Ion Exchange Process Research Articles

Resilient Nitrate Removal by a Biological Nitrate-Selective Ion Exchange (BIO-NIX) Process

Resilient Nitrate Removal by a Biological Nitrate-Selective Ion Exchange (BIO-NIX) Process

A promising approach to prepare gel electrolyte and electrocatalyst derived from natural long-staple cotton for high-performance flexible Zn-air battery

Due to the high energy density and risk-free operation, flexible zinc–air batteries (ZABs) have the potential to be energy sources for wearable electronic devices. Nonetheless, the performance of quasi-solid-state gel electrolytes diminishes progressively throughout the ion-exchange process, primarily due to water evaporation on the exposed cathode side, which shortens the useful lifetime of ZABs. Herein, we propose a distinctive gel polymer electrolyte membrane comprising cotton fiber (CF) from natural long-staple cotton and polyvinyl acetate (PVA) to effectively extend the battery lifespan, which is due to that the addition of CF improves surface wettability, liquid absorption and retention, and ionic conductivity (1.53 × 10−2 S cm−1) compared with single PVA electrolyte membrane. We also prepare a composite electrocatalyst (Co-N-C@GCF-950) by pyrolyzing the precursor of ZIF-67 in situ grown on the cotton fiber at 950 ℃. The flexible ZAB assembled with Co-N-C@GCF-950 as the cathode electrocatalyst and the CF-PVA membrane as the gel electrolyte shows a high open-circuit voltage of 1.5 V, and a stable charge-discharge voltage gap of 0.8 V for 11-h lifespan at a current density of 2 mA cm−2 under various bending conditions, which guides the future way of the application potential of environmental cotton fibers in the multiaspects for flexible metal-air batteries.

Fluorescence sensing and adsorption kinetics of Gd-doped AgInS2 I-III-VI quantum dots – A case study of Ag+ ions interactions

The poor fluorescence properties of magneto-fluorescent paramagnetic-ion (Gd, Mn, or Co) doped I-III-VI quantum dots (QDs) at higher paramagnetic-ion doping concentrations have limited their use in magnetic-driven water-based applications. This work presents, for the first time, the use of stable magneto-fluorescent Gd-doped AgInS2 QDs at high Gd mole ratios of 16, 20, and 30 for the fluorescence detection and adsorption of Ag+ ions in water environments. The effect of pH, initial concentration, contact time, and adsorbent dosage were systematically evaluated. The AgInS2 QDs with the least Gd mole ratio (16) exhibited the best fluorescence characteristics (LOD = 0.88, R2 = 0.9549) while all materials showed good adsorption properties under optimized conditions (pH of 2, initial concentration of 30 ppm, contact time of 10 min and adsorbent dosage of 0.02 g) and a pseudo 2nd order reaction was followed. The adsorption mechanism was proposed to be a combination of ion-exchange, electrostatic interaction, complexation, and diffusion processes. Application in environmental wastewater samples revealed complete removal of Ag + ions alongside Ti2+ Pb2+, Ni2+, Cr3+, and Zn2+ ions.

Groundwater Hydrochemistry and Aquifer Identification at Wana Area, Northwest of Mosul, Iraq

The suitability of groundwater for various uses is primarily determined by its major ions content, which is determined by its hydrochemical properties, including geogenic and anthropogenic factors. To gain a deeper understanding of groundwater management and sustainability in Wana, one of the most important agricultural areas northwest of Mosul, 18 wells were chosen and groundwater samples were taken from them over two seasons (October 2020 and April 2021) and their physicochemical properties were analyzed. The Piper diagram revealed that the most common type of groundwater in the study area is Ca-SO4. The mineral saturation index, cation exchange values, and Gibbs diagram results revealed that rock dissolution and weathering processes, including both gypsum and carbonate rocks, dominated the chemistry of groundwater in the region, with clastic rocks and ion exchange processes having a limited effect. This is also confirmed by the findings of the Principal Component Analysis, which further revealed that there is an effect of an anthropogenic factor caused by agricultural activities on the concentration of NO3-. The Cluster Analysis results revealed three groups of wells based on the water-bearing layers: those that draw water from the Quaternary deposits aquifer, those that draw water from the Fatha Formation aquifer, and those that draw water from both aquifers. The findings of this study can contribute to the preservation and sustainability of groundwater, as well as the optimal management of this crucial resource in the studied region.

