Micellar-enhanced Ultrafiltration Research Articles

Efficient removal of heavy metals in water utilizing facile cross-link conjugated linoleic acid micelles.

Micellar-enhanced ultrafiltration (MEUF) technology is an effective method to treat low-concentration heavy metal wastewater. However, the leakage of surfactants in the ultrafiltration (UF) process will inevitably cause secondary pollution. In this study, a biosurfactant of conjugated linoleic acid (CLA) with conjugated double bonds was selected to bind its micelles by simple thermal crosslinking to obtain morphologically stable stearic acid (SA) nanoparticles. The pure SA nanoparticles were obtained by repeated dialysis. The stability of the SA nanoparticles was verified by comparing the particle size distribution and solubility of the materials before and after crosslinking at different pH levels. The effectiveness of SA nanoparticle-enhanced UF in removing heavy metals was verified by exploring the adsorption performance of SA nanoparticles. The dialysis device was used to simplify the UF device, wherein SA nanoparticles were assessed as adsorbents for the elimination of Cu2+, Pb2+, and Cd2+ ions from aqueous solutions under diverse process parameters, including pH, contact time, metal ion concentration, and coexisting ions. The findings indicate that the SA nanoparticles have no evidence of secondary contamination in UF and exhibit compatibility with a broad pH range and coexisting ions. The maximum adsorption capacities for Cu2+, Pb2+, and Cd2+ were determined to be 152.77, 403.56, and 271.46 mg/g, respectively.

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.

Spectroscopic insights for the enhanced partitioning and removal of Reactive Violet 5 by mixed micellar formulations under optimized conditions: An ionic-nonionic mechanistic approach

This study demonstrates MEUF (micellar enhanced ultrafiltration) as an effective method for the removal of Reactive Violet 5 (RV5) coming from the synthetic waste. MEUF technique is currently employed to decrease aqueous systems toxicity by employing cationic surfactants micellar media, specifically CPC (cetylpyridinium chloride) and CTAB (Cetyltrimethylammonium bromide). The study also examines the impact of nonionic surfactant on the addition of Triton X-100 (TX-100), on solubilizing capacity of the cationic surfactants. Our goal is to determine the optimal conditions for achieving maximum removal efficiency. RV5 partitioning constant, Kb as well as Gibbs energy of the partition ΔGp determines surfactant and dye molecules interaction. Dye molecules initially interact with ionic surfactants to form ion pairs. Subsequently, these ion pairs become incorporated into micelles and later on can subsequently be removed by MEUFThe maximum values of ΔGp (free energy of partition) were determined to be −42.30 kJmol−1 and −37.15 kJmol−1 using cationic surfactants, CPC and CTAB, respectively. Increase in pollutant size results in easy filtration. This study examines the impact of different factors, such as pH, transmembrane pressure, electrolyte (NaCl), surfactant concentration and revolutions per minute (RPM), on the removal of RV5 from an aqueous system. MEUF efficiency has been evaluated through the determination of permeate flux and rejection percentage values. It has been noticed that both surfactants had the potential to effectively encapsulate RV5. However, overall, the highest R% (rejection percentage) of 97.17% was attained.

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.

Reversed micellar-enhanced ultrafiltration removal of oil from concentrated phospholipids

The de-oiling of concentrated phospholipids through ultrafiltration (UF) enhanced by reversed micelles using a polyethersulfone (PES) membrane was examined. Phospholipids could form reversed micellar structures with larger molecular weights in non-polar solvents, which were significantly different from oils and solvents with smaller molecular weights confirming the feasibility of membrane separation. Under the conditions of membrane retentate molecular weight of 50 kDa, transmembrane pressure difference of 0.30 MPa, inlet crossflow velocity of 2.78 × 10−4 m·s−1, temperature of 333.15 K, phospholipid feed concentration of 26.12 kg·m−3% and cycle ratio of 20:1, the retentate phospholipid content and phospholipid yield were 84.97% and 96.4%, respectively, and the permeate flux was 4.65 × 10−6 m·s−1. Phospholipids increased the hydrophobicity of the membrane surface and promoted concentrated phospholipid de-oiling. Finally, a mathematical model was established based on the two-dimensional concentration polarization mechanism indicating that permeate flux was mainly controlled by the convective transfer flow rate.

Progress of Ultrafiltration-Based Technology in Ion Removal and Recovery: Enhanced Membranes and Integrated Processes

Toxic ions from industrial wastewater entail important challenges to the environment. Ultrafiltration (UF) with low operation pressure and high permeability has been widely used for macromolecules and suspended solids separation. However, UF cannot be directly used to separate ions from wastewater due to the large pore size of UF membranes. Recently, the design of enhanced UF membrane structures and UF-based integrated processes expands the application of UF for ion removal. This review aims to summarize the latest developments of UF membranes preparation as well as integrated UF processes in ion removal. First, the advanced materials for UF membranes preparation are discussed, with specific attention on active nanomaterials including inorganic materials, organic materials, and biomaterial-based materials. The design principles such as pore size control and composite thin layer fabrication of enhanced UF-based membranes for ion removal are illustrated. Next, integrated processes such as micellar-enhanced UF, polymer-enhanced UF, electro-driven UF, and other UF-based combined processes are reviewed. Finally, current application limitations and future perspectives in the enhanced UF membrane for ion removal are discussed. This review presents potential approaches for the preparation and application of enhanced UF membranes in sustainable ion removal from wastewaters.

