Micellar-enhanced Ultrafiltration Process Research Articles

Micellar-enhanced ultrafiltration of heavy metal wastewater with palygorskite under various temperatures and pressures

The micellar-enhanced ultrafiltration process demonstrated significant potential for treating heavy-metal-contaminated wastewater. Operating conditions greatly influence complex formation and ultrafiltration efficiency, suggesting that optimizing these parameters could enhance both the process's effectiveness and its cost-efficiency. In this research, nano-palygorskite was used to treat wastewater contaminated with Cu2+, Zn2+, and Cd2+. The material was characterized using SEM, FTIR, XRD, and Zeta potential, and the effects of temperature and pressure variations on the process were investigated. Under conditions of pH 7.0 and 0.1 MPa, the retention rates of the three heavy metal ions rapidly equilibrated within 40 min, achieving removal efficiencies of 99.94 %, 99.75 %, and 99.56 %, respectively. Temperature changes significantly influenced the retention rates, which increased by approximately 5 % with increasing temperature. At pH 7.0 and 293 K, increasing the pressure improved the retention rates by approximately 3 %, reaching 99.31 %, 98.63 %, and 99.19 %, respectively. The experimental data fit the pseudo-2nd-order kinetic equation and Langmuir isotherm adsorption model, with maximum adsorption capacities of 10.44 mg/g, 9.41 mg/g, and 11.36 mg/g, respectively. Overall, gradual increases in the temperature and pressure accelerated the reaction rate, highlighting their beneficial effects on MEUF. This study underscores the potential of palygorskite as an effective inorganic complexing agent for heavy-metal-contaminated wastewater treatment.

Micellar-enhanced ultrafiltration with a novel modified membrane for removal of arsenate and emerging contaminants from water

Toxic metals and Antibiotics appear in water sources have potential threat or adverse effect on health of human being and other living species. The present paper reports a novel micellar-enhanced ultrafiltration process could efficiently remove the toxic metals like arsenate and antibiotics like Levofloxacin and Sulfamethazine from water. Contaminants removal by conventional ultrafiltration membrane is very low. Removal up to 92.8 %, 84.1 % and 95.3 % of Arsenate (AsO43-), Levofloxacin (LF) and Sulfamethazine (SMT) respectively was achieved by micellar-enhanced ultrafiltration with cationic surfactant Benzalkonium chloride as compared to conventional ultrafiltration, which rejected 91.4 %, 8.2 % and 7.9 % of Arsenate, LF, and SMT respectively. Hydrodynamic size of the molecule trapped by micelle enhances significantly helping the separation. The ultrafiltration membrane was modified with copper-chitosan supramolecular assembly and found that molecular weight cut-off decreased because of supramolecular assembly formation. Mechanical properties such as tensile stress and elongation at break were evaluate and it was found that the membrane had significantly higher tensile strength viz. up to 60.9 MPa as compared to virgin Polysulfone membrane 12.7 MPa. Thus, the present work paves the way for future work in the area for removal different contaminants. by micellar-enhanced ultrafiltration.

Toward Climate Neutrality: A Comprehensive Overview of Sustainable Operations Management, Optimization, and Wastewater Treatment Methods

Various studies have been conducted in the fields of sustainable operations management (SOM), optimization, and wastewater treatment, yielding unsubstantiated recovery. In the context of Europe’s climate neutrality vision, this paper reviews effective decarbonization strategies and proposes sustainable approaches to mitigate carbonization in various sectors such as buildings, energy, industry, and transportation and how these interlink with wastewater management. The study also explores the role of digitalization in decarbonization and reviews policies that can direct governments’ actions towards a climate-neutral society. This paper presents a review of optimization approaches applied in the fields of science and technology, incorporating modern optimization techniques based on various peer-reviewed published research papers. It emphasizes non-conventional energy and distributed power-generating systems along with the deregulated and regulated environment. Additionally, this paper critically reviews the performance and capability of the micellar-enhanced ultrafiltration (MEUF) process in the treatment of dye wastewater. The review presents evidence of the simultaneous removal of co-existing pollutants and explores the feasibility and efficiency of biosurfactants instead of chemical surfactants. Lastly, the paper proposes a novel Firm–Regulator–Consumer-Technology Enablers/Facilitators interaction framework to study operations, decisions and interactive cooperation considering the relationships between the four agents through a comprehensive literature review of SOM. The proposed framework provides support for exploring future research opportunities and holistic sustainability initiatives.

