Pure Water Research Articles

Photosynthesis of H2O2 in pure water over 2D metal-organic frameworks film by co-doping Ga and porphyrin

Hydrogen peroxide (H2O2) is a clean oxidizing agent and potential energy carrier. Photocatalytic H2O2 production has garnered increased attention due to its green and energy-saving process. However, existing photocatalysts face several challenges, such as limited response to visible light, the requirement for sacrificial reagents, and complications in powder recycling. In this work, we synthesized two-dimensional (2D) NH2-MIL-53(Al) films co-modified with Ga and tetrakis (4-carboxyphenyl) porphyrin (TCPP) with enhanced photocatalytic activity of 268.7 µmol∙g−1∙h−1 from only O2 and pure H2O, reaching 3.5 times higher than pure NH2-MIL-53(Al). Notably, in comparison with other reported MOF photocatalysts, NMA-Ga5%-L30 stands out with the highest photocatalytic H2O2 generation activity in a pure water system under visible light. Moreover, this sample film was readily recovered from a photocatalytic system and exhibits significant cycling stability. The heightened photocatalytic activity is attributed to the dual modification, which not only reduces the photogenerated band gap but also promotes the charge carrier’s separation and transfer. This work provides a strategy for the design of MOFs-based photocatalysts with easy recycle properties for artificial photosynthesis of H2O2.

The Influence of Light-Generated Radicals for Highly Efficient Solar-Thermal Conversion in an Ultra-Stable 2D Metal-Organic Assembly.

Solar-thermal water evaporation is a promising strategy for clean water production, which needs the development of solar-thermal conversion materials with both high efficiency and high stability. Herein, we reported an ultra-stable cobalt(II)-organic assembly NKU-123 with light-generated radicals, exhibiting superior photothermal conversion efficiency and high stability. Under the irradiation of 808 nm light, the temperature of NKU-123 rapidly increases from 25.5 to 215.1 °C in 6 seconds. The solar water evaporator based on NKU-123 achieves a high solar-thermal water evaporation rate of 1.442 and 1.299 kg m-2 h-1 under 1-sun irradiation with a water evaporation efficiency of 97.8 and 87.9 % for pure water and seawater, respectively. A detailed mechanism study revealed that the formation of light-generated radicals leads to an increase of spin density of NKU-123 for enhancing the photothermal effect, which provides insights into the design of highly efficient photothermal materials.

High performance and antifouling zeolite@polyethersulfone/cellulose acetate asymmetric membrane for efficient separation of oily wastewater

Microfiltration membranes have emerged as a promising alternative for oily wastewater treatment due to their high efficiency, low cost, and ease of operation. In this study, polyethersulfone (PES), cellulose acetate (CA), and 4A zeolite were blended to fabricate asymmetric membranes by the phase inversion technique and examined in oily wastewater treatment. Kerosene was chosen as a model polluting oil. The fabricated pure PES membrane (P), PES membranes incorporating 4A zeolite (ZP), PES membrane blended with CA (PC), and PES/CA blended membranes with 4A zeolite (ZPC) were characterized using field emission scanning electron microscopy, atomic force microscopy, Fourier-transform infrared spectroscopy, porosity, and contact angle to study the structure properties of these membranes. The performance of membranes was examined by water permeation, oil permeation flux, oil rejection, flux recovery ratio, and relative flux reduction. The ZPC membranes showed the highest performance in comparison with other prepared membranes. Incorporating 4A zeolite nanoparticles with 0.5 wt% into the PES/CA blended membrane significantly enhanced the microfiltration performance and decreased the contact angle of the P membrane from 70° to 29.8°. The effect of operation parameters such as transmembrane pressure (1–4 bar), feed temperature (25–50 ºC), and concentration of oil feed solution (250–1000 mg/L) on the permeation flux and oil rejection was studied on the PES/CA blended membrane containing 0.5 wt% 4A zeolite (0.5%ZPC). The 0.5%ZPC membrane showed improved porosity of 87.7% and it gave the highest value of pure water flux of 91.1 L/m2.h, oil permeation flux of 75.55 L/m2.h, maximum oil rejection of 98.8%, flux recovery ratio of 97.7%, and relative flux reduction of 21.8%. The permeation flux given by the 0.5%ZPC membrane was improved by about 8 times that of the P membrane. Re-usability studies verified the durability of the blended membranes and their performance in oily wastewater treatment.

