Study on Streptomycin Sulfate Recovery by Batch Foam Separation

The feasibility of foam separation as a technique was assessed for the recovery of streptomycin sulfate from the waste solution by using an anionic surfactant sodium dodecyl sulfate (SDS). The experimental parameters examined were SDS concentration, superficial gas velocity, initial pH, and liquid loading volume. The results showed that sodium dodecyl sulfate as the surfactant for foam separation had good foaming quality and could effectively concentrate streptomycin sulfate of the aqueous solution by technology of foam separation. The enrichment ratio and the recovery rate of streptomycin sulfate were 4.0 and 85%, respectively under the best operating conditions of sodium dodecyl sulfate concentration 0.4 g/L, superficial gas velocity 300 mL/min, liquid loading volume 300 mL and initial pH 6.0 when streptomycin sulfate concentration was 0.5 g/L.     

Influence of emulsifiers on film formation from cellulose acetate latexes. Modeling approach to the fate of emulsifiers in highly plasticized films. II

Experimental results on the redistribution of sodium dodecyl sulfate in cellulose acetate membranes produced from latexes (Part I) are interpreted in terms of a framework involving both thermodynamic (affinity of the components, composition) and kinetic (plasticizer evaporation rate) parameters. Two situations were examined, corresponding to liquid–liquid and liquid–solid phase separation. The proposed model better accounts for the observed phenomena than more classical views about the fate of emulsifiers.     

乳化剂对动态膜分离油水乳化液过程的影响

利用管状陶瓷膜基氧化锆动态膜分离油水乳化液，研究了4种工业常见乳化剂[斯盘80（SP-80）、十二烷基磺酸钠（SDS）、十二烷基硫酸钠（SLS）和十二烷基苯磺酸钠（SDBS）]对分离过程的影响。利用正交实验方法考察了乳化剂种类和浓度、乳化液温度和流量以及操作压力对过程的影响。正交实验结果表明，在SDS、1.0 g/L、50℃、120L/h和0.14MPa操作条件下，油水混合物稳定渗透通量最大。单因素实验结果表明，当乳化剂浓度增大时，稳定渗透通量减小；当乳化液温度升高时，稳定渗透通量先增加后降低。无机盐离子Na⁺、Ca²⁺和Al³⁺的存在均可使稳定渗透通量增加。当Al³⁺大于0.75g/L时，乳化液的稳定性被完全破坏，更有利于提高渗透通量。基于实验结果，采用分子模拟方法研究了不同实验条件下乳化剂的乳化效果，分析了SDS的油水界面形成能（E）和水的界面扩散系数（D）与乳化剂浓度和乳化液温度的关系。模拟结果表明，E和D绝对值均随着乳化剂浓度和乳化液温度增加而增大。实验和模拟结果均表明，乳化剂的乳化效果决定了油滴的平均粒径，基于油水分离的堵塞机理，也由此影响了稳定渗透通量。模拟结果从微观角度解释了实验现象，研究结果可为动态膜处理油水乳化液的工业应用提供依据。     

Preparation and testing of polyvinyl alcohol composite membranes for reverse osmosis

Thin film composite membranes were prepared by coating porous polysulfone membranes with a polyvinyl alcohol layer and further cross-linking its surface. The thin layer of cross-linked polyvinyl alcohol served as a selective membrane. The membranes were prepared under various conditions and tested for sodium chloride separation. A high sodium chloride separation was achieved but the permeation rate was low compared with commercially available thin film composite membranes. Resistance against the flow of solvent water and sodium chloride solute were determined for individual component barrier layers.     

Development of novel surface modified phase inversion membranes having hydrophobic surface-modifying macromolecule (nSMM) for vacuum membrane distillation

Eleven PES membranes, into which newly synthesized surface-modifying macromolecule (nSMM) was incorporated, were prepared by using the ‘phase inversion technique’ with different preparation conditions to find the effects of membrane casting parameters on the characteristics and performances of the surface modified PES membranes. The membranes so prepared were characterized by solute separation data from ultrafiltration experiments. The results showed that the mean pore size as well as the surface hydrophobicity increased with an increase in evaporation time for the casting solution blended with nSMM (without PVP). When PVP was added into the casting solution, the mean pore size as well as the contact angle decreased while the pure water permeation flux increased. The surface hydrophobicity decreased with an increase in gelation bath temperature.Four membranes were further prepared and subjected to vacuum membrane distillation (VMD). They were characterized by different analytical instruments and pure water permeation test before being used to VMD. The results showed that a distinctive surface layer was formed in nSMM blended PES membranes. It was also found that nSMM blended PES membranes were sufficiently hydrophobic and porous to be used for the separation of an ethanol/water mixture.     

