pH Of Feed Solution Research Articles

Removal of safranin from aqueous solution through liquid emulsion membrane

One of the real issues of the recent years is water contamination because of harmful synthetic dyes. Liquid Membranes (LM) resemble a promising alternative to the current separation processes, demonstrating various points of interest as far as effectiveness, selectivity, and operational expenses. The improvement of various Liquid Membranes designs has been a matter of examination by few researchers, particularly for the expulsion of dyes from aqueous solutions. The choice of organic surfactants plays an essential role in the efficiency of the dye removal. In LM design, the most significant step towards productivity is the decision of the surfactant type and its concentration. Liquid emulsion membrane (LEM) was used to remove safranin from aqueous solutions in which the emulsion was made with the help of D2EHPA as carrier, kerosene was used as a diluent and Span 80 (Sorbiton monooleate) was used as an emulsifying agent or surfactant. Various sorts of internal stages were utilized, to be specific sulphuric acid and sodium hydroxide. The impact of parameters influencing extraction efficiency such as pH of feed solution, concentrations of surfactant and emulsifying agent in membrane phase, volume ratio of internal phase to membrane phase, internal phase concentration, agitation speed and time of extraction were analyzed.

Enhanced separation of praseodymium and neodymium by kinetic “push and pull” system of [A336][NO3]-DTPA in a column extractor

A new approach was suggested in present work for improving the separation between Pr(III) and Nd(III) by a so-called kinetic “push and pull” system consisting of [A336][NO3] and DTPA in a column extractor. It is revealed that, when organic extractant [A336][NO3] is continuously pumped into the column extractor in the form of dispersed oil droplets and at the same time DTPA was injected into the aqueous feed solution when the extraction was just started, the separation factor of Pr(III) to Nd(III), βPr/Nd, increased obviously with the time, and could even achieve 21.7. Such an amazing increase in βPr/Nd value might be due to the extraction rate of Pr(III) by [A336][NO3] oil droplets being faster than that of Nd(III), while the complexing rate of Nd(III) with DTPA in the aqueous solutions being faster than that of Pr(III). The opposite order of the two rates for Pr(III) and Nd(III) result in their kinetic “push and pull” separation. In contrast, the βPr/Nd value in traditional thermodynamic separation reported in previous literatures is only around 5 or even less, even though using the same extractant [A336][NO3] and DTPA but by previously adding DTPA into the aqueous feed solutions for pre-complexing of Pr(III) and Nd(III). Various effects from the pH and addition amount of DTPA aqueous solutions, LiNO3 concentrations in initial aqueous feed solutions, the initial concentration ratios of Pr(III) to Nd(III) ions, the initial pH of aqueous feed solutions, and the concentrations of [A336][NO3] in organic phases, on the kinetic separation of Pr(III) and Nd(III) are discussed. The present work highlights a promising approach for separation of rare earths or other targets with extreme similarity in physicochemical properties.

Study on stable mass transfer and enrichment of phenol by 1-octanol/kerosene/polyvinyl chloride polymer inclusion membrane

A polymer inclusion membrane (PIM) that contains a polyvinyl chloride (PVC) polymer matrix and 1-octanol (OCT) as specific carrier (PO-PIM) was prepared to investigate the mass transfer behaviour of phenol in aqueous solutions. Results showed that the mass transfer behaviour of the PO-PIM for phenol conformed to the first-order kinetics. In addition, the mass transfer efficiency for phenol reached the maximum when the OCT content was 82.8 wt%. The mass transfer activation energy (Ea) was 14.46 kJ mol−1, which indicated that intramembranous diffusion was the main controlling factor in the mass transfer process. The introduction of hydrophobic additives, such as kerosene, liquid paraffin and vegetable oil, into the PO-PIM could remarkably improve its stability. In an aqueous solutions of phenol ranging from 0 mg L−1 to 9000 mg L−1, the initial flux (J0) of kerosene/PVC/OCT-PIM (KPO-PIM) was positively correlated with the initial concentration of phenol. For a stripping solution with a feed solution pH of 2.0 and a sodium hydroxide concentration of 0.1 mol L−1, the maximum permeability coefficient during stable mass transfer reached 12.55 μm s−1. At a mass transfer area of 3.14 cm2, an enrichment factor (EF) of 3.5 for 200 mg L−1 of phenolic aqueous solution was achieved within 48 h through KPO-PIM.