Reliable and efficient membrane processes for clean and sustainable production of fresh water from saline waste

AbstractBACKGROUNDIncreasing water scarcity due to growing demand highlights the urgency for innovative solutions. Seawater desalination is emerging as a crucial answer, with direct contact membrane distillation (DCMD) emerging as a promising technology in this context. In particular, membranes produced from ionic liquids constitute a well‐established avenue for the preparation of membranes by non‐solvent phase inversion (NIPS) in the field of desalination.RESULTSThe tests carried out as part of the DCMD, using PVDF membranes modified with the IL MPF6 and TBAPF6 synthesized during this study, in particular those containing 50% TBAFP6, demonstrate a notable improvement in hydrophobicity and porosity (121,48°, 79%). The results suggest that the flux of the PVDF‐TBAPF6 membrane shows a clear improvement of 300% compared to the support alone. Various parameters such as salinity, temperature and flow rate were examined, highlighting their impact on membrane performance. The low energy parameters (Ea = 43,36 Kj/mol, ΔH≠ = 40,86 Kj/mol) indicate a diffusion mechanism of vapor molecules, occurring by successive jumps through the IL interaction sites.CONCLUSIONExtensive experimental investigations have carefully anticipated the permeate flow in DCMD, aiming to efficiently extract pure water. DCMD is positioned as a promising technology for desalination and treatment of BRINE solutions. Therefore, this study can make a significant contribution to the expansion of DCMD by facilitating the prediction and optimization of operational parameters, thereby paving the way for expanded application of this technology.This article is protected by copyright. All rights reserved.

The Influence of Light‐Generated Radicals for Highly Efficient Solar‐Thermal Conversion in an Ultra‐Stable 2D Metal‐Organic Assembly

AbstractSolar‐thermal water evaporation is a promising strategy for clean water production, which needs the development of solar‐thermal conversion materials with both high efficiency and high stability. Herein, we reported an ultra‐stable cobalt(II)‐organic assembly NKU‐123 with light‐generated radicals, exhibiting superior photothermal conversion efficiency and high stability. Under the irradiation of 808 nm light, the temperature of NKU‐123 rapidly increases from 25.5 to 215.1 °C in 6 seconds. The solar water evaporator based on NKU‐123 achieves a high solar‐thermal water evaporation rate of 1.442 and 1.299 kg m−2 h−1 under 1‐sun irradiation with a water evaporation efficiency of 97.8 and 87.9 % for pure water and seawater, respectively. A detailed mechanism study revealed that the formation of light‐generated radicals leads to an increase of spin density of NKU‐123 for enhancing the photothermal effect, which provides insights into the design of highly efficient photothermal materials.

Robust Covalent Organic Framework Photocatalysts for H2O2 Production: Linkage Position Matters.

Covalent organic frameworks (COFs) are promising photocatalysts for hydrogen peroxide (H2O2) synthesis. However, the nature of organic polymers makes the balance between high activity and stability challenging. We demonstrate that the linkage position matters in the design of robust COF photocatalysts with durable high activity without sacrificial reagents. COFs with ortho- and para-linkages (o-COFs and p-COFs) were constructed by 1,3,5-triformylphloroglucinol with benzene-, pyridine-, pyrazine-orthodiamines and paradiamines. The pyrzaine-containing o-COFs with two pyridinic nitrogen atoms exhibited a H2O2 production rate of 4396 μmol g-1 h-1 together with long-time continuous H2O2 photosynthesis performance in pure water (48 h), superior to the corresponding p-COFs. A four-step reaction mechanism is proposed by density function calculations. Moreover, the active sites and origin of stability enhancement for o-COFs are clarified. This work provides a simple and effective molecular design strategy in the design of robust COF photocatalysts for artificial H2O2 photosynthesis.

