Micellar-enhanced Ultrafiltration Process Research Articles

Removal of Ni(II) ions from wastewater by micellar enhanced ultrafiltration using mixed surfactants

Ni(II) ions were removed from aqueous waste using micellar enhanced ultrafiltration (MEUF) with a mixture of surfactants. The surfactant mixture was the nonionic surfactant Tween 80 (TW80) mixed with the anionic surfactant sodium dodecyl sulfate (SDS) in different molar ratios ranging from 0.1–1.5. The operational variables of the MEUF process such as pH, applied pressure, surfactant to metal ion ratio and nonionic to ionic surfactant molar ratio (α) were evaluated. Rejection of Ni and TW80 was 99% and 98% respectively whereas that for SDS was 65%. The flux and all resistances (fouling resistance, resistance due to concentration polarization) were measured and calculated for entire range of α respectively. A calculated flux was found to be declined with time, which was mainly attributed to concentration polarization rather than resistance from membrane fouling.

Simultaneous removal of aniline and nickel from water by micellar-enhanced ultrafiltration with different molecular weight cut-off membranes

The aim of this study was to evaluate the performance of the micellar-enhanced ultrafiltration (MEUF) process for the simultaneous removal of aniline and nickel from the aqueous phase. A prepared polysulfone (PSf) membrane and two commercially available membranes (NP010 and UFX5) were used to investigate the effects of the molecular weight cut-off of the membranes on the performance of MEUF which highlighted the significance of the mean micelle size in this process. Increasing of sodium dodecyl sulfate (SDS) concentration and the addition of aniline and nickel into the solution would change the SDS micelle size. The best rejection of nickel and aniline, 97% and 70%, respectively, was achieved with NP010 membrane which has the smallest pore size (1kDa). The results demonstrated that the rejection of nickel and aniline are influenced by the co-presence of them in solution. The presence of nickel ions in the solution increased the aniline rejection. Moreover, the presence of aniline molecules enhanced the nickel rejection. In the mixed surfactant solution (SDS-Brij 35) for the prepared PSf membrane, nickel rejection and permeate flux achieved over 90% and 100kg/m2h, respectively at a pressure of 2.5bar.

Assessment of the micellar-enhanced ultrafiltration process with a tight UF membrane for the removal of aniline from water

Micellar-enhanced ultrafiltration (MEUF) is a promising method to remove low molecular weight (LMW) organic contaminants from water. In this work, a series of experiments were conducted in order to evaluate the efficiency of an MEUF process for the removal of aniline (as LMW organic contamination) using a 1 kDa molecular weight cut-off polyethersulfone membrane and sodium dodecyl sulfate (SDS) as an anionic surfactant. Furthermore, the effect of various parameters such as aniline and surfactant concentration, operating pressure, temperature, agitation velocity, the presence of a nonionic surfactant (Brij 35), and the pH of feed on the rejection of aniline and SDS, and relative permeation flux have been examined. In the presence of a nonionic surfactant, the maximum rejection of aniline (approximately 80%) was obtained. The results of this study also revealed that although the complete retention of aniline was not achievable, the MEUF process could, however, be utilized to facilitate aniline removal from aqueous phase.

Impact of selected wastewater constituents on the removal of sulfonamide antibiotics via ultrafiltration and micellar enhanced ultrafiltration

To better understand the environmental mobility of sulfonamide antibiotics and develop improved processes for their removal during wastewater treatment, stirred cell ultrafiltration (UF) experiments were conducted using both synthetic and real wastewater effluent. The interactions between selected sulfonamides (sulfaguanidine, sulfathiazole and sulfamerazine), solids and dissolved organic matter were systematically explored. The further impact of micellar enhanced ultrafiltration (MEUF), a process in which surfactants are added at micellar concentrations to enhance removal of various trace contaminants from aqueous streams, was then explored by using a cationic surfactant, cetyltrimethylammonium bromide (CTAB). Ultrafiltration of sulfonamides in the absence of other materials generally removed only 15–20% of the antibiotics. The presence of micellar solutions of CTAB generally improved removal of sulfonamides over UF alone, with rejections ranging from 20 to 74%. Environmental solids (sediment) further increased retention of sulfonamides using both UF and MEUF, but the presence of DOM did not influence rejection. Similar trends were observed on UF and MEUF of real effluent samples that had been spiked with the sulfonamides, confirming the environmental relevance of the observed interactions between sulfonamides, surfactant, and wastewater constituents. The results demonstrate that MEUF processes can be designed for the selective removal of such trace contaminants as sulfonamide antibiotics.