New insights into the relationship between draw solution chemistry and trace organic rejection by forward osmosis

This study elucidates the impact of draw solution chemistry (in terms of pH and draw solute species) and membrane fouling on water flux and the rejection of trace organic contaminants by forward osmosis. The results show that draw solution chemistry could induce a notable impact on both water flux and TrOCs rejection. In addition, the impact was further influenced by membrane fouling. The reverse flux of proton (or hydroxyl) could alter the feed solution pH, which governed the separation of ionisable TrOCs. In addition, charged compounds generally exhibited higher rejections than neutral ones by the clean membrane. Electrostatic interaction, rather than size exclusion, was therefore the dominant rejection mechanism for most compounds. There was also a weak correlation between rejection and molecular sizes of the 43 TrOCs. Compared with Na+, Li+ with a larger hydrated radius showed a significantly lower reverse salt flux, resulting in a lower ionic strength and therefore a stronger electrostatic interaction. A fouling cake layer consisted of low molecular weight neutral organics could also affect TrOC rejection due to pore blockage and cake-enhanced concentration polarisation.

Investigation of Naphthalene Removal from Aqueous Solutions in an Integrated Slurry Photocatalytic Membrane Reactor: Effect of Operating Parameters, Identification of Intermediates, and Response Surface Approach

A laboratory scale indigenous integrated slurry photocatalytic membrane reactor (PMR), coupling TiO2/UV-C photocatalysis and ultrafiltration (UF) membrane process was evaluated for the removal of naphthalene (NAP)—one of the low molecular weight polycyclic aromatic hydrocarbons (PAHs), frequently detected in municipal and industrial wastewaters. The different operational parameters such as initial NAP concentration (5–25 mg/L), catalyst dosage (0.1–0.9 g/L), and feed solution pH (3–9) were investigated for NAP and total organic carbon (TOC) removal. The experimental results obtained from the batch study of the integrated process showed 92.8% and 90.2% of NAP and TOC removals while the individual processes; UV-TiO2 (76.8% NAP and 56.4% TOC removals) and UF membrane separation process (49.1% NAP removal) exhibited low removal rates for the same experimental conditions. The NAP and TOC removals obtained during continuous flow studies were 93.1% and 91.4% at 180 min and thereafter remained constant up to 560 min of reactor running time. This study also includes the identification of intermediates that are formed after 30 min of operation of PMR. The photocatalytic degradation of NAP followed pseudo-first-order kinetics and the obtained experimental data were analyzed with response surface methodology (RSM) using design expert software.

Heterogeneous Fenton-like oxidation of pharmaceutical diclofenac by a catalytic iron-oxide ceramic microfiltration membrane

The oxidation of pharmaceutical diclofenac (DCF) was investigated in a catalytic membrane reactor (CMR) comprising a tubular porous alumina (α-Al2O3) membrane, as support material, with embedded iron oxide nanoparticles (nFe) in situ generated in its pores. The performance of the heterogeneous Fenton-type oxidation reaction was examined in a laboratory-scale membrane pilot, with the addition of hydrogen peroxide. Aiming to optimize this CMR, Central Composite Design with Response Surface Methodology was employed to assess the effects of three key process parameters and their interaction on DCF degradation. Encouraging results were obtained, showing a significant DCF oxidation/mineralization by the α-Al2O3/nFe CMR. Feed solution pH was found to be the most significant variable, with acidic values leading to improved performance. Under near optimum operating conditions (pH 3 and 42.9 mg/L H2O2), the removal and mineralization of DCF was ∼65% and ∼48%, respectively. Negligible iron leaching was observed in the tests, which confirms the effective embedding and stability of catalytic nanoparticles in the ceramic porous matrix, thus allowing multiple membrane utilization. Future research directions are proposed towards method optimization, with emphasis given to membrane modification for improving the adsorption of organic pollutants and their oxidation within the catalytic membrane matrix.