Separation of liquid mixtures by using polymer membranes. III. Grafted poly(vinyl alcohol) membranes in vacuum permeation and dialysis

A series of poly(vinyl alcohol) membranes were modifed by radiation-induced graft copolymerization with acrylic acid and methacrylic acid monomers. These grafted poly(vinyl alcohol) membranes were then tested for their separation and permeability characteristics in vacuum permeation and dialysis experiments. The permselectivity of the membranes toward methanol and water was studied on a vacuum permeation apparatus at 30, 40, and 50°C. The permeation process was found to be a temperature-activated process. The logarithm of the permeation rate varied linearly with the reciprocal of the absolute temperature. The permeability of the grafted membranes was found to increase with the degree of grafting, with no appreciable selectivity toward water in binary mixtures. The acrylic acid-grafted membranes generally showed greater improvement in permeability than the methacylic-grafted membranes. The permeability of the grafted membranes toward methanol, sodium chloride, urea, creatinine, and uric acid was studied in a dialyzer. In all cases, the grafted membranes showed an improved permeability toward these solutes over the commercial poly(vinyl alcohol) membranes. The dialysis results were then compared with those obtained for dialysis-grade cellophane membranes. For the case of sodium chloride, urea, and methanol, the permeability of the grafted membranes was comparable to that of cellophane. A comparison of commercial and grafted poly(vinyl alcohol) membranes in their permeability toward ionic solutes exhibited somewhat anomalous behavior in that the permeability of the commercial membranes was higher than that of the grafted membranes. This related to the ionic nature of the modified membrane. The permeability coefficients determined in the dialysis experiments were found to be directly related to the degree of hydration of the grafted membrane. This behavior was attributed to changes in the size and shape of voids within the membrane structure.     

A systematic study on the effects of synthesis conditions of polyamide selective layer on the CO2/N2 separation of thin film composite polyamide membranes

Different top layer fabrication methods (amine-first, acid-first, spin coating), organic phase solvents (hexane, heptane, mixed hexane/heptane), acid acceptors (triethylamine, sodium carbonate, sodium hydroxide), and surfactant sodium dodecyl sulfate concentrations (0, 0.05, and 0.1 wt%) were utilized to fabricate thin film composite polyamide membranes for CO₂/N₂ separation. The results, according to an L9 orthogonal array of Taguchi approach, showed that employing acid-first method increases both CO₂ permeance and CO₂/N₂ selectivity of the membranes at a feed gas pressure of 3 bars. On the other hand, sodium hydroxide, and triethylamine should be used, as acid acceptors, to maximize CO₂ permeance and CO₂/N₂ selectivity, respectively. Moreover, the use of hexane solvent and 0 wt% surfactant led to maximum permeance, while, hexane solvent and 0.1 wt% surfactant were needed to reach the highest selectivity. The above level setting of synthesis parameters also resulted in the minimum sensitivity of the fabrication process to the noise factors effects. As shown by the analysis of variance, acid acceptor, and organic solvent types were the most influential parameters on CO₂ permeance and CO₂/N₂ selectivity, respectively. The effects of fabrication method and surfactant concentration, as single factors, on permeation/selectivity responses were also investigated.     

Porous polymeric membranes by bicontinuous microemulsion polymerization: effect of anionic and cationic surfactants

Porous polymeric membranes made by polymerizing bicontinuous microemulsions stabilized with anionic sodium dodecyl sulfate (SDS) and cationic dodecyltrimethylammonium bromide (DTAB) as surface-active agents were investigated. The morphology, swelling and permeability characteristics of the membranes were found to be highly dependent on the surfactant concentration in both SDS and DTAB systems. The pore size of the DTAB system decreases on increasing the DTAB concentration, while the reverse trend was observed for the SDS system until its concentration exceeded 10 wt%. The membrane prepared using SDS was found to have a larger pore size in the range of 100 nm to 3 μm as compared to that of DTAB, which is less than 100 nm. In addition, the variation of SDS concentration led to a continuous change in the shape of particle aggregates of the membranes while it appeared to remain in globular form for the DTAB system. The remarkable differences between the membranes prepared using SDS and DTAB are discussed in terms of their different monolayer flexibilities.     

