Removal of Tannic Acid From Aqueous Solution by Cloud Point Extraction and Investigation of Surfactant Regeneration by Microemulsion Extraction

The aim of this work is the extraction of tannic acid (TA) with two commercial nonionic surfactants, separately: Lutensol ON 30 and Triton X‐114 (TX‐114).The experimental cloud point extraction results are expressed by four responses to surfactant concentration and temperature variations: extent of TA extraction (E), remaining solute (X_s,w) and surfactant (X_t,w) concentrations in dilute phase and volume fraction of coacervate (Φ_c) at equilibrium. An empirical smoothing method was used and the results are represented on three dimensional plots. In optimal conditions, the extraction extent of TA reaches 95 and 87 % using TX‐114 and Lutensol ON 30, respectively. Sodium sulfate, cetyltrimethylammonium bromide (CTAB) addition and pH effect are also studied. Finally, the possibility of recycling of the surfactant is proved.     

添加剂对非离子表面活性剂浊点的影响

研究了十二烷苯磺酸钠（LAS）、正丁醇、仲丁威对非离子表面活性剂TX－10浊点的影响。LAS与TX－10形成混合胶束，使TX－10增溶能力提高，浊点也提高；正丁醇对其影响比较复杂，少量正丁醇对浊点没有影响，当正丁醇量较大时，使单独TX－10体系浊点降低，使混合体系浊点略有升高；仲丁威使其浊点下降。正丁醇、仲丁威对TX－10浊点的影响与它们在胶束中的增溶位置有关。     

非离子表面活性剂TX114浊点萃取D2EHPA的规律

引言浊点萃取[1-2]是利用表面活性剂水溶液的增溶和分相行为实现溶质富集的分离技术。由于分相后表面活性剂的富集相(亦称凝聚相)与水相的体积比非常小(0.007～0.04)[3],所以,对于被增溶的物质能够提供非常高的富集倍数和萃取效率。目前浊点萃取技术主要广泛应用于痕量有害物质     

Cloud Point Extraction of Nitrobenzene using TX-100

Cloud point extraction (CPE) is carried out to extract nitrobenzene (NB) from aqueous solution using TX-100 as a nonionic surfactant. The effects of different operating parameters, like concentration of the feed mixture (both NB and surfactant), pH, temperature, and the presence of mono- and di-valent salts on the extraction of both the NB and surfactant have been studied in detail. The solubilization behavior of the NB in the surfactant micelle has been observed in the temperature range of 75°C to 90°C. Concentrations of surfactant and NB have been considered in the range of 0.03 M to 0.25 M and 100 mg/L to 400 mg/L, respectively. An optimum set of surfactant concentration, temperature, and salt concentration is obtained for the removal of NB from aqueous medium. The effects of temperature and concentrations of surfactants and NB on various thermodynamic parameters, like change in Gibbs-free energy (ΔG ⁰), change in enthalpy (ΔH ⁰), and change in entropy (ΔS ⁰) are observed and explained well. Experimental investigations have also been carried out for the recovery of the surfactant from the dilute phase applying solvent extraction (SE) in batch condition using heptane and hexane as the extracting medium.     

Cloud Point Extraction and Separation of Scandium and Yttrium (III) with Triton X‐114 in the Presence or Absence 8‐Hydroquiloline as an Added Chelate

Abstract

In this paper, the cloud point extraction and separation of scandium and yttrium (III) via use of Triton X‐114 with and without 8‐hydroquiloline (HQ) as an added chelate agent are investigated. The effects of various parameters, such as the aqueous phase pH, HQ concentration, Triton X‐114 concentration, heating temperature, and incubation time, on the cloud point extraction of scandium and yttrium (III) are studied. The results demonstrate that, there are different extraction and separation behaviors for scandium and yttrium (III) with and without HQ as an added chelate. And in contrast to solvent extraction, cloud point extraction is an excellent method to extract and separate scandium and yttrium (III).     

