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1.
Water Sci Technol ; 84(5): 1245-1256, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34534120

RESUMO

In this study, electrochemical oxidation of combed fabric dyeing wastewater was investigated using graphite electrodes. The response surface methodology (RSM) was used to design the experiments via the central composite design (CCD). The planned experiments were done to track color changes and chemical oxygen demand (COD) removal. The experimental results were used to develop optimization models using RSM and the artificial neural network (ANN) and they were compared. The developed models by the two methods were in good agreement with the experimental results. The optimum conditions were found at 150 A/m2, pH 5, and 120 min. The removal efficiencies for color and COD reached 96.6% and 77.69%, respectively. The operating cost at the optimum conditions was also estimated. The energy and the cost of 1 m3 of wastewater required 34.9 kWh and 2.58 US$, respectively. The graphite electrodes can be successfully utilized for treatment of combed fabric dyeing wastewater with reasonable cost.


Assuntos
Grafite , Águas Residuárias , Eletrodos , Redes Neurais de Computação , Têxteis
2.
Bioresour Technol ; 340: 125688, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34358985

RESUMO

This study presents the effect of mechanical, chemical, thermal, and hybrid pretreatment on anaerobic digestion of fruit-juice industrial waste (FW) co-digested with municipal sewage sludge (MSS). The pretreatment of the substrates with ultrasonication, microwave, weak alkali-acid caused an increase in cumulative biogas production of approximately 20.9, 14.9, 8.1, and 5.2%, respectively. Beside this, thermal and strong acid-alkali pretreatment reduced biogas production. The highest cumulative biogas and methane yield was increased with hybrid pretreatment which contains ultrasonication (US) and alkali (AL) pretreatment by 36% and 49%, respectively. Also, compared to untreated mixture, the soluble COD, carbohydrate, and protein removal efficiencies were increased from 42.6% to 65.6%, 65.1% to 86.6%, and 17.3% to 62.4%, respectively for US-AL pretreatment. The kinetic parameters of cumulative biogas production for the selected reactors were further estimated with Monod, Cone, and Transference Function models.


Assuntos
Biocombustíveis , Esgotos , Anaerobiose , Biocombustíveis/análise , Reatores Biológicos , Digestão , Resíduos Industriais , Metano
3.
Water Environ Res ; 2021 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-34453770

RESUMO

This study concerns the preparation of novel adsorbent prepared from calcium alginate bead modified with polyethyleneimine (PEI-CaAlg). The adsorption capacity of the PEI-CaAlg was examined by Remazol Brilliant Blue R (RBBR) and phosphate adsorption. PEI-CaAlg showed high removal efficiencies for RBBR (90.48%) and phosphate (88.10%). The removal of both RBBR and phosphate onto the PEI-CaAlg followed the Freundlich isotherm and the second-order model. The adsorption was studied in terms of thermodynamic and found to be feasible and spontaneous in nature. The reusability of the modified alginate beads was also examined up to five cycles. The removal efficiency was 90.48% at the first cycle and decreased to 75.15% at the end of the fourth cycle. The adsorption of color and phosphate from real textile wastewater was also instigated. The removal efficiencies for color and phosphate ions reached 80.24% and 90.00%, respectively. Therefore, the prepared PEI-CaAlg can be considered as a novel, eco-friendly, and cost-effective adsorbent for simultaneous dye and phosphate adsorption. PRACTITIONER POINTS: This study aims to modify the surface of calcium alginate beads with polyethyleneimine (PEI). The adsorption of RBBR and phosphate by the modified alginate beads (PEI-CaAlg) was investigated. PEI is an organic polymer with a linear/branch shape, which can increase the active sites on the adsorbent surface. PEI has one nitrogen atom in every three atoms provides a positive charge that can complex with the negatively charged molecules. The adsorption of RBBR and phosphate were carried out onto PEI-CaAlg.

