (17.87 mg g−1), which can be further enhanced to 31.40 mg g−1 with the addition of CNT. Moreover, the desalination process using the SB-ACCA-SA-CNT electrode was stable even after 50 cycles. The results show the great combination of cellulose from waste sugarcane bagasse with sodium alginate and carbon nanotubes in the fabrication of carbon materials as the CDI-utilized electrodes with high desalination capability and good durability.

COMPARISON OF BRACKET WATER DESALINATION TESTS IN THE FORM OF POWDER, GRANULES AND GREEN ALGAE HYDROGEL

This research was motivated by the problem of lack of clean water around the coast of Rainbow Beach in Karawang because the water quality is poor and still brackish. Untreated brackish water poses a risk to human health if drunk for a long time and can trigger skin diseases if used for bathing. The well water taken is located in the Pelangi Coastal Area, Pedes Karawang. This research aims to test the ability of brackish water desalination using powder, granules, and three variations of green algae hydrogel. This research uses a quasi-experimental method by comparing it with zeolite as a standard for brackish water desalination. The research results show that the resulting hydrogel preparation has a solid, brittle shape, a dark green color, and a distinctive odor of green algae. The best viscosity value is in the H4 formula. All green algae hydrogel formulas have good pH values, while the best swelling ratio value is in the H2 formula, and the best gel fraction value is in the H4 formula. From the results of the research that has been carried out, it can be concluded that the hydrogel, granule, and green algae powder preparations can desalinate brackish water based on the results of pH, temperature, salinity, sodium ion, and magnesium ion tests compared with zeolite, where the 6 g hydrogel preparation shows the best desalination capability of brackish water at the three well sample points