Extricating hydrogeochemical evolution of geothermal fluids of an unexplored section in North-Eastern Himalayas, Arunachal geothermal province, India

The thermal springs of the study area are situated in North-eastern Arunachal Himalayas, India along Subansiri and Siang River valleys with surface temperature ranging between 20 and 57 °C. The pH of thermal springs varies from 7.69 to 9.31, indicating near neutral to alkaline nature of thermal and non-thermal waters. The major geochemical processes influencing hydrochemistry are demonstrated using conventional graphical plots, geochemical modelling by PHREEQC and multivariate statistical analysis. The thermal waters of Chetu and Taksing in Subansiri valley are primarily Na–Cl and Na–HCO3 type, while, thermal water of Yangte in Siang valley is also mixed water-type and others of Ca–Mg–HCO3 type. The geochemically distinct type of waters is obvious from dendrogram derived from hierarchical cluster analysis. Quartz geothermometer predicts reservoir temperatures of thermal springs of 88 ± 13 °C; while, Na–K Giggenbach geothermometer predicts 182 °C and 176 °C for Chetu and Taksing hot springs. Thermal waters are immature and highly prone to mixing with meteoric waters as evident from enthalpy-chloride modelling. Evaporite dissolution, silicate weathering and ion exchange processes are found to contribute to total ion budget in geothermal waters. The saturation indices studies depict oversaturation of all thermal waters with calcite and dolomite. Considering all geochemical features, a conceptual hydrological model resembling geomorphology and origin of thermal springs of North-Eastern Arunachal Himalaya has been proposed. The thermal waters of Subansiri valley display very high Sr and F− content which prohibit them from drinking and utilization purposes. High concentration of toxic elements is addressed to geogenic causes over anthropogenic contributions due to lesser accessibilities at hot spring spots.

A harmless slagging treatment to separate key impurities from Fe-PGMs alloys for improving the recovery ratio of PGMs from spent auto-catalysts

Spent auto-catalysts are main secondary resources for platinum group metals (PGMs) Pt, Pd, and Rh. Considering their scarcity and excessive prices, recycling PGMs from spent auto-catalysts is important for sustainability of PGMs. The dissolution of Fe-PGMs alloys in acids is an important step that significantly influences the recovery ratio of PGMs from spent auto-catalysts by smelting using Fe as a PGMs collector. However, the presence of impurities, such as Si, in Fe-PGMs alloys makes them difficult to completely dissolve in acids, resulting in low PGMs recovery ratios. Few studies have been reported on solutions for eliminating these impurities from the Fe-PGMs without loss of PGMs. In this study, a green slag refining process was proposed to remove key impurities from Fe-PGMs alloys. Different compositions of CaO-SiO2-Al2O3-FeOx and CaO-Al2O3-FeOx slags were investigated to improve the removal of impurities such as Si, Ca, Mg, Ti, and Al in Fe-PGMs to increase the total recovery ratios of PGMs; the removal rates of Si, Ca, Al, Mg, and Ti were 99.2 %, 99.8 %, 99.8 %, 99.7 %, and 99.9 %, respectively, when a CaO-Al2O3-35Fe2O3 (C/A = 1.5; S/A = 1.2) slag was used at 1843 K. After slagging treatment, Fe-PGMs alloy could be easily dissolved in aqua regia, which is conducive to subsequent ion exchange or supramolecular recognition process to obtain high PGMs recovery ratios. This slagging treatment is considered a green and economic approach as the residual slag exhibits no hazardous elements and can be recycled or reused to prepare other products.

