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1.
Small ; 20(10): e2306522, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37884468

RESUMO

Mimicking efficient biocatalytic cascades using nanozymes has gained enormous attention in catalytic chemistry, but it remains challenging to develop a nanozyme-based cascade system to sequentially perform the desired reactions. Particularly, the integration of sequential hydrolysis and oxidation reactions into nanozyme-based cascade systems has not yet been achieved, despite their significant roles in various domains. Herein, a self-cascade Ce-MOF-818 nanozyme for sequential hydrolysis and oxidation reactions is developed. Ce-MOF-818 is the first Ce(IV)-based heterometallic metal-organic framework constructed through the coordination of Ce and Cu to distinct groups. It is successfully synthesized using an improved solvothermal method, overcoming the challenge posed by the significant difference in the binding speeds of Ce and Cu to ligands. With excellent organophosphate hydrolase-like (Km = 42.3 µM, Kcat = 0.0208 min-1 ) and catechol oxidase-like (Km = 2589 µM, Kcat = 1.25 s-1 ) activities attributed to its bimetallic active centers, Ce-MOF-818 serves as a promising self-cascade platform for sequential hydrolysis and oxidation. Notably, its catalytic efficiency surpasses that of physically mixed nanozymes by approximately fourfold, owning to the close integration of active sites. The developed hydrolysis-oxidation self-cascade nanozyme has promising potential applications in catalytic chemistry and provides valuable insights into the rational design of nanozyme-based cascade systems.


Assuntos
Estruturas Metalorgânicas , Hidrólise , Oxirredução , Estruturas Metalorgânicas/química , Catálise , Biocatálise
2.
Environ Sci Technol ; 2024 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-39126388

RESUMO

Membrane distillation (MD) has great potential in the management of hypersaline water for zero liquid discharge (ZLD) due to its high salinity tolerance. However, the membrane wetting issue significantly restricts its practical application. In this study, a composite membrane tailored for extreme concentrations and even crystallization of hypersaline water is synthesized by coating a commercial hydrophobic porous membrane with a composite film containing a dense polyamide layer, a cation exchange layer (CEL), and an anion exchange layer (AEL). When used in direct contact MD for treating a 100 g L-1 NaCl hypersaline solution, the membrane achieves supersaturation of feed solution and a salt crystal yield of 38.0%, with the permeate concentration at <5 mg L-1. The composite membrane also demonstrates ultrahigh antiwetting stability in 360 h of long-term operation. Moreover, ion diffusion analysis reveals that the ultrahigh wetting resistance of the composite membrane is attributed to the bipolar AEL and CEL that eliminate ion crossover. The literature review elucidates that the composite membrane is superior to state-of-the-art membranes. This study demonstrates the great potential of the composite membrane for direct crystallization of hypersaline water, offering a promising approach to filling the gap between reverse osmosis and conventional thermal desalination processes for ZLD application.

3.
Environ Sci Technol ; 56(22): 16240-16248, 2022 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-36322385

RESUMO

Fabricating two-dimensional transition-metal dichalcogenide (TMD)-based unique composites is an effective way to boost the overall physical and chemical properties, which will be helpful for the efficient and fast capture of elemental mercury (Hg0) over a wide temperature range. Herein, we constructed a defect-rich Cu2WS4 nano-homojunction decorated on covalent organic frameworks (COFs) with abundant S vacancies. Highly well-dispersed and uniform Cu2WS4 nanoparticles were immobilized on COFs strongly via an ion pre-anchored strategy, consequently exhibiting enhanced Hg0 removal performance. The saturation adsorption capacity of Cu2WS4@COF composites (21.60 mg·g-1) was 9 times larger than that of Cu2WS4 crystals, which may be ascribed to more active S sites exposed in hybrid interfaces formed in the Cu2WS4 nano-homojunction and between Cu2WS4 nanoparticles and COFs. More importantly, such hybrid materials reduced adsorption deactivation at high temperatures, having a wide operating temperature range (from 40 to 200 °C) owing to the thermostability of active S species immobilized by both physical confined and chemical interactions in COFs. Accordingly, this work not only provides an effective method to construct uniform TMD-based sorbents for mercury capture but also opens a new realm of advanced COF hybrid materials with designed functionalities.

