Extraction of metal–dye ion-association complexes by thin ether-type polyurethane membranes

The extraction and transport of various gold(III) chloride–organic dye ion-association complexes in aqueous solution through thin ether-type polyurethane membranes have been studied. The effects of the presence of salt, acid, different starting and receiving solution compositions, and temperature on the sorption process were investigated. Methylene Blue, Rhodamine B and Brilliant Green, which represent organic dyes from the thiazine, xanthene, and triphenylmethane groups, respectively, were used for this study. Gold(III) chloride and the individual organic dyes were extracted and transported through the membrane only if the solution conditions favored the formation of a neutral species. The ion-association complexes of gold(III) chloride with Methylene Blue and Rhodamine B were extracted and transported by the polymer only when the formation of the complex was more efficient than the individual extraction and transport of each of the species. The extraction of Brilliant Green under all conditions studied was very high, however, no transport occurred. The overall sorption of this dye was found to be independent of the presence of gold regardless of solution composition. High temperature resulted in a very high rate of transport of the gold(III) chloride–organic dye ion-pair.     

An investigation into the sorption of benzoic acids by polyurethane membrane

The extraction mechanism of organic compounds by ether- and ester-type polyurethane membrane has been investigated through a detailed study of sorption of monobromobenzoic acids. The effects of solution concentration, extraction time, surface area, pH, salts, and temperature on extraction were studied. It was found that monobromobenzoic acids are extracted in their neutral form, and that the extraction is controlled primarily by the relative strength of intra- and intermolecular hydrogen bonding. The ether-type polyurethane membrane allows a more efficient removal of monobromobenzoic acids from solution than the ester-type membrane. The extraction of benzoic acids with the ether-type membrane decreases as the temperature increases. When the ester-type polyurethane membrane is used, an extraction maximum is observed at room temperature with a decrease in extraction at lower and higher temperatures.     

Extraction of phenols using polyurethane membrane

The extraction of various phenols from aqueous and organic solutions using polyurethane membrane has been investigated. The effects of solution concentration, extraction time, surface area, pH, salts, and temperature on extraction were studied. The phenols are extracted as neutral species and the extraction is governed by a combined effect of intra- and intermolecular hydrogen bonding and nonspecific hydrophobic interactions. The ether-type membrane showed higher extraction capability for the phenols than the ester-type polyurethane membrane.     

Extraction of azo dyes by polyurethane foam

The extraction of 12 closely related mono-azo dyes by polyester and polyether-type polyurethane foams was studied to gain more information regarding the mechanism of the extraction of organic compounds. The effects on extraction of solution pH, dye concentration and salt concentration were investigated. It was found that the extraction of the dyes involved a neutral zwitterionic species and is highly dependent on the parameters studied. The dependency of the extraction on these parameters can be explained in a manner consistent with solvent extraction; however, the dual-mode sorption mechanism seems a more likely model. This mechanism involves both absorption related to solvent extraction, and an added component for surface adsorption. While the dual-mode sorption model explains the observed extraction behaviour, the data suggest that surface adsorption plays a much larger role than previously considered.     

Interactions of organic halides with a polyurethane elastomer

Interactions of halogen-substituted organic penetrants have been studied with a polyurethane membrane over the temperature interval of 25-60°C. Transport parameters such as diffusivity, solubility, and permeability have been measured. A temperature dependence of these quantities has been used to predict activation parameters for the transport mechanism. Equilibrium sorption data were used to estimate the entropy and Gibbs energy for the sorption process by using the Van't Hoff relationship. Furthermore, a phenomenological treatment has been suggested to estimate the classical Flory-Huggins interaction parameter for polyurethane-solvent pairs. These data were used to calculate the molar mass between crosslinks of the polyurethane network. For all the penetrants, the transport mechanism was found to be anomalous.     

聚二苯基乙炔耐溶剂纳滤膜的制备与性能

聚二苯基乙炔(PDPA)不溶于有机溶剂,是理想的新型耐溶剂纳滤膜材料。采用溶液浇铸法制备聚[1-(4-三甲基硅基)苯基-2-苯乙炔](PTMSDPA)均质膜,经脱硅反应得到PDPA膜,研究其乙醇渗透性能和染料截留性能。结果表明,乙醇渗透通量与压力呈正相关性,传质机理可能介于孔流机理和溶解扩散机理之间的过渡区。染料的分子尺寸、电荷性质以及染料和膜之间的相互作用共同影响PDPA膜的截留性能。     

