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1.
J Environ Sci (China) ; 85: 189-199, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31471026

RESUMO

Membrane fouling is an obstacle impeding the wide applications of ceramic membranes and organics are responsible for most of the membrane fouling issues in wastewater treatment. In this study, Fenton cleaning strategy was firstly proposed to clean ceramic membrane fouling in wastewater treatment. Fe2+ efficiently catalyzed fouling cleaning with H2O2 (1.5%) to recover the filterability of ceramic membrane. The maximum ∆TMP recovery (over 99%) was achieved at an optimal Fe2+ dosage of 124 mg/L after 6 hr of immersion cleaning. The total residual membrane fouling resistance decreased gradually from this optimum value as the Fe2+ dosage increased above 124 mg/L. The residual hydraulically reversible fouling resistance accounted for most of the membrane fouling and was basically removed (≤3.0 × 109 m-1) when Fe2+ dosages higher than 124 mg/L were used. The foulants responsible for the formation of a residual hydraulically reversible fouling layer (DOC (dissolved organic carbon), proteins, polysaccharides, EEM (fluorescence excitation-emission matrix spectra), SS (suspended solids), and VSS (volatile suspended solids)) were gradually removed as the Fe2+ dosage increased. These residual organic foulants were degraded from biopolymers (10-200 kDa) to low molecular weight substances (0.1-1 kDa), and the particle size of these residual foulants decreased significantly as a result. The strong oxidation power of hydrogen peroxide/hydroxy radicals towards organic foulants was enhanced by Fe2+. Fe2+ played a significant role in the removal of hydraulically reversible fouling and irreversible fouling from the ceramic membrane. However, Fe2+ (≥124 mg/L) increased the likelihood of forming secondary iron-organics aggregates.


Assuntos
Membranas Artificiais , Eliminação de Resíduos Líquidos/métodos , Biopolímeros , Cerâmica , Peróxido de Hidrogênio , Águas Residuárias
2.
Water Environ Res ; 91(10): 1350-1377, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31529571

RESUMO

The review scans research articles published in 2018 on physico-chemical processes for water and wastewater treatment. The paper includes eight sections, that is, membrane technology, granular filtration, flotation, adsorption, coagulation/flocculation, capacitive deionization, ion exchange, and oxidation. The membrane technology section further divides into six parts, including microfiltration, ultrafiltration, nanofiltration, reverse osmosis/forward osmosis, and membrane distillation. PRACTITIONER POINTS: Totally 266 articles on water and wastewater treatment have been scanned; The review is sectioned into 8 major parts;  Membrane technology has drawn the widest attention from the research community.


Assuntos
Purificação da Água , Fenômenos Químicos , Filtração , Floculação , Membranas Artificiais , Osmose , Eliminação de Resíduos Líquidos , Águas Residuárias
3.
Bioresour Technol ; 293: 122103, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31505391

RESUMO

Efficient quantification of interfacial energy related with membrane fouling represents the primary interest in membrane bioreactors (MBRs) as interfacial energy determines foulant layer formation. In this study, radial basis function (RBF) artificial neural networks (ANNs) with five related factors as input variables were applied to quantify interfacial energy with randomly rough membrane surface. It was found that, RBF ANNs could well capture the complex non-linear relationships between the related factors and interfacial energy. RBF ANN quantification showed high regression coefficient and accuracy, suggesting its high capacity to quantify interfacial energy. Compared to at least one-week time consumption of the advanced extensive Derjaguin-Landau-Verwey-Overbeek (XDLVO) approach, quantification by RBF ANNs only took several seconds for a same case, indicating the high efficiency of RBF ANNs. Moreover, the abilities of RBF ANNs can be further improved. The robust RBF ANNs proposed paved a new way to study membrane fouling in MBRs.


Assuntos
Reatores Biológicos , Membranas Artificiais , Redes Neurais (Computação) , Fenômenos Físicos , Software
4.
Chemosphere ; 235: 1154-1161, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31561306

RESUMO

A MBBR-MBR system has been developed with marine microorganisms enriched for saline wastewater treatment in this work, showing high COD and NH3-N removals. The behaviour of fouling-related components (EPS and SMP) has been studied as functions of operating time (40-90 days), salinity (0-30 g/L NaCl) and backflow ratio (0-300%, from MBR to MBBR). High biodegradability of the MBBR-MBR at optimal conditions can induce more biodegradation of humic acid-like (λex/λem: 350nm/430 nm) and fulvic acid-like (260nm/445 nm) molecules to soluble microbial by-product-like molecules (275nm/325 nm), reducing the membrane biofouling rate. The biodegradation process is suggested by the excitation-emission matrix (EEM) images. In the study of sudden salinity shock, results show that real-time monitoring the concentration of biofoulants is more effective (operative time extended by 60%) than monitoring the transmembrane pressure (operative time extended by 33%) to prevent membrane fouling. Due to an early warning from the real-time monitoring, the coming membrane-fouling is predictable and the operating conditions, such as backflow ratio, can be changed to minimize the biofouling rate.