Application of biosurfactant surfactin for the removal of heavy metals from contaminated water and soil via a micellar-enhanced ultrafiltration process

The presence of toxic metals in natural environments presents a potential health hazard for humans, and the removal of toxic metals remains a major challenge. In this study, biosurfactant surfactin was used to remove heavy metals from contaminated soil via a micellar-enhanced ultrafiltration (MEUF) process. Results demonstrate that anionic surfactin with two –COO− groups can bind heavy metals through electrostatic interactions at a pH above its pKa value and then be rejected by the ultrafiltration membranes, resulting in efficient removal of heavy metal ions. By optimizing the operation parameters, over 98% of metals can be removed by adding surfactin at a surfactin/metals ratio of 3:1. Moreover, membrane fouling was characterized and eliminated by an optimized cleaning strategy. Membrane flux recovery can be obtained at 94% without losing separation efficiency. Finally, the validity of the present process was confirmed on real contaminated water and soil, and over 99.2% of metals were removed. Hence, MEUF with surfactin is a reliable and efficient approach for removing heavy metals from contaminated water and soil.

Effect of anionic surfactants on the heavy metal ions removal by adsorption onto ion exchangers - batch and column studies

Adsorption of heavy metals by various sorbents has been widely studied by many scientists due to the processes of industrialization as well as the great concentration of these toxic and dangerous pollutants in the environment the elimination of which is significant important. The ion exchangers Lewatit MonoPlus SR7, Lewatit MonoPlus TP220, Purolite A830 and Lewatit AF5 were used as adsorbents to remove heavy metal ions (M(II)) such as zinc (Zn(II)), nickel (Ni(II)) and copper (Cu(II)) (especially Cu(II)) in the presence of anionic surfactants to examine the adsorption efficiency in such systems. The main objective of this paper were the kinetic, equilibrium, thermodynamic and column studies in the HCl–M(II)–anionic surfactant (AS) such as SDS (Sodium Dodecyl Sulfate), ABS (Dodecylbenzene Sulfonic Acid) or ABSNa50 (Sodium Dodecylbenzene Sulfonate) systems. The largest adsorption capacities were obtained in the HCl–M(II)–AS systems for Lewatit MonoPlus TP220 (Cu(II): 9.9–10 mg/g; Zn(II): 8.5–8.9 mg/g and Ni(II): 7.3–9.2 mg/g) compared to the other ion exchangers. Therefore, after the first selection, Lewatit MonoPlus TP220 and the systems containing Cu(II) were further examined. The isotherms models were applied in the experimental data analysis and show that the Langmuir (determination coefficient, R2 > 0.993) and Temkin (R2 = 0.948–0.965) isotherm models exhibit the best fitting. The results of the temperature-dependent adsorption of Cu(II) in the presence of SDS on Lewatit MonoPlus TP220 suggested that the adsorption was spontaneous, thermodynamically favourable, and exothermic in nature (the enthalpy, ∆H° = −7.19 kJ/mol (↓CMC) and −7.03 kJ/mol (↑CMC). The largest working ion exchange capacities of the anion exchange resin were obtained for the ABS surfactant (Cw = 30 g/L (↓CMC) and 12 g/L (↑CMC)). As follows from the current investigations Lewatit MonoPlus TP220 has a great potential for the removal of Cu(II) in the presence of ABS and SDS. For comparison, Cu(II) ions removal by the micellar enhanced ultrafiltration process was also presented and exhibits 54–73.88 % Cu(II) removal efficiency in the presence of SDS and ABS.