Applications of ion exchange resins in environmental remediation

AbstractThe presence of various types of contaminants such as heavy metals, emerging organic contaminants, pesticides, organic waste, organic dyes, radionuclide's, fluorides, etc. cause water pollution. These pollutants are of concern to engineers, environmentalists and scientists. Due to the lack of freshwater, it is very important to recycle the wastewater after treatment to remove organic contaminates and heavy metal pollutants. Chemical precipitation, ion exchange, adsorption, filtration via membranes, flocculation, coagulation, flotation, and electrochemical techniques are just a few of the methods used to eliminate contaminants from wastewater. The most popular and effective among these is the ion exchange process. New generation hybrid materials, inorganic three‐dimensional matrices and synthetic organic resins are some examples of the different types of ion exchange resins. Most investigations have found that pseudo‐first and second order kinetic studies are important in the contaminant removal process. The isotherm model, which also incorporates the Langmuir, Freundlich, Dubinin Radushkevich, and Temkin equations, proved appropriate for most of the research. For an example, orgnic polymeric materials can maximum uptake capacity of 4.28 mmolg‐1 Cr(VI) and 1.97 mmolg‐1 As(V) respectively. The effectiveness of ion exchanger and its current trends in various environmental applications have been the main topics of this review article.

Thermal stability and thermal conductivity of stacked Cs intercalated layered niobate

Layered materials exhibit competitively low thermal conductivity along the out-of-plane direction. The solution process is a promising method for preparing stacked structures. However, the thermal stability of the layered materials is poor after processing in solution, thus hindering their applications at high temperatures. One of the solutions to improve the thermal stability of layered structures is to expand the interlayer distance by inserting large-size metal ions. In this work, we studied the thermal properties of Cs+ intercalated layered niobate obtained by the ion-exchanged process. The layered structure of the Cs+ intercalated layered niobate survives after thermal treatment even at 1200 °C. The room temperature thermal conductivity of as prepared stacked Cs–HCa2Nb3O10 is as low as 0.11 W m−1 k−1. Upon thermal annealing, the thermal conductivity increases. After annealing at 1200 °C, the value is 0.90 W m−1 k−1. The finding suggests Cs+ intercalated layered niobate is a promising material for high-temperature insulation applications.

CaAl–NO2 LDH hybrid self-healing microcapsules with chloride triggering: Towards synergistic corrosion resistance

The synergistic corrosion resistance microcapsules (SCRMs) were synthesized by utilizing CaAl–NO2 LDH (NO2-LDH) as chloride trigger and high-performance corrosion inhibitor to hybridize self-healing microcapsules. The morphology, chemical structure and self-healing performance of the microcapsules were characterized. The chloride triggering and corrosion resistance property of the SCRMs were evaluated. The interaction of hybrid wall, NO2-LDH and chloride ion was calculated by first-principles. The findings revealed that the microcapsules show regular spherical with obvious core-wall structure. EDS and chemical structure measurements confirmed that NO2-LDH was successfully embedded within the microcapsule wall. The SCRMs showed excellent corrosion resistance property in simulated chloride-contaminated concrete pore solution (SCPS), and the highest inhibition efficiency was 97.85%. The microcapsule wall was hybridized by NO2-LDH species through chemical pathways. The first-principles calculation results confirmed that Ca and Al species are the main factors for chloride ion immobilization of hybrid wall. The ion exchange process of microcapsules destroys the molecular force of NO2-LDH@ethyl cellulose hybrid wall and improves the mechanical triggering efficiency of microcapsules in cement-based composites.