4.
Water Sci Technol ; 84(3): 752-762, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34388132

RESUMO

In this study, an electro-oxidation (EO) process using graphite electrodes as electrode pairs was used for the removal of chemical oxygen demand (COD), ammoniacal nitrogen (NH4+-N), and color from real textile printing wastewater. The effects of solution pH, sodium chloride (NaCl) dosage, sodium hypochlorite (NaOCl), which is the oldest and still most important chlorine-based bleach, dosage, and oxidation time were investigated on the removal efficiencies. Operating conditions for the EO reactor were applied to current density 1 mA/cm2, distance between the electrodes: 2 cm, 150 min operation time, and stirring speed of 500 rpm. At optimum conditions: pH 9.5, applied current density 1 mA/cm2, NaCl dosage of 8 g/L, NaOCl dosage of 44.4 mg/L and 150 min electro-oxidation time, the obtained removal efficiencies were 86.5% and 91.1% for chemical oxygen demand (COD) and ammoniacal nitrogen, respectively. Efficiency was increased to 91.1% for ammoniacal nitrogen from 21.7% after applying EO combined with NaOCl addition compared to individual NaOCl addition.


Assuntos
Águas Residuárias , Poluentes Químicos da Água , Análise da Demanda Biológica de Oxigênio , Eletrodos , Nitrogênio , Oxirredução , Impressão Tridimensional , Cloreto de Sódio , Têxteis , Eliminação de Resíduos Líquidos , Poluentes Químicos da Água/análise
5.
Water Environ Res ; 2021 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-34288251

RESUMO

In this study, calcium alginate (Ca-Alg) beads, an inexpensive, easily available, biodegradable material, were activated with anionic surfactant and used for the treatment of wastewater contaminated with waste motor oil. First, polyethyleneimine (PEI) was used to bind sodium dodecyl sulfate (SDS) onto the Ca-Alg beads' surface. Three different SDS concentrations (25, 50, & 100 mg/L) were prepared and treated with Ca-Alg beads for 1, 2, 4, 6, and 24 h. SDS binding yield reached equilibrium at the end of the 24 h, and the binding efficiencies of 25, 50, and 100 mg SDS/L were determined 84%, 72%, and 48%, respectively. The effect of pH between 2 and 10 was also investigated on oil adsorption. Maximum adsorption efficiency (77%) was obtained in the range of pH 6-8. After determining the optimum pH value for oil adsorption, the effect of beads amount (2.5-30 g/L) was also investigated on oil removal efficiency. When the amount of beads increased from 2.5 to 30 g/L, the oil adsorption efficiency increased from 77% to 95%. It was also observed that the oil adsorption efficiency increased when the size of the beads decreased from 4 to 1 mm. For the kinetic calculation, three different concentrations (250, 500, &1000 mg/L) of oily solution were prepared, and oil adsorption was investigated versus time. The kinetic studies for the adsorption of the oily solution using SDS functionalized Ca-Alg beads showed the second-order kinetics. When the initial oil concentration increased from 250 to 1000 mg/L, the amount of adsorbed oil molecules increased from 8.34 to 22.12 mg/g. Langmuir and Freundlich isotherm models were used to explain the relationship between adsorbent and adsorbate, and Langmuir isotherm was the most suitable model because of its high regression coefficient (r2 ) value. Column studies were also carried out, and it was concluded that the proposed adsorbent can be used effectively in the treatment of oily wastewater. PRACTITIONER POINTS: Although there are numerous adsorption studies and studies on the use of alginate beads in various fields in the literature, its use in oil treatment has not been found to our knowledge. The study aims to produce a selective adsorbent for the removal of oil from water by functionalizing the surface of the alginate beads with active agents. In conventional adsorption studies, pollutants are transported from liquid phase to solid phase. With the proposed new adsorbent material, oils will be specifically removed from wastewater and used as fuel. Thus, obtaining an organic origin adsorbent with high calorific value constitutes the original value of the study. In addition, no secondary pollutants will emerge after the adsorption process.