Nanofiltration separation of succinic acid from post-fermentation broth: Impact of process conditions and fouling analysis

In this study a pilot-scale setup was used in the nanofiltration (NF) process for recovery of succinic acid from model solutions and the actual post-fermentation broth left after the bioconversion of glycerol. The effects of composition and pH of feed solutions, initial concentration of components and the magnitude of applied transmembrane pressure (TMP) on the separation efficiency, the value of the permeate flux and retention ratio of individual components present in the feed solutions, were investigated. In order to estimate the mechanism of membrane layer fouling formation, the experimental data obtained were compared to the Hermia model.

Recovery and separation of rhenium and molybdenum from aqueous solutions that simulate mine waters using magnetite nanoparticles functionalized with amine-derivative groups

The recovery and separation of rhenium and molybdenum from acidic aqueous solutions that simulate mine waters is studied through an adsorption process using magnetite nanoparticles functionalized with tertiary (TA-MNP) and quaternary amine (QA-MNP) groups as adsorbents. The functionalized nanoparticles (FMNP) were efficiently synthetized and physical and chemically characterized. An average particle size in the range of 6–8 nm based on HR-TEM analysis was determined for the nanoparticles, which exhibited a high saturation magnetization varying between 53 and 60 emu/g. Several factors that affected the recovery of Re(VII) and Mo(VI) from aqueous solution using the synthesized FMNP were studied, such as the adsorbent dose, initial concentration of metal and pH of the aqueous feed solution. In all experiments, QA-MNP presented a slightly better adsorption of both metals compared to TA-MNP. At pH 3, maximum rhenium loading capacities of 30 and 38 mgRe(VII)/gadsorbent were measured using TA-MNP and QA-MNP, respectively. In turn, maximum loading capacities of 60 and 65 mgMo(VI)/gadsorbent were determined utilizing TA-MNP and QA-MNP, respectively. Re(VII) and Mo(VI) equilibrium and kinetics were established in adsorption experiments. A pseudo-second-order kinetic model provided a good fit to the experimental data for the two metals using both adsorbents. Freundlich and Langmuir adsorption isotherm explained the experimental results.

Photocatalytic decolorization of Basic Blue 41 using TiO2-Fe3O4-bentonite coating applied to ceramic in continuous system

Photocatalytic degradation/decolorization of Basic Blue 41 dye assisted by UV radiation has been studied over TiO2-Fe3O4 supported by bentonite. In this experiment, photocatalytic decolorization process was performed continuously; where dye feed solution was supplied to a coated-ceramic vessel. The influence of the initial concentration, pH, and flow rate of the dye feed solution on the degradation efficiency process was examined in this study. The results showed that the increase in the dye concentration and flow rate reduces decolorization efficiency. The highest decolorization efficiency was at pH of 5.5. The kinetic study of this photo-decolorization indicated that under the experimental condition, the photocatalytic kinetic process followed first-order kinetics on the basis of Langmuir–Hinshelwood heterogeneous reaction mechanism, where the reaction rate constant, namely kr, is 0.7707 and the adsorption rate constant, namely K, is 0.01298.

Intensified solvent extraction and separation of cobalt from Ni-rich leaching solution in impinging stream-rotating packed bed contactor

ABSTRACT This work describes the separation of Ni and Co from a real feed solution in chloride media with high Ni content. The extractant used was P507 (2-ethylhexyl phosphoric acid-2-ethylhexyl ester) in a laboratory scale Impinging Stream–Rotating Packed Bed (IS-RPB) contactor. Key variables including feed solution pH, extractant concentration, saponification degree, high gravity level and total volumetric flow rate of fluids amongst other variables were examined. A McCabe–Thiele diagram of the extraction stage predicted that at a total volumetric flow rate of 90 L/h, feed solution pH of 5, saponified P507 concentration of 25% and high gravity of 83, almost 99% of cobalt, would be extracted within three stages. With regard to the scrubbing results, the co-extracted nickel was scrubbed efficiently from the loaded organic solution using a mixture of 0.02 M CoCl2 and 0.5 M hydrochloric acid solution, The purified Co solution was achieved after stripping the loaded-organic phase with 1 M HCl. The maximum value of the overall volumetric mass transfer coefficient for the IS-RPB extractor was found to be 0.16 s−1 which was superior to that of conventional extractors such as mixer-settler and centrifugal extractors, providing strong confidence for its industrial application.