季膦盐离子液体/表面活性剂/盐双水相的性质及萃取效果研究

向水相中加入有机物或盐, 在一定组成范围内, 可以形成密度不同的两相, 即双水相, 目前在生物萃取领域有广泛的应用。离子液体/表面活性剂体系的双水相体系符合绿色化学的要求, 而且目前研究尚不多见。采用离子液体四丁基膦氯化铁盐、十四烷基三丁基膦氯化铁盐（[P4444]FeCl₄、[P44414]FeCl₄）和两种表面活性剂十二烷基硫酸钠、十二烷基苯磺酸钠（SDS、SDBS）及柠檬酸钠混合形成双水相体系, 并绘制了[P4444]FeCl₄（[P44414]FeCl₄）/SDS（SDBS）/盐4个体系的相图, 用粒度测试研究发现, 双水相的上相粒度约为60~80 nm, 下相粒度太小而未能检测出来。使用紫外-可见分光光度法研究了双水相体系对不同性质染料的萃取效果。结果表明, 离子液体的疏水链长度和表面活性剂疏水链上存在苯环与否都对体系中双水相的区域产生影响。4个双水相体系都对水溶性染料有很好的萃取作用, 但是对油溶性染料萃取效果不佳。此项研究促进了离子液体在化学分离领域的开发利用。     

Studies on syntheses and permeabilities of special polymer membranes. XVI. Permeation and separation characteristics of aqueous polymer solutions for acrylonitrile-styrene copolymer membranes

The permeation and separation characteristics of aqueous polymer solutions using acrylonitrile-styrene copolymer membranes were investigated under various conditions. The membranes obtained from dimethyl sulfoxide solution of acrylonitrile-styrene copolymer have not a sufficient reproducibility and stability of permeation. These lacks were improved by adding ethylene glycol or glycerol to the casting solution and treating the membranes with pressure. The permeation and separation characteristics were influenced significantly by the additional amount of above additives, the heat treatment temperature, and the operating pressure. It was found that the concentration polarization of poly(vinyl alcohol) molecules onto the surface of the acrylonitrile-styrene copolymer membranes is smaller than that onto hydrophilic polymer membranes such as membranes of cellulose acetate, cellulose nitrate, and nylon 12, etc. Moreover, the acrylonitrile-styrene copolymer membranes show better performance for separation and concentrating of aqueous polymer solutions than hydrophilic membranes.     

Swollen Emulsion Polymerization of Styrene with Cetyl and/or Lauryl Alcohol as Swelling Agent

The kinetics of swollen emulsion polymerization of styrene was investigated. Two types of fatty alcohol, namely, cetyl alcohol and lauryl alcohol, were used as swelling agents in the presence of sodium dodecyl sulfate as emulsifier and potassium persulfate as initiator. The polymerizations were carried out in a magnetic-drive, sealed, cylindrical polymerization reactor, in nitrogen atmosphere. The effects of emulsifier concentration and the weight ratio of emulsifier to swelling agent on the variation of total monomer conversion with the polymerization time, average particle size, and the size distribution of the latex were examined. A significant decrease in the polymerization rate was observed at especially lower emulsifier concentrations in the presence of cetyl alcohol. The maximum average diameter of the latex with the sodium dodecyl sulfate-cetyl alcohol system was obtained as 0.30 μm. Lauryl alcohol was tried as a novel swelling agent. It was found that lauryl alcohol was an effective swelling agent without using sodium dodecyl sulfate. The latexes having average diameters of 1.0 μm and 0.67 μm (highly monodisperse) were obtained using 0.6 g and 2.0 g lauryl alcohol, respectively, at 300 mL of reaction volume. If it was used together with sodium dodecyl sulfate, the presence of lauryl alcohol did not cause any significant decrease in the polymerization rate as in the case of sodium dodecyl sulfate-cetyl alcohol system, but the average diameters of the latexes obtained with different sodium dodecyl sulfate-lauryl alcohol combinations were rather small compared to the sodium dodecyl sulfate-cetyl alcohol system at the same polymerization conditions.     

