Aliquat Research Articles

Characterization of a novel end product tolerant and thermostable cellulase from Neobacillus sedimentimangrovi UE25

Recent advancements in biorefinery processes necessitate search for cost effective and thermostable cellulases. This study was designed to characterize the cellulase obtained from a thermophilic bacterium, Neobacillus sedimentimangrovi UE25. A combined pretreatment of NaOH and methyltrioctylammonium chloride was given to sugarcane bagasse (SB) for lignin removal and the pretreated SB was utilized as a carbon source for the cellulase production. The thermostable cellulase thus obtained was characterized by adopting central composite design which has not been reported earlier for this purpose. Cellulase showed its maximum activity at pH 7 and temperature 60 ℃ and it remained active in the presence of many salts and detergents. Endoglucanase (EG) was found to be stable for 30 min at 80 ℃. The purification of EG by using DEAE column yielded specific activity and purification fold of 365.866 IU mg−1 and 4.264, respectively. The purified EG had a molecular weight of ∼45 kDa. End product tolerance of EG was also evident, as an activity of 228.57 IU mL−1 was observed in the presence of 60 mM glucose which revealed that it does not lose its activity upon accumulation of end-product when the reaction is prolonged. The purified EG exhibited Vmax and Km of 294 U mL−1 min−1 and 36 µM, respectively, in the presence of 60 mM glucose. This novel thermostable cellulase can finds its applications in industrial sector.

An Ionic Supported Liquid Membrane for the Recovery of Bisphenol A from Aqueous Solution.

In this work, a flat supported liquid membrane (FSLM) was applied for the extraction of bisphenol A (BPA) from aqueous solutions, using an ionic liquid as a carrier. The liquid membrane consists of tricaprylmethylammonium chloride (aliquat 336®) diluted in 2-octanol. Furthermore, to obtain the best transport efficiency, the impacts of various experimental parameters were investigated. These parameters included aliquat 336® concentration, the concentration of BPA in the feed phase, the pH of the feed phase, the concentration of NaOH in the receiving phase, the polymeric support nature, the percentage of extractant in the organic phase, and the solvent nature. The optimum conditions of the experiment were 50% (v/v) aliquat 336®/2-octanol as the organic phase, a transport time of 8 h, and 1 × 10−2 mol L−1 NaOH as the receiving phase. The BPA was successfully recovered (the recovery percentage was about 89%). Supported liquid membrane-based aliquat 336®/2-octanol displayed an acceptable stability with re-impregnation after 5 days of operation.

Recovery of Metals from Electronic Waste-Printed Circuit Boards by Ionic Liquids, DESs and Organophosphorous-Based Acid Extraction.

The extraction of metals from waste printed circuit boards (WPCBs) with ionic liquids (ILs), Deep Eutectic Solvents (DESs) and organophosphorous-based acid (Cyanex 272) has been presented. The study was undertaken to assess the effectiveness of the application of the new leaching liquids, and the new method of extraction of metals from the leachate and the solid phase with or without the leaching process. Solvent extraction from the liquid leachate phase has been studied in detail with popular ILs, such as tetraoctylphosphonium bromide, {[P8,8,8,8][Br] and tributyltetradecylphosphonium chloride, [P4,4,4,14][Cl] using Aqueous Biphasic Systems (ABS) method. Trihexyltetradecylphosphonium bis(2,4,4-trimethylpentyl) phosphinate, [P6,6,6,14][Cyanex272], ([P6,6,6,14][BTMPP]), trihexyltetradecylphosphonium thiocyanate, [P6,6,6,14][SCN], methyltrioctylammonium chloride (Aliquat 336), as well as bis(2,4,4-trimethylpentyl)phosphinic acid (Cyanex 272) were also used in the extraction of metals from the leachate. Two DESs (1) {choline chloride + lactic acid, 1:2} and (2) {choline chloride + malonic acid, 1:1} were used in the extraction of metals from the solid phase. The extraction behavior of metals with DESs was compared with that performed with three new bi-functional ILs: didecyldimethylammonium salicylate, [N10,10,1,1][Sal], didecyldimethylammonium bis(2-ethylhexyl) phosphate, [N10,10,1,1][D2EHPA], and didecyldimethylammonium bis(2,4,4-trimethylpentyl) phosphinate, [N10,10,1,1][Cyanex272]. The [P6,6,6,14][Cyanex272]/toluene and (Cyanex 272 + diethyl phosphite ester) mixtures exhibited a high extraction efficiency of about 50–90% for different metal ions from the leachate. High extraction efficiency of about 90–100 wt% with the ABS method using the mixture {[P8,8,8,8][Br], or [P4,4,4,14][Cl] + NaCl + H2O2 + post-leaching liquid phase} was obtained. The DES 2 revealed the efficiency of copper extraction, ECu = 15.8 wt% and silver, EAg = 20.1 wt% at pH = 5 from the solid phase after the thermal pre-treatment and acid leaching. The solid phase extraction efficiency after thermal pre-treatment only was (ECu = 9.6 wt% and EAg = 14.2 wt%). The use of new bi-functional ILs did not improve the efficiency of the extraction of metal ions from the solid phase. Process factors such as solvent concentration, extraction additives, stripping and leaching methods, temperature, pH and liquid/solid as well as organic/water ratios were under control. For all the systems, the selectivity and distribution ratios were described. The proposed extraction processes can represent alternative paths in new technologies for recovering metals from electronic secondary waste.