Effect of conventional and Gemini surfactants on the micellar-enhanced ultrafiltration process performance for the separation of Au(III) from aqueous solutions: A dissipative particle dynamics study

Dissipative particle dynamics (DPD) simulation was used to investigate the self-assembled structure of dodecyl trimethyl ammonium bromide (DTAB) and Gemini hexamethylene-1, 6-bis (dodecyl dimethyl ammonium bromide) (12−6−12) surfactants in the aqueous solution. The influence of simulation time and surfactant concentration was studied as the effective parameters on the formation of micelles. The results indicate that by increasing the surfactant concentration, the micellar clusters deform to spherical, wormlike, cylindrical and lamellar shapes, respectively. Subsequently, the effect of surfactant and gold concentrations was investigated for the first time on the performance of the micellar-enhanced ultrafiltration (MEUF) process in the separation of Au(III) from aqueous solutions. The separation efficiency of gold mesomolecules and micellar binding constant was also estimated. The simulation results show the excellent effect of the presence of micelles in the separation of Au(III) using the MEUF process. As the surfactant concentration increases and the micelles grow in size, the probability of bonding between the metal mesomolecules and the micelles also increases and the passage of the gold beads through the polymeric membrane decreases.

Optimisation studies on removal of fluoride by micellar enhanced ultrafiltration

Removal of fluorine from water is one of the key problems in supply of pure drinking water. Permissible limit of fluoride in drinking water was determined to 1.5 ppm by world health organization. There are different techniques for fluoride removal like ion-exchange, precipitation, adsorption, and membrane techniques but this can be more effective through one membrane technique which is Micellar Enhanced Ultrafiltration (MEUF). In this method surfactants create micelles, which are retained by ultrafiltration membranes. Application of MEUF process for removal of fluoride was studied using polyethersulfone (PES) based ultrafiltration membranes and cationic surfactant (cetylpyridinium chloride-CPC) in batch process. The PES membranes prepared by phase inversion method was ultra-porous in nature with a molecular weight cut-off (MWCO) of 50 kDa. A 20-run factorial design was performed using central composite design (CCD) with Response surface methodology (RSM) to optimize fluoride removal using micellar enhanced ultrafiltration. The effect of different variables like surfactant concentration, pressure drop and time on fluoride removal was investigated in this study. The statistical analysis indicated that among the parameters tested, surfactant concentration, time, interaction between surfactant concentration and pressure drop and pressure drop, and time had a significant effect on reduction of fluoride concentration. A correlation coefficient of R2 = 0.9672 indicated the model was adequate to predict the reduction of fluoride concentration with optimum conditions at surfactant concentration (3 CMC (critical micelle concentration)), pressure drop (7 kg/cm2) and 30 mins of time with 0.79 ppm of fluoride concentration.

Effect of various types of anions and anionic surfactants on the performance of micellar-enhanced ultrafiltration process in the removal of Pb(II) ions: An optimization with the response surface methodology

In the present study, the micellar-enhanced ultrafiltration (MEUF) process was employed for the removal of Pb2+ ions from aqueous solutions using sodium dodecyl sulfate (SDS) and sodium lauroyl sarcosinate (Sarkosyl) as the anionic surfactants. The performance of Sarkosyl was compared to SDS, a frequently used surfactant in the MEUF processes, to evaluate their efficiency in the removal of lead ions. Sodium chloride (NaCl) was used as the electrolyte and the role of lead salt anions, lead nitrate (Pb(NO3)2) and lead chloride (PbCl2), was also investigated for the first time in the MEUF process. The MEUF process was modeled using response surface methodology (RSM), and experiments were designed and carried out based on the central composite design (CCD). Two categorical variables of anionic surfactants and lead salts, and two numerical variables of Pb2+ and electrolyte concentrations were considered as the studied factors in this design. The process was assessed in terms of its ability to simultaneously maximize Pb2+ rejection and permeate flux. The results showed that increasing the concentration of NaCl significantly reduces the permeate flux, while lead ions concentration has a negligible impact on the permeate flux. The response surface plots also indicated that the effect of the anionic surfactant type on the permeate flux is insignificant. In the studied range of lead concentrations, the highest removals of Pb2+ ions were observed at the concentration of 21 mg/L of Pb(NO3)2 and 0.05 M of NaCl, equal to 79.27% and 94.74% for Sarkosyl and SDS anionic surfactants, respectively.