6.
Colloids Surf B Biointerfaces ; 205: 111867, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34120090

RESUMO

This study aims to investigate the modification of polyethersulfone (PES) membrane with boron nitride quantum dots (BNQD) for improving the antifouling performance. The composite membranes were synthesized by blending different amounts of BNQD (0.50, 1.00, and 2.00 wt.%) into PES with the non-solvent induced phase separation (NIPS) method. UV-vis absorption, X-ray diffraction (XRD), and transmission electron microscopy (TEM) were used to characterize BNQD. Moreover, porosity, pore size, contact angle, permeability, bovine serum albumin (BSA) rejection, and antifouling properties were determined for composite membranes. The enhanced biological activity of BNQD was investigated based on antioxidant, antimicrobial, anti-biofilm, bacterial viability inhibition, and DNA cleavage studies. The BNQD showed 19.35 % DPPH radical scavenging activity and 76.45 % ferrous ion chelating activity at 500 mg/L. They also exhibited good chemical nuclease activity at all concentrations. BNQD had moderate antibacterial activity against all tested microorganisms. Biofilm inhibition percentage of BNQD was determined as 82.31 % at 500 mg/L. Cell viability assay demonstrated that the BNQD showed strong cell viability inhibition 99.9 % at the concentration of 1000 mg/L. The porosity increased from 56.83 ± 1.17%-61.83 ± 1.17 % while BNQD concentration increased from 0 to 2.00 wt%. Moreover, the hydrophilicity of BNQD nanocomposite membranes also increased from 75.42 ± 0.56° to 65.34 ± 0.25°. The mean pore radius is far slightly changed from 16.47 ± 0.35 nm to 19.16 ± 0.22 nm. The water flux increased from 133.5 ± 9.5 L/m2/h (for pristine membrane) to 388.6 ± 18.8 L/m2/h (for PES/BNQD 2.00 wt% membrane). BSA flux increased from 38.8 ± 0.9 L/m2/h to 63.2 ± 2.7 L/m2/h up to 1.00 wt% amount of BNQD nanoparticles.


Assuntos
Incrustação Biológica , Pontos Quânticos , Incrustação Biológica/prevenção & controle , Compostos de Boro , Membranas Artificiais , Polímeros , Sulfonas , Ultrafiltração
7.
Environ Technol ; : 1-11, 2021 May 12.
Artigo em Inglês | MEDLINE | ID: mdl-33906587

RESUMO

In this study, environmental-friendly composite polyethersulfone (PES) membranes based on basalt powder were prepared by phase inversion method. The effects of polymer percentage, the basalt percentage, and the thickness of the membrane were investigated on the distilled water flux, compaction factor, bovine serum albumin (BSA) rejection, contact angle, fouling factor and the parameters were modelled by response surface methodology (RSM). The distilled water flux increased when the basalt was added to the membrane up to 6% percentage of the polymer amount. The blending of basalt also provided resistance against the membrane compaction. The BSA rejection experiments approved the positive effects of basalt on the rejections efficiencies. At higher basalt percentages, the rejection efficiencies increased from 78% at the raw membrane to 99% for the composite membranes had 10% basalt. The adding of basalt to the membranes decreased the contact angles. The hydrophilicity of the membranes contained basalt in their structures was higher than those which had not basalt. By comparison with the neat membranes and the basalt added membrane, it can be said that the basalt increased the flux recovery and decreased the irreversible fouling factors. The basalt increased the antifouling properties for the composite membranes. Finally, the prepared membranes were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX).

8.
Water Sci Technol ; 83(5): 1242-1249, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33724950

RESUMO

Recently, the utilization of wastes, recovery of high value-added products from waste, and their use as raw materials in other industries with the logic of industrial symbiosis has become an important issue. In this study, removal efficiency of Reactive Orange 16 (RO16) dye from aqueous solution was studied using TiO2 catalyst recycled from an industrial waste effluent. The recycling of TiO2 waste from a paints manufacturing industry was carried out by sintering the TiO2-containing waste. The catalyst usability of TiO2-containing powder was then investigated in the removal of RO16 dye by photocatalytic oxidation process. In photocatalytic oxidation studies, TiO2/UV and TiO2/UV/H2O2 processes were investigated, where the effect of annealing temperature, the effect of H2O2 concentration, and the adsorption and photocatalytic effects on RO16 dye removal were studied. The results showed that 100% RO16 removal was obtained for the 10 mg/L initial RO16 concentration using the TiO2 (1 g/L)/UV process. At high initial RO16 concentration (50 mg/L), 100% RO16 removal was achieved by adding 10 mM H2O2.