4.
Environ Sci Technol ; 54(20): 12929-12937, 2020 10 20.
Artigo em Inglês | MEDLINE | ID: mdl-33040523

RESUMO

Dissolved organic matter (DOM) composition in salt lakes is critical for water quality and aquatic ecology, and the salinization of salt lakes affects the DOM composition. To the best of our knowledge, no study has explored the effects of salinity on salt lake DOM composition at the molecular level. In this work, we selected Qinghai Lake (QHL) and Daihai Lake (DHL) as typical saline lakes. The two lakes have similar geographical and climatic conditions, and the salinity of QHL is higher than that of DHL. Fourier transform ion cyclotron resonance mass spectrometry coupled with electrospray ionization was applied to compare the DOM molecular composition in the two lakes. At higher salinity, the DOM showed larger average molecular weight, higher oxidation degree, and lower aromaticity. Moreover, the proportion of DOM that is vulnerable to microbial degradation (e.g., lipids), photo-degradation (e.g., aromatic structures), or both processes (e.g., carbohydrates and unsaturated hydrocarbons) reduced at higher salinity. On the contrary, compounds that are refractory to microbial degradation (e.g., lignins/CRAM-like structures and tannins) or photo-degradation (e.g., aliphatic compounds) accumulated. Our study provides a useful and unique method to study DOM molecular composition in salt lakes with different salinity and is helpful to understand DOM transformation during the salinization of salt lakes.


Assuntos
Lagos , Salinidade , Espectrometria de Massas , Peso Molecular
5.
Environ Res ; 185: 109463, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32247147

RESUMO

The power generation performance of a microbial fuel cell (MFC) greatly depends on the relative amount of electricigens in the anodic microbial community. Running the MFC multiple times can practically enrich the electricigens, and thus improve its power generation efficiency. However, Gram-positive electricigens cannot be enriched well because of their thick non-conductive peptidoglycan layer. Herein, we report a new Gram-positive electricigen enrichment method by regulating the peptidoglycan layer of the bacteria using lysozyme. Lysozyme can partially hydrolyze the peptidoglycans layer of Gram-positive Firmicutes to improve the permeability of cell wall, and thus enhance its electricity generation activity. The stimulation of Gram-positive electricigen endows MFCs a high power generation community structure, which results in the power density 42% higher than that of the control sample. Our work has provided a new and simple method for optimizing the anode community structure by regulating weak electricigens in the community with lysozyme.


Assuntos
Fontes de Energia Bioelétrica , Peptidoglicano , Parede Celular , Eletricidade , Muramidase
6.
Environ Sci Technol ; 52(21): 12642-12648, 2018 11 06.
Artigo em Inglês | MEDLINE | ID: mdl-30335978

RESUMO

Coagulation is an important process to remove organics from water. The molecular composition and structure of organic matter influence water quality in many ways, and the lack of information regarding the organics removed by different coagulants makes it challenging to optimize coagulation processes and ensure reclaimed water safety. In this paper, we investigated coagulation of secondary biological effluent from a municipal sewage treatment plant with different coagulants. We emphasized investigation of organics removal characteristics at the molecular level using Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS) coupled with electrospray ionization (ESI). We found that conventional coagulants can only partially remove condensed polycyclic aromatics and polyphenols with low H/C (H/C < 0.7) and highly unsaturated and phenolic compounds and aliphatic compounds with high O/C (O/C > 0.6). A new coagulant, CBHyC, had better removal efficiencies for all organics with different element compositions and molecular structures, especially organics that are resistant to conventional coagulants such as highly unsaturated and phenolic compounds and aliphatic compounds located in 0.3 < O/C < 0.8 and 1.0 < H/C < 2.0 regions and sulfur-containing compounds with higher O/C (e.g., anionic surfactants and their metabolites or coproducts). This study provides molecular insights into the organics removed by different coagulants and provides data supporting the possible optimization of advanced wastewater treatment processes.