Assuntos
Biofilmes , Incrustação Biológica/prevenção & controle , Reatores Biológicos , Membranas Artificiais , Águas Residuárias/química , Biodegradação Ambiental , Salinidade , Análise Espectral , Purificação da Água/métodos
5.
J Environ Manage ; 251: 109555, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31539697

RESUMO

To determine the most efficient pretreatment for ceramic membrane filtration (CMF) of primary clarifier effluent (PE), the effectiveness of ozonation and coagulation was investigated from the viewpoint of both virus removal and mitigation of membrane fouling. Our results showed virus removal by coagulation to be more efficient as a CMF pretreatment, whereas ozonation showed better efficiency when used as a CMF posttreatment. The effect of ozonation and coagulation on ceramic membrane fouling was investigated during short-term operation. With the use of coagulation before CMF (PACl + CMF), irreversible fouling resistance was 0.5 × 1011 m-1 at a dosage of 150 mg/L of polyaluminum chloride (PACl), which was 10 times lower than when ozonation was used as a pretreatment to CMF (O3+CMF) (0.7 × 1012 m-1 at 50 mg-O3/L). This result indicates coagulation to be more efficient than ozonation for mitigating ceramic membrane fouling. Based on these results, the process sustainability of PACl + CMF was then investigated during longer-term operation. At a dosage of 150 mg/L of PACl, the PACl + CMF process could be sustainably operated for 120 h without any need for chemically enhanced backwashing, which was twice as long as for PACl dosages of 50 and 100 mg/L. Coagulation is thus a more efficient pretreatment for CMF of PE from the viewpoint of both virus removal and mitigation of ceramic membrane fouling. The hygienic safety of reclaimed water can be further improved if ozonation is used as a CMF posttreatment.


Assuntos
Ozônio , Purificação da Água , Cerâmica , Membranas Artificiais , Águas Residuárias
6.
J Environ Manage ; 251: 109524, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31542619

RESUMO

The presence of excess fluoride in aqueous media above local environmental standards (e.g., the U.S. Environmental Protection Agency (EPA) standard of 4 mg/L) affects the health of aquatic life. Excess fluoride in drinking water above the maximum contaminant level (e.g., the World Health Organization (WHO) standard of 1.5 mg/L) also affects the skeletal and nervous systems of humans. Fluoride removal from aqueous solutions is difficult using conventional electrochemical, precipitation, and adsorption methods owing to its ionic size and reactivity. Thus, new technologies have been introduced to reduce the fluoride concentration in industrial wastewater effluents and various drinking water sources. Membrane technology is one of the newer technologies found to be very effective in significantly reducing fluoride to desired standards levels; however, it has received less attention than other technologies because it is perceived as a costly process. This study critically reviewed the performance of various membrane process and compared it with effluent and zero liquid discharge (ZLD) standards. The performance review has been conducted with the consideration of the theoretical background, rejection mechanisms, technical viability, and parameters affecting flux and rejection performance. This review includes membrane systems investigated for the defluoridation process but operated under pressure (i.e., reverse osmosis [RO] and nanofiltration [NF]), temperature gradients (i.e., membrane distillation [MD]), electrical potential gradients (i.e., electrodialysis [ED] and Donnan dialysis [DD]), and concentration differences (i.e., forward osmosis [FO]). Moreover, the study also addressed the advantages, limitations, & applicable conditions of each membrane based defluoridation process.