Selective separation of gold and palladium using the improved Gemini Micellar-Enhanced ultrafiltration

The aim of this study was to selectively separate precious metals such as gold and palladium from a binary solution using the Gemini micellar-enhanced ultrafiltration (GMEUF) process. The selectivity of this process was improved by adding the chelating agent ethylene diamine tetra-acetic acid (EDTA) to the solution. It means that one of these two metals can interact with the surface of Gemini micelles and reject by the membrane. The other metal must tend to bind to the ligand and enter the permeate stream. The effect of various parameters such as solution pH, operating pressure, flow rate, molar concentration ratio of the surfactant to the metal (S/M) and molar concentration ratio of the chelating agent to the metal (C/M) was investigated on the selective separation of these metals by a commercial polyethersulfone (PES) membrane and two Gemini surfactants. The rejection of gold and palladium in the optimal conditions of the above parameters reached the values of 90.2% and 21.4%, respectively, for the solutions containing N1-dodecyl-N1,N1,N2,N2-tetramethyl-N2-octylethane-1,2-diaminium bromide (CG12) micelles. In the presence of pentanediyl-1,5-bis (dimethyl cetyl ammonium bromide) (G5) micelles, these rejection values changed to 91.7% and 27.1%, respectively. The obtained results indicated a good selectivity in the separation of gold and palladium by the improved GMEUF process.

Self-organised surfactant assemblies as nanostructured dye carriers: a mixed micellar comparative approach for enhanced dye solubilisation

ABSTRACT The reported work is focused on the solubility of Rhodamine B (cationic dye), as an important methodology to investigate the extent of incorporation or penetration of dye inside the micelles spectroscopically, so the solubilised dye can be filtered via Micellar-enhanced ultrafiltration process to keep our environment safe from toxic effects of industrial effluent. Solutions were prepared by using micellar media of anionic surfactants i.e. Sodium dodecyl sulphate (SDS), Sodium Oleate (SO) as well as mixed micellar media of said anionics with non-ionic surfactant i.e. Triton X-100 (TX-100). The extent of solubilisation has been, quantitatively, calculated using data of differential spectroscopy, in terms of partition coefficient Kx and Gibbs energy of partition, ∆Gp. It has been observed that mixed micellar media has better solubilisation capacity than micellar solution of individual surfactants. A better micellar solubilisation and ultimately the high Gibbs energy of partition, ∆Gp with SO/TX-100 system i.e. −40.89 as compared to SDS/TX-100 system (−37.03) has been observed due to the presence of long carbon chain in SO.

Investigating micellar-enhanced ultrafiltration (MEUF) of mercury and arsenic from aqueous solution using response surface methodology and gene expression programming

• Micellar enhanced ultrafiltration (MEUF) for the removal of mercury and arsenic was investigated. • Response surface methodology (RSM) was used to assess the impact of operating parameters on selected metals removal efficiency by MEUF. • The gene expression programming (GEP) model was tested to optimize the MEUF process. • Proposed RSM and GEP models were validated and compared based-on statistical analysis. Heavy metals such as mercury and arsenic in water resources have become a global concern due to their toxic, persistent, bio-accumulative, and carcinogenic characteristics. To address health-related issues as well as environmental concerns, it is important to eliminate mercury and arsenic contaminants from water streams. In this study, mercury and arsenic ions were removed from aqueous solutions through micellar-enhanced ultrafiltration (MEUF) using sodium dodecyl sulfate (SDS) and cetylpyridinium chloride (CPC) as chelating agents, respectively. Response surface methodology (RSM), based on the full factorial design (FFD) method, was applied to optimize the process parameters. The relationship between the removal of targeted heavy metals and process variables, including pressure, metal concentration, pH, and molar ratio of surfactant to metal defined by the proposed quadratic models. The models were statistically significant, as shown by analysis of variance. Experimental results presented the optimum operating parameters for > 95% mercury removal were: 2.5 bar pressure, 10 ppm mercury concentration, SDS to mercury MR of 12:1, and pH 8.0. In the case of arsenic, >90% removal was achieved with pressure at 2.5 bar, 15 ppm arsenic concentration, and CPC to arsenic MR at 8:1, and pH 8.0. Statistical validation of RSM models using predicted and experimental results indicated that the proposed model effectively provided a relationship between targeted heavy metal removal and process variables. Additionally, the MEUF performance for mercury and arsenic removal from an aqueous solution was predicted using a gene expression programming model that presented a good fit with the experimental results.