Adsorption of Safranin-T from wastewater using waste materials- activated carbon and activated rice husks

Textile effluents are major industrial polluters because of high color content, about 15% unfixed dyes and salts. The present paper is aimed to investigate and develop cheap adsorption methods for color removal from wastewater using waste materials activated carbon and activated rice husk-as adsorbents. The method was employed for the removal of Safranin-T and the influence of various factors such as adsorbent dose, adsorbate concentration, particle size, temperature, contact time, and pH was studied. The adsorption of the dye over both the adsorbents was found to follow Langmuir and Freundlich adsorption isotherm models. Based on these models, different useful thermodynamic parameters have been evaluated for both the adsorption processes. The adsorption of Safranin-T over activated carbon and activated rice husks follows first-order kinetics and the rate constants for the adsorption processes decrease with increase in temperature.     

镁铝二元水滑石的焙烧产物对染料废水酸性红88的吸附

研究了镁铝水滑石的焙烧产物(LDO)对阴离子染料废水酸性红88(AR88)的吸附特征。分别考察了染料的初始浓度、吸附剂投加量、初始pH值、反应温度和竞争离子等因素的影响,并用XRD、红外光谱对水滑石以及吸附前后的LDO进行了表征。实验结果表明：LDO对高浓度的AR88具有良好的去除效果,在15 ℃、pH=10～11下,1.0 g·L^-1的LDO对浓度为2 000 mg·L^-1的AR88的去除率可高达99.95%,吸附容量为1 999.0 mg·g^-1。经4次回收重复利用的LDO对AR88的去除率仍为90%以上。     

Sorption of food dyes on polyurethane foam and aluminum oxide

The sorption of food dyes Sunset Yellow (E-110), Tartrazine (E 102), Ponceau 4R (E-124), Fast Green FCF (E-143) on polyether-based polyurethane foam, and α-Al₂O₃ from water solutions has been studied. It has been found that the maximum sorption is observed in the range of 0.2 M HCl-pH 2 on polyurethane foam and at pH 2–4 on aluminum oxide. Under the optimal conditions the recoveries on polyurethane foam and α-Al₂O₃ are 20–30% and 70–80%, respectively. It has been shown by diffuse reflectance spectroscopy that, for all dyes except for Fast Green FCF, only one form of the dye that dominates under these conditions in the aqueous solution is extracted on the sorbents in the range of 0.5 M HCl, pH 8.0. Possible models of the interaction between the dyes and the sorbent surface are proposed.     

Polymer gel/organic dye complexes in aqueous salt solutions

The present work is devoted to the study of the complex formation of polymer gel with organic dye and their properties in the aqueous salt solutions. Two systems were studied: 1) polyelectrolyte gel based on poly(diallyldimethylammonium chloride) and water soluble oppositely charged organic dyes (alizarin red S and catechol violet) and 2) organogel based on poly(N-vinylcaprolactam) and dithizone. The collapse of the polyelectrolyte gels in the presence of oppositely charged dyes together with the effective absorption of dyes was observed. The shrinking degree and the dye absorption by the gel depends on the dye concentration. In the case of PVCa gel in organic media the dye absorption takes place. The main attention has been concentrated on the study of the behaviour of gel/dye complex immersed in the salt solution if dye is the chelating ligand for metal ions. It was shown that polyelectrolyte gels generally form stable complexes with oppositely charged dyes. The behaviour of PVCa-dithizone-chloroform system was studied in AgNO₃ aqueous solution. The release of dithizone to the external aqueous solution of AgNO₃ reservoir is completely suppressed. Absorption spectra of gel/dye and gel/dye/metal ion systems were studied. It was shown that metal ions penetrate inside the gel phase and the dye/metal ion complexes form within the gel. The dependence of the optical density for the systems of gel/dye/metal ion on the salt concentration is observed.     

Removal of some dyes from industrial effluents by polymeric materials and gamma-irradiation

The radiolysis of two basic dyes (Astrazon Red 6B and Astrazon Blue BG-200%), was investigated as a function of dye concentration, pH, irradiation dose and dose rate. It was found that the Astrazon Red 6B dye showed more radiation degradation than the Astrazon Blue BG-200% dye. Combining irradiation with the conventional treatment enhanced the degree of degradation. Addition of oxygen or hydrogen peroxide showed this enhancement, while nitrogen showed no change. A pH drop was observed and may be attributed to the degradation of the dye molecules to lower molecular weight compounds such as organic acids. Experiments on the adsorption or exchange the dyes onto GAC, some polymeric ion exchange resins and polymeric membranes were carried out showing that GAC had the highest adsorption capacity. By combined treatment of irradiation and adsorption, the total removal of these toxic dyes was achieved.     