Extraction of lead ions from aqueous solution by co-stabilization mechanisms of magnetic Fe2O3 particles and nonionic surfactants in emulsion liquid membrane

A study of the impact of nonionic surfactants (span 80) on the emulsification of kerosene in the presence of magnetic α-Fe2O3 particles and the stability of the formed emulsions was carried out. Generally, emulsion liquid membrane (ELM) contains Bis-2-ethylhexyl phosphoric acid (D2EHPA) as a carrier, H2SO4 as an internal phase, kerosene as organic phase stabilized by an emulsifier, and co-emulsifier, which have been utilized to investigate its ability in the extraction of lead (Pb) from aqueous solutions. Further, the influence of experimental parameters affecting ELM stability and its extraction efficiencies such as emulsification time, homogenizer speed, surfactant concentration, Fe2O3-span 80 ratio, H2SO4 concentration, and the volume ratio of oil to internal phase (O/I), was examined. Additionally, investigation of the pH of feed solution, extractant concentration, agitating speed, the ratio of emulsion to the external phase (EM/E), initial lead (Pb) concentration, and contact time were carried out. The results confirmed the existence of co-stabilization strategy, which leads to the stability of the emulsion and improvement in the extraction efficiency of lead ions (Pb) to 97.2% after 8.0 min of mixing time under best-operating conditions with 0.3% membrane breakage.

High-selectivity membrane absorption process for recovery of ammonia with electrospun hollow fiber membrane

Excessive ammonia nitrogen in wastewater seriously endangers ecological environment, so high-flux and selectivity membrane is urgently needed for ammonia removal using membrane absorption (MA). In this paper, a high-performance electrospun hollow fiber membrane was fabricated and solvent vapor welding treatment was adopted to enhance mechanical strength. The post-treatment membrane showed 103.8% higher in the Young’s modulus than the pristine membrane. High mechanical strength, porosity and hydrophobicity of the membrane make it superior in mass transfer and selectivity. The effects of membrane thickness, pH and temperature of feed solution on experimental overall mass transfer coefficient (KOE) and selectivity coefficient (SNH3/H2O (g)) were intensively investigated to examine the membrane performance in MA application. The results show KOE is 1.35 * 10−5 m s−1 and SNH3/H2O (g) is 7.58 when pH is 11, which are higher than that of commercial membrane. Moreover, the selectivity can be improved greatly from 6.91 to 9.74 by increasing the thickness of the hollow fiber membrane from 55 ± 5 μm to 115 ± 5 μm. The welded electrospun hollow fiber membrane demonstrates great potential for ammonia removal in MA application.

Verification of a Combined Fouling Model to Predict Flux Decline during Ultrafiltration of Organic Solutes

Studies were conducted to investigate the blocking mechanism and flux decline behavior while treating organic solutes contained in glycerin-water solutions (triglycerides, TG and fatty acid, FA). Two ultrafiltration membranes were tested, polyethersulphone (PES 25 kDa) and polyvinylidenfluoride (PVDF 30 kDa) membranes. Influence of TG and its combination (TG-FA mixtures) as foulant models, pH of feed solutions (3–10) and membrane surface chemistry were investigated. Combined blocking model was applied and the fitting were discriminate that the flux decline of PES membrane was dominated by pore blockage at the early stage and later by cake resistance during the entire filtration time. However, for PVDF membrane, cake formation mechanism was acknowledged as the major contributor to the fouling mechanism for all the parameters tested. On the other hand, the model predicts there are two stages of filtration appeared to occur, involving pore blockage at the early stage followed by cake formation.