Kinetic research on ion exchange regeneration of quaternary ammonium-based CO2 sorbent for direct air capture

To satisfy the Paris Agreement's 1.5 °C goals, direct air capture (DAC) has become an increasingly crucial technology. However, the ultralow partial pressure of CO2 in ambient air contributes to a low desorption rate and high regeneration energy consumption. In this study, we proposed a fast regeneration method for CO2 sorbents based on an ion exchange process. Utilizing an alkaline solution rich in hydroxide (OH–) ions, the quaternary ammonium (QA)-based ion exchange resin can be changed from carbonate (CO32–) to OH– form, which directly captures CO2 from ambient air. The results showed that the working capacity of the sorbents in the OH– form was 1.85 mmol⋅g−1, which was double that of the CO32– form (0.88 mmol⋅g−1). The kinetics showed that the ratio of OH–/HCO3– at inlet, concentration, and external diffusion influence the desorption rate of CO32– because of the ion exchange reaction. With a high ratio of OH–/HCO3– at inlet, 1 M alkaline solution, and 3 mL⋅s−1 cyclic flow rate, the desorption time of the sorbents was approximately 20 min. Finally, because the energy consumption of the entire process comprises mainly electric energy required to regenerate the alkaline solution after ion exchange, it is expected to establish an electrochemical DAC system to utilize renewable energy efficiently.

Composition-driven morphological evolution of BaTiO3 nanowires for efficient piezocatalytic hydrogen production

Hydrogen production from water by piezocatalysis is very attractive owing to its high energy efficiency and novelty. BaTiO3, a highly piezoelectric material, is particularly suitable for this application due to its high piezoelectric potential, non-toxic nature, and physicochemical stability. Owing to the critical role of morphology on properties, one-dimensional (1D) materials are expected to exhibit superior water-splitting performance and thus there is a need to optimise the processing conditions to develop outstanding piezocatalysts. In the present work, piezoelectric BaTiO3 nanowires (NWs) were hydrothermally synthesised with precursor Ba:Ti molar ratios of 1:1, 2:1, and 4:1. The morphology, defect chemistry, and hydrogen evolution reaction (HER) efficiency of the as-synthesised BaTiO3 NWs were systematically investigated. The results showed that the morphological features, aspect ratio, structural stability and defect contents of the 1D morphologies collectively have a significant impact on the HER efficiency. The morphological evolution mechanism of the 1D structures were described in terms of ion exchange and dissolution-growth processes of template-grown BaTiO3 NWs for different Ba:Ti molar ratios. Notably, the BaTiO3 NWs synthesised with Ba:Ti molar ratio of 2:1 displayed high crystallinity, good defect concentrations, and good structural integrity under ultrasonication, resulting in an outstanding HER efficiency of 149.24 μmol h−1g−1 which is the highest obtained for nanowire morphologies. These results highlight the importance of synthesis conditions for BaTiO3 NWs for generating excellent piezocatalytic water splitting performance. Additionally, post-ultrasonication tested BaTiO3 NWs demonstrated unexpected photocatalytic activity, with the BTO-1 sample (1:1 Ba:Ti) exhibiting 56% photodegradation of RhB in 2 h of UV irradiation.

Synthesis of Zeolites from Coal Fly Ash Using Alkaline Fusion and Its Applications in Removing Heavy Metals

The article presents studies of the influence of parameters of synthesis modes and alkali concentration on the synthesis of zeolite materials from coal fly ash (CFA). The purpose of the study was to synthesise zeolite materials from CFA using the method of alkaline fusion and to determine the susceptibility of selected heavy-metal ions to removal from solutions in an ion exchange process on a selected mesoporous zeolite. It was found that the crystalline phase of sodalite was dominated in all of the samples synthesized. The specific surface area (SBET) of the samples was evaluated using the standard Brunauer–Emmett–Teller (BET) method using N2 sorption. Crystalline zeolite materials have been used to study the efficiency of removing heavy metals from aqueous solutions of Ni2+, Cd2+ and Pb2+. The adsorption data were analyzed using the Langmuir and Freundlich isotherm model. When comparing the estimated coefficient of determination (r2), it was noticed that the sorption data are more accurately described by the Langmuir isotherm and the pseudo-second-order kinetic model. The results of metal adsorption experiments suggest that the synthesized zeolite material has great potential to be used as an inexpensive and alternative source in the production of adsorbents.