Removal of Nutrients from Water Using Biosurfactant Micellar-Enhanced Ultrafiltration

The removal of NH4+, NO3-, and NH3- from wastewater can be difficult and expensive. Through physical, chemical, and biological processes, metals and nutrients can be extracted from wastewater. Very few scientific investigations have employed surfactants with high biodegradability, low toxicity, and suitability for ion removal from wastewater at different pH and salinity levels. This research employed a highly biodegradable biosurfactant generated from yeast (sophorolipid) through micellar-enhanced ultrafiltration (MEUF). MEUF improves nutrient removal efficiency and reduces costs by using less pressure than reverse osmosis (RO) and nanofiltration (NF). The biosurfactant can be recovered after the removal of nutrient- and ion-containing micelles from the filtration membrane. During the experiment, numerous variables, including temperature, pH, biosurfactant concentration, pollutant ions, etc., were evaluated. The highest amount of PO43- was eliminated at a pH of 6.0, which was reported at 94.9%. Maximum NO3- removal occurred at 45.0 °C (96.9%), while maximum NH4+ removal occurred at 25.0 mg/L (94.5%). Increasing TMP to 200 kPa produced the maximum membrane flow of 226 L/h/m2. The concentrations of the contaminating ion and sophorolipid were insignificant in the permeate, demonstrating the high potential of this approach.

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.

Highly Selective Methodology for Entrapment and Subsequent Removal of Cobalt (II) Ions under Optimized Conditions by Micellar-Enhanced Ultrafiltration

Micellar-enhanced ultrafiltration (MEUF), being a separation technique, was used to remove cobalt metal ion (Co2+) from their aqueous solutions in an application to reduce the toxicity level from industrial effluents using a micellar solution of anionic and cationic surfactants. The metal ions were first adsorbed by using anionic surfactants, i.e., sodium dodecyl sulfate (SDS) and sodium oleate (SO). The calculations for partition (Kx) and binding constants (Kb) and their respective free energy of partition and binding (ΔGp and ΔGb kJmol-1) helped significantly to find out the extent of binding or interaction of Co2+ with the surfactant and ΔGp and ΔGb were found to be -29.50 and -19.38 kJmol-1 for SDS and -23.95 and -12.67 kJmol-1 in the case of SO. MEUF work was also performed to find out the optimal conditions to remove metal pollutants from the aqueous system. For the said purpose, various factors and concentrations effect were studied, such as the concentration of the surfactant, concentration of the electrolyte (NaCl), transmembrane pressure, RPM, and pH. The efficiency of this process was checked by calculating various parameters, such as rejection percentage (R%) and permeate flux (J). A maximum rejection of 99.95% with SDS and 99.99% with SO was attained.

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.

Mixed Micellar Solubilization of Naphthol Green B Followed by Its Removal from Synthetic Effluent by Micellar-Enhanced Ultrafiltration under Optimized Conditions.

In this manuscript, the application of cetyltrimethylammonium bromide (CTAB) and cetylpyridinium chloride (CPC) for the removal of Naphthol Green B (NGB) as a synthetic effluent has been studied. The solubilization of NGB by a single and mixed micellar system using Triton X-100 (TX-100) as a nonionic surfactant has been performed to establish both the extent of the partitioning (kx) of NGB and ultimately their respective Gibbs free energies ΔGp as well. An applied methodology, micellar-enhanced ultrafiltration (MEUF), has also been studied in different micellar media of cationic surfactants by variation in some selective parameters, such as the concentration of surfactant, electrolyte, pressure, pH, and RPM to obtain optimum conditions. The results have been analyzed by a UV/visible double beam spectrophotometer. ΔGp was found to be −39.65 kJ/mol and −47.94 kJ/mol by CTAB and CPC, respectively, in the presence of a nonionic surfactant. The maximum value of Gibbs free energy (ΔGp) of the partition was obtained by CPC. The values of the rejection coefficient (R%) and permeate flux (J) are also calculated. A maximum removal of 99.77% and 98.53% by CTAB and CPC, respectively, was obtained. It has been observed that both of the surfactants are strong candidates for NGB removal.

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.