A novel approach in the removal of ciprofloxacin antibiotic in an aquatic system using polymer inclusion membrane

Ciprofloxacin (CIP) in the aquatic environment has been widely studied due to its ability to be persistent in the environment. Residues of this contaminant are ubiquitous in different environmental media due to the inability of conventional wastewater treatment plants (WWTPs) to remove them completely. Various advanced wastewater treatments have been used to attenuate this contaminant; however, it remained refractory in the environment. In this study, we investigated the removal of ciprofloxacin using poly(vinyl)chloride (PVC) and cellulose triacetate (CTA) based polymer inclusion membranes (PIMs). Different parameters were investigated, such as the effect of the types of carriers (Bis-2-(ethylhexyl) phosphate (B2EHP) and tricapryl-methylammonium chloride (Aliquat 336), pH, initial concentration of feed solution, and concentration of the stripping solution. The produced PIM was chemically and mechanically stable. At optimum conditions, the removal efficiency of 99.2%, transport efficiency of 70%, and a permeability coefficient of 20.1 μ m/s were recorded using PVC/B2EHP membrane, whilst a removal efficiency of 95% was recorded using CTA/B2EHP membrane. However, using Aliquat 336 as the carrier, the highest removal efficiency of 60% was recorded. Finally, the PIM was used to remediate CIP in real environmental samples (river water and wastewater). From an initial concentration of 200 ng/L, it was reduced to 1.8 ng/L in river water and 2.2 ng/L in wastewater which is 99.1% and 98.9 % removal, respectively. Thus, PIM could be considered a suitable alternative for the removal of CIP in the aquatic environment. • Removal of CIP using polymer inclusion membranes (PIMs) was demonstrated. • Effects of different carriers, pH, feed and stripping solutions were investigated. • The removal efficiencies of the prepared PIMs are within 60%–99%. • The PIMs were used to remediate CIP in real samples, 98%–99% removals were achieved. • It may be used for the removal other recalcitrant antibiotics such as levofloxacin.

Tunable Multi-Phase System for Highly Chemo-Selective Oxidation of Hydroxymethyl-Furfural.

Three different multiphase systems (MP 1-3) comprised of two immiscible liquids, with or without an ionic liquid (IL: methyltrioctyl ammonium chloride), were investigated for the oxidation of 5-hydroxymethyl-furfural (HMF) over 5 % Ru/C as a catalyst and air (8 bar) as an oxidant. These conditions proved versatile for an excellent control of the reaction selectivity to 4 distinct products derived from full or partial oxidation of the carbonyl and alcohol functions of HMF, and each one achieved in 87-96 % isolated yield at complete conversion. MP1 based on water and isooctane, yielded 2,5-furandicarboxylic acid (FDCA, 91 % yield). In MP2, obtained by adding the IL to MP1, the oxidation proceeded towards the formation of 5-formyl-2-furancarboxylic acid (FFCA, 87-89 % yield). MP2 also proved successful in the design of a one pot-two step oxidation/reduction sequence to prepare 5-hydroxymethyl-2-furancarboxylic acid (HMFCA, 85 % yield). In MP3, the use of an acetonitrile/cyclooctane biphase yielded 2,5-diformylfuran (DFF, 96 % yield). All the multiphase systems MP 1-3 allowed a perfect segregation of the catalyst in a single phase (either the hydrocarbon or the IL) distinct from the one containing HMF and its oxidation products. This was crucial not only for the catalyst/product separation but also for the recycle of Ru/C that was possible under all the tested conditions. Accordingly, MP-reaction were run in a semicontinuous mode without removing the catalyst from the reactor nor resorting to conventional separation and activation techniques. Negligible Ru leaching, less than 0.96 ppb, was measured in all cases.

