SOLVENT EXTRACTION ENHANCED MICROFILTRATION OF STRONTIUM AND TECHNETIUM WITH DI-2-ETHYLHEXYLPHOSPHORIC ACID AND QUATERNARY AMMONIUM SALTS

ABSTRACT

Application of extractants in form of microphase (micelles or microdrops) separated from aqueous matrix by microfiltration, “solvent extraction enhanced microfiltration (SEEMF)” is closely related to micellar enhanced ultrafiltration (MEUF) technique.

Uptake of strontium from aqueous solutions with microphase di-2-ethylhexylphosphoric acid (DEHPA) and pertechnetate with quaternary ammoniumsalts (QAS): trioctylmethylammonium chloride, benzyldodecyl-dimethylammonium bromide, and n-(α-carbethoxypenthadecyl)trimetyl-ammonium chloride was investigated as a function of microphase concentration and composition, pH and salinity of aqueous phase. Recovery of microfiltration on cellulose acetate 200 nm filters reached 95% for strontium with 4×10^?3 M DEHPA and 99% for technetium with 10^?4 M trioctyl-methylammonium chloride. A substantial part of 88-99% retention of technetium with investigated quaternary ammonium salts on microfilter may be caused by the filter wetting or sorption phenomena.     

The role of cationic surfactants in the selective flotation of phosphate ore constituents

The quaternary amine salts cetylrimethyl ammonium bromide (CTAB) and cetylpyridinium bromide (CPB), as well as the primary amine salts dodecylammonium acetate (DAA) and cetylammonium acetate (CAA), were used to determine the flotation characteristics of the major constituents of phosphate ores. The pure chemicals tricalcium phosphate (T.C.P.) and calcium carbonate and the pure minerals francolite, calcite and quartz were investigated.Adsorption of CTAB on francolite is limited to a very loose packed monolayer which is very similar to that on CaCO₃ but not T.C.P. The low affinity of francolite to CTAB and hence its lower floatability were interpreted in terms of the coexisting surface carbonate groups and surface roughness.Effective separation of T.C.P. from the CaCO₃ mixture is reached on using 0.2 mM CTAB solution. Quartz, on the other hand, is readily floated from synthetic ores by quaternary ammonium and primary ammonium salts, but the latter are less superior and their selectivity decreases with increasing chain length. Phosphates and carbonates float almost equally with DAA and CAA.The adsorption and flotation properties of three types of phosphate ores, namely (I) siliceous- , (II) siliceous—calcareous- , and (III) calcareous phosphates were studied. Considerable upgrading of the ores I and II was obtained from 18.1 to 29.8% P₂O₅ and from 17.0 to 27.3% P₂O₅, but little was achieved with sample III.     

Properties of the Quaternary Ammonium Salts with Novel Counterions

The Krafft temperatures, surface tensions and bacteriostatic efficacies of a series of dodecyl/tetradecyltrimethylammonium salts with new type counterions based on the general formula RN⁺(CH₃)₃?A^? were measured. The results revealed that the Krafft temperatures of the studied products were below 0?°C and the surface tensions of water were decreased to 22?C42?mN?m^?1 when applying these surfactants at a concentration range from 10^?2 to 10^?4?mol?L^?1. Moreover, the physicochemical parameters such as the saturation adsorption value, the minimum area per surfactant molecule and the standard thermodynamic parameters of adsorption and micellization varied with different counterions for these prepared quaternary ammonium salts. In addition, the bacteriostatic tests showed that the counterions with shorter carbon chain lengths were associated with greater efficacy for the novel quaternary ammonium salts studied here.     

Biocidal polymers active by contact. III. Ageing of biocidal polyurethane coatings in water

Polyurethane coatings prepared from hydroxytelechelic polybutadiene with pendant qua-ternary ammonium salts (QAS) are able to kill microorganisms, these biocidal polymers were submitted to various ageing conditions. The activity remained constant after exposure to a very high number of bacteria (Escherichia coli). Nevertheless immersion in water caused a slow decrease of activity with time whatever the QAS examined (? N⁺R₂R′ with R = Me or Bu and R′ = n-octyl to n-hexadecyl). The phenomenon can be analysed in two stages. The first one, short (5–10 days) and limited, is due to the diffusion of a water-soluble synthesis residue. At the end of this period, the samples are still active and the activity is only due to a contact polymer-bacteria. The second stage is much slower and is accompanied by a transformation of QAS in amine. This is attributed to an equilibrium between QAS, amine, and alkyl bromide slowly shifted toward the formation of amine because of a weak solubility of alkyl bromide in water. Increasing the lipophilicity and bulkiness of the QAS substituents improves the durability of the biocidal activity. Some samples still exhibit a good activity after more than 1 year of ageing in harsh conditions. © 1993 John Wiley & Sons, Inc.     