The effect of gamma radiation on some organicpH indicators

The effect of gamma-radiation on the color intensity of a series of representative organic dyes, commonly used as pH indicators, has been studied. In aqueous medium, at commonly used concentration levels, the dyes demonstrate ability to indicate pH after gamma-doses of 10³-10⁴ r. In general all the dyes show less sensitivity to radiation in neutral or basic media than in acid media. The compounds demonstrate a pseudo first order degradation reaction rate which was shown to be the expected radiation effect zero order rate. Of those compounds studied, methyl orange proved to be the most sensitive to radiation while bromocresol green is the most resistant to radiation damage. It was found that addition of small amounts of ethyl alcohol to the medium was effective in decreasing dye radiation damage to a large degree. Research sponsored by the U.S. Atomic Energy Comission under contract with the Union Carbide Corporation.     

Transport of alkali halides through a liquid organic membrane containing a ditopic salt-binding receptor

A ditopic receptor is shown to have an impressive ability to recognize and extract the ion pairs of various alkali halides into organic solution. X-ray diffraction analysis indicates that the salts are bound in the solid state as contact ion pairs. Transport experiments, using a supported liquid membrane and high salt concentration in the source phase, show that the ditopic receptor can transport alkali halide salts up to 10-fold faster than a monotopic cation or anion receptor and 2-fold faster than a binary mixture of cation and anion receptors. All transport systems exhibit the same qualitative order of ion selectivity; that is, for a constant anion, the cation selectivity order is K+ > Na+ > Li+, and for a constant cation, the anion transport selectivity order is I- > Br- > Cl-. The data suggest that with a ditopic receptor, the polarity of the receptor-salt complex can be lowered if the salt is bound as an associated ion pair, which leads to a faster diffusion through the membrane and a higher maximal flux.     

Post‐Synthetic Polymerization of UiO‐66‐NH2 Nanoparticles and Polyurethane Oligomer toward Stand‐Alone Membranes for Dye Removal and Separation

Metal–organic frameworks (MOFs) are widely used as porous materials in the fields of adsorption and separation. However, their practical application is largely hindered by limitations to their processability. Herein, new UiO‐66‐Urea‐based flexible membranes with MOF loadings of 50 ( 1 ), 60 ( 2 ), and 70 wt % ( 3 ) were designed and prepared by post‐synthetic polymerization of UiO‐66‐NH₂ nanoparticles and a polyurethane oligomer under mild conditions. The adsorption behavior of membrane 3 towards four hydrophilic dyes, namely, eosin Y (EY), rhodamine B (RB), malachite green (MG), and methylene blue (MB), in aqueous solution was studied in detail. It exhibits strong adsorption of EY and RB but weak adsorption of MG and MB in aqueous solution. Owing to the selective adsorption of these hydrophilic dyes, membrane 3 can remove EY and RB from aqueous solution and completely separate EY/MB, RB/MG, and RB/MB mixtures in aqueous solution. In addition, the membrane is uniformly textured, easily handled, and can be reused for dye adsorption and separation.     

Diffusion of aniline through a polyethylene terephthalate track-etched membrane

Transport of aniline through a polyethylene terephthalate (PETP) track-etched membrane (pore size 0.03 μm, thickness 10 μm) without an external electric field has been studied. Diffusion is accompanied by the accumulation of aniline in the pore solution (concentrations of the penetrant in the pores are 10² times as large as in the feed). Aniline is likely to be protonated within the membrane even at pH of the external solution exceeding the pK_a of aniline salt. Transport only occurs through a deprotonated membrane (pH > 6). Inorganic electrolytes accelerate or retard the diffusion of aniline, depending on their nature and concentration (from a 2 mol/L NaCl solution aniline is transported even against its concentration gradient). Transport of aniline correlates with the difference in mobilities of cation and anion of the salt (LiCl and CsCl are exceptions), which implies the diffusion potential created by salt diffusion to be the driving force of aniline transport. Most of the said features of aniline diffusion resemble the diffusion behavior of cations and are explainable by the existence of aniline in the membrane in a cationic form. Experimental estimate of pH in the pores agrees with this suggestion. The regularities observed for aniline may apply to other ionizable penetrants.     