Treatment of edible oil processing wastewater using micellar-enhanced ultrafiltration process

In the present study, micellar-enhanced ultrafiltration (UF) has been applied to treat edible oil processing wastewater using linear alkylbenzene sulfonate (LAS) and sodium dodecyl sulfate (SDS) as surfactants. In particular, the effects of different operating conditions on process performance were investigated in terms of product flux and reductions of wastewater turbidity, oil and grease content, chemical oxygen demand (COD), electrical conductivity (EC), and total dissolved solids (TDS). Experimental results showed that transmembrane pressure and temperature of wastewater had direct effect on permeate flux while surfactant concentration influenced it reversely. To achieve the highest pollutants removal, the optimum operating conditions were found and applied. Finally, optimum permeate quality was compared to the permissible limits of environmental standards. As a result, LAS was shown to reduce pollution indicators more effectively in comparison with SDS, since combination of LAS and UF could eliminate turbidity, oil and grease, COD, EC, and TDS by 98, 95.7, 84.7, 90.6, and 90.7%, respectively.

Wastewater treatment of raisins processing factory using micellar-enhanced ultrafiltration

In this work, the treatment of raisins processing wastewater using micellar-enhanced ultrafiltration (MEUF) with two cationic surfactants, hexadecyl pyridinium chloride and Cetyl trimethyl ammonium bromide, has been investigated. The effect of process parameters, such as transmembrane pressure (TMP), temperature, and surfactant concentration, on permeate flux and rejection of the wastewater pollutants have been studied. COD, turbidity, TDS, and electrical conductivity were selected as the indicators of wastewater pollution. The obtained results show that rising TMP or temperature led to rejection decrease and flux increase. However, rejection of pollutants increased and flux decreased with increasing surfactant concentration. Applying surfactants enhanced the rejection of the pollutants, thereby a considerable amount of wastewater pollution was omitted and the turbidity of the wastewater was decreased to a high extent through this process. As a result, the MEUF process can be applied as an efficient method for the treatment of raisins factories’ wastewater.

Prediction of MEUF process performance using artificial neural networks and ANFIS approaches

In the present study, a micellar-enhanced ultrafiltration (MEUF) procedure for the separation of lead ions from aqueous solution using response surface methodology (RSM) has been proposed. Due to the extreme complexity and nonlinearity of membrane separation processes, two models, including a feed forward artificial neural network (ANN) and an adaptive neuro-fuzzy inference system (ANFIS) have been utilized. These simulation methods have been given extreme accurate model that are more efficient than the second quadratic mathematical model for both response variables. The results of ANN and ANFIS models have been shown that the independent predicted rejection and permeate values were compared to measured target values and good correlations were found (R2>0.92, R2>0.97) for two above mentioned approaches, respectively.

Optimization of lead removal from aqueous solution by micellar-enhanced ultrafiltration process using Box-Behnken design

The main objective of this research was to use Box-Behnken experimental design (BBD) and response surface methodology (RSM) for optimization of micellar-enhanced ultrafiltration (MEUF) to remove lead ions from synthetic wastewater using spiral-wound ultrafiltration membrane. The critical factors selected for the examination were surfactant concentration, molar ratio of surfactant to metal (S/M) and solution pH. A total of 17 experiments were accomplished towards the construction of a quadratic model for both target variables. The experimental results were fitted with a second-order polynomial equation by a multiple regression analysis, and more than 95%, 93% of the variation could be predicted by the models for lead rejection and permeation flux, respectively. The optimum condition was found by using the obtained mathematical models. Optimization indicated that in CSDS=2mM, pH=6.57 and S/M= 9.82 maximum flux and rejection efficiency can be achieved, simultaneously.