Assuntos
Águas Residuárias , Purificação da Água , Fluoretos , Membranas Artificiais , Osmose , Água
7.
J Environ Manage ; 251: 109618, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31563603

RESUMO

This paper aims to develop novel hydrophilic ionic liquid membranes using pervaporation for the recovery of biobutanol. Multiple polyvinyl alcohol (PVA) membranes based on three commercial ionic liquids with different loading were prepared for various experimental trials. The ionic liquids selected for the study include tributyl (tetradecyl) phosphonium chloride ([TBTDP][Cl]), tetrabutyl phosphonium bromide ([TBP][Br]) and tributyl methyl phosphonium methylsulphate ([TBMP][MS]). The synthesized membranes were characterized and tested in a custom-built pervaporation set-up. All ionic liquid membranes showed better results with total flux of 1.58 kg/m2h, 1.43 kg/m2h, 1.38 kg/m2h at 30% loading of [TBP][Br], [TBMP][MS] and [TBTDP][Cl] respectively. The comparison of ionic liquid membranes revealed that by incorporating [TBMP]MS to PVA matrix resulted in a maximum separation factor of 147 at 30 wt% loading combined with a relatively higher total flux of 1.43 kg/m2h. Density functional theory (DFT) calculations were also carried out to evaluate the experimental observations along with theoretical studies. The improved permeation properties make these phosphonium based ionic liquid a promising additive in PVA matrix for butanol-water separation under varying temperature conditions.


Assuntos
Líquidos Iônicos , Butanóis , Membranas Artificiais , Álcool de Polivinil , Água
8.
Chem Commun (Camb) ; 55(67): 10023-10026, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-31378804

RESUMO

Inspired by the formation mechanism of a biological membrane potential, we described the generation of an artificial membrane potential through redox-regulating anion distribution on the two sides of a polypyrrole film. The polarity of the membrane potential could be regulated by the redox reaction.


Assuntos
Materiais Biomiméticos/química , Polímeros/química , Pirróis/química , Técnicas Eletroquímicas , Potenciais da Membrana , Membranas Artificiais , Oxirredução
9.
Soft Matter ; 15(33): 6630-6641, 2019 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-31403143

RESUMO

The mechanics of blister delamination and growth plays a major role in a diversity of areas including medicine (skin pathology and mechanics of cell membranes), materials (adhesive and fracture) or soft robotics (actuation and morphing). The behavior of a blister in this context is typically difficult to grasp as it arises from the interplay of two highly nonlinear and time-dependent processes: membrane attachment and decohesion from a substrate. In the present work, we device a simplified approach, based on experimental systems, to predict the deformation path of a blister under various conditions. For this, we consider the problem of a growing blister made of a rubber-like membrane adhered on a rigid substrate, and develop a theoretical and experimental framework to study its stability and growth. We start by constructing a theoretical model of viscoelastic blister growth which we later validate with an experimental setup. We show that blister growth is controlled by the competition between two instabilities: one inherent to the rubber, and a second one pertaining to the adhesion with the substrate. Using these concepts, we show that a "targeted" stable blister shape can be achieved by controlling two parameters: the thickness of the film and the inflation rate.


Assuntos
Simulação por Computador , Membranas Artificiais , Modelos Teóricos , Adsorção , Elasticidade , Cinética , Propriedades de Superfície , Termodinâmica , Viscosidade
10.
Int J Nanomedicine ; 14: 5033-5050, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31371945

RESUMO

Background: Repairs to deep skin wounds continue to be a difficult issue in clinical practice. A promising approach is to fabricate full-thickness skin substitutes with functions closely similar to those of the natural tissue. For many years, a three-dimensional (3D) collagen hydrogel has been considered to provide a physiological 3D environment for co-cultivation of skin fibroblasts and keratinocytes. This collagen hydrogel is frequently used for fabricating tissue-engineered skin analogues with fibroblasts embedded inside the hydrogel and keratinocytes cultivated on its surface. Despite its unique biological properties, the collagen hydrogel has insufficient stiffness, with a tendency to collapse under the traction forces generated by the embedded cells. Methods: The aim of our study was to develop a two-layer skin construct consisting of a collagen hydrogel reinforced by a nanofibrous poly-L-lactide (PLLA) membrane pre-seeded with fibroblasts. The attractiveness of the membrane for dermal fibroblasts was enhanced by coating it with a thin nanofibrous fibrin mesh. Results: The fibrin mesh promoted the adhesion, proliferation and migration of the fibroblasts upwards into the collagen hydrogel. Moreover, the fibroblasts spontaneously migrating into the collagen hydrogel showed a lower tendency to contract and shrink the hydrogel by their traction forces. The surface of the collagen was seeded with human dermal keratinocytes. The keratinocytes were able to form a basal layer of highly mitotically-active cells, and a suprabasal layer. Conclusion: The two-layer skin construct based on collagen hydrogel with spontaneously immigrated fibroblasts and reinforced by a fibrin-coated nanofibrous membrane seems to be promising for the construction of full-thickness skin substitute.