Titania nanowires as substrates for sensing and photocatalysis of common textile industry effluents

Sensing and photocatalysis of textile industry effluents such as dyes using mesoporous anatase titania nanowires are discussed here. Spectroscopic investigations show that the titania nanowires preferentially sense cationic (e.g. Methylene Blue, Rhodamine B) over anionic (e.g. Orange G, Remazol Brilliant Blue R) dyes. The adsorbed dye concentration on titania nanowires increased with increase in nanowire dimensions and dye solution pH. Electrochemical sensing directly corroborated spectroscopic findings. Electrochemical detection sensitivity for Methylene Blue increased by more than two times in magnitude with tripling of nanowire average length. Photodegradation of Methylene Blue using titania nanowires is also more efficient than the commercial P25-TiO₂ nanopowders. Keeping illumination protocol and observation times constant, the Methylene Blue concentration in solution decreased by only 50% in case of P25-TiO₂ nanoparticles compared to a 100% decrease for titania nanowires. Photodegradation was also found to be function of exposure times and dye solution pH. Excellent sensing ability and photocatalytic activity of the titania nanowires is attributed to increased effective reaction area of the controlled nanostructured morphology.     

Cloud-point extraction of rhodamine 6G by using Triton X-100 as the non-ionic surfactant

Cloud-point extraction (CPE) using the non-ionic surfactant Triton X-100 was used successfully to remove a highly toxic dye, rhodamine 6G (R6G), from water and wastewater. The effects of different analytical parameters such as pH, concentration of Triton X-100 (TX-100) and salts, equilibrium temperature, and incubation time on the efficiency of the extraction of R6G were studied in detail, and optimum conditions for dye extraction were obtained. Thermodynamic parameters including changes in Gibbs free energy, enthalpy, and entropy were also calculated, and these parameters indicated that the CPE of R6G was feasible, spontaneous, and endothermic in the temperature range of 75-95 degrees C. The equilibrium solubilization capacity of TX-100 was found to be 1.10 mmol/mol by using Langmuir isotherm models. No significant interference effects were observed in the presence of phenol and its derivatives, some acidic and basic dyes and most of the anions and cations. It was concluded that the CPE process described in this paper can be an alternative technique for removal of dyes and other pollutants from waters and wastewaters.     

Extraction of water miscible organic dyes by reverse micelles of alkyl glucosides

The extraction of methyl orange or methylene blue from an aqueous phase to an organic phase of reverse micelles of alkyl glucosides was investigated. Dodecyl glucoside, a biodegradable and biocompatible surfactant, was employed as a kind of alkyl glucosides, since a stable Winsor II system consisting of the water-in-oil type microemulsion and aqueous phases was formed when an organic solution containing dodecyl glucoside was contacted with an aqueous solution. The water content in the reverse micellar organic phase increased with an increase in the concentration of dodecyl glucoside. The extraction ratio of dyes also increased with increasing the concentration of dodecyl glucoside. Furthermore, the extraction ratio of dyes was dramatically dependent upon the pH of an aqueous phase and temperature.     

A New method of determining the extent of binding of an ionic dye to a polyelectrolyte in solution

A method of determining the free dye concentration in a dye/polyelectrolyte solution is described. The method utilizes the tendency of cationic dyes to adsorb to a cellulose dialysis membrane, and the nature of the membrane binding is studied by spectrophotometric methods. The binding of the cationic dye toluidine blue to the polyanion sodium carboxymethylcellulose in solution is used as an example. The proposed technique gives reliable estimates of free dye concentration over a wide range of polyanion and dye concentrations, both in the presence and absence of added simple electrolyte. The method possesses inherent advantages over estimates of free dye concentration obtained by absorption spectrophotometry and is more versatile than fluorimetry.     

离子液体内耦合液膜迁移苯酚的研究

本文以N-甲基咪唑为原料,采用微波合成法,制备了疏水性离子液体1-丁基-3-甲基咪唑六氟磷酸盐([BMIM]PF6),并将其作为液膜,对苯酚的内耦合液膜迁移进行了研究,考察了温度、搅拌速度、料液相酸度、初始浓度及解析相NaOH浓度等因素对苯酚迁移的影响,得出了最佳迁移条件:温度300 K,搅拌速度350 r/min,料液相pH为3.65,解析相NaOH浓度为0.8 mol/L.在最佳液膜条件下,对于10 mg/L苯酚溶液,迁移110 min,迁移率可以达到97.3%,膜相中有少量苯酚滞留.离子液体可循环使用.