The removal selectivity of heavy metal cations in micellar-enhanced ultrafiltration: A study based on critical micelle concentration

Micellar enhanced ultrafiltration (MEUF) is a process to remove heavy metal by complexing it with the counterionic surfactant micelle, and the complex formed was subsequently removed using ultrafiltration. The surfactant is usually added in excess, which renders high rejection (low selectivity) for all metal cations in the mixture. This work emphasises MEUF conducted at surfactant dosage around the critical micelle concentration (CMC). Few studies revealed that the presence of counterions could lower the CMC of a charged surfactant. The magnitude of reduction depends on the strength of electrostatic interaction between the counterions and surfactant. Such observation suggests that the MEUF process's selectivity could be altered based on the dosage of surfactant and the types of cations presented in the solution. This work started with determining CMC of sodium dodecyl sulfate (SDS) in the presence of single or binary metal cations at varying pH (pH 3, pH 10 and without pH adjustment). The lowest CMC (4.00 mM) was obtained in the solution containing 100 ppm copper (II) at pH 3, about 42% lower compared to CMC of SDS obtained in pure water without pH adjustment (7.00 mM). Then, the filtration was performed using 7 mM of SDS, under varying pH (pH 3, pH 10 and no pH adjustment), initial metal concentration of 100 mg/L, pressure of 2.5 bar using polyethersulfone (PES) membrane of 10 k Da molecular weight cut-off (MWCO). Overall, the highest metal rejection was obtained at pH 10, with 66% of copper and 26% of chromium (III) was rejected. The highest selectivity of copper (II) over chromium (III) was observed at neutral pH. Such findings could be due to the higher diffusivity of copper cations over chromium cations in aqueous since copper cations can reach the micelle surface and form metal-micelle complex faster than chromium cations.

An efficient removal of crystal violet from aqueous solution using rhamnolipid micellar solubilization followed by ultrafiltration and modeling of flux decline

Micellar‐enhanced ultrafiltration (MEUF) using rhamnolipid (RHL) biosurfactant has been shown to be an effective and promising method for removal the hazardous heavy metal ions and organic pollutants from aqueous stream. However, the potential application of rhamnolipid was not explored much in the treatment of dye wastewater. The aim of this study was to evaluate the performance of the rhamnolipid based MEUF process for the removal of crystal violet (CV) from the aqueous solution. MEUF experiments were performed in both dead-end stirred cell and cross-flow cell. Response surface methodology was used to optimize the MEUF feed conditions. Under optimal feed conditions (RHL: 175 × 10-3 kg m-3; CV: 32 × 10-3 kg m-3; NaCl: 15 kg m-3 and pH: 8.3), the maximum CV rejection efficiency was found to be 99.5%. This study also investigated the effects of the transmembrane pressure difference, cross-flow velocity and feed temperature, on the CV rejection efficiency and profiles of permeate flux and fouling resistance. A model based on resistance-in-series theory coupled with Hermia’s cake filtration model adapted to cross-flow was developed together with the expression of transition time of fouling mechanism, to analyze the flux decline behavior during operation. The experimental flux decline data were in good agreement with the model predictions. The proposed model was also found to be applicable to sodium dodecyl sulfate (SDS) based MEUF process for removal of CV. For similar CV rejection efficiency, the present study showed a 31.5% lower operating cost compared to SDS based system.

Removal of Reactive Red 120 from Model Textile Waste Solution by Micellar-Enhanced Ultrafiltration

The textile wastewater effluents discharged into the water bodies is one of the main issues of environmental contamination. A novel process which results particularly suitable for the treatment of this effluent is the Micellar-enhanced Ultrafiltration (MEUF). The possibility of removing Reactive Red-120 dye using the MEUF process with Cetylpyridinium Bromide as a surfactant has been investigated in this experiment. The total Flux and Rejection properties were analysed at varying concentrations of the surfactant, and combination of salts. The application of MEUF process is very appreciable owing to the efficiency it renders being at par with the levels of RO or NF but at a much cheaper cost.