Effective solar-driven evaporators with urchin-like CuO particles and directional polyvinylidene fluoride scaffolds via directional dimethyl sulfoxide crystallization and non-solvent induced phase separation

Solar-driven evaporators with vertical channels usually exhibit excellent desalination due to the fast water transportation and excellent salt tolerance, which are often fabricated via a directional liquid nitrogen-assisted ice templating method and freeze-drying process. However, they are reliant on a very limited number of water-soluble polymers and hydrophilic inorganic materials, and the freeze-drying process costs a long time and much energy. A highly efficient and straightforward process for the fabrication of solar-driven evaporators with directional channels from water-insoluble materials is urgent. Here, water-insoluble polyvinylidene fluoride was dissolved in dimethyl sulfoxide (DMSO), and then the solution was engineered to PVDF scaffolds by the combination of directional DMSO crystallization with the commonly porous membrane formation method of non-solvent (water) induced phase separation. The result is the creation of oriented perpendicular pores to the surfaces and framberry-like microparticles on the pore walls. After the in situ deposition of urchin-like CuO particles with high solar adsorption on PVDF scaffolds, PVDF/CuO solar-driven evaporators have been successfully constructed. The evaporate rate depends on the PVDF content and CuO loading. Briefly, PVDF/CuO evaporators fabricated from high PVDF content of more than 3 wt% have low porosity, slow water supply, and poor hydrophilicity, resulting in a low evaporate rate and high evaporation enthalpy. The optimized 3D PVDF/CuO evaporator (V3-9 h) with a PVDF content of 3 wt% and CuO loading of 31.3 ± 1.6 wt% has a high pure water evaporation rate of 3.2 ± 0.2 and 3.5 ± 0.3 kg m-2h−1 under sun illumination at 1 and 2 kW m−2, respectively. And the evaporation enthalpy is as low as 1083.8 ± 25.5 J/g, 55 % lower than pure water. Moreover, the sample exhibits a similar evaporation rate in 3.5 wt% NaCl solution because the verticle channels endow the evaporator with excellent salt tolerance. The facile and scalable fabrication process of solar-driven evaporators with directional channels will greatly boost the development of cost-effective desalination.

Adjustable chromatographic performance of silica-based mixed-mode stationary phase through the control of co-grafting amounts of imidazole and C18 chain

In this paper, three imidazole- and C18- bifunctional silica stationary phases (Sil-Im-C18) were prepared by adjusting introduction interval of octadecyltrichlorosilane (ODS) and 3-imidazol-1-ylpropyl(trimethoxy)silane (TMPImS), which can be used for reversed-phase liquid chromatography (RPLC) and ion exchange chromatography (IEC) with adjustable performance. The successful preparation of Sil-Im-C18 were confirmed by the characterizations of elemental analysis, infrared spectroscopy (FTIR) and contact angle (CA). Chromatographic performance of Sil-Im-C18 were evaluated by the separation of Tanaka test mixture, alkylbenzenes, linear PAHs and a set of analytes with different properties (uracil, phenol, 1,2-dinitrobenzene and naphthalene), and compared with commonly used C18 column. It was found that the chromatographic performance of Sil-Im-C18 changed significantly with the difference in bonding amount of imidazole and C18. Sil-Im-C18 demonstrated the excellent separation performance towards polycyclic aromatic hydrocarbons (PAHs), phenylesters, phenylamines, phenols and inorganic anions, and notably, nucleobases and nucleosides can be separated using pure water as mobile phases. The van Deemter plot showed that the column efficiency of Sil-Im-C18-3 was 64,933 plate·m−1 for naphthalene, indicated that Sil-Im-C18 was reasonably chromatographic columns. The RSD values of retention time were 0.22 %-0.61 % for 10 needles alkylbenzenes injected continuously at 50 °C to investigate thermal stability and repeatability, all the fluctuations of k of naphthalene were less than 2.3 % for Sil-Im-C18-1 during flushing 24 h with the mobile phase at different pH values (pH = 3 and 8), the retention time of alkylbenzenes were almost same for Sil-Im-C18-1 at different time, the RSD values of retention time of alkylbenzenes were 0.45 %-2.28 % for two batches Sil-Im-C18-1, revealing the excellent repeatability, thermal stability, durability and reproducibility of Sil-Im-C18, and implying a commercial prospect.

