Removal of Safranine from Aqueous Solution by Using Adsorptive Bubble Separation Techniques

Safranine, a cationic dye, was removed from synthetic wastewater by ion flotation. Over 98% of safranine was removed from the solution in 10 min. A stoichiometric amount of surfactant (1 mol of surfactant to 1 mol of dye) was found to be most effective for safranine removal. The separation efficiency of safranine decreased with increasing concentration of NaNO3. Safranine was also removed by adsorbing colloid flotation technique using Fe(OH)3 as the coagulant. Sodium lauryl sulfate was used as the collector, and over 97% of safranine was removed in 5 min. The separation efficiency decreased with increasing ionic strength of the solution. The deleterious effect of neutral salt was compensated somewhat with the aid of Al^3 as the activator. Both ion flotation and adsorbing colloid flotation may be applicable in the removal of safranine from wastewater.     

Separation of Co(II) from dilute aqueous solutions by precipitate and adsorbing colloid flotation

Ion, precipitate and adsorbing colloid flotation of cobalt(II) have been investigated at different pH values, using N-dodecylpyridinium chloride (DPCl), A strong cationic surfactant, and sodium lauryl sulfate (NaLS), a strong anionic surfactant, as collectors. In case of adsorbing colloid flotation, hydrous manganese dioxide was used as an adsorbent. The precipitate flotation curves experimentally obtained with the two tested collectors were compared with the corresponding theoretical one calculated from the data published for Co(II) hydrolysis. The effects of the collector concentration, ageing of the water-MnO₂–Co(II) system, bubbling time period, cobalt(II) concentration and foreign salts on the percent removal of Co(II) by adsorbing colloid flotation using DPCl as collector were determined. Removals approaching 100% could be achieved under the optimum conditions.     

Adsorptive Bubble Separation of Dinitrophenol

Dinitrophenol was removed from aqueous solution by various adsorptive bubble separation techniques. Foam fractionation of dinitrophenol with hexadecyltrimethylammonium bromide(HTA) was most effective with over 99% removal in 15 min. The addition of a surfactant in greater than stoichiometric amounts was required for effective separation. Solvent sublation of the dinitrophenol-HTA complex was also effective. The separation efficiency of solvent sublation of dinitrophenol-HTA was similar to that of foam fractionation. The separation by solvent sublation of dinitrophenol without adding any surfactant was very poor. Adsorbing colloid flotation with Fe(OH)₃ was not effective in removing dinitrophenol from aqueous solution.     

Removal of Zn(II) from dilute aqueous solutions and radioactive process wastewater by foam separation

Ion, precipitate and adsorbing colloid flotations of zinc(II) from dilute aqueous solutions have been investigated over a wide pH range using the anionic surfactant Aerosol OT or the cationic collector cetyl pyridinium chloride. In case of adsorbing colloid flotation (ACF) iron oxyhydroxide and aluminium hydroxide were used, either separately or together, as coprecipitants. The precipitate flotation curves were compared with the corresponding theoretical one calculated from the data published for Zn(II) hydrolysis. In addition to the effect of pH on the percent removal the effects of collector concentration, ionic strength, bubbling time and metal ion concentration were investigated and the optimum conditions were established. High removals could be achieved especially with ACF. The results obtained are discussed with respect to the chemical state of zinc, the ionization behaviour of the collectors and properties of the coprecipitants. The developed ACF process was applied to the removal of⁶⁵Zn from radioactive process wastewater.     

Adsorptive bubble separation of zinc and cadmium cations in presence of ferric and aluminum hydroxides

The adsorptive bubble separation of zinc and cadmium cations from solution in the presence of ferric and aluminum hydroxides was carried out by means of Tween 80 (nonionic surfactant), and sodium laurate and stearate (anionic surfactants). The mechanism of metal removal is different depending on the nature of the surfactant used. The removal of zinc cations by adsorbing colloid flotation is higher than that of cadmium cations. It increases with increases in the amount of hydroxide precipitate and the concentration of Tween 80. The removal of zinc cations by ion flotation is lower than that of cadmium cations. It does not change with increases in the hydroxide amount. It increases, however, with increased sodium laurate or stearate concentration. Both separation methods turned out to be helpful for studying both the solution's structure and the interactions at the solution-solid interface.     