Assuntos
Esgotos , Purificação da Água , Espectrometria de Massas , Águas Residuárias , Água
7.
J Environ Manage ; 222: 409-419, 2018 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-29883876

RESUMO

Pollution caused by volatile organic compounds (VOCs) and odorous pollutants in the air can produce severe environmental problems. In recent years, the emission control of VOCs and odorous pollutants has become a crucial issue owing to the adverse effect on humans and the environment. For treating these compounds, biotrickling filter (BTF) technology acts as an environment friendly and cost-effective alternative to conventional air pollution control technologies. Besides, low concentration of VOCs and odorous pollutants can also be effectively removed using BTF systems. However, the VOCs and odorants removal performance by BTF may be limited by the hydrophobicity, toxicity, and low bioavailability of these pollutants. To solve these problems, this review summarizes the design, mechanism, and common analytical methods of recent BTF advances. In addition, the operating conditions, mass transfer, packing materials and microorganisms (which are the critical parameters in a BTF system) were evaluated and discussed in view of improving the removal performance of BTFs. Further research on these specific topics, together with the combination of BTF technology with other technologies, should improve the removal performance of BTFs.


Assuntos
Reatores Biológicos , Compostos Orgânicos Voláteis , Poluentes Atmosféricos , Biodegradação Ambiental , Filtração , Gases
8.
Environ Sci Technol ; 51(14): 8110-8118, 2017 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-28628308

RESUMO

Landfill leachate concentrate is a type of refractory organic wastewater with high environmental risk. Identification of refractory components and insights into the molecular transformations of the organics are essential for the development of efficient treatment process. In this report, molecular compositions of dissolved organic matter (DOM) in leachate concentrate, as well as changes after anaerobic/aerobic biodegradation and coagulation with salts, were characterized using electrospray ionization (ESI) coupled with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). DOM in leachate concentrate were more saturated and less oxidized with more nitrogen and sulfur-containing substances (accounting for 50.0%), comparing with natural organic matter in Suwannee River. Selectivity for different classes of organics during biodegradation and coagulation processes was observed. Substances with low oxidation degree (O/C < 0.3) were more reactive during biodegradation process, leading to the formation of highly oxidized molecules (O/C > 0.5). Unsaturated (H/C < 1.0) and oxidized (O/C > 0.4) substances containing carboxyl groups were preferentially removed after coagulation with Al or Fe sulfate. The complementary functions of biodegradation and coagulation in the treatment of DOM in leachate concentrate were verified at the molecular level. Lignin-derived compounds and sulfur-containing substances in leachate concentrate were resistant to biodegradation and coagulation treatments. To treat leachate concentrate more effectively, processes aimed at removal of such DOM should be developed.


Assuntos
Biodegradação Ambiental , Águas Residuárias/química , Poluentes Químicos da Água/química , Eliminação de Resíduos , Rios , Sais , Poluentes Químicos da Água/metabolismo
9.
Environ Sci Technol ; 50(7): 3897-904, 2016 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-26974542

RESUMO

Low molecular weight (MW) charged organic matter is poorly removed by conventional coagulants but contributes to disinfection byproduct formation during chlorination of drinking waters. We hypothesized that CIEX, a new Al-based hybrid coagulant with ion-exchange functional groups, would be new mechanistic approach to remove low MW organic matter during coagulation and would perform better than polyaluminum chloride (PACl) or metal-salt based coagulants. We measured coagulation performance using dissolved organic carbon (DOC) in a high hardness surface water. CIEX achieved excellent turbidity removal and removed 20% to 46% more DOC than FeCl3, Al2(SO4)3, or PACl, depending on dose. The improved DOC removal was attributable to better removal of low MW organic matter (<2 kDa). We further studied removal mechanisms in a model water containing a low MW organic acid (salicylic acid (SA)). CIEX achieved high removal of organic acids (>90% of SA) independent of pH, whereas removal by metal salts was lower (<15%) and was strongly pH dependent. CIEX ion-exchange capability is facilitated by its covalently bound quaternary ammonium group, which conventional coagulants lack. Plus, unlike other cationic polymers that react with chloramines to form N-nitrosodimethylamine (NDMA), CIEX has a low molar yield (9.3 × 10(-7) mol NDMA per mol CIEX-N).