A novel ion exchange-electrodialysis hybrid system to treat rare-earth oxalic precipitation mother liquid: Contamination reduction, efficient Y3+ recovery, and acid separation

A novel ion exchange process combined with selective electrodialysis (SED) process has been demonstrated to not only efficiently recover low concentration rare-earth elements (REEs) and separate hydrochloric acid, but also significantly reduce membrane fouling. Two resins with different functional groups were selected for pretreatment and recovery of Y3+ from Y rare-earth oxalic precipitation (Y REOP) mother liquor. CH-93 resin showed a Y recovery rate of over 94 %, and the Y recovery efficiency remained above 90 % after 5 cycles. The mother liquor treated with resin (R-T) and the untreated mother liquor (W-R-T) were subjected to acid separation via SED, and membrane fouling was systematically evaluated. Compared with W-R-T group, the hydrochloric acid recovery efficiency of R-T group increased by 21.01 % (12 V), and the unit energy consumption decreased by 54.30 % (12 V). The results of 3D fluorescence excitation-emission matrix (3D-EEM) and fluorescent region integration (FRI) showed the dissolved organic matter (DOM) on AEM and CEM in R-T group both decreased by >45 %. The AEM of W-R-T group showed the highest fluorescence intensity ratio in V region (36 %), indicating humic acid-like substances were the main cause of AEM fouling. Generally, this study provides a new approach for the resource utilization of REOP mother liquor.

Behaviour of barium in the tropical estuaries: Implications to its marine budgets and paleo-oceanographic applications

Marine Barium (Ba) is extensively used as a tracer for biogeochemical processes and paleo-oceanographic proxy for past river discharge, salinity, and long-term hydrological changes. However, poor constrain on the riverine Ba flux to oceans due to its modification in the estuary hinder such applications. The prerequisite for an accurate Ba flux estimate is to have a detailed understanding of Ba behaviour, extent of modifications in the estuary, and net input to the ocean. A comprehensive study of Ba was conducted in four Indian estuaries draining through diverse geological/tectonic settings under different climatic regimes, such as the Narmada, Tapi, and the Mandovi falling into the Arabian Sea and the Hooghly (a distributary of the Ganga) into the Bay of Bengal. Dissolved Ba distributions in the surface waters of these estuaries exhibit nonconservative behaviour along the salinity gradient, exhibiting a systematic gain of Ba at low (∼2.5–7) salinity in the Hooghly and mid-salinity (∼8–18) in the estuaries linked to the Arabian Sea. The Ba gain is attributed to its release from the particulates and contributions via submarine groundwater discharge (SGD). The Ba gain in the Narmada and the Hooghly estuary was higher during nonmonsoon despite lower riverine sediment supply and SGD compared to monsoon, suggesting that tidally induced resuspension of estuary sediments and solute-particulate interactions that release Ba through the ion exchange process are the primary driver in determining surface water Ba distributions in these estuaries. The estimate of excess Ba supply in these estuaries is much higher than its riverine supply, ∼4 times higher in the Hooghly to ∼30 times in the Narmada estuary. The estimate of excess Ba supply from the global estuaries ∼4.5 Gmol yr−1 is comparable to global riverine supply∼5.5 G mol yr−1, highlighting its significant role in global marine budgets. Mass balance calculation of Ba suggests that SGD and particulate release contribute an average of ∼17% and ∼ 32% of the total dissolved Ba in the Hooghly estuary, whereas ∼10% and ∼ 76% in the Narmada estuary respectively. The Ba/Ca ratio shows inverse relation with salinity and is compatible with the exponential fits. Extrapolation of the Ba/Ca-salinity relation to open ocean Ba/Ca ratio yields salinity of ∼35 in the Hooghly, close to the average open ocean salinity within ∼10% uncertainty, whereas it yields salinity ∼41 in the Narmada (pre-monsoon), which translates to large uncertainty (∼20%) due to huge release of particulate Ba. This uncertainty could further amplify in longer time scales (e.g. glacial-interglacials) due to sea level and climate changes and its impact on estuarine process. Therefore, regional calibrations in conjunction with other constraining proxies are the way forward to employ Ba/Ca ratio as a paleo-oceanographic proxy in coastal oceans.

