Recovery of Surfactant from an Aqueous Solution Using Continuous Multistage Foam Fractionation: Mixed Surfactant System

A continuous multistage foam fractionation column with bubble caps was used for surfactant recovery from mixed surfactant solutions containing polyethylene glycol tert-octylphenyl (OPEO₁₀) and cetylpyridinium chloride (CPC) and the effects of air flow rate, foam height, and feed flow rate were investigated under a steady state of conditions. For the mixed surfactant system, the effect of synergism in the surfactant adsorption density was found. For separation efficiency, the total residual factor remained unchanged with an increasing feed molar fraction of OPEO₁₀ (α), suggesting that the addition of OPEO₁₀ does not increase the total separation efficiency. The residual factor of CPC increased with an increasing molar fraction of OPEO₁₀ (α), while the residual factor of OPEO₁₀ was lower for the mixed surfactant systems. A competitive removal was found in that the OPEO₁₀ can compete with CPC for the bubble surface. The total separation factors and enrichment ratio of mixed surfactant systems were in-between the two single surfactant systems at a long foam residence time and, in contrast, showed antagonism at short foam residence. This is due to the difference in liquid entrainment in foam at long and short foam residence times.     

Surfactant Recovery from Water Using a Multistage Foam Fractionator: Effect of Surfactant Type

Abstract

The purpose of this study was to investigate the recovery of surfactants using a multistage foam fractionator for three types of surfactants: cationic (cetyl pyridinium chloride, CPC); anionic (sodium dodecyl sulfate, SDS); and nonionic (polyoxyethylene(20 Princen , H.M. ; Mason , S.G. ( 1965 ) Shape of a fluid drop at a fluid-liquid interface I. Extension and test of two-phase theory . J. Colloid Sci. , 20 ( 2 ): 156 – 172 . [Google Scholar]) sorbitan monolaurate, Span80). The studied system was operated at a constant temperature of 25°C with a surfactant concentration in the range of 50 to 100% of CMC (critical micelle concentration). For any surfactant system, the enrichment ratio of surfactant increased with increasing foam height and number of stages but decreased with increasing effects of the air flow rate and feed concentration. For all studied surfactants, the removal efficiency of the surfactant was not significantly affected by changing the air flow rate, foam height, and feed concentration in the studied ranges. An increase in the number of stages showed a great improvement of both the enrichment ratio and the removal fraction for all three types of surfactants. In a comparison among the three studied surfactants, the separation performance, in terms of the enrichment ratio and removal was found to lie in the following order: CPC >Span80 > SDS, which can be explained by the foamability and foam stability of each surfactant.     

Surfactant Recovery by Foam Fractionation using the Gas-Liquid Contactor,Emulsion Venturi

Sodium dodecylbenzene sulfonate (SDBS), an anionic surfactant, was removed from its aqueous solution by foam fractionation in an emulsion venturi, a gas-liquid contactor functioning in self-aspiration. The performance of the reactor was evaluated by measuring the self-aspired gas flow and the mass transfer coefficient in the presence and the absence of SDBS. Data confirmed that both the gas flow self-aspired and the mass transfer coefficient increased with increasing the recirculated liquid flow. However, the presence of SDBS decreased the mass transfer capacity of the reactor influencing self-aspiration capacity in a positive manner. The percentage removal of SDBS in the emulsion venturi increased with increasing the recirculated liquid flow; at the highest liquid flow value used in this work (1.4 m³/h), 96% of SDBS was removed from the solution after 20 min of foam operating. The process was dependant on initial surfactant concentration. Neutral pH and temperature of 25°C were the optimal conditions for the foam separation of SDBS in the emulsion venturi.     

Continuous Foam Fractionation of Phosphate by a Cationic Surfactant

Abstract

Continuous foam fractionation experiments in one equilibrium stage were performed using ethylhexadecyldimethylammonium bromide and potassium dihydrogen phosphate. The pH of the solution was maintained at 5.4 at which only H₂PO₄- was present. The effects of surfactant and phosphate concentrations and liquid and gas flow rates on the percent stripping of phosphate and the distribution factor of phosphate were studied. Equilibria between surface and bulk liquid phases were found to be adequate to explain the inverse relationship between the distribution factor of phosphate and the phosphate and surfactant concentrations.

For optimum separation of phosphate, defined as percent stripping, [100(c_f — cw)/cf], low liquid and high gas flow rates must be used with dilute solutions of both surfactant and phosphate. Further, multiple equilibrium stages should be employed.     