Assuntos
Compostos Orgânicos/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Hidróxido de Alumínio/química , Carbono/análise , Cloretos/análise , Coloides/química , Floculação , Troca Iônica , Microscopia Eletrônica de Transmissão , Peso Molecular , Tamanho da Partícula , Ácido Salicílico/química , Solubilidade , Espectroscopia de Infravermelho com Transformada de Fourier
10.
Chemosphere ; 362: 142582, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38871192

RESUMO

This investigation elucidates the influence of micron-scale aeration bubbles on the improvement of anti-fouling characteristics within submerged membrane bioreactors (sMBRs). A systematic examination of sludge properties, hydraulic dynamics, and fouling tendencies revealed that the application of microbubble aeration, specifically at dimensions of 100 µm, 80 µm, and 30 µm, significantly reduced sludge electrostatic repulsion and augmented particle size distribution, as opposed to the utilization of coarse bubble aeration of 1 mm. Notably, the employment of 100 µm bubbles achieved a significant reduction in the proportion of smaller particles (<10 µm) and sludge viscosity, thereby facilitating a more homogenous and vigorous turbulence at the membrane interface. These optimized conditions were instrumental in the substantial reduction of membrane fouling, which was corroborated by the diminished rate of fouling, reduced resistance accumulation, and lesser foulant deposition. The investigation identified sludge particle size, turbulent kinetic energy, and shear stress as the predominant factors influencing the development of membrane fouling. The findings underscore the pronounced advantages of employing 100 µm-sized bubbles in aeration strategies, providing enhanced understanding for the optimization of aeration parameters to improve sMBR efficiency and maintenance.


Assuntos
Reatores Biológicos , Membranas Artificiais , Tamanho da Partícula , Esgotos , Eliminação de Resíduos Líquidos , Esgotos/química , Eliminação de Resíduos Líquidos/métodos , Incrustação Biológica/prevenção & controle , Microbolhas , Viscosidade
11.
Curr Biol ; 34(10): 2077-2084.e3, 2024 05 20.
Artigo em Inglês | MEDLINE | ID: mdl-38663397

RESUMO

Fungal biomineralization plays an important role in the biogeochemical cycling of metals in the environment and has been extensively explored for bioremediation and element biorecovery. However, the cellular and metabolic responses of fungi in the presence of toxic metals during biomineralization and their impact on organic matter transformations are unclear. This is an important question because co-contamination by toxic metals and organic pollutants is a common phenomenon in the natural environment. In this research, the biomineralization process and oxidative stress response of the geoactive soil fungus Aspergillus niger were investigated in the presence of toxic metals (Co, Cu, Mn, and Fe) and the azo dye orange II (AO II). We have found that the co-existence of toxic metals and AO II not only enhanced the fungal biomineralization of toxic metals but also accelerated the removal of AO II. We hypothesize that the fungus and in situ mycogenic biominerals (toxic metal oxalates) constituted a quasi-bioreactor, where the biominerals removed organic pollutants by catalyzing reactive oxygen species (ROS) generation resulting from oxidative stress. We have therefore demonstrated that a fungal/biomineral system can successfully achieve the goal of toxic metal immobilization and organic pollutant decomposition. Such findings inform the potential development of fungal-biomineral hybrid systems for mixed pollutant bioremediation as well as provide further understanding of fungal organic-inorganic pollutant transformations in the environment and their importance in biogeochemical cycles.


Assuntos
Aspergillus niger , Biodegradação Ambiental , Biomineralização , Aspergillus niger/metabolismo , Metais Pesados/metabolismo , Metais Pesados/toxicidade , Poluentes do Solo/metabolismo , Poluentes do Solo/toxicidade , Estresse Oxidativo
12.
Water Res ; 235: 119925, 2023 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-37028213