Vanadium recovery by electrodialysis using polymer inclusion membranes

Industrial applications and environmental awareness recently prompted vanadium recovery spell from secondary resources. In this work, a polymer inclusion membrane containing trioctylmethylammonium chloride as carrier was successfully employed in electrodialysis for vanadium recovery from acidic sulfate solutions. The permeability coefficient of V(V) increased from 0.29 µm·s-1 (without electric field) to 4.10 µm·s-1 (with the 20 mA·cm-2 current density). The transport performance of VO2SO4-, which was the predominant species containing V(V) in the acidic region (pH <3), was influenced by the aqueous pH value and sulfate concentration. Under an electric field, a low concentrated H2SO4 solution (0.2 M) effectively stripped V(V) from the membranes, avoiding the requirement of a highly concentrated H2SO4 without electric field. Under the optimum conditions, the permeability coefficient and flux reached 6.80 µm·s-1 and 13.34 µmol·m-2·s-1, respectively. High selectivity was observed for the separation of V(V) and Mo(VI) from mixed solutions of Co (II), Ni (II), Mn (II), and Al (III). Additionally, the separation between Mo(VI) and V(V) was further improved by adjusting the acidity of the stripping solution. The V(V) selectivity for the resulting membrane was higher than that of commercial anion exchange membranes.

Influence of Membrane Type on Some Electrical Properties of a Single Microbial Fuel Cell

The effects of different parameters on the electric output of air-cathode microbial fuel cells were investigated in this work. The single microbial fuel cell was equipped by modifying Proton Exchange Membranes (PEM). Two membrane types were prepared: first by using the combination of Poly Vinyl Alcohol (PVA) with Polystyrene Sulfonate (PSSNa), while the second membrane was elaborated by mixing Poly Vinyl Chloride (PVC) with Methyl Tri-Octyl Ammonium (MTOA) chloride. The PEMs were incorporated into the air-cathode to form a Membrane Electrode Assembly (MEA) to promote electricity generation. PVA/PSSNa and PVC-MTOA membranes were synthesized by solution casting method. Fourier Transform Infrared Spectroscopy (FTIR), Ultraviolet (UV) Visible spectroscopy, Scanning Electronique Microscope (SEM), Differential Scanning Calorimetry (DSC), and water Contact Angle (CA) were used as characterization techniques to explore the membrane structure and properties. The performance and the electric capacity of the microbial fuel cell in real time were operated using an external resistance of 5kΩ. Impedance and resistance capacity were determined using the polarization method. It was found that the internal resistance of the PVA/PSSNa and PVC-MTOA membranes were 50 and 350Ω respectively. The voltage values at open circuit of the cells using PVA/PSSNa and PVC-MTOA membranes were 600mV and 150mV respectively. The values of power, current, and power density, are quite interesting. Cells with PVA/PSSNa and PVC-MTOA membranes gave values of 18.24 and 9.64mW.cm-2 respectively.

Removal of Methylene Blue Dye from Waste Water Using Ionic Liquid Modified Aluminium Isopropoxide under Ultrasonic Irradiations

In this paper, Methyltrioctylammonium Chloride modified Aluminiumisopropoxide researched asadsorbent for the removal of Methylene Blue (MB) dye from waste water through a novel and efficientadsorption process under ultrasonication. Ultrasonic irradiations remarkably boosted the adsorption ratecomparative to conventional shaking while maintaining the same adsorption capacity. In addition, theeffects of initial MB concentration, Adsorbent dosage, pH, reaction time and temperature on the adsorptionwere studied. It was found that the isotherm data had a good correlation with the Langmuir isothermthrough analysing the experimental data by various models. The results showed thatMethyltrioctylammonium chloride modified Aluminiumisopropoxide was four times effective for theadsorption of MB dye under ultrasonication.