Role of Surfactants Cetyl Pyridinium Chloride (CPC) and Cetyltrimethyl Ammonium Bromide (CTAB) in the Reverse Micellar Extraction of Ternary Mixture of Acid Dyes from Textile Effluent

AbstractTextile industry produces colored effluent which is the major cause of water pollution. Removal of color from effluent is very important before discharging. Extraction of ternary mixture of anionic dyes, namely, Acid Orange 7 (AO-7), Acid Blue 1(AB-1) and Acid Yellow 17 (AY-17) was carried out from aqueous solutions using reverse micelles of Cetyl Pyridinium Chloride (CPC) and Cetyltrimethyl ammonium bromide (CTAB) in isoamyl alcohol. Extraction efficiency of CPC and CTAB was studied under various experimental conditions, such as pH of feed solution, concentration of surfactant, extraction time, temperature and initial dye concentration. Under the optimized experimental conditions, 93–98 % of dyes were extracted. It was observed that CTAB is more efficient than CPC for extraction of dyes from aqueous medium.

Utilization of Chemical Deposition Technique for Preparation of Miniature 170Tm Sources and Preliminary Quality Assessment for Potential Use in Brachytherapy

This article describes the preparation of a 170Tm source by chemical deposition technique, its encapsulation in a titanium holder, and preliminary quality evaluation for potential utility as a brachytherapy source. The procedure consisted of electrodeposition of Ni on a Cu wire followed by chemical deposition of 170Tm on it. Influence of feed solution pH, carrier Tm concentration, and reaction time were studied for optimum deposition of 170Tm on substrate. After sealing the source core in a titanium capsule, quality control tests were performed. Distribution of 170Tm on substrate was evaluated by autoradiography. Inactive Tm source was characterized by scanning electron microscope (SEM) and energy-dispersive X-ray (EDS) analyses. Under optimized conditions (pH 5, 10 μg Tm carrier, 5 h), 170Tm source core could be prepared by deposition of >95% of 170Tm radioactivity on substrate. Swipe tests and immersion tests on encapsulated sources confirmed that removable radioactivity and radioactivity leakage levels were within stipulated limits. Autoradiography of 170Tm source confirmed uniformity of radioactivity distribution. While SEM analysis confirmed good adhesion of Tm on substrate, EDS analysis confirmed elemental constituents of the Tm-deposited substrate. The objective of preparing a 170Tm source by chemical deposition for potential brachytherapy applications could be successfully achieved.

REMOVAL OF FLUORIDE FROM SHATT AL-ARAB DRINKING WATER USING A NOVEL LOW COST MATERIAL

Drinking water contamination by fluoride component (F-) is considered as a main public problem in Basra city. The current study highlights on the removal of (F-) from drinking water using effective and low cost materials namely, banana shell and new technical that prepared from orange shell loaded with Zirconyl chloride solutions (Z-r4 (O-H)8 (H2-O)16] Cl8 (H2-O)12) to develop active adsorption sites for fluoride . High removal efficiency of 94.4 was achieved using fixed bed column loaded (Zc-dejr) under optimum operating conditions, 15.1 ppm of feed concentration, 4.5 pH of feed solution and 4 cm of bed depth. Result of breakthrough profile showed that Thomas was coincided well with the experimental data. Two model, Pseude first order and Pseudo second order where used for finding the mechanism of adsorption kinetics for fluoride (F-) removal by two-bio adsorbents. The result showed that the external adsorption besides to the intra-particle diffusion contributes to the rate influential step. Lagmaier model gives the better result model for the two adsorbents then Temkin isotherm model (TIM). The final concentration of fluoride in treated water with the banana shell adsorbent was 1 mg/l, and with the new solution (Z-r4 (O-H)8(H2-O)16] Cl8 (H2-O)12 ) was 0.5 mg /l which is acceptable with the standard World Health Organization (WHO).