RESUMO

Singlet oxygen (1O2) attracts much attention in persulfate-based advanced oxidation processes (PS-AOPs), because of its wide pH tolerance and high selectivity toward electron-rich organics. However, there are conflicts about the 1O2 role in PS-AOPs on several aspects, including the formation of different key reactive oxygen species (ROS) at similar active sites, pH dependence, broad-spectrum activity, and selectivity in the elimination of organic pollutants. To a large degree, these conflicts root in the drawbacks of the methods to identify and evaluate the role of 1O2. For example, the quenchers of 1O2 have high reactivity to other ROS and persulfate as well. In addition, electron transfer process (ETP) also selectively oxidizes organics, having a misleading effect on the identification of 1O2. Therefore, in this review, we summarized and discussed some basic properties of 1O2, the debatable role of 1O2 in PS-AOPs on multiple aspects, and the methods and their drawbacks to identify and evaluate the role of 1O2. On the whole, this review aims to better understand the role of 1O2 in PS-AOPs and further help with its reasonable utilization.


Assuntos
Oxigênio Singlete , Poluentes Químicos da Água , Oxigênio Singlete/química , Espécies Reativas de Oxigênio , Oxirredução , Transporte de Elétrons , Peróxidos/química , Poluentes Químicos da Água/química
13.
Environ Sci Technol ; 46(9): 5198-204, 2012 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-22475021

RESUMO

Electrochemical reduction of carbon dioxide (CO(2)) to useful chemical materials is of great significance to the virtuous cycle of CO(2). However, some problems such as high overpotential, high applied voltage, and high energy consumption exist in the course of the conventional electrochemical reduction process. This study presents a new CO(2) reduction technique for targeted production of formic acid in a microbial electrolysis cell (MEC) driven by a microbial fuel cell (MFC). The multiwalled carbon nanotubes (MWCNT) and cobalt tetra-amino phthalocyanine (CoTAPc) composite modified electrode was fabricated by the layer-by-layer (LBL) self-assembly technique. The new electrodes significantly decreased the overpotential of CO(2) reduction, and as cathode successfully reduced CO(2) to formic acid (production rate of up to 21.0 ± 0.2 mg·L(-1)·h(-1)) in an MEC driven by a single MFC. Compared with the electrode modified by CoTAPc alone, the MWCNT/CoTAPc composite modified electrode could increase the current and formic acid production rate by approximately 20% and 100%, respectively. The Faraday efficiency for formic acid production depended on the cathode potential. The MWCNT/CoTAPc composite electrode reached the maximum Faraday efficiency at the cathode potential of ca. -0.5 V vs Ag/AgCl. Increasing the number of electrode modification layers favored the current and formic acid production rate. The production of formic acid was stable in the MFC-MEC system after multiple batches of CO(2) electrolysis, and no significant change was observed on the performances of the modified electrode. The coupling of the catalytic electrode and the bioelectrochemical system realized the targeted reduction of CO(2) in the absence of external energy input, providing a new way for CO(2) capture and conversion.


Assuntos
Fontes de Energia Bioelétrica , Dióxido de Carbono/química , Eletrodos , Indóis , Nanotubos de Carbono , Compostos Organometálicos , Oxirredução
14.
Sensors (Basel) ; 12(8): 10450-62, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23112609

RESUMO

Multi-walled carbon nanotube (MWCNT)-modified electrodes can promote the direct electron transfer (DET) of cytochrome c (Cyt c). There are several possible mechanisms that explain the DET of Cyt c. In this study, several experimental methods, including Fourier transform infrared spectroscopy, circular dichroism, ultraviolet-visible absorption spectroscopy, and electron paramagnetic resonance spectroscopy were utilized to investigate the conformational changes of Cyt c induced by MWCNTs. The DET mechanism was demonstrated at various nano-levels: secondary structure, spatial orientation, and spin state. In the presence of MWCNTs, the secondary structure of Cyt c changes, which exposes the active site, then, the orientation of the heme is optimized, revolving the exposed active center to the optimum spatial orientation for DET; and finally, a transition of spin states is induced, providing relatively high energy and a more open microenvironment for electron transfer. These changes at different nano-levels are closely connected and form a complex process that promotes the electron transfer of Cyt c.