Foam Separation of Stannous Ion from Aqueous Solution

Sn(II) was removed from solution using various foam separation techniques. It was found that Sn(II) could be effectively removed by adsorbing colloid flotation using either Fe(OH)₃ or Al(OH)₃ as the adsorbing colloid. Over 99% of the Sn(II) was removed from a solution initially containing 50 ppm Sn(II).     

溶剂气浮法去除水中的刚果红的研究

以十六烷基三甲基溴化铵为表面活性剂, 与阴离子型染料刚果红形成缔合物, 对该缔合物的溶剂气浮过程进行研究. 研究多种参数对溶剂气浮过程的影响, 如气浮速率、共存溶质的量、pH等参数对溶剂气浮去除率的影响. 研究表明表面活性剂与染料的物质的量之比为2∶1, 约24 min水中刚果红的去除率可达97%;NaCl会大大降低溶剂气浮的去除率;溶剂气浮的速率随着气流速率的增加而增加, 但高速率反而降低溶剂的去除率;共存溶质乙醇存在会使去溶剂去除率降低, 有机溶剂的量对溶剂气浮影响较小;pH中性去除率最佳;考察了不同温度下溶剂气浮的热力学及动力学, 研究表明, 溶剂气浮过程遵从一级动力学, 计算了该过程中的气浮表观活化能为7.48 kJ/mol.     

Adsorbing colloid flotation separation and polarographic determination of Mo(VI) in water

A method is described for the flotation and determination of Mo(VI) in water at ng/ml levels. Mo(VI) is preconcentrated and separated by adsorbing colloid flotation employing aluminium(III) hydroxide as collector and sodium lauryl sulphate as surfactant at pH 5.3 ± 0.1. The molybdenum content in the froth is estimated by using the catalytic wave of Mo(VI) in the presence of nitrate by charging current compensated d.c. polarography (CCCDCP) or differential pulse polarography (DPP). The effect of variables such as pH, ionic strength, concentration of collector and surfactant, time of stirring and gas flow-rate on the recovery of Mo by flotation is reported. The effects of various cations and anions on the flotation and determination of Mo are studied. This method is employed for the determination of molybdenum in natural fresh water samples.     

Removal of organic dyes from water by liquid-liquid extraction using reverse micelles

In the present work, solvent extraction using reverse micelles is proposed for the removal of organic dyes from water. In this approach, the dye is solubilized in the aqueous core of the reverse micelles, which are present in the organic phase. The organic phase is subsequently separated from the aqueous phase leading to signifi-cant removal of dye. Experimental results reveal that the electrostatic interaction between the oppositely charged surfactant head group present in the reverse micelles and the dye molecule plays a key role in the separation. The removal of the anionic methyl orange dye from water is carried out in the presence of cationic hexadecyltrimethyl ammonium bromide surfactant, whereas the removal of the cationic methylene blue dye is carried out in the presence of anionic sodium dodecylbenzene sulfonate surfactant. Amyl alcohol is used as the solvent. The influence of parameters such as dye concentrations, surfactant concentrations, pH, and KCl and NaBr concentrations on the percentage removal of dye was studied. The percentage removal of dye is decreased with the increase in dye concentration in the feed. The increase in surfactant concentration resulted in higher dye removal, because more reverse micelles could be hosted in the organic phase. The increase in aqueous phase pH resulted in enhanced removal of methyl orange from water, while in the case of methylene blue the percentage removal decreased. The increase in KCl and NaBr concentrations resulted in decreased percentage removal of methylene blue, whereas the percentage removal of methyl orange was increased. The effect of pH and salt concentration is explained based on charge transfer mechanism and electrostatic interactions and dye-surfactant complex formation.     