Optimization of process parameters using response surface methodology for Pd(II) extraction with quaternary ammonium salt from chloride medium: kinetic and thermodynamics study

In this study, liquid–liquid extraction with Aliquat 336 in the presence of cyclohexane as a mobile carrier was investigated to purify Pd(II) from industrial wastewater. Kinetic and thermodynamics analysis showed that Pd(II) extraction was of first-order reaction: the reaction was endothermic reaction which was governed by the diffusion region. The influence of temperature on isotherm model was also investigated. With an increase in reaction temperature, all three isotherms Langmuir, Freundlich and Temkin isotherm become inaccurate. Results show that the Langmuir isotherm model was preferred for the study of the Pd(II) ion experimental isotherm. Response surface methodology was employed to study the five independent variables which have an effect on the percentage of extraction of palladium(II) ions as a dependent variable. Optimum extraction conditions for the five independent variables were as follows: Aliquat 336 concentration (0.6 M), pH of feed solution (2.0), stirring speed (600 rpm), reaction time (10 min.) and reaction temperature (318 K).

Enhancing the separation performance of vanadium from a black shale leaching solution by supported liquid membrane using trialkylamine

To enhance the separation efficiency of vanadium from impurities, the highly selective separation of vanadium from multiple impurities and the transport mechanism of vanadium from a black shale leaching-solution, by a supported liquid membrane (SLM) using trialkylamine (N235) as the carrier, were investigated. The effects of parameters such as feed-solution pH, carrier concentration, stripping-solution species, and diluent nature were studied. The separation performance of the SLM system for vanadium from the main impurities in the black shale acid leaching-solution—Fe, Al, P, Si, K, and Mg—was also discussed. The diffusion parameters and facilitated transport mechanism were evaluated using a first-order kinetic model. By enhancing the mass transfer of vanadium and the competitive extraction between vanadium and the impurity ions, the performance of the SLM system for the separation of vanadium from the highly impure black shale leaching-solution was significantly improved. These results show that highly selective separation of vanadium from impurities can be achieved using the N235-SLM system, indicating promising prospects for application in the vanadium industry.

Phenol Removal from Water by Polyamide and AgCl Mineralized Thin-Film Composite Forward Osmosis Membranes

This study systematically investigated phenol removal from water and phenol fouling of membranes in forward osmosis (FO) using thin-film composite (TFC) polyamide and silver chloride (AgCl) mineralized thin-film composite (MTFC) membranes. The influence of operating parameters (membrane orientation, phenol concentration, draw solution concentration, pH, and ionic strength) on phenol rejection and phenol adsorption to the membrane was investigated to elucidate the phenol transport behaviors in the FO process. Overall, phenol rejection improved with increased draw solution concentration or feed solution pH. At a feed solution pH of 11, TFC membranes exhibited their highest phenol rejection of 97.0% and MTFC membranes exhibited their highest phenol rejection of 98.8%. Phenol adsorption on the membrane surface may be related to the solute hydrophobic character, electrostatic interaction, and reverse salt diffusion. Six-hour fouling experiments show that the phenol fouling of FO membranes is reversible and eas...

Optimization of extraction conditions using central composite design for the removal of Co(II) from chloride solution by supported liquid membrane

The extraction conditions for the removal of cobalt(II) from chloride aqueous solution were studied by using supported liquid membrane. The effects of four factors such as the acidity of feed solution (pH), Cyanex301 concentration, cobalt ion concentration in the feed phase as well as sulfuric acid concentration in the stripping phase were investigated by using central composite design which is a subcategory of response surface methodology. The optimum conditions obtained for pH, Cyanex301 concentration, initial cobalt concentration in feed solution, and sulfuric acid concentration were 6, 1mol/L, 98.86mg/L and 1.26mol/L, respectively. The percentage of cobalt extraction equal to 48.21% obtained from the predicted model was in agreement with the experimental data (45.84%), after 3.5h in the experimental conditions. In addition, the other factors such as the types of solvent as a diluent, stripping solution, and the types of extractants and mixtures were studied at the optimum point. The results showed that the percentage of cobalt extraction achieved was 46.85% within 3.5h, in the extraction conditions (Cyanex301 as an extractant, kerosene or chloroform as a diluent and the mixture of sulfuric acid and nitric acid as the stripping phase).