Assuntos
Citocromos c/química , Elétrons , Nanotubos de Carbono/química , Animais , Citocromos c/metabolismo , Cavalos , Análise Espectral
15.
Water Res ; 222: 118945, 2022 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-35963137

RESUMO

Sulfate scaling, as insoluble inorganic sulfate deposits, can cause serious operational problems in various industries, such as blockage of membrane pores and subsurface media and impairment of equipment functionality. There is limited article to bridge sulfate formation mechanisms with field scaling control practice. This article reviews the molecular-level interfacial reactions and thermodynamic basis controlling homogeneous and heterogeneous sulfate mineral nucleation and growth through classical and non-classical pathways. Common sulfate scaling control strategies were also reviewed, including pretreatment, chemical inhibition and surface modification. Furthermore, efforts were made to link the fundamental theories with industrial scale control practices. Effects of common inhibitors on different steps of sulfate formation pathways (i.e., ion pair and cluster formation, nucleation, and growth) were thoroughly discussed. Surface modifications to industrial facilities and membrane units were clarified as controlling either the deposition of homogeneous precipitates or the heterogeneous nucleation. Future research directions in terms of optimizing sulfate chemical inhibitor design and improving surface modifications are also discussed. This article aims to keep the readers abreast of the latest development in mechanistic understanding and control strategies of sulfate scale formation and to bridge knowledge developed in interfacial chemistry with engineering practice.


Assuntos
Minerais , Sulfatos , Termodinâmica
16.
Chemosphere ; 307(Pt 3): 135863, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-35961451

RESUMO

Covalently-bound organic silicate-aluminum hybrid coagulants (CBHyC) have been shown to efficiently remove low molecular weight organic contaminants from wastewater. However, the interaction dynamics and motivations during the coagulation of contaminant molecules by CBHyC are limited. In this study, a molecular dynamics (MD) simulation showed that CBHyC forms core-shell structure with the aliphatic carbon chains gather inside as a core and the hydrophilic quaternary ammonium-Si-Al complexes disperse outside as a shell. This wrapped structure allowed the coagulant to diffuse into solutions easily and capture target contaminants. The adsorption of anionic organic contaminants (e.g., diclofenac) onto the CBHyC aggregates was driven equally by van der Waals forces and electrostatic interactions. Cationic organic contaminants (e.g., tetracycline) were seldom bound to CBHyC because of substantial repulsive forces between cationic molecules and CBHyC. Neutrally-charged organic molecules were generally bound through hydrophobic interactions. For adenine and thymine deoxynucleotide, representatives of antibiotic resistance genes, van der Waals forces and electrostatic interaction became the dominant driving force with further movement for adenine and thymine, respectively. Driving forces between target contaminant and coagulant directly affect the size and stability of formed aggregate, following the coagulation efficiency of wastewater treatment. The findings of this study enrich the database of aggregation behavior between low molecular weight contaminants and CBHyC and contribute to further and efficient application of CBHyC in wastewater treatment.


Assuntos
Compostos de Amônio , Águas Residuárias , Adenina , Alumínio , Carbono , Diclofenaco , Simulação de Dinâmica Molecular , Estrutura Molecular , Silicatos , Tetraciclinas , Timina
17.
Water Res ; 212: 118091, 2022 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-35093603

RESUMO

Graphene oxide (GO) coating has recently been reported as a novel approach to increase membrane flux of membrane distillation (MD), yet the phenomena underlying the process are still not fully understood. In this study, a mathematical model based on capillary-film assumption was developed and validated with the results (R2>0.99) from a series of MD experiments. According to the model, when GO layer was placed at the evaporation interface, the temperature difference across the membrane surface increases significantly (44.2%∼92.0%) and the temperature polarization coefficient is increased greatly from 0.29∼0.38 to around 0.55. This leads to a big increase of driving force for higher heat flow and subsequently mass flux (17.8∼45.5%). However, the vapor pressure on membrane surface was decreased due to Kelvin effect of GO capillary pores, which has a negative influence on the driving force, accounting for about 26.9% to 52.6% drop in the achieved flux. In comparison, when GO layer was placed at the condensation interface, the temperature difference across the membrane surface decreases slightly (7.2∼12.2%), but the reduced vapor pressure on GO capillary pores due to Kelvin effect become the dominant factor affecting membrane flux, resulting in an increase mass flux of 12.4∼16.4%. The model developed in this study provides a theoretical foundation for understanding the role of GO coating on flux improvement, and can be used for further development of high flux membranes.