Assuntos
Colágeno/farmacologia , Fibrina/farmacologia , Hidrogéis/farmacologia , Membranas Artificiais , Nanofibras/química , Poliésteres/farmacologia , Pele Artificial , Animais , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Derme/citologia , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Humanos , Recém-Nascido , Queratinócitos/citologia , Queratinócitos/efeitos dos fármacos , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Ratos
11.
Bioresour Technol ; 292: 121852, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31386944

RESUMO

Membrane fouling is considered as a main drawback for MBR technology especially treating industrial wastewater. Therefore, this study aimed to investigate the effect of fouling in membrane bioreactor (MBR) treating pharmaceutical wastewater with the addition of ferric hydroxide. Two identical lab-scale MBRs, namely, a control MBR (Co-MBR) and an enhanced MBR dosed with ferric hydroxide (Fe-MBR), were operated in parallel. The results demonstrate membrane fouling was retarded by 35% with the addition of iron. Further exploration of membrane fouling mechanisms showed iron addition resulted in increase in biomass floc size, enhancement of bacteria activity and reduction of dissolved organic concentration, especially carbohydrate, biopolymer and low molecular weight compounds concentrations in mixed liquor. There was also lower abundance of bacterial associated with biofilm formation in the Fe-MBR compared with the Co-MBR. These findings collectively contributed to the positive impacts on membrane fouling mitigation.


Assuntos
Membranas Artificiais , Águas Residuárias , Reatores Biológicos , Compostos Férricos
12.
J Nanobiotechnology ; 17(1): 86, 2019 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-31387581

RESUMO

BACKGROUND: Controllable and multiple DNA release is critical in modern gene-based therapies. Current approaches require complex assistant molecules for combined release. To overcome the restrictions on the materials and environment, a novel and versatile DNA release method using a nano-electromechanical (NEMS) hypersonic resonator of gigahertz (GHz) frequency is developed. RESULTS: The micro-vortexes excited by ultra-high frequency acoustic wave can generate tunable shear stress at solid-liquid interface, thereby disrupting molecular interactions in immobilized multilayered polyelectrolyte thin films and releasing embedded DNA strands in a controlled fashion. Both finite element model analysis and experiment results verify the feasibility of this method. The release rate and released amount are confirmed to be well tuned. Owing to the different forces generated at different depth of the films, release of two types of DNA molecules with different velocities is achieved, which further explores its application in combined gene therapy. CONCLUSIONS: Our research confirmed that this novel platform based on a nano-electromechanical hypersonic resonator works well for controllable single and multi-DNA release. In addition, the unique features of this resonator such as miniaturization and batch manufacturing open its possibility to be developed into a high-throughput, implantable and site targeting DNA release and delivery system.


Assuntos
DNA/química , Nanoestruturas/química , Polieletrólitos/química , Acústica/instrumentação , Fenômenos Biofísicos , Desenho de Equipamento , Análise de Elementos Finitos , Técnicas de Transferência de Genes , Terapia Genética/métodos , Membranas Artificiais , Propriedades de Superfície
13.
Pestic Biochem Physiol ; 159: 22-26, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31400780

RESUMO

Herbicide efficacy depends on herbicides crossing cell and organelle membranes. We evaluated an artificial membrane system to understand how herbicides cross biological membranes. This understanding aids in predicting herbicide behavior in planta and, consequently, efficacy, mode of action, and whether active transporter-based herbicide resistance mechanisms may be possible. Five herbicides with different log Kow and pKa values were assessed: glyphosate, 2,4-D, clopyralid, sulfentrazone and glufosinate. The artificial membrane apparatus included four semipermeable membranes containing buffers with pH 2.7, 5 and/or 7.4, floating in a bath of diethyl ether. These conditions were based on the pH from different cellular compartments and the pKa for these herbicides. Changes in herbicide concentration due to movement were measured using radioactivity or liquid chromatography mass spectrometry. In general, herbicide behavior followed the pattern predicted by their calculated pKa and log Kow. Herbicides added to an acidic phase (pH 2.7) were more mobile than when they were added to the more basic phase (pH 7.4), except when herbicide's pKa was lower than the pH of the starting phase. Clopyralid, 2,4-D, and sulfentrazone showed significant acid trapping behavior due to their weak acid functional groups. Sulfentrazone and 2,4-D had a high affinity for the nonpolar, diethyl ether bath, especially when they were protonated at low pH. Our findings illustrate the robustness of the system to provide predictions about herbicide behavior at the subcellular level.