Selectivity Coefficients for Divalent Oxyanions from the Continuous Foam Fractionation of a Quaternary Ammonium Surfactant

Abstract

An experimental investigation is presented of the continuous, single equilibrium stage foam fractionation of chromate (CrO₄ ^2-) and of thiosulfate (S₂O₃ ^2-) from 0.4 to 3.0 × 10–⁴ M aqueous solutions. The cationic surfactant, ethyl-hexadecyldimethylammonium bromide (EHDA-Br), is modeled as a soluble ion exchanger, considering the exchange of CrO₄ ^2- and S₂O₃ ^2- or EHDA-CrO₄ ^? and EHDA-S₂O₂ ^? for Br^?. The data indicate that EHDA-CrO₄ ^? or EHDA- S₂O₃ ^? is exchanged with Br^?. The selectivity coefficient for chromate is 3.90 and that for thiosulfate is 16.8.     

Foam Fractionation Rates

Abstract

An empirical model enables the relation of the batch foam fractionation rate as a power function of the air rate and of the instantaneous residual surfactant concentration, eliminating the bubble size which is difficult to control and to measure. For the cationic surfactant, ethylhexadecyl-dimethylarnmonium bromide, the batch foam fractionation rate is directly proportional to the residual surfactant concentration to the first power, except for dilute (>45 mg/liter) solutions, and including suspensions containing colloidal ferric oxide and polynucleated, complexed cyanider Constants obtained from batch data can be used in the analogue equation for continuous operation to predict accurately the continuous foam fractionation rate, for a single air rate but over a substantial range of feed rates and feed surfactant concentrations. Continuous data from an entirely different column can be fit by a power function equation of the same form, with the power on the effluent or bottoms surfactant concentration again being unity. The accuracy of the predictive equations is in the range 10–18%.     

Foam Fractionation and Drainage

Abstract

The effect of drainage on the lesser accumulation ratio R in foam is calculated. If time t ₀ alloted to drainage is varied, In R - 1) is expected to be, in simplest instances, proportional to t ₀. The expansion factor 1/φ of the foam, when this reaches the receptacle, depends on t ₀ but the product (R - 1)φ ought to be independent of t ₀ These conclusions are not contradicted by the meager published data.     

Foam Fractionation of Negative Ions

Abstract

Negatively charged ions can be separated successfully by foam fractionation. Among them, free cyanide ions were removed by cetyl trimethyl ammonium bromide or a similar compound. At low concentrations (<5 mg/L), quantitative removal of free cyanide ions was observed. Further observations revealed that when the concentration was increased to 57 mg/L, a reduction in concentration equivalent to 47% could be achieved. Finally, a correlation between cyanide separation and surfactant concentration was found.     

The Continuous Foam Fractionation of Phenol

Abstract

The continuous foam fractionation of phenol using a quaternary ammonium salt, ethylhexadecyldimethylammonium bromide, has been investigated. Experiments were conducted to determine the effects of pH and percentage reflux on the phenol removal. It was found that approximately 80% removal of phenol was obtained at a pH of 11.9 with 70% reflux. Poor removal occurred in the slightly basic region of 8.0 to 10.0; while adequate removal was obtained with no pH adjustment. Maximum removal occurred at 70 to 80% reflux. Sodium hydroxide was used to adjust the pH in most cases. Although similar effects were found using ammonium hydroxide, the percent removal of phenol was, in general, lower.     

Fractionation of Nanocellulose by Foam Filter

The foam fractionation method was applied for nanocellulose. Experiments were carried out with enzymatically pretreated nano-fibrillated cellulose (NFC) from softwood, as well as commercial products. Narrow channels (plateaus) between bubbles prevent the flow of coarse particles along the water, so that foam acts like a filter. The advantage of the method is no risk of clogging, which could be a big problem for conventional filters or screens. Mean particle size (effective size by means of dynamic light scattering measurement) was reduced by foam fractionation, and the reduction range depended on the cellulose grade and the type of surfactant. The yield turned out to be low, probably because of particle aggregation due to the interaction with surfactant.     

泡沫分离方法回收钪

采用十二烷基聚氧乙烯琥珀酸单酯磺酸钠和十二烷基硫酸钠混合物作为表面活性剂，间歇式泡沫分离回收水溶液中的钪。讨论了料液pH值、表面活性剂浓度、鼓泡气流率、离子强度和操作时间等对分离效果的影响，得到了适宜的工艺条件。     

泡沫分离除去水溶液中微量硫酸铜

为了探索设备和工艺简单、低污染、生产过程费用低的脱盐新方法,以十二烷基苯磺酸和十六烷基三甲基氢氧化铵为表面活性物质,采用泡沫分离技术对脱除水溶液中微量的硫酸铜进行了研究.重点考察了溶液的pH、表观气速、表面活性剂浓度,泡沫塔液面高度及改变分离阴阳离子的先后顺序对分离效果的影响,在最佳操作条件下:CuSO_4的去除率达到97.2%,富集比达到4.2.与其他表面活性剂相比,没有向溶液中引入新的金属离子和酸根离子,从而为脱盐提供了新的方法和依据.     