Investigation of micellar‐enhanced ultrafiltration (MEUF) using rhamnolipid for heavy metal removal from desalter effluent

AbstractThe removal of heavy metals from desalter effluent is an important issue due to the toxicity of these pollutants. In this study, micellar‐enhanced ultrafiltration (MEUF) is applied for the removal of heavy metals from synthetic desalter effluent. MEUF is a process in which surfactants above their critical micellar concentration (CMC) form micelles. Micelles bind compounds with low molecular weight; then, these are rejected by a semi‐permeable membrane. Rhamnolipid is an anionic biosurfactant that has advantages such as biodegradability and low CMC. Rhamnolipid complexation with synthetic desalter effluent demonstrates high efficiency for heavy metal removal. The highest overall removal efficiency was reached at a rhamnolipid concentration of 300 mg/L with 94.07%, 81.93%, 99.81%, 76.00%, and 41.91% for Zn+2, Mg+2, Cu+2, Mn+2, and Na+, respectively. Additionally, loading capacity on rhamnolipid micelles was evaluated to have better selectivity for Mn+2 > Cu+2 > Zn+2 > Mg+2 > Na+. Also, the results showed that phenol has a significant effect on heavy metal removal, decreasing CMC, which increases micelles. Finally, the permeate flux decreases after increasing the rhamnolipid concentration due to the formation of the gel layer, creating an additional resistance to the permeate flux that goes through the membrane. This work shows that MEUF with rhamnolipid is a reliable method for heavy metal removal from desalter effluent.

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.

Removal of Copper(II) in the Presence of Sodium Dodecylobenzene Sulfonate from Acidic Effluents Using Adsorption on Ion Exchangers and Micellar-Enhanced Ultrafiltration Methods.

The selective removal of Cu(II) in the presence of sodium dodecylobenzene sulfonate from acidic effluents was made using the adsorption and micellar-enhanced ultrafiltration methods. Lewatit MonoPlus TP220 showed the best adsorption behavior in the systems containing Cu(II) in the presence of ABSNa50 surfactant compared to the other adsorbents (removal efficiency ≈ 100%, sorption capacity ≈ 10 mg/g). The kinetics followed the pseudo-second order kinetic equation. The Langmuir adsorption capacities were 110 mg/g (the system with ABSNa50 above CMC) and 130.38 mg/g (the system with ABSNa50 below CMC). The working ion exchange capacities were Cw = 0.0216 g/mL and Cw = 0.0135 g/mL. The copper removal by the micellar-enhanced ultrafiltration method was 76.46% (0.1 mol/L HCl).

Positively charged PVC ultrafiltration membrane via micellar enhanced ultrafiltration for removing trace heavy metal cations

One of the major focuses in the field of sewage is the development of low-pressure driven and high-efficiency filtration membrane, particularly for removing extremely low-concentration heavy metals cations. A new type of polyvinyl chloride (PVC) blended ultrafiltration (UF) membrane was fabricated to reject heavy metal cations (e.g., Cd2+, Co2+, Ni2+, Cu2+, and Zn2+) from simulated waters using micellar enhanced ultrafiltration (MEUF) in this research. The positively charged PVC UF membrane was fabricated by blending PVC and amphiphilic poly (methyl methacrylate-co- dimethylaminoethyl methacrylate) (PMD) which was in-situ quaternized by methyl iodide (CH3I), then the PVC/PMD blended membrane was fabricated via nonsolvent induced phase separation (NIPS) process. The membranes' pore morphology, surface chemical compositions, surface charge, water contact angle, mechanical strength and water flux were investigated in detail. The influence of pH, transmembrane pressure, sodium dodecylbenzene sulfonate (SDBS) concentration on the filtration of pure SDBS solution was studied. SDBS was subsequently used as surfactant to remove heavy metal ions by micellar enhanced ultrafiltration (MEUF). For a molar ratio of 40:1 (SDBS: metal cation), the rejection of feed solution containing 10 ppm metal cations (e.g., Cd2+, Co2+, Ni2+, Cu2+, and Zn2+) surpassed 96% with MEUF method. The results showed that the prepared membrane had low-pressure driven and high-efficiency performance, which provided a potential solution for the high-efficiency removal of trace heavy metals cations.

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 cooperative effect between cyclic naphthenic acids and surfactant enhances the separation efficiency

Naphthenic Acids (NAs) are responsible for corrosion, produced water pollution, and are toxic to marine life. Therefore, more efficient NAs extraction techniques, such Micellar-Enhanced Ultrafiltration (MEUF), have been developed. In this work, Molecular Dynamics simulations were employed to deepen the comprehension of the behavior and properties of NA in interfacial systems and micellar systems. The calculated distribution coefficient (log D) in different water/oil interfaces demonstrated the greater affinity between NA and cyclic structures, showing a more negative free energy in the systems with toluene. Furthermore, simulations with different NAs and surfactant showed that micelle is effective in NAs carriage by two different interaction conformations, both by intercalation and adsorption of NAs on micelle surfaces, guiding to a micelle increase of about 5%. Radial distribution, hydrogen-bond, and non-bonded analysis indicated that NAs affect interactions between surfactant molecules' by diminishing the Lennard-Jones contribution. Moreover, the incorporated alicyclic molecules are responsible for facilitating the absorption of more NAs by the micelle. So, to enhance NAs separation from oil or produced water, cyclic molecular systems may be employed.