Assuntos
Herbicidas/metabolismo , Ácido 2,4-Diclorofenoxiacético/metabolismo , Aminobutiratos/metabolismo , Glicina/análogos & derivados , Glicina/metabolismo , Concentração de Íons de Hidrogênio , Membranas Artificiais , Ácidos Picolínicos/metabolismo , Sulfonamidas/metabolismo , Triazóis/metabolismo
14.
Phys Chem Chem Phys ; 21(34): 18595-18604, 2019 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-31414082

RESUMO

With application to the nitrite reductase hexameric protein complex of Desulfovibrio vulgaris, NrfH2A4, we suggest a strategy to compute the energy landscape of electron transfer in large systems of biochemical interest. For small complexes, the energy of all electronic configurations can be scanned completely on the level of a numerical solution of the Poisson-Boltzmann equation. In contrast, larger systems have to be treated using a pair approximation, which is verified here. Effective Coulomb interactions between neighbouring sites of excess electron localization may become as large as 200 meV, and they depend in a nontrivial manner on the intersite distance. We discuss the implications of strong Coulomb interactions on the thermodynamics and kinetics of charging and decharging a protein complex. Finally, we turn to the effect of embedding the system into a biomembrane.


Assuntos
Desulfovibrio vulgaris/enzimologia , Modelos Moleculares , Nitrito Redutases/química , Dimiristoilfosfatidilcolina/química , Transporte de Elétrons , Cinética , Membranas Artificiais , Conformação Proteica , Multimerização Proteica , Termodinâmica
15.
J Environ Manage ; 249: 109359, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31404857

RESUMO

Membrane based technologies are highly reliable for water and wastewater treatment, including for removal of total oil and grease from produced water. However, performances of the pressure driven processes are highly restricted by membrane fouling and the application of traditional air bubbling system is limited by their low shear stress due to poor contacts with the membrane surface. This study develops and assesses a novel finned spacer, placed in between vertical panel, for membrane fouling control in submerged plate-and-frame module system for real produced water filtration. Results show that permeability of the panel is enhanced by 87% from 201 to 381 L/(m2 h bar). The spacer system can be operated in switching mode to accommodate two-sided panel aeration. This leads to panel permeability increment by 22% higher than the conventional vertical system. The mechanisms of finned spacer in encouraging the flow trajectory was proven by visual observation and flow simulation. The fins alter the air bubbles flow trajectory toward the membrane surface to effectively scour-off the foulant. Overall results demonstrate the efficacy of the developed spacer in projecting the air bubble trajectory toward the membrane surface and thus significantly enhances membrane panel productivity.


Assuntos
Purificação da Água , Água , Ar , Reatores Biológicos , Filtração , Membranas Artificiais
16.
J Environ Manage ; 249: 109382, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31421481

RESUMO

Textile industry generates a high volume of wastewater containing various type of pollutants. Although high color and chemical oxygen demand (COD) removals are achieved with the combination of biological and chemical treatment processes, reverse osmosis (RO) process is generally needed for water recovery due to high conductivity of the textile wastewater. In this study, a pilot scale RO process containing one spiral wound membrane element was operated under three different operational modes, i.e. concentrated, complete recycle and continuous, to collect more information for the prediction of a real-scale RO process performance. It was claimed that complete recycle mode of operation enabled mimicking the operational conditions exerted on the first membrane, whereas continuous mode of operation created conditions very similar to the ones exerted on the last membrane element in a real scale RO process train. In the concentrated and continuous mode of operation, water recovery and flux were around 70% and 19 L/m2/h (LMH). Permeate produced in the RO process can be safely reused in the dyeing process as the feed and permeate conductivities were around 5500 µS/cm and 150 µS/cm, respectively, at 70% water recovery. However, color concentration in the concentrate exceeded the discharge limits and would need further treatment. The RO performance was accurately predicted by ROSA simulations.