Assuntos
Peróxido de Hidrogênio , Purificação da Água , Catálise , Titânio , Águas Residuárias
9.
Water Sci Technol ; 83(3): 622-630, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33600366

RESUMO

Aspergillus parasiticus (A. parasiticus) CBS 100926T was used as a biosorbent for the removal of Methylene Blue (MB), Congo Red (CR), Sudan Black (SB), Malachite Green Oxalate (MGO), Basic Fuchsin (BF) and Phenol Red (PR) from aqueous solutions. The batch biosorption studies were carried out as a function of dye concentration and contact time. The biosorption process followed the pseudo-first-order and the pseudo-second-order kinetic models and the Freundlich and Langmuir isotherm models. The resulting biosorbent was characterized by Scanning Electron Microscopy (SEM), X-Ray Diffractometer and Fourier Transformer Infrared Spectroscopy (FTIR) techniques. The results of the present investigation suggest that A. parasiticus can be used as an environmentally benign and low cost biomaterial for the removal of basic and acid dyes from aqueous solution.


Assuntos
Corantes , Poluentes Químicos da Água , Adsorção , Aspergillus , Biomassa , Concentração de Íons de Hidrogênio , Cinética , Espectroscopia de Infravermelho com Transformada de Fourier , Termodinâmica
10.
Water Sci Technol ; 83(3): 701-714, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33600373

RESUMO

In this study, we investigated the production conditions of Quercus coccifera hydrochar, which is an inexpensive and easy available adsorbent, for the adsorption of Basic Red 18 (BR18) azo dye. The hydrochar was produced in the eco-friendly subcritical water medium (SWM). The effects of the pH (2-10), adsorbent size (45-106 µm), adsorbent dose (0.5-1.5 g/L), dye concentration (40-455 mg/L), and contact time (5-120 min) were studied via optimization experiments. The optimum conditions were pH 10, particle size of 45 µm, particle amount of 1.5 g/L, dye concentration of 455 mg/L, and 60 min. The removal efficiency increased sharply for the first 5 min; after that the removal efficiency reached a steady state at 60 min, with a maximum removal of 88.7%. The kinetic studies for the adsorption of BR18 dye in aqueous solution using hydrochar showed pseudo-second-order kinetics. The Langmuir and Freundlich isotherm models were used to explain the relationship between adsorbent and adsorbate, and Freundlich isotherm was the most suitable model because of its high regression coefficient (R2) value. The intraparticle diffusion model was used to determine the adsorption mechanism of BR18 onto Q. coccifera acorn hydrochar. Desorption studies were also carried out using different types of acid and different molarities.


Assuntos
Quercus , Poluentes Químicos da Água , Adsorção , Corantes , Concentração de Íons de Hidrogênio , Cinética , Termodinâmica , Água
11.
Chemosphere ; 263: 127892, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32822943

RESUMO

Nitrogen-doped porous graphene oxide (N-PGO) was synthesized, characterized, and applied as a hydrophilic nanomaterial in fabrication of polyethersulfone (PES) membrane for Reactive Red 195 dye and bovine serum albumin (BSA) protein separation. The N-PGO nanosheets not merely showed a good adhesion towards polymers, but simultaneously promoted hydrogen bonding action. Therefore, high-efficiency permeation passageway in the separation layer of membranes was attained. X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDX) and Fourier transform infra-red spectroscopy (FTIR) analyses approved nitrogen doping, which increased hydrophilicity and hydrogen bonding ability of PGO in water filtration. The pure water permeation of nanocomposite membranes could reach as high as 190 L m-2 h-1 at 3 bar. A dye rejection efficiency higher than 92% and BSA rejection higher than 95% were accordingly obtained. Atomic force microscopy (AFM) images approved formation of a rough surface that was decreased by addition of low amounts of the PGO. SEM images provided from the surface also confirmed enlarged pore size and increased porosity. Antifouling properties were investigated by BSA filtration, and results showed that the flux recovery ratio of the N-PGO membrane was improved. Overall, the N-PGO hybrid membranes exhibited potential for application in separation of typical proteins and dyes with good antifouling properties.