Study on surface modification and optical properties of Nd-doped phosphate glass

Using laser neodymium glass (N31) as the substrate, through ion exchange and hydrogen reduction process, a high-efficiency light absorption layer was formed from the substrate around the glass. It has been discovered that increasing the ion exchange temperature and time enhanced the exchange depth of laser glass, but excessive temperature and prolonged time will lead to corrosion of laser glass. The experiment shows that the best exchange temperature is 460°C and the best exchange time is 720min. When the hydrogen pressure was 0.8MP, the reduction temperature was 480°C and the reduction time was 12000 min, the absorption rate of the sample at 1053nm was 95.8%.

Reclamation of urban pollution impacted groundwater by advanced treatment processes: Effect of prechlorination on the removal of metals, ammonium and NOM at pilot scale

The need for new water resources in water scarcity regions has driven the exploration of water reclamation through a variety of treatment technologies. The present study aims at reclaiming impacted urban groundwater through two different treatment routes: one based on adsorption and ion-exchange processes on consecutive pyrolusite, granular activated carbon, zeolite and Fe(oxy)hydroxide filters (route L1) and a second one relying on sorption (on pyrolusite) and RO-membrane filtration (route L2). Both routes were operated without and with prechlorination to ascertain whether NaClO, beyond inactivating undesired pathogens, affected the removal of target parameters (Mn, As, NH4+, DOC) and the formation of trihalomethanes (THMs). Results showed that route L1 was successful at removing Mn, As, pathogens and THMs at levels below those stipulated by the legislation on reuse and drinking water. Only NH4+ failed to decrease below its threshold limits for drinking water, but only in the absence of prechlorination. However, concentration of Cl− and Na+ increased during treatment due to the chemicals used, compromising reuse of the produced water in specific industrial sectors requiring low contents of these ions. Route L2 showed a consistent high removal of all targeted parameters (also NH4+) without and with prechlorination conditions, producing a finished water with high potential for reuse and production of drinking water. DOC and its fluorescent fulvic and humic-like fractions were moderately removed by route L1 but highly removed by route L2. The outperformance of route L2 in terms of produced water quality must be balanced by the associated treatment cost, as it was 8–10 % higher for route L2 than for route L1. This made evident that a trade-off between quality and cost must be faced. This study demonstrates that reclamation of urban groundwater through the proposed treatment routes has a huge potential for reuse for a wide diversity of final purposes (urban, agricultural, industrial, environmental and recreational uses) and, although it may need further exploration, likely for drinking water purposes.

Hexagon flower-shaped architectures constructed of Fe-composited lanthanum hydroxide nanosheets for superior phosphate removal: Synthesis and mechanism study

In response to phosphorus pollution, developing functional materials for phosphate adsorption is an ideal method to reach an ultralow phosphate concentration in effluent. Herein, a hexagon flower-shaped architecture constructed of Fe-composited lanthanum (La)-based hydroxide nanosheets was fabricated from LaFe cyano-bridged metal frameworks (CMs) via a self-templating strategy using NH3‧H2O as the conversion reagent. The ion exchange process using weak alkaline reagent enables the formation of secondary nanosheets on the architecture, thus leading to a high surface area and a large number of mesopores that provide abundant active sites and mass transfer channels for phosphate adsorption. A superior adsorption capacity of 127.5 mg P/g can be obtained on the La/Fe-based architecture, which also shows satisfactory applicability over a wide pH range. A ligand exchange between -OH and phosphate ions is verified as the main adsorption mechanism, which properly accounts for its excellent selectivity for phosphate adsorption when coexisting with other anions/cations and natural organic matters. Overall, the present study provides a new method for constructing porous La-based hydroxide materials for phosphorus control in water.