有机硅表面活性剂对水体中多环芳烃的浊点萃取研究

Cloud point extraction （CPE） processes with two silicone surfactants, Dow Coming DC-190 and DC-193, were studied as preconcentration and treatment for the water polluted by three trace polycyclic aromatic hydrocarbons （PAHs）： anthracene, phenanthrene and pyrene. For all cases, the volumes of surfactant-rich phase obtained by two silicone surfactants were very small, i.e. a lower water content in the surfactant-rich phase was obtained. For example, less than 3% of the initial solution was obtained in a 1% （by mass） surfactant solution, which was much smaller than that of TX-114 in the same surfactant concentration. And TX-114 is known as a high compact surfactant-rich phase among most nonionic surfactants, thus the comparison showed that an excellent enrichment was ensured in the analysis application by the CPE process with the silicone surfactants, and the lower water content obtained in the surfactant-rich phase is also important in the large scale water treatment. The influences of additives and phase separation methodology on the recovery of PAHs were discussed. Comparing with DC-193, DC-190 has a lower cloud point and a higher recovery （near 100%） of all the three PAHs in same surfactant concentration, which was required for application as a preconcentration process prior to HPLC system. However the DC-190 solution is hard to be phase separated only by heating, whereas DC-193 has a relative higher phase separating speed by heating, but a high cloud point （around 360K） limits its application. Due to the phase separation by heating is the only method of CPE suitable to the large scale water treatment, the mixtures of two silicone surfacrants solutions were investigated in this study. A solution containing 1% of mixed DC-190 and DC-193 （in the ratio of 90 ： 10） removed anthracene, phenanthrene and pyrene near 100% with a relative low cloud point and quick phase separating speed.     

Removal of cationic dyes from aqueous solutions by kaolin: Kinetic and equilibrium studies

Experimental investigations were carried out using commercially available kaolin to adsorb two different toxic cationic dyes namely crystal violet and brilliant green from aqueous medium. Kaolin was characterized by performing particle size distribution, BET surface area measurement and XRD analysis. The effects of initial dye concentration, contact time, adsorbent dose, stirring speed, pH, salt concentration and temperature were studied in batch mode. The extent of adsorption was strongly dependent on pH of solution. Free energy of adsorption (ΔG⁰), enthalpy (ΔH⁰) and entropy (ΔS⁰) changes were calculated. Adsorption kinetic was verified by pseudo-first-order, pseudo-second-order and intra-particle-diffusion models. The rate of adsorption of both crystal violet and brilliant green followed the pseudo-second-order model for the dye concentrations studied in the present case. The dye adsorption process was found to be external mass transfer controlled at earlier stage and intra-particle diffusion controlled at later stage. Calculated external mass transfer coefficient showed that crystal violet dye adsorbed faster than brilliant green on kaolin. Adsorption of crystal violet and brilliant green on kaolin followed the Langmuir adsorption isotherm.     

Cloud Point Extraction of Orange II and Orange G Using Neutral and Mixed Micelles: Comparative Approach Using Experimental Design

The aim of this work was to compare two synthetic dyes, Orange G (7-Hydroxy-8-(phenylazo)-1,3-naphthalenedisulfonic acid, disodium salt) and Orange II (p-(2-Hydroxy-1-naphthylazo) benzenesulfonic acid, sodium salt), towards cloud point extraction from colored water. Three commercial non-ionic surfactants were used in this work: Oxo-C₁₅E₇, Oxo-C₁₀E₃, and Triton X-100. The experimental extraction results were expressed by the following three responses: percentage of the extracted dye (E), residual concentrations of dye in the dilute phase (X_s,w), and the volume fraction of coacervate (?_C) at the equilibrium. The results obtained for each parameter were represented on three dimensional diagrams using an empirical smoothing method. In optimal conditions Orange II concentration in the effluent was reduced to about 227 times, whereas E did not exceed 55% using Oxo-C₁₅E₇ in the case of Orange G extraction. However, when a small amount (0.025 wt.%) of cetyltrimethylammonium bromide (CTAB) was combined with Oxo-C₁₀E₃ as a mixed micelles system, the results showed that the extraction percentage of Orange G increased from 55 to 98%. Indeed, the concentration of this dye in the effluent was reduced to about 400 times. Finally, the extraction extent of both dyes was found to be low at basic pH, which may be useful for surfactant regeneration.     