Separation of cadmium and copper from phosphorous rich synthetic waters by micellar-enhanced ultrafiltration

In this study, micellar-enhanced ultrafiltration (MEUF) was proved to be a viable technique for the purification of phosphorous rich waters. The experiments were conducted in order to study the simultaneous removal of heavy metals from phosphorous rich synthetic waters by evaluating the effect of pH (3.5–5) and the feed concentrations of sodium dodecyl sulphate ( C SDS, 3.5–20 mM), phosphorous ( C Phosph., 0–1.3 g/dm 3), zinc ( C Zn, 0.8–2 mg/dm 3) and nickel ( C Zn, 2–4 mg/dm 3) on the rejection coefficients of cadmium and copper. Zinc and nickel feed concentrations had no statistically significant effect and the metal competition was negligible. pH, SDS and phosphorous feed concentration did show a significant effect on the MEUF process. Rejection coefficients up to 98% were achieved for both metals when no phosphorous was present and at SDS feed concentration of 20 mM. The phosphorous feed concentration showed a bigger negative effect on the rejection coefficient of copper at higher pH levels due to complex formation. At low pH values and in the presence of phosphorous the heavy metals were present as divalent cations and no complex formation was observed. In these conditions, copper rejection coefficients were very similar to cadmium, achieving up to 80% removal of heavy metals. At higher pH levels the presence of Cu 3(PO 4) 2 was more substantial and the rejection coefficients of copper decreased to 65%. The research presented in this manuscript could lead to novel uses of MEUF for the purification of nutrients from wastewater streams prior to their recovery, closing phosphorous cycles in anthropogenic systems.

Micellar enhanced ultrafiltration process for the treatment of olive mill wastewater

Olive mill wastewater (OMW) is an important environmental pollution problem, especially in the Mediterranean, which is the main olive oil production region worldwide. Environmental impact of OMW is related to its high organic load and particularly to the phytotoxic and antibacterial action of its phenolic content. In fact, polyphenols are known as powerful antioxidants with interesting nutritional and pharmaceutical properties. In the present work, the efficiency of OMW Micellar Enhanced Ultrafiltration (MEUF) treatment for removal and concentration of polyphenols was investigated, using an anionic surfactant (Sodium Dodecyl Sulfate salt, SDS) and a hydrophobic poly(vinyldene fluoride) (PVDF) membrane. The effects of the process experimental conditions on the permeate flux were investigated, and the secondary membrane resistance created by SDS molecules was evaluated. The initial fluxes of OMW processing by MEUF using SDS were 25.7 and 44.5 l/m2 h under transmembrane pressures of 3.5 and 4.5 bar, respectively. The rejection rate of polyphenols without using any surfactant ranged from 5 to 28%, whereas, it reached 74% when SDS was used under optimum pH (pH 2). The MEUF provides a slightly colored permeate (about 88% less dark), which requires clearly less chemical oxygen demand (COD) for its oxidation (4.33% of the initial COD). These results showed that MEUF process can efficiently be applied to the treatment of OMW and for the concentration and recovery of polyphenols.

Fuzzy modeling and simulation for lead removal using micellar-enhanced ultrafiltration (MEUF)

In the present paper, a three factor, three-level response surface design based on Box–Behnken design (BBD) was developed for maximizing lead removal from aqueous solution using micellar-enhanced ultrafiltration (MEUF). Due to extremely complexity and nonlinearity of membrane separation processes, fuzzy logic (FL) models have been driven to simulate MEUF process under a wide range of initial and hydrodynamic conditions. Instead of using mathematical model, fuzzy logic approach provides a simpler and easier approach to describe the relationships between the processing variables and the metal rejection and permeation flux. Statistical values, which quantify the degree of agreement between experimental observations and numerically calculated values, were found greater than 91% for all cases. The results show that predicted values obtained from the fuzzy model were in very good agreement with the reported experimental data.

Application of micellar enhanced ultrafiltration and activated carbon fiber hybrid processes for lead removal from an aqueous solution

Micellar enhanced ultrafiltration (MEUF) and activated carbon fiber (ACF) hybrid processes were used to investigate the removal condition of lead ions and surfactant sodium dodecyl sulfate (SDS) from an aqueous solution. Lead removal efficiency increased with the increase of initial surfactant concentration. Molar ratio of lead to SDS up to 1: 5 has shown over 90% removal efficiency of lead, and the optimum molar ratio of lead to SDS was found to be 1: 5. Lead removal efficiency increased with the increase of pH, while it was maintained below 30% without surfactant. Lead removal was mainly due to the adsorption mechanism and no secondary layer was formed to reduce the flux. Lower molecular weight cut-off (MWCO) membrane has shown higher removal efficiency than higher MWCO one. Permeate flux decreased with the increase of molar ratio of lead to SDS. Flux decline was mainly due to the accumulation of micelles on the membrane surface. The presence of copper as a co-existing heavy metal highly affected the lead removal while nickel did not. Two sets of ACF unit in series were able to remove SDS surfactant effectively from the effluents of MEUF process.