Robust Covalent Organic Framework Photocatalysts for H2O2 Production: Linkage Position Matters

AbstractCovalent organic frameworks (COFs) are promising photocatalysts for hydrogen peroxide (H2O2) synthesis. However, the nature of organic polymers makes the balance between high activity and stability challenging. We demonstrate that the linkage position matters in the design of robust COF photocatalysts with durable high activity without sacrificial reagents. COFs with ortho‐ and para‐linkages (o‐COFs and p‐COFs) were constructed by 1,3,5‐triformylphloroglucinol with benzene‐, pyridine‐, pyrazine‐orthodiamines and paradiamines. The pyrzaine‐containing o‐COFs with two pyridinic nitrogen atoms exhibited a H2O2 production rate of 4396 μmol g−1 h−1 together with long‐time continuous H2O2 photosynthesis performance in pure water (48 h), superior to the corresponding p‐COFs. A four‐step reaction mechanism is proposed by density function calculations. Moreover, the active sites and origin of stability enhancement for o‐COFs are clarified. This work provides a simple and effective molecular design strategy in the design of robust COF photocatalysts for artificial H2O2 photosynthesis.

Effect of marine clay minerals on the thermodynamics of CH4 hydrate: Evidence for the inhibition effect with implications

Clay minerals are widely distributed in hydrate-bearing sediments worldwide, especially in the clayey-silty sediments in the South China Sea. The debate on the influence of clay on the thermodynamics of natural gas hydrate (NGH) remains and impedes the fundamental understanding of hydrate-clay interactions and the design of effective production strategies for energy recovery. Specifically, the phase equilibria of MH in the presence of clay and how different types of water associated with clay particles affect NGH thermodynamics and stability are not fully elucidated and warrant investigation. In this study, the phase equilibria of methane hydrate (MH) were measured in the presence of typical clays from the South China Sea, i.e., montmorillonite, kaolinite, and illite. The shift of MH phase equilibria curve to a more stringent pressure was identified with Na-montmorillonite showing the most significant inhibition. The leftward shift (inhibition) of phase equilibrium temperature (Teq) is up to 3.9 K at a pressure of 10.40 MPa for Na-montmorillonite compared with pure water. Furthermore, we develop a thermodynamic model based on the classical Chen-Guo model first accounting for the change in water activity (aw) due to cation exchange of Na-montmorillonite. The developed model exhibits good predictability with the measured phase equilibira data. The inhibition on the phase equilibria of MH is linked to the reduction of aw due to the clay-bound water for clays with a swelling nature. The findings of this study offer direct evidence and explanations on how clay minerals thermodynamically inhibit CH4 hydrate. It provides valuable insights into the resource estimation of clayey-silty NGH in nature and facilities the design of suitable production strategies targeting clay-rich hydrate-bearing sediments.

Facile construction of gefitinib-loaded zeolitic imidazolate framework nanocomposites for the treatment of different lung cancer cells.

Gefitinib (GET) is a revolutionary targeted treatment inhibiting the epidermal growth factor receptor's tyrosine kinase action by competitively inhibiting the ATP binding site. In preclinical trials, several lung cancer cell lines and xenografts have demonstrated potential activity with GET. Response rates neared 25% in preclinical trials for non-small cell lung cancer. Here, we describe the one-pot synthesis of GET@ZIF-8 nanocomposites (NCs) in pure water, encapsulating zeolitic imidazolate framework 8 (ZIF-8). This method developed NCs with consistent morphology and a loading efficiency of 9%, resulting in a loading capacity of 20wt%. Cell proliferation assay assessed the anticancer effect of GET@ZIF-8 NCs on A549 and H1299 cells. The different biochemical staining (Calcein-AM and PI and 4',6-Diamidino-2-phenylindole nuclear staining) assays assessed the cell death and morphological examination. Additionally, the mode of apoptosis was evaluated by mitochondrial membrane potential (∆ψm) and reactive oxygen species. Therefore, the study concludes that GET@ZIF-8 NCs are pledged to treat lung cancer cells.