Assuntos
Corantes/química , Nanocompostos/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Animais , Bovinos , Corantes/análise , Filtração , Grafite/química , Ligação de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Membranas Artificiais , Nitrogênio , Polímeros/química , Porosidade , Soroalbumina Bovina/química , Sulfonas , Água/química , Poluentes Químicos da Água/análise
12.
J Fungi (Basel) ; 6(4)2020 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-33105686

RESUMO

Food processing industry by-products (apple, pomegranate, black carrot, and red beet pulps) were evaluated as raw materials in pigment production by the filamentous fungi Aspergillus carbonarius. The effect of fermentation conditions (solid and submerged-state), incubation period (3, 6, 9, 12, and 15 d), initial substrate pH (4.5, 5.5, 6.5, 7.5, and 8.5), and pulp particle size (<1.4, 1.4-2.0, 2-4, and >4 mm) on fungal pigment production were tested to optimize the conditions. Pigment extraction analysis carried out under solid-state fermentation conditions showed that the maximum pigment production was determined as 9.21 ± 0.59 absorbance unit at the corresponding wavelength per gram (AU/g) dry fermented mass (dfm) for pomegranate pulp (PP) by A. carbonarius for 5 d. Moreover, the highest pigment production was obtained as 61.84 ± 2.16 AU/g dfm as yellowish brown at initial pH 6.5 with < 1.4 mm of substrate particle size for 15-d incubation period. GC×GC-TOFMS results indicate that melanin could be one of the main products as a pigment. SEM images showed that melanin could localize on the conidia of A. carbonarius.

13.
Chemosphere ; 244: 125383, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31790993

RESUMO

The effect of electrochemical pre-treatment on fungal treatment of pistachio processing wastewater (PPW) was investigated. Electrocoagulation (EC) and electrooxidation (EO) were used as electrochemical pre-treatment step before fungal treatment of PPW. Aluminum (Al/Al), iron (Fe/Fe), and stainless steel (SS/SS) electrode pairs were selected as anode/cathode for EC whereas boron doped diamond (BDD/SS) was preferred as anode/cathode electrode pairs for EO experiments in this study. The impact of current density (50-300 A/m2) and operating time (0-240 min) were tested for chemical oxygen demand (COD) and total phenol removal. After pre-treatment of PPW, four different fungus species (Coriolus versicolor, Funalia trogii, Aspergillus carbonarius, and Penicillium glabrum) were tested for further treatment. Penicillium glabrum supplied maximum COD and total phenol removal efficiency compared to other fungus strains. The combined electrochemical-assisted fungal treatment process supplied 90.1% COD and 88.7% total phenol removal efficiency when supported with EO pre-treatment. Pre-treatment of PPW with EO method provided better results than EC method for fungal treatment. Operating cost of the combined process was calculated as 6.12 US$/m3. The results indicated that the proposed combined process supplied higher pollutant removal compared to the individual electrocoagulation, electrooxidation, and fungal treatment process.


Assuntos
Resíduos Industriais/análise , Pistacia , Eliminação de Resíduos Líquidos/métodos , Alumínio/análise , Biodegradação Ambiental , Análise da Demanda Biológica de Oxigênio , Boro , Eletrocoagulação/métodos , Eletrodos , Fungos/metabolismo , Ferro , Fenol , Fenóis , Águas Residuárias
14.
Environ Sci Technol ; 52(7): 4108-4116, 2018 04 03.
Artigo em Inglês | MEDLINE | ID: mdl-29510032