Anchoring metal-organic framework-derived hollow CoV2O6 nanocubes onto lattice tensile strained V2CTx MXene for superior overall water splitting

MXene is considered as a kind of promising two-dimensional layered carbide/nitride in the field of overall water splitting attributed to hydrophilic surface, controllable interlayer spacing, and desirable metal conductivity. Nevertheless, the re-stack effect still hinders its large-scale development. Therefore, in this work, metal-organic frameworks-derived hollow CoV2O6 nanocubes anchored on the surface of lattice tensile strained V2CTx MXene (TS-V2CTx/CoV2O6 HN) as electrocatalysts are prepared through ion exchange process and the following liquid nitrogen quenching treatment. Lattice tensile strain could boost ions transfer of transition metals due to the enlarger interlayer spacing. The heterostructure between CoV2O6 and V2CTx MXene could optimize the adsorption energy of H- and O-containing intermediates to obtain the best ΔGH* for hydrogen evolution reaction (HER) and decrease the ΔG value of rate determining step for oxygen evolution reaction (OER). Besides, the CoV2O6 components acting as intercalation agents could avoid the self-aggregation of MXene nanosheets. Simultaneously, the hollow structure also offers high active area to promote electrolyte permeation and accelerate electron/ion transfer. As a consequence, the TS-V2CTx/CoV2O6 HN acquires extraordinary HER and OER performance with the overpotential of 32.2 and 235.0 mV at the current density of − 10 mA/cm2 and 10 mA/cm2, respectively, which is quite remarkable compared to the recent MXene-based electrocatalysts. Moreover, the overall water splitting device assembled by TS-V2CTx/CoV2O6 HN demonstrates a low cell voltage of 1.358 V at 10 mA/cm2. Thence, this work donates an exciting avenue to overcome the re-stack issue of V2CTx MXene, constructing a superior electrocatalyst with high activity and desirable reaction kinetics.

Constructing a compact and brilliantly stable LDH film by screening nucleation dynamics and structure

Nowadays, Mg alloys have been attracting worldwide attention because of their appropriate physico-chemical properties and biocompatibility. However, the high chemical reactivity and poor corrosion resistance hinder its practical applications seriously. Here, we proposed a new method that can screen compact and brilliant stability film based on the fundamental problem of Mg alloy LDH films, thereby constructing a hydrocalumite-like LDH (CaAl-HCL) film. On the one hand, the bridge between the compactness of the film and the supersaturation of film-forming agents is constructed through thermodynamics and dynamics, enabling the designing of compact films. On the other hand, the poor stability of the film induced by the ion-exchange process is improved by choosing a seven-coordinated structure.

Improved copper-based catalysts for alcohol-assisted CO2 hydrogenation: A comparative study between novel nano-stabilized and deposition-precipitation method

A growing awareness of the need to control CO2 concentration in atmosphere spurs the demand for novel technologies to convert CO2 to useful chemicals. The conversion of CO2 into high-quality liquid fuel such as methanol is a primary focus, and using active catalysts is the key to achieving successful methanol synthesis from CO2 hydrogenation under mild conditions. A new way of synthesizing catalysts with highly dispersed nano copper particles, as well as the characteristics of the catalysts are reported in this study. This is the first instance of methanol catalysts being prepared using a combination of copolymer of polyethylene glycol and maleic acid (PEG-MA) as a stabilizer and layered hydrotalcite (HTC) as a support material. This resulted in a significant decrease in particle size and exhibited efficient catalytic performance in a 1-butanol promoted CO2 hydrogenation reaction at 170 °C, 3 MPa. The work also confirms the status of Zn as an influential factor for methanol synthesis. The application of ion-exchange process and stabilizers in catalyst preparation process effectively improves the CO2 conversion rate and methanol selectivity, which also inspires the development of catalysts in various fields.