Application of experimental design approach and artificial neural network (ANN) for the determination of potential micellar-enhanced ultrafiltration process

In this study, micellar-enhanced ultrafiltration (MEUF) was applied to remove zinc ions from wastewater efficiently. Frequently, experimental design and artificial neural networks (ANNs) have been successfully used in membrane filtration process in recent years. In the present work, prediction of the permeate flux and rejection of metal ions by MEUF was tested, using design of experiment (DOE) and ANN models. In order to reach the goal of determining all the influential factors and their mutual effect on the overall performance the fractional factorial design has been used. The results show that due to the complexity in generalization of the MEUF process by any mathematical model, the neural network proves to be a very promising method in compared with fractional factorial design for the purpose of process simulation. These mathematical models are found to be reliable and predictive tools with an excellent accuracy, because their AARE was ±0.229%, ±0.017%, in comparison with experimental values for permeate flux and rejection, respectively.

Equilibrium Distribution Model of Betaine between Surfactant Micelles and Water: Application to a Micellar-Enhanced Ultrafiltration Process

The aim of this work was to determine the optimal surfactant concentration and operating conditions for betaine recovery from aqueous solutions by micellar-enhanced ultrafiltration (MEUF). Initial centrifugal ultrafiltration experiments with commercial 5 kDa cutoff polyethersulfone membranes showed that optimal betaine extraction was achieved with 200 mol/m3 of sodium dodecyl sulfate (SDS) as surfactant, at pH 1, with phosphoric acid for pH adjustment. The degree of betaine extraction increased with SDS concentration but remained constant with increasing betaine concentration for a given initial SDS concentration. The equilibrium distribution constants, KS, of betaine between SDS micelles and water were determined assuming a theoretical pseudophase separation model. Continuous MEUF with a 5 kDa cutoff TiO2 tubular ceramic membrane was performed in order to concentrate the micellar solution. Complete rejection of the micelles by the membrane was observed, resulting in 54% of the betaine and 99% of the SDS in micellar form, in agreement with the values estimated using the proposed theoretical model.

Flux decline analysis in micellar-enhanced ultrafiltration of synthetic waste solutions for metal removal

It is known that micellar-enhanced ultrafiltration (MEUF) is an efficient and economic process for the removal of trace metal ions and organics from aqueous media. In this work, flux decline behavior in MEUF of aqueous solutions containing trace Cu(II) (1.6–8 mM) and anionic surfactants sodium dodecyl sulfate (SDS) or sodium dodecyl benzene sulfate (SDBS) was studied at 25 °C in batch mode. An UF membrane that had average pore size comparable to those of Cu(II)-adsorbed micelles was adopted. All experiments were performed as a function of stirring speed (200–400 rpm), solution pH (3.0–5.0), molar concentration ratio of surfactant to metal (S/M, 2.5–12.7), and applied pressure (69–345 kPa). It was shown that more than 90% of Cu(II) could be removed at an S/M ratio of 12.7 and pH 5 using SDS. The blocking filtration law was used to identify the mechanism(s) of flux decline during the MEUF processes. Finally, the specific cake resistances in both SDS and SDBS systems were evaluated and compared.

Removal of metal ions from aqueous solutions by micellar enhanced ultra-filtration (MEUF)

Removal of metal ions from aqueous solutions by micellar enhanced ultra-filtration (MEUF) The results of preliminary research on the possibility of removing of chromium(III) and copper(II) ions from micellar solutions in MEUF were described. The effectiveness of metal ions removal in the classical UF and MEUF was compared. It was confirmed that in the classical UF the retention of metal ions is small, independent of the concentration of the feed solution. The cross-flow micellar enhanced ultrafiltration experiments showed the usefulness of this method for the separation of metal ions from micellar solutions. The retention of metal ions in MEUF process is almost total in the case of the solutions of low concentration. However, for more concentrated solutions the retention is much smaller.