Desulfurization of pittsburgh coal by microbial column flotation

Microbial column flotation usingThiobacillus ferrooxidans was applied for desulfurization of Pittsburgh coal of CWM (Coal-Water Mixture) size between 38 μm and 75 μm. The coal contained ferrous ion which would interfere separation of pyrite from coal by microbial flotation. The wash-out of ferrous ion with 0.5N HC1 solution enabled pyrite removal from coal. The coal was divided into two parts, the small-size coal between 38 μm and 53 μm, and the large-size coal between 53 μm and 75 μm. The pyritic sulfur content was decreased from 2.88% of the feed coal to 0.98% of the product coal for the largesize coal and from 2.77% of the feed coal to 1.12% of the product coal for the small-size coal by microbial flotation. The decrease was based on removal of liberated pyrite particles (between 20 μm and 70 μm). However, the fine particles (less than 20 μm) could not be removed even though the pyrite particles were liberated from coal particles. The microbial column flotation was more effective for desulfurization of the large liberated pyrite particle than that of the small. It was not effective for desulfurization of the locked pyrite particles that were buried in coal particles. Both the pyrite liberation from coal and its particle size are important factors for the pyrite removal by microbial column flotation.     

Rapid separation of humic acid in fresh waters by coprecipitation and flotation

After removal of suspended matter in 1 liter of water by flotation with a cationic surfactant, humic acid at theg/l level is separated from fulvic acid by coprecipitation with milligram quantities of iron(III) hydroxide at pH 7 followed by flotation with anionic surfactants. The iron(III) hydroxide is dissolved in 2M hydrochloric acid, and the acid-insoluble humic acid is filtered off on an ultrafilter and then dissolved in 10 ml of 0.1M potassium hydroxide solution for measurements of absorption spectra, molecular weight distribution and complexing ability. The time required for the separation is ca. 1 h.     

表面活性剂改性有机沸石对废水中亚甲基蓝的吸附行为

用表面活性剂十六烷基三甲基溴化铵(CTMAB)和十二烷基硫酸钠(SDS)复合改性沸石,制备了阴阳离子表面活性剂改性沸石,利用X射线衍射和红外吸收光谱表征了改性前后沸石的结构,并研究了改性沸石对亚甲基蓝的吸附行为.结果表明,改性后沸石的吸附性能明显增强;在溶液pH 8、常温,吸附时间100 min、改性沸石用量20 g/...     

Ion flotation of nickel using ethylhexadecyldimethylammonium bromide

Nickel ions react with the surfactant ethylhexadecyldimethylammonium bromide (EHDABr) to foam a surface-active sublate which can be removed from aqueous chloride solutions by ion flotation. A typical ion-flotation procedure involves passing a fixed volume of air through a 250-ml solution containing 4.0 ppm nickel and 0.05 M KCl at a pH of 5 at a rate of 60 ml/min for 60 min. The method is simple and rapid with 87% removal of the nickel.     

泡沫浮选法分离富集三七中的4种人参皂苷

采用泡沫浮选法对三七提取液中的人参皂苷Rg1、Re、Rb1和Rd进行了分离富集,并用高效液相色谱法分别测定了含量.考察了浮选液浓度、浮选时间、浮选液pH值、氮气流速和电解质NaCl浓度对浮选效率的影响.结果表明:泡沫浮选法对4种皂苷均有较好的分离富集效果,尤其是对人参二醇型皂苷(Rb1,Rd)效果更为明显.当浮选液浓度为2.0 mg/mL,pH值为2～3,氮气流速为20 mL/min,浮选时间10 min,电解质氯化钠浓度0.20 mol/L,泡沫浮选效果最佳.     

Dye aggregation and influence of pre-micelles on heterogeneous catalysis: A photophysical approach

Common cationic dyes used for laser and fluorescent probes present low solubility in water. In order to increase the dye concentration in aqueous solutions, anionic surfactant can be added. The strong interaction between anionic surfactant and cationic dye can affect drastically the dye absorption and fluorescence properties. Here we observed that the fluorescence of the species in aqueous solution is maximized at condition of complete micellization of surfactants at critical micelle concentration (CMC). In addition, combined measurements of absorption, emission and fluorescence lifetime provide fundamental information on the critical concentration of H-aggregates formation and monomer separation, induced by pre-micelles and homomicelles on different surfactant sodium dodecylsulphate (SDS) concentration. The experimental results show how to find precisely the critical concentration of H-aggregates by optical method in two different xanthene-derived molecules: rhodamine 6G and rhodamine B. The adequate transference of electron from excited dye to the conduction band of semiconductor (TiO₂) promotes the creation of reactive species that provides the degradation of dye with advantage of use of irradiation in the visible region and strong photobleaching with direct exposure to the visible light irradiation in a scale of time of 10 min.     