Ultrasound assisted approach for the desulfurization of model fuel using ionic liquid anchored carbon obtained from Prosopis juliflora

Carbon from the wood of Prosopis juliflora tree was oxidized and blended with minimal amount of activated charcoal and modified using trioctylmethylammonium chloride (Ionic liquid) for adsorptive removal of sulfur from the model fuel oil, Dibenzothiophene (DBT) in n-hexane. The oxidative desulfurization was performed by ultrasonication and the mechanism was ascertained by characterization of adsorbent material before and after adsorption using characterization techniques such as UV, FT-IR, SEM-EDX, XRD, XRF, XPS and TGA respectively. The porous morphology and specific surface area of the adsorbent was characterized using BET-N2 isotherm and the material was found to be mesoporous with specific area of 104.86 m2 g−1. The removal efficiency of 100 mg L−1 Dibenzothiophene under oxidized condition with 0.3 g of adsorbent dosage and ultrasound assistance for 60 min was found to be 99%. From the isotherm studies, kinetic models and thermodynamic parameters it was found that the adsorption process is endothermically favourable following pseudo-second-order kinetics. The regeneration of the carbonaceous adsorbent was achieved using n-pentane as the solvent.

Removal of perchlorate from aqueous solution using quaternary ammonium modified magnetic Mg/Al-layered double hydroxide

The magnetic and non-magnetic layered double hydroxide (LDH@Fe3O4 and LDH) were developed via simple co-precipitation method. After modified by methyltrioctylammonium chloride (N8881Cl), the absorption capability of the materials for inorganic pollutant perchlorate (ClO4-) improved obviously through ion exchange. Then the characteristics of studied materials were examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectronic spectroscopy (XPS) and Zeta potential measurements. The removal performance of ClO4- from water was investigated, and the effects of adsorption parameters on the efficiency were studied, such as contact time, initial concentration, pH and co-existing anions. The adsorption process was quite rapid and the removal rate could reach over 90% on N8881Cl-LDH@Fe3O4 within just 1 min. Maximum adsorption capacities were observed as 50.58 and 60.68 mg g−1 for N8881Cl-LDH and N8881Cl-LDH@Fe3O4 at 303 K. Moreover, the pH and common co-existing anions had little effects on adsorption capacity of ClO4-. It was found that the equilibrium adsorption process could be well described by pseudo-second-order kinetic model and Langmuir adsorption isotherm model. In brief, the N8881Cl-LDH@Fe3O4 synthesized in this study has the characters of low cost, mild conditions and easy operation, showing satisfactory absorption performance such as fast adsorption and low pH-dependence, which is potential on ClO4- removal from aqueous solution.

From liquid hot water pretreatment solution to lignin-based hydrophobic deep eutectic solvent for highly efficient extraction of Cr (VI)

Liquid hot water (LHW) pretreatment has been widely investigated attributed to its advantages, such as environmental friendliness, the potential application of dissolved hemicellulose, and no chemical addition. Expanding the portfolio of products that can be made from LHW pretreatment solutions will be critical to enabling a viable LHW-based economy. We provide a one-step method to separate and functionalize lignin from the LHW pretreatment solution. A hydrophobic deep eutectic solvent (hDES) was prepared by using methyltrioctylammonium chloride (MTAC) and the LHW pretreatment solution and directly applied to the extraction of Cr (VI) in an aqueous solution. In the process of forming hDES, the removal rate of liquid hot water lignin (LHWL) was reached 99%. The new LHW-hDES exhibited excellent extraction performance for Cr (VI), the extraction capacity was as high as 198.402 mg g−1, optimum extraction conditions at the mass of hDES 0.10 g, vortex time 90 s, room temperature, and natural pH. Notably, we have shown that the method of combining the separation and functionalization of lignin in the LHW pretreatment solution, which can provide a way of thinking for the application of the LHW pretreatment solution.