Experimental and neural network modeling of micellar enhanced ultrafiltration for arsenic removal from aqueous solution

The optimization of micellar-enhanced ultrafiltration (MEUF) of arsenic (As) contaminated aqueous solution using cetylpyridinium chloride (CPC) as surfactant was studied through experimental and artificial neural network (ANN) modeling. Experimental studies were carried out by varying operational conditions such as time, pressure, molar ratio of CPC to As, concentration of As and pH of feed solution. Root mean square error (RMSE) and coefficient of determination (R<sup>2</sup>) were considered as performance criterion to evaluate the predicted results of ANN model. The experimental studies provided optimum operating parameters such as pressure 1.8 bar, molar ratio of CPC to As was 5:1, As concentration 1 mM and pH 8.0 of feed solution. ANN model presented reliable results with RMSE values 0.259, 0.553 and 0.623 for training, validation and testing datasets, respectively, while R<sup>2</sup> values for training, validation and testing dataset were noted as 0.962, 0.942 and 0.932, respectively. The proposed ANN model traced input-output relationship to predict As removal efficiency (RE) of MEUF process. Therefore, ANN model can be considered as a competitive, powerful and fast alternate because of its high computational speed, accuracy and economics in MEUF process optimization without doing laborious experimental work.

Removal of Phenol from Wastewater Using Micellar-Enhanced Ultrafiltration with Quaternary Ammonium Salt Cationic Gemini Surfactants

Micellar-enhanced ultrafiltration (MEUF) as a surfactant-based separation process is promising for the treatment of low concentration organic wastewater. Gemini surfactant becomes the focus of the field of MEUF increasingly due to its excellent performance in MEUF. In order to investigate the effect of operational factors on the effectiveness of MEUF process, quaternary ammonium salt Gemini surfactants were used for the removal of phenol. The critical micelle concentration (CMC) values of cationic gemini surfactants (CG12, CG14, and CG16) were analyzed. Then the influence of various factors, include CG concentration, phenol concentration, electrolyte concentration and operating pressure, on the removal performance was investigated. Finally, BBD experimental design was carried out to identify optimal operational conditions. The results showed that hydrophobic chain length of Gemini surfactant s have significant effect on its CMC value and the MEUF process. The longer the hydrophobic chain length, the higher phenol rejection. However, it can result in membrane fouling. CG concentration has significant influence on phenol rejection and permeation flux. And phenol concentration has a direct impact on its removal. In addition, the optimal operational condition is that CG12 concentration at 10 CMC, phenol concentration at 1 mM, and NaCl concentration at 25 mM. The corresponding optimal phenol rejection is 91.16%, the optimal permeate flux is 29.33 L/m2 h.

Analysis of flux decline during rhamnolipid based micellar-enhanced ultrafiltration for simultaneous removal of Cd+2 and crystal violet from aqueous solution

Micellar enhanced ultrafiltration (MEUF) experiments were carried out with rhamnolipid (RHL) biosurfactant in a stirred cell for removal of Cd+2 and crystal violet (CV), simultaneously from aqueous solution. The influence of various operating conditions on the transient profiles of permeate flux and observed rejections were investigated. Experimental results revealed that for the treatment of aqueous feed under optimal conditions (RHL: 1730 × 10−3 kg. m−3; Cd+2: 30 × 10−3 kg. m−3; CV: 15 × 10−3 kg. m−3; NaCl: 5 kg.m−3; pH:7.8), the process condition (414 kPa, 600 rpm and 40 °C) was found to be the most suitable to achieve the permeate flux of (75 ± 1.5) L.m-2. h-1 at volume concentration ratio of 2 with more than (98 ± 0.1)% rejections of both the pollutants (Cd+2 and CV) and minimum surfactant loss (<3 %) to the permeate. The rapid decline in permeate flux at the earlier stage of filtration was attributed to adsorption-pore blocking followed by gradual decline at the later stage due to the growth of a cake layer of RHL-pollutant aggregates on the membrane surface. The transition of fouling mechanism occurred in the range of 200−390 s depending on the operating conditions. A combined model based on resistance-in-series theory coupled with Hermia’s constant pressure cake-filtration model was developed to analyze the profiles of flux decline and observed rejections of Cd+2, CV and RHL. The predicted results showed a good agreement with the experimental data. The developed model was successfully tested to other MEUF studies. The estimated model parameters in this study would help in design and scaling up of such MEUF process.