Use of Sodium Alginate-Poly(vinyl pyrrolidone) Membranes for Pervaporation Separation of Acetone/Water Mixtures

Pervaporative separation of acetone from water at a concentration range of 0–100 wt% were studied using sodium alginate (NaAlg)/Poly vinyl pyrrolidone (PVP) membranes. Membranes were prepared in different ratios (w/w) (100/0, 95/5, 90/10, 85/15, 80/20, 75/25) of NaAlg/PVP by crosslinking with CaCl₂. Experimental studies were carried out to investigate the effects of the operating temperature, feed composition, and membrane thickness on the pervaporation performance. The optimum operating temperature, membrane thickness, NaAlg/PVP ratio, and feed composition were determined as 40°C, 70 µm, 75/25 (w/w), and 20 wt% acetone, respectively. The effect of PVP content in the membranes was investigated on pervaporation performance. The permeation rate was increased with increasing the PVP content; however, there was no appreciable change about the separation factor. The permeation rate and separation factor values were found to be in the range of 0.304–1.023 kg/m² h and 16–57, respectively. In addition, the sorption-diffusion properties of the alginate membranes were investigated at the operating temperature and the feed composition. It was found that the sorption selectivity was the dominant factor for the separation of acetone/water mixtures.     

Amphiphilic ABA‐type triblock copolymers for the development of high‐performance poly(vinylidene fluoride)/poly(vinyl pyrrolidone) blend ultrafiltration membranes for oil separation

ABA‐type amphiphilic triblock copolymers (TBCs) were synthesized by a reversible addition fragmentation chain transfer (RAFT) process with a telechelic polystyrene macro‐RAFT agent and 4‐[n‐(acryloyloxy)alkyloxy]benzoic acid monomers. Ultrafiltration (UF) membranes were fabricated by a phase‐inversion process with blends of the TBC, poly(vinylidene fluoride) (PVDF), and poly(vinyl pyrrolidone) (PVP) in dimethylformamide. The UF‐fabricated membranes were characterized by scanning electron microscopy, atomic force microscopy, water contact angle measurement, thermogravimetric analysis, and differential scanning calorimetry. Pure water permeation, molecular weight cutoff values obtained by the permeation of different molecular weight polymers as probe solutes, bovine serum albumin (BSA) solution permeate flux, and oil–water emulsion filtration tests were used to evaluate the separation characteristics of the fabricated membranes. The tripolymer blend membranes exhibited a higher flux recovery ratio (FRR) after the membrane was washed with sodium lauryl sulfate (0.05 wt %) solution for a BSA solution (FRR = 88%) and oil–water emulsion (FRR = 95%) feeds when than the PVDF–PVP blend membrane (57 and 80% FRR values for the BSA solution and oil–water emulsion, respectively). The pendant carboxylic acid functional moieties in this ABA‐type TBC have potential advantages in the fabrication of high‐performance membranes. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45132.     

Synthesis and Characterization of Polyimide Mixed Matrix Membranes

Polyimides of Matrimid 5218 and P84 as backbone and different fillers including silica aerosil, zeolite 4A, carbon nanotubes, and carbon molecular sieves were used to synthesize flat mixed matrix membranes (MMMs). Effects of different polymer types and concentrations, different filler types and contents, and fabrication procedure were investigated. Scanning Electron Microscopy (SEM) analysis showed acceptable connections between the two phases and the MMMs performed higher performance compared to the polymeric membranes. Thermal treatment of the MMMs, as a defect repairing technique, was found very effective. Performed pervaporation and gas permeation experiments showed better separation performances of the MMMs with respect to those of the neat polymeric membranes. The results showed up to seven and two times increment in separation factors of MMMs regarding to neat polymeric membranes for pervaporation and gas separation experiments, respectively, while permeation rates nearly remained constant indicating effectiveness of the proper filler incorporation within polymer matrices approach.     

Development of polybenzoxazine membranes for ethanol–water separation via pervaporation

Polybenzoxazine membranes have been successfully synthesized from bisphenol-A, formaldehyde, and three different types of diamines: hexa-methylenediamine (hda), tetraethylenepentamine (tepa), and tetraethylenetriamine (teta) via a facile “quasi-solventless” method. To study the possibility of using polybenzoxazine membranes in a pervaporation system for ethanol–water separation, the sorption and swelling behaviors of these membranes were investigated. When hda was used as a reactant, the resulting polybenzoxazine membranes showed the best service time and interestingly only water permeated the membranes under the studied operation conditions. The total permeation flux was found to be 1.52 kg/m²h and the separation factor was higher than 10,000. Additionally, an increased permeation flux was achieved by raising the temperature of the feed solution and decreasing the membrane thickness. The optimum conditions for this study were 70 °C for the feed mixtures when a 200 μm thick was used.     