Greener Surfactant-Assisted Microextraction Method for the Determination of Fluoroquinolones in Chicken Livers by High-Performance Liquid Chromatography

A simple and environmentally friendly surfactant-assisted microextraction method combined with high-performance liquid chromatography fluorescence detection was developed for the determination of six fluoroquinolones in chicken livers. In the method, the analytes were transported into the hydrophobic extraction by ionic and nonionic surfactants. Three different surfactants were studied for this purpose, cationic Methyltrioctyl ammonium chloride (Aliquat 336), anionic sodium dodecyl sulfate (SDS), and nonionic trioctyl phosphine oxide (TOPO). Under optimum conditions, the limits of detection (LODs) and limits of quantification (LOQs) obtained using anionic surfactant ranged from 5 to 23 µg kg-1 and 15 to 78 µg kg-1 respectively. The LODs obtained from using cationic surfactant ranged from 9 to 21 µg kg-1 while the LOQs ranged from 31 to 71 µg kg-1. The LODs obtained from the method using nonionic surfactant ranged from 9 to 20 µg kg-1 and the LOQs ranged from 29 to 67 µg kg-1. Surfactant assisted-dispersive liquid liquid microextraction using SDS and Aliquat 336 were statistically compared and no significant statistical difference was observed between the two methods. The results obtained in this study indicate that the proposed method is cost-effective and environmentally friendly for the extraction and determination of fluoroquinolones in solid biological samples.

New Insights on the Effects of Water on Polymer Inclusion Membranes Containing Aliquat 336 Derivatives as Carriers.

Surface characterization of polymer inclusion membranes (PIMs) using the polymers cellulose triacetate and polyvinyl chloride, containing different ionic liquids (ILs) as carriers, has been performed. Three different ILs have been tested: commercial trioctyl methylammonium chloride (Aliquat 336–AlqCl−) and two derivatives bearing the counter anion NO3− or SCN− (AlqNO3 and AlqSCN, respectively). Surface analysis was performed by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) for both dry membranes and PIMs immersed for 4 days in ultrapure water to investigate the effect of the interaction of water with the membrane’s morphology and composition. XPS analysis of the PIMs revealed that immersion in ultrapure water causes a decrease in the atomic concentration percentage (A.C.%) of the specific IL atoms (Cl, S, and N) when compared with dry samples. Moreover, SEM images of the PIMs containing the IL AlqNO3 showed an alteration in the morphology of the membrane due to water contact at surface level, whereas no changes were observed at a bulk level. These changes in the surface composition of the water equilibrated PIMs may be associated with the solubilization of the IL in the water solution, which, therefore, may affect the reactivity of the membrane’s surface. To better understand this effect, PIMs containing both AlqCl and AlqNO3 as carriers were used for arsenic (V) transport. It was found that AlqCl was the most effective IL and that the effectivity of the PIM on As(V) removal was not affected after five cycles of the membrane’s reuse.

Fluoride removal from natural waters by polymer inclusion membranes

A polymer inclusion membrane (PIM) containing commercial ionic liquid methyltrioctylammonium chloride (Aliquat 336) as a carrier and cellulose triacetate (CTA) as a base polymer has been used for the first time to remove fluoride from natural waters. Due to the anion-exchange characteristics of the carrier, a 1 M NaCl solution has been used as a receiving phase. It has been found that the addition of tributyl phosphate (TBP) in the formulation of the PIM increased the membrane's performance. Several parameters have been investigated using a PIM made of 30% CTA, 50% Aliquat 336, and 20% TBP (% in mass) including the effect of other ions such as chloride and sulphate and the effect of pH. Only when the feed phase contains high amounts of chloride (concentration 10 times higher than fluoride) a slight decrease on PIM's efficiency is observed (85% defluoridation). The separation system developed here has been used satisfactorily for fluoride removal from different naturally occurring waters. Moreover, the membrane's reusability has also been investigated, showing that the membrane can be used for four cycles without loss of efficiency in removing fluoride.