Separation of Neutral Red and Methylene Blue from Wastewater using Two Aqueous Phase Extraction Methods

Abstract

The aim of this work was the two‐aqueous phase extraction of neutral red and methylene blue from wastewater. This has been achieved on the basis of phase separation properties of non‐ionic surfactants above the so‐called cloud point curve and the solubilization phenomena of coacervate micelles (surfactant rich phase). Three commercial surfactants were used in this work; the Oxo‐C₁₅E₇ which is an ethoxylate fatty alcohol (Dehydol LT 7), Triton X‐114 (iso‐C₈H₁₇‐C₆H₄‐(OCH₂CH₂)_7,5OH), and Triton X‐100 (iso‐C₈H₁₇‐C₆H₄‐(OCH₂CH₂)_9,5OH) which are alkyl phenol ethoxylate surfactants. The phase diagrams of binary water/surfactants systems were drawn and the effect of sodium sulphate on water‐surfactant systems was therefore studied. Oxo‐C₁₅E₇ and Triton X‐114 were used for the cloud point extraction of neutral red and methylene blue from their aqueous solutions at 100 mg/L and 7 mg/L, respectively. The experimental extraction results were expressed by the following three responses: percentage of the extracted dye (E), residual concentrations of dye in the dilute phase (X_s,w), and the volume fraction of coacervate (φ_C) at the equilibrium. The results obtained for each parameter were also represented on three‐dimensional diagrams using an empirical smoothing method. The empirical modelling data were in agreement with the experimental ones. The main advantage was sought between E, which has reached 99% in the case of neutral red, whereas in the case of mehtylene blue 92% was obtained with respect to (φ_C), which should have a minimum value. At the optimal conditions, neutral red and methylene blue concentrations in the effluent were reduced to about 500 times and 7 times, respectively.     

Metachromic interactions between azo and triphenylmethane dyes in aqueous solution

Interactions between dilute aqueous solutions of the triphenylmethane dye Crystal Violet and the disazo dyes Brilliant Orange or Brilliant Yellow at room temperature produce strong metachromic absorptions at 494 nm which are absent from the spectra of either component alone. The addition of acetone, ethanol or methanol to these solutions or raising their temperature reverses the interaction. It is suggested that these observations are consistent with a strong interaction occurring between adjacent molecules of crystal violet which are held together in a specific orientation by interacting with a stereoregular network of disazo dyes held together by hydrogen bonding.     

Extraction and recovery of rhodamine B,methyl violet and methylene blue from industrial wastewater using D2EHPA as an extractant

The extraction behavior of cationic dyes namely rhodamine B (RB), methyl violet (MV) and methylene blue (MB) from industrial wastewater has been investigated using di-(2-ethylhexyl) phosphoric acid (D2EHPA) in hexane as a carrier. The extraction of cationic dyes increases with decreasing feed phase pH and increasing D2EHPA concentration in organic phase. The stripping percentage of dyes using acetic acid as the stripping agent from loaded D2EHPA was found to increase with increasing acid concentration. 98% stripping efficiency of dyes was achieved with 8.5 mol/L acetic acid solution at an organic:aqueous phase ratio (O/A) of 2:1. Parameters examined include D2EHPA concentration, effect of diluents, effect of pH, effect of initial dye concentration, equilibration time, and various stripping agents, aqueous to organic phase ratio in extraction and organic to aqueous phase ratio in stripping.     

高铁酸钾氧化脱色三苯甲烷染料废水

采用高铁酸钾对水溶性三苯甲烷染料结晶紫和碱性品红废水进行氧化脱色研究。考察了高铁酸钾投加量、反应温度和染料浓度对脱色率的影响。结果表明,高铁酸钾能够有效去除染料废水中的色度,投加量和反应温度均存在最佳值。当结晶紫和碱性品红废水的质量浓度低于50mg/L时,脱色率几乎不受染料浓度的影响。2种三苯甲烷染料相比较,碱性品红比结晶紫更容易被氧化降解。     

Removal of Copper(II) from a Concentrated Sulphate Medium by Cloud Point Extraction Using an N,N′-Bis(salicylaldehyde)Ethylenediimine Di-Schiff Base Chelating Ligand