Assuntos
Grafite , Purificação da Água , Destilação , Membranas Artificiais
18.
Carbohydr Polym ; 296: 119944, 2022 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-36087992

RESUMO

Poly/oligosaccharides are renewable natural resources with abundant chirality. Herein, we develop a general route to prepare optically active particles by using poly/oligosaccharides as both chiral inducers and growth templates. By complexing with Cu(NH3)42+ ions, OH groups on C2 and C3 in poly/oligosaccharides can transfer the chirality to Cu(II) and retain it in CuO. At the same time, poly/oligosaccharides direct growth of CuO by in situ transformation of Cu(NH3)42+ ions. Cellulose nanocrystal (CNC) and starch (ST) are used as representative polysaccharides, and ß-cyclodextrin (ß-CD) as a representative oligosaccharide, thus dandelion, duchesnea, and chrysanthemum-like composite particles with chiroptical activity are obtained. Besides, chiral CuO/poly(oligo)saccharide particles (CSP) demonstrate enantioselective ability by differentiating coordination with tryptophan (Trp) enantiomers and form Cu-Trp metal organic framework architectures with different morphologies. The study provides an easily accessible approach to prepare novel functional materials by poly/oligosaccharide-based chiral induction and hold great promise in chiral applications.


Assuntos
Celulose , beta-Ciclodextrinas , Celulose/química , Oligossacarídeos , Amido , Estereoisomerismo , Triptofano , beta-Ciclodextrinas/química
19.
Water Res ; 195: 116976, 2021 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-33706215

RESUMO

Membrane technology has been widely used in the wastewater treatment and seawater desalination. In recent years, the reverse osmosis (RO) membrane represented by polyamide (PA) has made great progress because of its excellent properties. However, the conventional PA RO membranes still have some scientific problems, such as membrane fouling, easy degradation after chlorination, and unclear mechanisms of salt retention and water flux, which seriously impede the widespread use of RO membrane technology. This paper reviews the progress in the research and development of the RO membrane, with key focus on the mechanisms and strategies of the contemporary separation, anti-fouling and chlorine resistance of the PA RO membrane. This review seeks to provide state-of-the-art insights into the mitigation strategies and basic mechanisms for some of the key challenges. Under the guidance of the fundamental understanding of each mechanism, operation and modification strategies are discussed, and reasonable analysis is carried out, which can address some key technical challenges. The last section of the review focuses on the technical issues, challenges, and future perspective of these mechanisms and strategies. Advances in synergistic mechanisms and strategies of the PA RO membranes have been rarely reviewed; thus, this review can serve as a guide for new entrants to the field of membrane water treatment and established researchers.


Assuntos
Cloro , Purificação da Água , Filtração , Membranas Artificiais , Nylons , Osmose
20.
Water Res ; 203: 117541, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34416650

RESUMO

Efficient removal of low-concentration refractory pollutants is a crucial problem to ensuring water safety. The use of heterogeneous catalysis of molecular imprinting technology combined with traditional catalysts is a promising method to improve removal efficiency. Presently, the research into molecular imprinting targeting catalysts focuses mainly on material preparation and performance optimization. However, more researchers are investigating other applications of imprinting materials. This review provides recent progress in photocatalyst preparation, electrocatalyst, and Fenton-like catalysts synthesized by molecular imprinting. The principle and control points of target catalysts prepared by precipitation polymerization (PP) and surface molecular imprinting (S-MIP) are introduced. Also, the application of imprinted catalysts in targeted degradation of drugs, pesticides, environmental hormones, and other refractory pollutants is summarized. In addition, the reusability and stability of imprinted catalyst in water treatment are discussed, and the possible ecotoxicity risk is analyzed. Finally, we appraised the prospects, challenges, and opportunities of imprinted catalysts in the advanced oxidation process. This paper provides a reference for the targeted degradation of refractory pollutants and the preparation of targeted catalysts.


Assuntos
Impressão Molecular , Poluentes Químicos da Água , Purificação da Água , Catálise , Águas Residuárias , Poluentes Químicos da Água/análise
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