Kinetic study on extraction of metal-cyanide complex ions by the N263-TBP system

In this study, the extraction of metal-cyanide complex ions in gold-leaching, cyanide-containing wastewater by a trioctylmethylammonium chloride (N263)-tributyl phosphate (TBP)-n-octanol-sulfonated kerosene system was investigated. The effects of N263 and TBP concentrations, the aqueous phase pH, and phase ratio (O/A) on the extraction were investigated by adopting the response surface methodology, and the operating parameters were optimized. The optimal solution was obtained by solving the model optimally. A Cu ion concentration of 3,000 mg/L, an N263 concentration of 0.459 mol/L, a TBP concentration of 0.214 mol/L, an initial pH of the aqueous phase of 10.064, and O/A of 0.900 were determined to be optimal for realizing an extraction yield of 99%. The effects of column height, oil droplet volume, metal ion concentration, N263 and TBP concentrations, and temperature on the mass transfer rate were investigated using the single droplet method. Kinetic studies showed that the kinetic equation for the extraction system was Rf (Mass transfer rate) = 1.57 × 10-4·CCu·CTBP·CN263. The apparent activation energy of Cu(I) was 15.186 kJ/mol. The extraction process was controlled by the diffusion process. Furthermore, the chemical reaction occurred at the two-phase interface, where the copper cyanide complex ions preferentially bound to TBP at the interface between the two phases, and the bound anion cluster then reacted with the N263 cation to form the extractive complex, which then entered the organic phase from the interface.

Tailoring hydrophobic deep eutectic solvent for selective lithium recovery from dilute aqueous solutions

• A green system can efficiently extract Li + in extremely dilute aqueous solutions. • A deep eutectic solvent and organic phosphoric acid system was proposed. • The effect of operating conditions on the efficiency of Li + extraction was studied. • It can selectively extract Li + from mixed ion solutions with high Na + content. • The extraction system can realize stable recycling. The efficient recovery of lithium-ion (Li + ) from seawater is expected to be a promising solution to the shortage of lithium resources. This work demonstrated an application of a hydrophobic deep eutectic solvent (HDES) based system for Li + recovery from dilute aqueous solutions (≤1 ppm). Methyltrioctyl ammonium chloride (N 8881 Cl) and decanoic acid (DecA) with a molar ratio of 1:2 were used as the extractant and bis(2-ethylhexyl) phosphate (DEHPA) as the co-extractant. N 8881 Cl/2DecA-DEHPA showed the highest extraction efficiency (80%) in a single extraction with the initial pH of the aqueous phase, the volume ratio of organic to the aqueous phase (O/A), and the volume fraction of HDES to be 11.10, 1/3 and 50%, respectively. FTIR analysis revealed the existence of cation exchange between Li + and DEHPA. A total of ten regeneration cycles of extraction processes demonstrated that the extraction system was stable for selective extraction of Li + . The separation factor of Li/Na (β Li/Na ) in the mixed ion solution was 9.76, indicating that the N 8881 Cl/2DecA-DEHPA system has the capability to selectively extract Li + with a high Li/Na ratio. This will help design possible green HDES for lithium recovery from dilute aqueous solutions, e.g., raw and concentrated seawater.

Green synthesis of benzaldehydes by the selective oxidation o benzyl alcohols using hexacyanoferrate (III) and bromate under phase transfer catalysis

The selective oxidation of benzyl alcohols and substituted benzyl alcohols was carried out in greener solvents like ethyl acetate and toluene by hexacyanoferrate (III) and bromate ions under phase transfer catalysis. Various phase transfer catalysts like tetrabutylphosphonium bromide, tetrabutylammonium bromide, tetrabutylammonium hydrogen sulphate, cetyltrimethylammonium bromide and tricaprylmethylmmonium chloride were used. A pinch of sodium tungstate dihydrate is added as a co-catalyst when bromate is used an oxidant and hexacyanoferrate (III) is used in presence of mineral acids. The products obtained were precipitated as their 2,4- dinitrophenylhydrazone, purified, weighed and the yield was found to be &gt; 90 %. The products were recrystallized in ethanol and analyzed by melting point and by various spectral techniques. It was proved that corresponding benzaldehydes were formed and there was no further oxidation to corresponding acids. All the catalysts were found effective in bringing out the reaction but based on yield and ease of reaction, the order of reactivity is tricaprylmethylammonium chloride &gt; tetrabutylphosphonium bromide &gt; tetrabutylammonium bromide &gt; tetrabutylammonium hydrogen sulphate &gt; cetyltrimethylammonium bromide. The selective oxidation of benzyl alcohols is very difficult to proceed in organic solvents without the aid of a phase transfer catalyst. Yield of products is found to be slightly more in ethyl acetate than that in toluene due to difference in polarity.