Various chelating ligands have been investigated for the cloud point extraction of several metal ions. However, limited studies on the use of the Schiff base ligands have been reported. In this work, cloud point extraction behavior of copper(II) with N,N′‐bis(salicylaldehyde)Ethylenediimine Schiff base chelating ligand, (H₂SALEN), was investigated in aqueous concentrated sulphate medium. The extraction process used is based on the formation of hydrophobic H₂SALEN–copper(II) complexes that are solubilized in the micellar phase of a non‐ionic surfactant, i.e. ethoxylated (9.5EO) tert‐butylphenol. The copper(II) complexes are then extracted into the surfactant‐rich phase above cloud point temperature. Different parameters affecting the extraction process of Cu(II), such as equilibrium pH, extractant concentration, and non‐ionic surfactant concentration were explored. The extraction of Cu(II) was studied in the pH range of 2–11. The results obtained showed that it was profoundly influenced by the pH of the aqueous medium. The concentration factor, C_f, of about 17 with extraction efficiency of E % ≈100 was achieved. The stoichiometry of the extracted complex of copper(II) was ascertained by the Yoe–Jones method to give a composition of 1:1 (Cu:H₂L). The optimum conditions of the extraction‐removal have been established as the following: (1) 1.86 × 10^?3 mol/L ligand; (2) 3 wt% surfactant; (3) pH of 8 (4) 0.5 mol/L Na₂SO₄ and (5) temperature of 60 °C.     

Temperature‐induced surfactant‐ mediated pre‐concentration of uranium assisted by complexation

Cloud‐point extraction (CPE) was used with lipophilic chelating agent to extract uranium(VI) from aqueous solutions. The methodology used is based on the formation of metal complexes soluble in a micellar phase of a non‐ionic surfactant, Triton X‐114. The metal ions complexes are then extracted into the surfactant‐rich phase at a temperature above the cloud‐point temperature. The influence of surfactant concentration on extraction efficiency was studied and the advantage of adding 8‐hydroxyquinoline (8HQ) as lipophilic chelating agent was evidenced. High extraction efficiency was observed, indicating the feasibility of extracting U(VI) using CPE. This study describes a four‐step process—(1) extraction, (2) thermo‐induced phase splitting, (3) back‐extraction and (4) second phase splitting—for the recovery of uranium from water. In our conditions, the extraction yield is quantitative and the concentration factor obtained is superior to 100. After stripping with a diluted nitric acid solution (pH < 1), the system can be recycled through a new four‐step cycle. Copyright © 2006 Society of Chemical Industry     

The photochemistry of triphenylmethane dyes in films of poly(methylmethacrylate)

Photobleaching of the halides of the triphenylmethane dyes crystal violet and malachite green in thin films of poly(methylmethacrylate) is described. The reaction proceeds via the triplet excited state of the dye which undergoes an intramolecular electron transfer reaction, forming the triarylmethyl and halogen free radicals. Quantum yields of triplet formation depend on the concentration of the dye which suggests that the intersystem crossing process involves more than one dye molecule. The rate of reaction depends on the rate at which radicals are formed which are free of the solvent cage and on the reactivity of the radicals.     

An economic and sensitive method for extracting chromium speciation in airborne inhalable dust,using a green sample treatment coupled with electrothermal atomic absorption

ABSTRACT

A new approach of cloud point extraction CPE procedure is optimized for hexavalent chromium determination in airborne dusts. Triton X-114 is used as a surfactant and 1-(2-pyridylazo)-2-naphthol as a specific complexing agent for the trivalent chromium’s removal from the aqueous phase to isolate hexavalent chromium compounds. The parameters influencing the extraction protocol (pH, surfactant concentration, and temperature are optimized. The obtained detection and quantification limits are 0.1 and 0.4 μg/L, respectively. The linearity is verified, with a regression coefficient close to 0.999 and the extraction recovery exceeds 99%. The method was successfully applied to analyze airborne samples collected from workplaces.     