RESUMO

The main objective of this study is to examine how the charge densities of four monovalent anions-fluoride (F-), chloride (Cl-), bromide (Br-), and nitrate (NO3-)-influence their Donnan (charge) exclusion by a charged nanofiltration (NF) membrane. We systematically studied the rejection behavior of ternary ion solutions containing sodium cation (Na+) and two of the monovalent anions as a function of the pH with a polyamide NF membrane. In the solutions containing F- and Cl- or F- and Br-, F- rejection was higher than Cl- or Br- rejection only when the solution pH was higher than 5.5, suggesting that F- (which has a higher charge density) was repelled more strongly by the negatively charged membrane. The order of change in the activation energy for the transport of the four anions through the polyamide membrane as a response to the increase of the membrane negative charge was the following: F- > Cl- > NO3- > Br-. This order corroborates our main hypothesis that an anion with a smaller ionic radius, and hence a higher charge density, is more affected by the Donnan (charge)-exclusion mechanism in NF. We conclude with a proposed mechanism for the role of ionic charge density in the rejection of monovalent anions in NF.


Assuntos
Cloretos , Fluoretos , Ânions , Nitratos
15.
Water Sci Technol ; 76(11-12): 3114-3125, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29210697

RESUMO

Adsorption and advanced oxidation processes are being extensively used for treatment of wastewater containing dye chemicals. In this study, the adsorption and Fenton behavior of iron rich Terra Rosa soil was investigated for the treatment of aqueous anthraquinone dye (Reactive Blue 19 (RB19)) solutions. The impact of pH, initial dye concentration, soil loading rate, contact time and temperature was systematically investigated for adsorption process. A maximum removal efficiency of dye (86.6%) was obtained at pH 2, soil loading of 10 g/L, initial dye concentration of 25 mg/L, and contact time of 120 min. Pseudo-first-order, pseudo-second-order, Elovich, and Weber-Morris kinetic models were applied to describe the adsorption mechanism and sorption kinetic followed a pseudo-second-order kinetic model. Moreover, Langmuir, Freundlich and Temkin isotherm models were used to investigate the isothermal mechanism and equilibrium data were well represented by the Langmuir equation. The maximum adsorption capacity of soil was found as 4.11 mg/g using Langmuir adsorption isotherm. The effect of soil loading and hydrogen peroxide (H2O2) dosage was solely tested for Fenton oxidation process. The highest removal efficiency of dye (89.4%) was obtained at pH 2, H2O2 dosage of 10 mM, soil loading of 5 g/L, initial dye concentration of 50 mg/L, and contact time of 60 min. Thermodynamic studies showed that when the adsorption dosage of dye was 25 mg/L at 293-313 K, adsorption enthalpy (ΔH) and entropy (ΔS) were negative and adsorption free energy (ΔG) was positive. This result indicated that the adsorption was exothermic. Morphological characteristics of the soil were evaluated by X-ray fluorescence (XRF), scanning electron microscopy (SEM), and attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy before and after the adsorption and oxidation process.


Assuntos
Antraquinonas/química , Corantes/química , Solo/química , Poluentes Químicos da Água/química , Adsorção , Peróxido de Hidrogênio , Concentração de Íons de Hidrogênio , Resíduos Industriais , Ferro , Cinética , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , Termodinâmica , Eliminação de Resíduos Líquidos , Purificação da Água/métodos
16.
Water Sci Technol ; 76(3-4): 705-711, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28759452

RESUMO

In this study, polyethersulfone (PES) ultrafiltration membrane surface was modified with nano-sized zinc oxide (nZnO) and silver (nAg) to improve the membrane filterability of the mixed liquor and used to treat fruit-juice industry wastewater in a submerged membrane bioreactor (MBR). The nAg was synthesized using three different methods. In the first method, named as nAg-M1, PES membrane was placed on the membrane module and nAg solution was passed through the membrane for 24 h at 25 ± 1 °C. In the second method, named as nAg-M2, PES membrane was placed in a glass container and it was shaken for 24 h at 150 rpm at 25 ± 1 °C. In the third method, named as nAg-M3, Ag nanoparticles were loaded onto PES membrane in L-ascorbic acid solution (0.1 mol/L) at pH 2 for 24 h at 150 rpm at 25 ± 1 °C. For the preparation of nZnO coated membrane, nZnO nanoparticles solution was passed through the membrane for 24 h at 25 ± 1 °C. Anti-fouling performance of pristine and coated membranes was examined using the submerged MBR. The results showed that nZnO and nAg-M3 membranes showed lower flux decline compared with pristine membrane. Moreover, pristine and coated PES membranes were characterized using a permeation test, contact angle goniometer, and scanning electron microscopy.