泡沫分离除去水溶液中微量金属离子

以十二烷基苯磺酸为表面活性物质,采用泡沫分离技术分别对脱除水溶液中微量的铁、铜、钠离子的分离过程进行了研究.重点考察了溶液的pH、表观气速、表面活性剂浓度及泡沫塔装液量对分离效果的影响.结果表明在各自最佳操作条件下铁离子(Ⅲ)的去除率为95.2%,富集比为13.6;铜离子(Ⅱ)的去除率为94.6%,富集比为16.5;钠离子去除率为73.1%,富集比为32.3.与常规的表面活性剂十二烷基硫酸钠相比,十二烷基苯磺酸在泡沫分离过程结束后不会在体系中引入新的金属离子,这为探索脱盐新方法提供了依据.     

从废旧聚苯乙烯泡沫塑料中回收苯乙烯

本文采用有机溶剂甲苯作为消泡剂，用热裂解法从废旧聚苯乙烯泡沫塑料中回收苯乙烯，苯乙烯收率可达８０％以上。     

糖-蛋白质混合体系泡沫分离过程研究

利用环流泡沫分离技术对若干糖 -蛋白质 (牛血清白蛋白 )混合模拟体系进行了分离实验 ,研究了 p H值对溶液表面张力和分离效果的影响 ,在综合考虑蛋白质泡沫夹带量、去除率、糖的损失率及分离因子的基础上 ,得到了泡沫分离的最优 p H值。研究结果表明 ,采用环流泡沫分离技术可以实现糖与蛋白质的分离 ,是生物多糖与蛋白质初级分离的一种有效方法     

Separation of Cyanide Ions by Foam Fractionation

Abstract

The technique of adsorption of cyanide ions on foam bubbles was studied as an alternative to chemical oxidation which is practiced in cyanide waste treatment. The technique of foam fractionation was previously applied to the removal of heavy metals and proved to be successful. The free cyanide ions and complex species both responded positively to the formation of a separate foam phase. The results obtained so far show that satisfactory separation of cyanide compounds is possible if certain parameters are properly selected. There are other factors which have not been investigated before, and they seem to have a major role in the performance of this operation.     

泡沫分离技术及其发展现状

探讨了泡沫分离技术的原理、泡沫分离设备及泡沫分离技术的研究进展。泡沫分离过程的性能受很多因素的影响 ,例如 ,进料液浓度、气泡尺寸、气体流量、泡沫的排液、进料位置、聚并、温度等。阐述了现有的几种新技术 ,如低重力条件操作、通过压力梯度而提高分离效率。此外 ,还简要介绍了泡沫分离塔中传质单元数和传质单元高度的概念。     

卧式加压溶气泡沫分离水溶液中低含量蛋白质

以大豆蛋白为目标蛋白,蛋白水溶液为模拟体系,采用卧式加压溶气泡沫分离装置考察了原料液流量、pH值、溶气水流量等因素对蛋白质脱除率的影响,并根据其分子结构特征从过程工程视角分析了以卧式泡沫分离装置由水中去除的优势.结果表明,最佳操作条件为:原料液浓度8mg/L,原料液流量50L/h,pH值4.5,溶气水流量275L/h,该条件下水中蛋白质的脱除率可达90.5%.     

Removal of Trace Metal Impurities from Pretreated Phosphoric Acid by Foam Fractionation

Demands for phosphoric acid are growing rapidly in various industries. This has highlighted the importance of optimizing its production and purification methods. Phosphoric acid can be produced by a wet process. However, due to the presence of many organic and inorganic impurities in the wet product, purification of the resulting product is a major concern in this industry. Removal of trace metal impurities (such as magnesium, cadmium, chromium, zinc, etc.) from produced phosphoric acid in a wet process was investigated by foam fractionation in a semi-batch setup using sodium dodecyl sulfate (SDS) as the surfactant. Effects of inlet air velocity, surfactant concentration, and surfactant selectivity were investigated. The optimum air velocity and surfactant concentration were obtained as 0.020 cm/min and 0.7 g/L, respectively. At the optimum condition, the total removal efficiency and enrichment factor reached were 70.2% and 4.39, respectively, while the acid loss was 8.3%. The total metal removal efficiency was increased to 95.3% in a two-stage experimental run.     

泡沫分离法除去水溶液中微量铜离子的工艺

以十二烷基苯磺酸为表面活性物质,自制的单金属离子水溶液为研究体系,对泡沫分离法除去水溶液中金属离子的工艺进行了研究,重点考察了溶液的pH、鼓泡气体流量、表面活性剂浓度及泡沫塔装液量的影响. 结果表明,十二烷基苯磺酸具有良好的起泡性能,对水溶液中铜离子的去除效果也比较理想,最佳操作条件下富集比为18.2,去除率为96.1%,与常规的表面活性剂十二烷基硫酸钠相比,十二烷基苯磺酸在泡沫分离过程结束后不会在体系中残留金属离子,这为探索脱盐新方法提供了依据.