Micellar enhanced ultrafiltration (MEUF) of mercury-contaminated wastewater: Experimental and artificial neural network modeling

MEUF was applied efficiently to remove mercury (Hg) from simulated wastewater by using polyacrylonitrile membrane and sodium dodecyl sulfate (SDS) as surfactant. In this process leakage of surfactant monomer to permeate water causing a secondary pollution that was addressed by using MEUF followed by activated carbon fiber (MEUF-ACF). The effect of operating parameters including, concentration of Hg and pH of feed solution, molar ratio of SDS to Hg, and retentate pressure was investigated to optimize MEUF process. Moreover, artificial neural network (ANN) model was proposed to predict Hg removal efficiency to optimize MEUF process without doing laborious and time-consuming experimental work. ANN model performance was evaluated on the basis of statistical values such as mean square error (MSE) and coefficient of determination (R2).The experimental results presented that optimum operating parameters were found as 10 ppm of Hg concentration, pH 7.0, molar ratio of SDS to Hg 8:1 and retentate pressure was 1.5 bar. MEUF results showed 95.75% and 50.91% removal of Hg and SDS, respectively, while 96.83% Hg and 97.15% of SDS rejection was achieved using MEUF-ACF. The statistical values of proposed ANN model presented high degree of agreement between experimental and predicted values by ANN (R2>0.95 for training, validation and testing dataset). Resultantly, MEUF-ACF can eradicate issue of secondary pollution and proposed ANN model can be a competitive, powerful and fast alternate to laborious experimental work for MEUF process optimization.

Effective separation of methylene blue dye from aqueous solutions by integration of micellar enhanced ultrafiltration with vacuum membrane distillation

Micellar enhanced ultrafiltration is widely used for separation of dyes and other dissolved organics from aqueous solutions. However, generation of reject water that contains highly concentrated dyes, surfactants and electrolytes is a major concern in this process. In this study, micellar enhanced ultrafiltration (MEUF) was integrated with vacuum membrane distillation (VMD) for effective removal of methylene blue dye from aqueous solutions with enhanced water recovery. Activated carbon loaded polyethersulfone (PES) ultrafiltration membrane was used in the process with sodium dodecyl sulphate as an anionic surfactant for micelle formation. The reject of MEUF was further processed via VMD for additional water recovery using a tetraethyl orthosilicate crosslinked polystyrene (PSt) membrane. Effect of feed dye concentration, surfactant concentration and feed pressure on MEUF process performance was evaluated. The effect of feed dye concentration, degree of vacuum and membrane thickness on VMD was also studied. A theoretical model based on modified resistance in series model was used to predict MEUF process flux. Also, an interesting model based on computational fluid dynamics was developed to predict the liquid entry pressure for dye solution which is an important parameter in VMD. The final concentrated dye in VMD retentate could directly be used as an emulsion in paint or textile industry, with simultaneous generation of utility water.

Simultaneous removal of arsenate and nitrate from aqueous solutions using micellar-enhanced ultrafiltration process

Arsenate (As(V)) and nitrate (NO3– removal from aqueous solutions was investigated via micellar-enhanced ultrafiltration (MEUF) using a prepared polyacrylonitrile (PAN) membrane and cetylpyridinium chloride (CPC) as the cationic surfactant. The PAN ultrafiltration (UF) membrane was produced using the phase inversion method and used in a dead-end cell system. The morphology and physiochemical properties of the prepared membrane were characterized using SEM, EDX, XRD, FTIR, and AFM. Parameters, including surfactant concentration, solution pH, and transmembrane pressure (TMP) were examined to determine their effects on the permeate flux and removal efficiency of As(V) and NO3–, besides CPC rejection. Increasing CPC concentration from 0.1 to 5 mM, removal of As(V) and NO3– increased from 49.3% to 96.9% and from 0.3% to 90.5%, and the permeate flux reduced from 36.6 to 10.2 L/m2/h and from 54.2 to 33.3 L/m2/h, respectively. In addition, simultaneous removal of As(V) and NO3– via MEUF was studied, which showed that removal of NO3– was majorly prevented by As(V) because of competitive binding of CPC micelles between NO3– and As(V); however, As(V) removal was only slightly inhibited by NO3–. It was shown that the prepared PAN membrane could remove more than 90% of As(V) and NO3– under optimal conditions (CPC concentration = 5 mM, pH = 7–8, and TMP = 1 bar), using the MEUF process.