Assuntos
Reatores Biológicos , Indústria Alimentícia , Frutas , Resíduos Industriais/análise , Membranas Artificiais , Águas Residuárias/química , Ácido Ascórbico , Bebidas , Filtração , Microscopia Eletrônica de Varredura , Nanopartículas , Polímeros , Prata , Sulfonas , Ultrafiltração/métodos
17.
Water Sci Technol ; 75(3-4): 670-685, 2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-28192361

RESUMO

This study was performed to synthesize membranes of polyethersulfone (PES) blended with graphene oxide (GO) and PES blended with GO functionalized with photoactive semiconductor catalyst (TiO2 and ZnO). The antifouling and self-cleaning properties of composite membranes were also investigated. The GO was prepared from natural graphite powder by oxidation method at low temperature. TiO2 and ZnO nanopowders were synthesized by anhydrous sol-gel method. The surface of TiO2 and ZnO nanopowders was modified by a surfactant (myristic acid) to obtain a homogeneously dispersed mixture in a solvent, and then GO was functionalized by loading with these metal oxide nanopowders. The PES membranes blended with GO and functionalized GO into the casting solution were prepared via phase inversion method and tested for their antifouling as well as self-cleaning properties. The composite membranes were synthesized as 14%wt. of PES polymer with three different concentrations (0.5, 1.0, and 2.0%wt.) of GO, GO-TiO2, and GO-ZnO. The functionalization of membranes improved hydrophilicity property of membranes as compared to neat PES membrane. However, the lowest flux was obtained by functionalized membranes with GO-TiO2. The results showed that functionalized membranes demonstrated better self-cleaning property than neat PES membrane. Moreover, the flux recovery rate of functionalized membranes over five cycles was higher than that of neat membrane.


Assuntos
Desinfetantes/química , Grafite/química , Membranas Artificiais , Polímeros/química , Semicondutores , Sulfonas/química , Catálise , Desinfetantes/síntese química , Grafite/síntese química , Interações Hidrofóbicas e Hidrofílicas , Óxidos , Polímeros/síntese química , Solventes , Sulfonas/síntese química , Propriedades de Superfície
18.
Water Sci Technol ; 75(1-2): 141-154, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28067654

RESUMO

In this study, an electrocoagulation reactor (ECR) and photocatalytic reactor (PCR) were tested to understand the performance of combined electrocoagulation and photocatalytic-degradation of olive washing wastewater (OWW). The effects of initial pH (6.0, 6.9, 8.0, 9.0), applied voltage (10.0, 12.5, 15.0 V), and operating time (30, 60, 90, 120 min) were investigated in the electrocoagulation reactor when aluminum electrodes were used as both anode and cathode. The pH, conductivity, color, chemical oxygen demand (COD), and phenol were measured versus time to determine the efficiency of the ECR and PCR process. It was observed that electrocoagulation as a single treatment process supplied the COD removal of 62.5%, color removal of 98.1%, and total phenol removal of 87% at optimum conditions as pH 6.9, applied voltage of 12.5 V, and operating time of 120 min. Moreover, final pH and conductivity were 7.7 and 980 µS/cm, respectively. On the other hand, the effect of semiconductor catalyst type (TiO2 and ZnO) and loading (1, 2, 3 g/L) were tested using PCR as a stand-alone technique. It was found that photocatalytic degradation as a single treatment process when using 1 g/L ZnO achieved the COD removal of 46%, color removal of 99% with a total phenol removal of 41% at optimum conditions. Final pH and conductivity were 6.2 and 915 µS/cm, respectively. Among semiconductor catalysts, TiO2 and ZnO performed identical efficiencies for both COD and total phenol removal. Moreover, combination in which electrochemical degradation was employed as a pre-treatment to the photocatalytic degradation process obtained high COD removal of 88% and total phenol, as well as color removal of 100% for the OWW. The electrochemical treatment alone was not effective, but in combination with the photocatalytic process, led to a high-quality effluent. Finally, sludge collected from the electrocoagulation process was characterized by attenuated total reflection Fourier transform infrared and X-ray powder diffraction analyses.