Strong Synergy between Pd Single Atom and Zn Vacancy Boosts Photocatalytic Pure Water Splitting

Single‐atom and vacancy‐engineered photocatalysts have shown their remarkable strengths in improving carrier transfer dynamics, yet constructing the integration of single atoms and vacancies as the active site is still challenging. Herein, an icing‐assisted photochemical strategy has been employed to anchor Pd single atoms in Zn vacancies on CdxZn1−xS nanorods to form a Pd–S4 tetrahedron coordination structure, enabling exceptional photocatalytic water splitting performance in the absence of any sacrificial agents. Under visible light irradiation, the H2 evolution rate of Pd/Cd0.1Zn0.9S reaches 608.2 μmol g−1 h−1, which is around 229, 6.7, 6.1, and 2 times to that of ZnS, Cd0.1Zn0.9S, Pd/ZnS, and Pd NPs/Cd0.1Zn0.9S, respectively. Detailed experimental and theoretical analyses confirm that Pd–S hybridized electronic states and Pd single atoms are beneficial for enhancing the charge separation/transfer, accelerating the formation of H* and the release of H2.

Enhanced properties of a positive-charged nanofiltration membrane containing quaternarized chitosan through second interfacial polymerization for the removal of salts and pharmaceuticals.

Nanofiltration (NF) membrane technology has been widely used in the removal of salts and trace organic pollutants, such as pharmaceuticals and personal care products (PPCPs), due to its superiority. A positive-charged composite NF membrane with an active skin layer was prepared by polyethyleneimine (PEI), trimethyl benzene chloride, and quaternate chitosan (HTCC) through second interfacial polymerization on the polyethersulfone ultrafiltration membrane. The physicochemical properties of the nanocomposite membrane were investigated using surface morphology, hydrophilicity, surface charge, and molecular weight cut-off (MWCO). The influence of the concentration and reaction time of PEI and HTCC was documented. The optimized membrane had a MWCO of about 481 Da and possessed a pure water permeability of 25.37 L·m-2·h-1·MPa-1. The results also exhibited salt rejection ability as MgCl2 > CaCl2 > MgSO4 > Na2SO4 > NaCl > KCl, showing a positive charge on the fabricated membrane. In addition, the membrane had higher rejection to atenolol, carbamazepine, amlodipine, and ibuprofen at 89.46, 86.02, 90.12, and 77.21%, respectively. Moreover, the anti-fouling performance and stability of the NF membrane were also improved.

Nitrogen-Rich Triazine-Based Covalent Organic Frameworks as Efficient Visible Light Photocatalysts for Hydrogen Peroxide Production.

Covalent organic frameworks (COFs) have been widely used in photocatalytic hydrogen peroxide (H2O2) production due to their favorable band structure and excellent light absorption. Due to the rapid recombination rate of charge carriers, however, their applications are mainly restricted. This study presents the design and development of two highly conjugated triazine-based COFs (TBP-COF and TTP-COF) and evaluates their photocatalytic H2O2 production performance. The nitrogen-rich structures and high degrees of conjugation of TBP-COF and TTP-COF facilitate improved light absorption, promote O2 adsorption, enhance their redox power, and enable the efficient separation and transfer of photogenerated charge carriers. There is thus an increase in the photocatalytic activity for the production of H2O2. When exposed to 10 W LED visible light irradiation at a wavelength of 420 nm, the pyridine-based TTP-COF produced 4244 μmol h-1 g-1 of H2O2 from pure water in the absence of a sacrificial agent. Compared to TBP-COF (1882 μmol h-1 g-1), which has a similar structure but lacks pyridine sites, TTP-COF demonstrated nearly 2.5 times greater efficiency. Furthermore, it exhibited superior performance compared to most previously published nonmetal COF-based photocatalysts.

Water Arrangements upon Interaction with a Rigid Solute: Multiconfigurational Fenchone-(H2O)4-7 Hydrates.

Insight into the arrangements of water molecules around solutes is important to understand how solvation proceeds and to build reliable models to describe water-solute interactions. We report the stepwise solvation of fenchone, a biogenic ketone, with 4-7 water molecules. Multiple hydrates were observed using broadband rotational spectroscopy, and the configurations of four fenchone-(H2O)4, three fenchone-(H2O)5, two fenchone-(H2O)6, and one fenchone-(H2O)7 complexes were characterized from the analysis of their rotational spectra in combination with quantum-chemical calculations. Interactions with fenchone deeply perturb water configurations compared with the pure water tetramer and pentamer. In two fenchone-(H2O)4 complexes, the water tetramer adopts completely new arrangements, and in fenchone-(H2O)5, the water pentamer is no longer close to being planar. The water hexamer interacts with fenchone as the least abundant book isomer, while the water heptamer adopts a distorted prism structure, which forms a water cube when including the fenchone oxygen in the hydrogen bonding network. Differences in hydrogen bonding networks compared with those of pure water clusters show the influence of fenchone's topology. Specifically, all observed hydrates except one show two water molecules binding to fenchone through each oxygen lone pair. The observation of several water arrangements for fenchone-(H2O)4-7 complexes highlights water adaptability and provides insight into the solvation process.