Interaction of Quercus Infectoria Natural Dye with Cationic and Anionic Surfactants: Adsorption/Micellization of Dye

The interaction of Indian natural dye, that is, Himalaya (Quercus infectoria) with cationic surfactant (cetyl trimethyl ammonium bromide) and anionic surfactant (sodium lauryl sulphate) has been studied. The spectrophotometric data showed an interaction between the natural dye and surfactants. Critical micelle concentration (CMC) of the surfactants, determined by measurement of specific conductance and surface tension methods, was found to be increase in case of anionic surfactant while that was found to decrease in case of cationic surfactant. Thermodynamic and surface parameters showed domination of micellization of dye in case of cetyl trimethyl ammonium bromide and domination of adsorption of dye in case of sodium lauryl sulphate.     

Preparation of microspheres by an emulsification-complexation method

Microspheres were prepared by complexation of a cationic polymer, polyquaternium-24, and an anionic surfactant, sodium lauryl sulfate (SLS). The cationic polymer solution was emulsified in dimethylsiloxane to give water in silicone emulsion (W/Si), and it was used as a template for the formation of microspheres. The emulsion was dispersed into the SLS solution. In this process, two kinds of droplets, silicone dropletes and microspheres composed of the cationic polymer and SLS, were formed, evidenced by X-ray energy dispersive spectra. The mean diameter of the microspheres was reduced from 105.7 to 64.8 mum as the stirring rate for W/Si preparation increased from 300 to 1000 rpm. It is believed that water droplets in W/Si emulsion, when exposed to SLS solution, could be solidified by the complexation of the cationic polymer and the anionic surfactant.     

Foam Separation of Cadmium From Waste Water

Foam separation techniques are evaluated to determine if they would be feasible for removing cadmium (II) from waste water. Variables such as pH, ionic strength, collector concentration, and interfering ions were studied to determine their effects on separation. Sodium laury sulfate, sodium sterate, and hexadecyltrimethyl-ammonium bromide were chosen as the collector; Fe(OH)₃ and Al(OH)₃ were used as the adsorbing colloid, and sodium tripolyphosphate was used as modifier. It was found that cadmium could be effectively removed using various foam separation techniques. Cadmium levels were reduced from 5 ppm to 0.003 ppm in 60 minutes foaming with sodium laury sulfate. Foam separation of cadmium sterate with hexadecyltrimethyl-ammonium bromide was effective even at very high ionic strength, such as 1.0M NaNO₃.     

The effect of triethylenetetraamine (Trien) on the ion flotation of Cu(2+) and Ni(2+)

Ion flotation is a separation process involving the adsorption of a surfactant and counterions at an air/aqueous solution interface. It shows promise for removing toxic heavy metal ions from dilute aqueous solutions. Here we report the effect of a neutral chelating ligand, triethylenetetraamine (Trien), on the ion flotation of cations with dodecylsulfate, DS(-), introduced as sodium dodecylsulfate, SDS. Ion flotation in the aqueous SD-Cu(II)-Ca(II)-Trien system gave strongly preferential removal of Cu(II) over Ca(II), which is a reversal of the order of selectivity seen in the SDS-Cu(II)-Ca(II) system containing no Trien. The removal rates of Cu(2+) and Ni(2+) with DS(-) were much faster in the presence of Trien than for simple aquo ions, and the final metal concentration was significantly lower. Surface tension measurements showed that Trien enhanced the surface activity and adsorption density for SDS-Cu(II) and SDS-Ni(II) solutions. The overall change in the Gibbs free energy for adsorption resulting from complexation was -3.60 kJ/mol for Cu(II) and -3.50 kJ/mol for Ni(II). This included the effects of hydrophobic interactions between the metal-Trien complexes at the air/solution interface, along with changes in the amount of dehydration associated with cosorption of the metal-Trien complex with DS(-) at the air/solution interface.