Assuntos
Técnicas Eletroquímicas/métodos , Olea , Processos Fotoquímicos , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Alumínio/análise , Análise da Demanda Biológica de Oxigênio , Cor , Técnicas Eletroquímicas/instrumentação , Eletrodos , Indústria Alimentícia , Concentração de Íons de Hidrogênio , Resíduos Industriais/análise , Fenol , Fenóis/química , Esgotos/análise
19.
Environ Technol ; 38(21): 2743-2751, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28004596

RESUMO

In this study, the degradation of azo dye solutions (Reactive Red 180 and Reactive Orange 16) of textile industry wastewater was investigated for using innovative hybrid process of photocatalytic and membrane distillation (MD) processes. Photocatalytic oxidation was conducted with semiconductor catalysts (ZnO and TiO2) and their mixture under UVA and UVC irradiation. More effective results were obtained under UVA at the initial stages of the reactions for both dye solutions. ZnO and TiO2 catalysts have given similar efficient results, but results with ZnO were better at initial stages. For the next stage, hybrid design of MD and photocatalytic processes was performed sequentially. Initially, the photocatalytic process was conducted for at least 1 h at initial values of 100 mg/L RR-180 dye solutions and 1 g/L ZnO catalyst loading under UVA irradiation and then treated solution was run through the distillation module at different temperatures (30°C and 40°C) and flow rates (210, 425, and 665 mL/min). Three types of membranes (polypropylene, polytetrafluoroethylene, and polyvinylidene fluoride) with different pore sizes (0.45 and 0.22 µm) were used in the module. Increasing temperature on the side of treated solution and decreasing the temperature on the other side has increased the distillate efficiency.


Assuntos
Corantes , Indústria Têxtil , Purificação da Água , Catálise , Destilação , Titânio
20.
Water Sci Technol ; 74(3): 564-79, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27508361

RESUMO

Marine pollution has been considered an increasing problem because of the increase in sea transportation day by day. Therefore, a large volume of bilge water which contains petroleum, oil and hydrocarbons in high concentrations is generated from all types of ships. In this study, treatment of bilge water by electrocoagulation/electroflotation and nanofiltration integrated process is investigated as a function of voltage, time, and initial pH with aluminum electrode as both anode and cathode. Moreover, a commercial NF270 flat-sheet membrane was also used for further purification. Box-Behnken design combined with response surface methodology was used to study the response pattern and determine the optimum conditions for maximum chemical oxygen demand (COD) removal and minimum metal ion contents of bilge water. Three independent variables, namely voltage (5-15 V), initial pH (4.5-8.0) and time (30-90 min) were transformed to coded values. The COD removal percent, UV absorbance at 254 nm, pH value (after treatment), and concentration of metal ions (Ti, As, Cu, Cr, Zn, Sr, Mo) were obtained as responses. Analysis of variance results showed that all the models were significant except for Zn (P > 0.05), because the calculated F values for these models were less than the critical F value for the considered probability (P = 0.05). The obtained R(2) and Radj(2) values signified the correlation between the experimental data and predicted responses: except for the model of Zn concentration after treatment, the high R(2) values showed the goodness of fit of the model. While the increase in the applied voltage showed negative effects, the increases in time and pH showed a positive effect on COD removal efficiency; also the most effective linear term was found as time. A positive sign of the interactive coefficients of the voltage-time and pH-time systems indicated synergistic effect on COD removal efficiency, whereas interaction between voltage and pH showed an antagonistic effect.


Assuntos
Eletrocoagulação/métodos , Filtração/métodos , Águas Residuárias/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Análise da Demanda Biológica de Oxigênio , Eletrocoagulação/instrumentação , Eletrodos , Filtração/instrumentação , Hidrocarbonetos/análise , Petróleo/análise , Água do Mar/química , Navios , Purificação da Água/instrumentação
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