Frustrated-Laser-Induced Thermal Starting Plumes in Fresh and Salt Water

The results of a photothermal spectroscopy technique that effectively images convective and conductive heat flow in liquids via a thermal lensing effect are described. Pure water; sodium chloride solutions at salinities of approximately 5, 15, 25, and 35 g/kg; and an artificial seawater of 35 g/kg were studied across a range of temperatures. This system was studied because of the importance of thermal pluming in seawater. ‘Frustrated’ thermal starting plumes were observed near the temperature of maximum density. The physical characteristics of these thermal starting plumes are reported.

Prognostic model and failure mechanisms of steam generators in Sodium-Cooled fast reactors

This paper presents a prognostic model for sodium-cooled fast reactor (SFR) steam generators (SGs). The purpose of the model is to estimate the remaining useful life of SFR SGs and thus to support the decision-making of autonomous control. SFR SGs are of great interest for plant integrity due to their harsh operation environment. They operate at higher temperatures and higher coolant-to-steam pressure differences than those of current light water reactors (LWR). The severity of the SFR SG failure consequences, which include water-sodium contact, is another reason. Understanding its failure mechanisms is important for the development of its prognostic model. Based on our literature review and physics-based analysis, we concluded that creep would be a dominant degradation mode of SFR SGs due to SFR’s high-temperature and high-pressure environment. Thus, creep is the focus of the prognostic model. Various other failure modes were also investigated in this study. The mechanical fatigue due to flow-induced vibration is usually observed in early developmental phases and would not be an important issue during normal operation. The thermal fatigue due to thermal stripping is occasionally observed in other components in SFRs but does not affect SG integrity. Pure water stress corrosive crack, fretting, and so on are commonly observed in LWR SGs but are significantly less important in SFR SGs because of the high temperatures, high pressure differences, and chemical properties of liquid sodium. Based on these investigations, a prognostic model focusing on creep failures was developed. It estimates the failure probability profile by sampling the Larson-Miller parameter (LMP) and temperature and associated uncertainties through Monte Carlo methods. Two case studies were presented. The first one demonstrated the model’s capability to calculate the failure probability for a new specimen within a given time. If the tube is working under temperatures of 500C ± 3 and pressures of 15.2 MPa, which leads to LMP of 20,100 ± 50, the failure probabilities within 50, 70, and 90 years are approximately 0.1 %, 3.2 %, and 17.5 %. The second demonstrated how adjusting the workload can help to protect the integrity of the component. For an old tube reaching 99 % of its lifespan, continuing to run at temperatures of 500C ± 3 and LMP of 20,100 ± 50 leads to a failure probability of about 29.0 % within a year. If the temperature is reduced by 5C, the failure probability can be reduced to 2.5 %, and, if the pressure is also reduced such that the LMP is increased by 100, the failure probability can further be reduced to 0.12 %.

Fabrication and characterization of TiO2‐hydroxyapatite composite‐loaded Polysulfone membranes with integrated biocompatibility for dialysis application