Effects of membrane hydrophilicity on the removal of a trihalomethane via micellar-enhanced ultrafiltration process

Micellar-enhanced ultrafiltration (MEUF) process was explored for obtaining pure water from an aqueous solution containing small amount of trihalomethanes (THMs). A homologous series of polyethylene glycol alkylether was used as nonionic surfactant. To understand effects of membrane hydrophilicity on the performance of MEUF process, membranes for the ultrafiltration were prepared from polysulfone blends containing various amount of a hydrophilic copolymer, poly(1-vinylpyrrolidone-co-acrylonitrile) (P(VP-AN)). An increase in the permeate flux was observed with an increase of the membrane hydrophilicity. The performance of MEUF process in removing THM and surfactant was shown to depend on the membrane characteristics, surfactant characteristics, and operating pressure. The rejections of THM and surfactant were increased with increasing hydrophobicity of surfactant and hydrophilicity of membrane. The rejections of THM examined with hydrophilic membranes were increased with increasing operating pressure, while those examined with hydrophobic membranes were decreased with increasing operating pressure. THM included in water could be removed up to 99% via MEUF process. The performance of MEUF examined with hydrophilic membranes could be explained with the rejection of micelles containing THM, while that examined with hydrophobic membranes could be explained with hydrophobic interactions between surfactant and membrane materials.

Rapid recovery of dilute copper from a simulated Cu–SDS solution with low-cost steel wool cathode reactor

Copper–surfactant wastewaters are often encountered in electroplating, printed circuit boards manufacturing, and metal finishing industries, as well as in retentates from micellar-enhanced ultrafiltration process. A low-cost three-dimensional steel wool cathode reactor was evaluated for electrolytic recovery of Cu ion from dilute copper solution (0.2 mM) in the presence of sodium dodecyl sulfate (SDS), octylphenol poly (ethyleneglycol) 9.5 ether (TX), nonylphenol poly (oxyethylene) 9 ether (NP9) and polyoxyethylene (20) sorbitan monooleate (TW) and also mixed surfactants (anionic/nonionic). The reactor showed excellent copper recovery ability in comparison to a parallel-plate reactor. The reactor rapidly recovered copper with a reasonable current efficiency. 93% of copper was recovered at current density of 1 A m −2 and pH 4 in the presence of 8.5 mM SDS. Initial solution pH, cathodic current density, solution mixing condition, SDS concentration, and initial copper concentrations significantly influenced copper recovery. The copper recovery rate increased with an increase in aqueous SDS concentrations between 5 and 8.5 mM. The influences of nonionic surfactants on Cu recovery from SDS–Cu solution depended not only on the type of surfactants used, but also on applied concentrations. From the copper recovery perspective, TX at 0.1 mM or NP should be selected rather than TW, because they did not inhibit copper recovery from SDS–Cu solution.

Removal and recovery of palladium(II) ions from water using micellar-enhanced ultrafiltration with a cationic surfactant

The removal of palladium, present as Pd(II), from aqueous solutions has been performed by a micellar-enhanced ultrafiltration process employing the cationic surfactant dodecyl-trimethylammonium chloride (DTAC). The effect of surfactant concentration and solution pH were investigated. Addition of DTAC at concentrations above the critical micellar concentration results in Pd(II) removal exceeding 95%. The possibility of Pd(II) recovery from the retentate was also examined. After the ultrafiltration process, metal ions are concentrated on the micelle surface. The addition of a strong electrolyte can be very useful to expel the metal from the micelles. Our results show that addition of aqueous MgCl 2 at a concentration of 0.8 M enables us to recover palladium with a yield of 66%.

Surfactant Solubilization and the Direct Encapsulation of Interfacially Active Phenols in Mesoporous Silicas

The solubilization of phenols in micelles of cetyltrimethyl ammonium bromide leads to microstructural changes from spherical micelles to wormlike micelles and then to vesicles. These microstructures are then used to template silicas. There is a transition from highly ordered hexagonal mesoporous silicas of the M41S family to lamellar structures, as the phenolic dopant concentration is increased. The results have implication to the removal of phenols from aqueous waste streams through the micellar enhanced ultrafiltration process. The entrapment of phenols in mesoporous silicas provides a way to sequester such contaminants in concentrated form.