Sodium Alkyl Ether Sulfonates (SAES): Dual Anionic‐Nonionic Behavior in Synthetic Brine Having High Salinity and Hardness

Due to the presence of non‐sulfonated residual alkyl ether (AE), sodium alkyl ether sulfonate (SAES) may exhibit clear point‐cloud point solubilization behavior in brine. Accordingly, the effect of temperature on the compatibility of iC17EOxS (x = 7 and 10), nC₁₇EO10S, along with their analogous nonionic surfactants iC₁₇EOxH (x = 7 and 10) and nC17EO10, in addition to iC9EO14 in brine has been investigated. Depending on their molecular structures, these surfactants exhibited concentration‐dependent clear point and cloud point solubilization behavior. The cloud point was associated with the AE component whereas the clear point was attributed to the sulfonated one. Interestingly, an increase in the cloud point of the nonionic component with respect to the corresponding nonionic AE (100 % active) was observed. Adding iC9EO14 (100 % active) to iC17EO7S (x_an = 0.0–0.362) resulted in a significant decrease in the clear point of iC17EO7S from above 100 °C to below 22 °C with a concomitant increase in iC17EO7/iC9EO14 mixture cloud point from 68 °C. (x_an = 0) to 72 °C (x_an = 0.325). This relatively modest increase by 4 °C was attributed to the interrelationship of different competitive mechanisms, namely an increase in mixed micelle charge with increasing x_an, the dehydration of OE groups via ion (SO₃^?)‐dipole (O → CH₂) interactions, and possible shielding of SO₃^? groups by iC9EO14 nearby extended EO groups. To the best of our knowledge, this is the first instance where dual anionic‐nonionic solubilization behavior of SAES in brine characterized by high salinity and hardness is being reported.     

Cloud Point Extraction and Spectrophotometric Determination of Sulfide in Water Samples using Ethylene Blue Formation Reaction

Abstract

A rapid, selective, and sensitive cloud point extraction process using mixed micelle of a nonionic surfactant, Triton X-114, and an anionic surfactant, SDS, to extract sulfide from aqueous solutions was investigated. The method is based on the color reaction of sulfide with N,N-diethyl-p-phenylenediamine (DPD) in the presence of suitable oxidizing reagent (Fe³⁺) in acid media and cloud point extraction of ethylene blue (EB) dye. Various factors and optimal extraction and reaction conditions like: acid, Fe³⁺, reagent, and surfactant concentration were studied and the analytical characteristics of the method (e.g., limit of detection, linear range, RSD%) were obtained. Linearity was obeyed in the range of 1–100 ng mL^?1 of sulfide ion. The detection limit of the method is 0.5 ng mL^?1 of sulfide ion. The interference effect of some anions, cations, and neutral species was also tested. The method was applied to the determination of sulfide in spring, river, and waste water samples.     

Nonionic surfactants induced cloud point extraction of Polyhydroxyalkanoate from Cupriavidus necator

Polyhydroxyalkanoate synthesized by Cupriavidus necator DSM 428 was purified from the crude fermentation broth as such by performing nonionic surfactants (Triton X100, Triton X114 & Tergitol 6) induced cloud point extraction. Polyhydroxyalkanoate was extracted into the micelle-rich bottom phase (coacervate phase), while most of the cellular impurities partitioned into the aqueous phase. Cloud point temperatures and the extraction efficiency of different cloud point systems were studied at different pH value and in the presence of additives. Maximum extraction of biopolymer was achieved (recovery of 84.4%) with a purity of 92.49% at 3 pH with the addition of 0.1 M ammonium chloride in the mixed surfactant system at a reduced cloud point temperature of 33°C.     

Cloud point extraction of 2,4−dichlorophenol from aqueous samples employing β−cyclodextrin

In this study, β?cyclodextrin (β?CD) was used to enhance the extraction of 2,4?dichlorophenol (2,4?DCP) from the aqueous sample in cloud point extraction (CPE) using spectrophotometric method. Several parameters have been investigated with and without the presence of β?CD modifier, such as pH, equilibration temperature, analyte concentration, and water content in the CPE and CPE?βCD systems, respectively. Equilibrium data are described by the Langmuir isotherm in both CPE systems with and without β?CD modifier. The thermodynamic parameters (positive values of ΔH° and ΔS°, negative values of ΔG°) indicate that the solubilization of 2,4?DCP in a polyethylene glycol silicone surfactant (DC193C) is endothermic, entropy gained, and spontaneous in both systems. In the CPE?βCD system, the results show that the β?CD modifier is capable of enhancing the extraction of 2,4?DCP pollutant from aqueous samples.