AbstractBackgroundThe use of Polysulfone (PSf) as membrane material for dialysis therapy is becoming more common. However, the PSf membrane can cause the adsorption of blood proteins followed by the adhesion of platelets, destruction of red blood cells, and thrombus formation. One of the biggest challenges in creating membranes for hemodialysis (HD) applications is ensuring biocompatibility. Therefore, to maintain the biocompatibility of PSf membranes, further modifications are necessary.MethodsIn this study, the performance and biocompatibility of PSf membranes were improved by the impregnation of TiO2‐hydroxyapatite composite as an additive. The TiO2‐hydroxyapatite composite was first synthesized via sintering at 1200°C, and then a dope solution composed of pristine PSf polymer solution in N‐Methyl‐2‐pyrrolidone solvent (NMP) and different wt% ratios of the synthesized composite were prepared, and resultant membranes were fabricated using a film applicator via a phase inversion scheme using water as a non‐solvent exchange medium. The synthesized composite was characterized using SEM, EDX, and XRD techniques.ResultsThe FTIR analysis confirmed the weak interaction of PSf polymer with the hydroxyapatite moiety of the composite. The interaction of the synthesized composite within the membrane matrix was evaluated via leaching ratio results. The hydrophilicity, pore profile, and pure water permeation flux rates were also determined. The results of the biocompatibility study showed that membranes based on TiO2‐hydroxyapatite composite had reduced adsorption of BSA protein by 34.41% as well as less than 5% hemolysis ratio. Additionally, the study displayed thrombus formation ranging from 2.08% to 8.69%, respectively. The dialysis results indicated that compared with the original PSf membrane, the TiO2‐hydroxyapatite composite showed high clearance rates for urea (73.81%) and creatinine (72.13%) solutes, respectively.ConclusionTherefore, blending TiO2‐hydroxyapatite composite in the PSf membrane significantly improved the biocompatibility and removal ability of uremic solutes.

Investigation of the effect of permeation and antifouling characteristics of hybrid poly(vinylidene fluoride) membranes tailored with ZIF‐67 metal–organic frameworks

AbstractHerein the ZIF‐67, a hydrophilic cobalt‐based zeolitic imidazolate framework is synthesized and incorporated with a poly(vinylidene fluoride) (PVDF) to fabricate hybrid ultrafiltration membranes by phase inversion method. The characteristics of PVDF/ZIF‐67 membranes are examined using different analytical techniques such as Fourier‐transform infrared spectroscopy, X‐ray diffractometer, scanning electron microscope, atomic force microscope, and contact angle analysis. The membrane performance is probed using pure water flux (PWF), bovine serum albumin (BSA), and humic acid (HA) rejection. The maximum water flux of 162.5 Lm2 h−1 with BSA and HA rejection of 97% and 98.2%, respectively, exhibited by 1.5 wt% ZIF‐67. The contact angle value is reduced from 83.5 to 58.6° indicating the increase in hydrophilic nature of PVDF membranes by the addition of ZIF‐67. The presence of ZIF‐67 in the PVDF membrane matrix showed outstanding anti‐bacterial properties against Escherichia coli and Staphylococcus aureus. Overall, the PVDF/ZIF‐67 ultrafiltration membranes demonstrate the potential for water treatment applications.

Efficient chlorination reaction of Pt/RuO2/g-C3N4 under visible light irradiation for simultaneous removal of ammonia and bacteria from mariculture wastewater

The removal of ammonia nitrogen (NH4+-N) and bacteria from aquaculture wastewater holds paramount ecological and production significance. In this study, Pt/RuO2/g-C3N4 photocatalysts were prepared by depositing Pt and RuO2 particles onto g-C3N4. The physicochemical properties of photocatalysts were explored by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), X-ray diffraction (XRD), and UV–vis diffuse reflectance spectrometer (UV–vis DRS). The photocatalysts were then applied to the removal of both NH4+-N and bacteria from simulated mariculture wastewater. The results clarified that the removals of both NH4+-N and bacteria were in the sequence of g-C3N4 < RuO2/g-C3N4 < Pt/g-C3N4 < Pt/RuO2/g-C3N4. This magnificent photocatalytic ability of Pt/RuO2/g-C3N4 can be interpreted by the transfer of holes from g-C3N4 to RuO2 to facilitate the in situ generation of HClO from Cl− in wastewater, while Pt extracts photogenerated electrons for H2 formation to enhance the reaction. The removal of NH4+-N and disinfection effect were more pronounced in simulated seawater than in pure water. The removal efficiency of NH4+-N increases with an increase in pH of wastewater, while the bactericidal effect was more significant under a lower pH in a pH range of 6–9. In actual seawater aquaculture wastewater, Pt/RuO2/g-C3N4 still exhibits effective removal efficiency of NH4+-N and bactericidal performance under sunlight. This study provides an alternative avenue for removement of NH4+-N and bacteria from saline waters under sunlight.