Separation and estimation of anionic surfactants by thin layer chromatography: i. Mixtures of sodium dodecyl benzenesulfonate,sodium dodecyl sulfate and sodium dodecanesulfonate

The conditions for separation and quantitative determination of anionic surfactants such as sodium dodecylbenzenesulfonate, sodium dodecanesulfonate and sodium dodecyl sulfate by thin layer chromatography (TLC) were investigated. Analytical results for mixtures of 2 or 3 components under optimal TLC conditions were in satisfactory agreement with known values. The absolute errors and variation coefficients both were within ca. 4%.     

Lipase-mediated synthesis of alkyl ricinoleates and 12-hydroxy stearates and evaluation of the surfactant properties of their sulfated sodium salts

An efficient and simple lipase-mediated synthesis of alkyl ricinoleates and 12-hydroxy stearates was performed by transesterification of methyl ricinoleate/12-hydroxy stearate and various alcohols in a solvent-free system without estolide formation. The reaction conditions were optimized by varying the temperature, pressure, and dosage of lipase. Sulfates of alkyl ricinoleates/12-hydroxy stearates were evaluated for surfactant properties such as surface tension, critical micelle concentration, emulsifying properties, foaming power, and calcium tolerance. The surfactant properties of sulfated alkyl ricinoleates were found to be superior to the sulfated alkyl 12-hydroxy series. The surfactant properties of the above two series of compounds were then compared with sodium dodecyl sulfate, and the properties of sulfated dodecyl ricinoleate and sulfated dodecyl 12-hydroxy stearate were found to be comparable with sodium dodecyl sulfate.     

Separation Characteristics of Dimethylformamide/Water Mixtures through Alginate Membranes by Pervaporation,Vapor Permeation and Vapor Permeation with Temperature Difference Methods

Abstract

In this study permeation and separation characteristics of dimethylformamide (DMF)/water mixtures were investigated by pervaporation (PV), vapor permeation (VP), and vapor permeation with temperature difference (TDVP) methods using alginate membranes crosslinked with calcium chloride. The effects of membrane thickness (30–90 µm), feed composition (0–100 wt%), operating temperature (30–50°C) on the permeation rates and separation factors were investigated. The permeation rate was found to be inversely proportional to the membrane thickness whereas separation factor increased as the membrane thickness was increased. It was observed that the permeation rates in VP and TDVP were lower than in PV however the highest separation factors were obtained with TDVP method. Alginate membranes gave permeation rates of 0.97–1.2 kg/m² h and separation factors of 17–63 depending on the operation conditions and the method. In addition, sorption‐diffusion properties of the alginate membranes were investigated at the operating temperature and the feed composition. It was found that the sorption selectivity was dominant factor for the separating of DMF/water mixtures.     

表面活性剂双水相萃取分离氨基酸研究

用溴化十二烷基三乙铵(C12NE)与十二烷基硫钠(SDS)混合体系形成双水相,测定混合摩尔比与分相比例的关系,并以苯丙氨酸为萃取对象研究其在双水相体系中的分配及多级错流萃取效果。实验结果表明,当C12NE与SDS摩尔比为(1.6∶1)—(1.7∶1)时体系有分相,其中当C12NE与SDS摩尔比为1.65∶1时,分相所得上下相体积比为1∶1,且分相时间为10 m in左右,为适合实验条件。双水相体系萃取苯丙氨酸的结果表明,单级萃取率可达80%以上,二级萃取率可达99%以上。     

Recovery of Co2+ Ions from Aqueous Solutions by Froth Flotation

ABSTRACT

The recovery of Co(II) ions from aqueous solutions under acidic conditions (pH 5) was investigated in flotation columns with inside diameters of 4.0 and 8.0 cm. Three surfactants, dodecylamine, cetyl pyridinium chloride, and sodium dodecyl sulfate, were used as collectors. Sodium dodecyl sulfate was found to be the most efficient; all three, however, produced hydrated froths, leading to rather low recoveries and separation efficiencies. The volumetric gas flow rate was found to affect the process in relation to the amount of surfactant added and the column diameter. The scale-up of the column should be done in terms of the same superficial gas velocity in order to maintain similar levels of metal ion recovery.