Assuntos
Águas Residuárias , Purificação da Água , Membranas Artificiais , Osmose , Têxteis , Eliminação de Resíduos Líquidos , Água
17.
J Environ Manage ; 249: 109394, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31434051

RESUMO

The forward osmosis (FO) membrane process has recently established in many applications such as desalination, wastewater reuse, water purification, food processing, resource recovery and sustainable power generation. However, many researchers raise the demand for systematic investigation on FO membrane fouling, which leads to reduced flux yield. In this study, the effect of coagulation/persulfate as a feed pre-treatment was used to mitigate FO organic fouling during municipal wastewater treatment, and compared with a control coagulation and potassium persulfate pre-treatments. Mass balance results using size exclusion chromatography exhibited that the decrease in the flux with consecutive filtration cycles was likely due to humic-like molecules in the feedwater. Coagulation/persulfate contributed to a more significant flux improvement than stand-alone coagulation or persulfate pre-treatment, resulting in a smaller amount of organics attachment to the membrane. A better flux enhancement by coagulation/persulfate was again evidenced by a higher decrease in the attachment of reversible and irreversible organic foulants on the membrane surface. This study identified the major organic components responsible for FO fouling and established the potential of coagulation/persulfate pre-treatment for reducing organic fouling of FO membrane during municipal wastewater treatment.


Assuntos
Águas Residuárias , Purificação da Água , Filtração , Membranas Artificiais , Osmose
18.
Chem Commun (Camb) ; 55(71): 10571-10574, 2019 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-31417999

RESUMO

A portable dual-mode sensing platform based on a self-standing TiO2 nanotube membrane is developed for simultaneously performing both qualitative analysis by the naked eye and quantitative analysis by ionic current. This dual-mode diagnosis strategy exhibits a high performance in telomerase detection in urine specimens from patients with bladder cancer.


Assuntos
Nanotubos/química , Telomerase/urina , Titânio/química , Neoplasias da Bexiga Urinária/diagnóstico , Técnicas Biossensoriais/instrumentação , Técnicas Biossensoriais/métodos , Cor , Ouro/química , Humanos , Membranas Artificiais , Nanopartículas Metálicas/química , Prata/química , Neoplasias da Bexiga Urinária/urina
19.
J Environ Manage ; 249: 109358, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31450197

RESUMO

The aim of this study is to evaluate the performance and antifouling properties of polyethersulfone (PES) membrane incorporated with dual nanofiller, zinc oxide (ZnO) and multi-walled carbon nanotube (MWCNT). The synergistic effect of the these nanofillers in PES membrane is studied by blending different ratio of ZnO/MWCNT nanofiller into the PES membrane. The fabricated membranes were characterized in terms of cross-section and surface morphology, surface hydrophilicity, pore size and porosity. The filtration performance of the membranes was tested using 50 mg/L humic acid (HA) solution as model solution. SEM image and gravimetric evaluation reported that the incorporation of both MWCNT and ZnO into the PES membrane improved porosity significantly up to 46.02%. Lower water contact angle of PES membrane incorporated with equal ratio of MWCNT and ZnO (PES 3) revealed that it has neat PES membrane properties and more hydrophilic membrane surface than single filler. PES 3 outperform other membranes with excellent HA permeate flux of 40.00 L/m2.h and rejection of 88.51%. Due to hydrophilic membrane surface, PES 3 membrane demonstrate efficient antifouling properties with lower relative flux reduction (RFR) and higher flux recovery ratio (FRR). PES 3 also showed notable antibacterial properties with less bacterial attached to the membrane compared to neat PES membrane (PES 0).


Assuntos
Óxido de Zinco , Antibacterianos , Membranas Artificiais , Polímeros , Sulfonas
20.
Sci Total Environ ; 685: 1193-1200, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31390709

RESUMO

Harmful algal blooms (HABs) are considered a major threat for seawater reverse osmosis (SWRO) plants. The presence of HABs in the raw feed water can cause increase of chemical consumption within the desalination plant, increase membrane fouling rate and might lead to plant shutdown. The removal of Algal Organic Matters (AOMs) during the pretreatment will help in increasing the membrane lifetime, reduce operation cost and increase the plant reliability. In this study, the efficiency of liquid ferrate and ferric chloride during coagulation on the removal of AOMs was investigated. The liquid ferrate was generated in-situ by wet oxidation of ferric iron using hypochlorite in a caustic medium. Two seawater models were employed, the first one contains 10 mg c/L of sodium alginate and the second one contains also 10 mg c/L of Chaetoceros affinis algae (CA). During the advanced coagulation, liquid ferrate proved to be more effective in removing AOM than ferric chloride, with an overall DOC removal of 90%, enabling 100% algal removal and the inactivation of 99.99% of the microorganisms. The results presented in this study highlights the efficiency of liquid ferrate as seawater pretreatment during the HABs events.


Assuntos
Água do Mar/química , Purificação da Água/métodos , Cloretos , Diatomáceas , Compostos Férricos , Proliferação Nociva de Algas , Ferro , Membranas Artificiais , Oxirredução
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