Removal of lead ions using OA-Fe3O4 magnetic nanoparticles-based pickering emulsion liquid membrane: process optimization using box–behnken response surface methodology

ABSTRACT The purpose of this study is to explore the pickering emulsion liquid membrane (PELM) performance for removing divalent lead ions (Pb II) from aqueous solution. In the present work, the membrane phase was prepared by dissolving methyltrioctylammonium chloride (Aliquat 336) with Mahua oil and adding oleic acid coated-ferrosoferric oxide (OA-Fe3O4) as magnetic nanoparticles. Experimental investigation on percentage removal of lead ions was carried out by studying the influencing process parameters such as pH, agitation speed, stripping concentration, initial feed concentration, surfactant concentration, treat ratio, M/S ratio and carrier concentration. The optimum condition to remove 98.52% of lead ions from the feed solutions has achieved at a stripping phase concentration of 0.3 M, treat ratio of 3, agitation speed of 300 rpm, initial feed concentration of 10 ppm and stabilizer concentration of 2 wt%. The experimental results were validated using box–behnken response surface methodology. The extraction ability of OA-Fe3O4 magnetic nanoparticles-based PELM has been evaluated using statistical optimization of all the affecting process factors using the design of the experiments.

Treatment of cyanide-bearing wastewater by the N263-TBP synergistic extraction system

In this study, a trioctylmethylammonium chloride (N263)- tributyl phosphate (TBP)-n-octanol-sulfonated kerosene (N263-T) synergistic extraction system and an N263-n-octanol-sulfonated kerosene (N263–O) system were used to treat cyanide (CN)-bearing wastewater. The extraction saturation capacity of the two systems was measured. The influences of the initial pH and phase ratio (O/A) of the two systems on extraction were compared and analyzed. Fourier transform infrared (FTIR) spectroscopy, ultraviolet–visible (UV–Vis) spectroscopy, and slope methods were used to analyze the characteristic functional groups in the loaded organic phase, the compositions of the extracted compounds in the extraction reactions and the reaction mechanism. The results indicated that the saturated extraction capacity of the N263-T system, which was much larger than that of the N263–O system, for metal CN complex ions was 4354.31 mg/L. In addition, the N263-T system operated over a wider pH range. The extraction rates of copper (Cu), zinc (Zn), and iron (Fe) ions at pH 14 were 97.4%, 99.1%, and 87.2%, respectively. There was a strong compatibilization effect of TBP on the extraction system. The extraction efficiency of the N263-T system for metal CN complex ions was higher than that of the N263–O system when O/A = 0.4. The saturated loaded N263-T and N263–O systems were stripped by 1 mol/L NaOH +2 mol/L NaSCN solution at O/A = 3. The metal ion concentration in the stripping solution could be enriched to 11996.6 and 8913.3 mg/L for the N263-T and N263–O systems, respectively. During the extraction process, the binding ratios of N263 cations to Cu(CN)32−, Zn(CN)42−, and Fe(CN)63− were 2:1, 2:1, and 3:1, respectively. The binding ratios of TBP to Cu(CN)32−, Zn(CN)42−, and Fe(CN)63− in wastewater were 3:1, 4:1, and 6:1, respectively. The PO group in TBP was linked to the CN group of the metal CN complex ion by hydrogen bonds using the water molecule as a bridge to form a supramolecular anion group, which entered into the organic phase and combined with the N263 cation under the action of ion association.

Study of Asphaltene Deposition in the Presence of a Hydrophobic Deep Eutectic Solvent Using XDLVO Theory

This study aims to theoretically investigate the performance of an ionic liquid-based hydrophobic deep eutectic solvent (HDES), methyltrioctylammonium chloride:glycerol (1:2), as an asphaltene depo...