Synthesis,Characterization and Surface-Activity of Hydroxyethyl Group-Containing Quaternary Ammonium Surfactants

A novel series of hydroxyethyl group-containing quaternary ammonium salts were synthesized from mono-, di-, tri-alkyl tertiary amines, hydrochloric acid and ethylene oxide by a two-step process with mild reaction conditions. The structures of the quaternary ammonium salts were characterized by infrared spectroscopy and ¹H-nuclear magnetic resonance spectroscopy. The surface tensions at the critical micelle concentrations were measured to investigate the surface activities of the prepared compounds. The results showed that the hydroxyethyl group quaternary ammonium salts exhibit high surface activities.     

Extraction of Rare Earth Metals Using Liquid Surfactant Membranes Prepared by a Synthesized Surfactant

Abstract

Three surfactants, l-glutamic acid dioleyl ester ribitol (nonionic, 2C ₁₈Δ⁹ GE), l-glutamic acid dioleyl ester quaternary ammonium chloride (cationic, 2C ₁₈Δ⁹ GEC ₂ QA), and dioleyl dimethyl quaternary ammonium chloride (cationic, 2C ₁₈Δ⁹ QA) were synthesized for potential use in liquid membrane operations. These surfactants have strongly hydrophobic, twin oleyl chains as the hydrophobic moiety. Using the synthesized surfactants, extraction of rare earth metals was carried out by liquid surfactant membranes in a stirred tank. The extraction behavior of 12 kinds of rare earth metals was systematically studied with 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester (commercial name: PC-88A) as a carrier. Different surfactants having an identical hydrophobic moiety can have significantly different behaviors in rare earth extractions by liquid surfactant membranes, where extraction efficiency appears to be governed by the nature of the interfacial microenvironment between oil and water. An interfacial reaction model which takes into account the adsorption of a surfactant at the interface has been proposed to evaluate the permeation rate of rare earth metals by liquid surfactant membranes. It was found that a cationic surfactant strongly enhances the extraction rate of rare earth metals compared with the conventional surfactant, Span 80. The cationic surfactant 2C ₁₈Δ⁹ GEC ₂ QA appears to be one of the best surfactants currently available for rare earth extraction by liquid surfactant membranes.     

Dehydrating Effect of Concentrated Aqueous Alkaline Solutions in Aliphatic Nucleophilic Substitutions Carried out in Aqueous-Organic Two-Phase Systems. The Different Behavior of Various Phase-Transfer Catalysts: Quaternary Salts,Crown Ethers and Cryptands

Concentrated aqueous NaOH and KOH solutions affect the hydration and hence the reactivity of anions (Cl⁻, Br⁻, I⁻, SCN⁻, N⁻₃) in aliphatic nucleophilic substitutions catalyzed by lipophilic quaternary onium salts, cryptands and crown ethers under phase-transfer (PTC) condtions. In the presence of aqueous 50% NaOH or 53% KOH non-hydrated anions are transferred from the aqueous into the organic phase by quaternary salts. The anionic reactivity thus becomes identical to that found under anhydrous homogeneous conditions in non-polar organic media. Unlike quaternary salts, in the presence of cryptates water is not completely removed even at the highest KOH concentration, i.e. conditions in which aH₂O ∼ 0. Residual hydration depends on the nature of the anion and is the highest for anions with localized and/or less polarizable charge, such as Cl⁻, Br⁻ and N⁻₃. As a consequence, rate constants noticeably increase in comparison with those found under conventional PTC conditions, but don't reach those of anhydrous solutions. Behavior of crown ethers is in between that of quaternary salts and cryptates, since residual hydration in the presence of 53% aqueous KOH is lower than that of cryptates, whereas anionic reactivity become practically identical to that found under anhydrous conditions. A comparison of the catalytic efficiency of lipophilic quaternary salts, cryptands and crown ethers under various reaction conditions is also included.     

Keggin型磷钨钒杂多酸季铵盐的合成、表征及抑菌效果的研究

以不同钒原子数取代Keggin型磷钨杂多酸并与十六烷基三甲基溴化铵反应合成了3种杂多酸季铵盐.通过红外光谱(IR)、X-射线衍射(XRD)、紫外(UV)等表征手段确定了杂多酸以及杂多酸季铵盐的结构.结果表明,在红外光谱中,引入钒原子后阴离子负电荷增加,导致相应的特征峰出现红移现象;从X-射线衍射谱图中确定了杂多酸季铵盐的二级结构,最后通过热重分析(TG)得出杂多酸季铵盐所含结晶水的数目.通过杯碟法测试了目标产物对大肠杆菌、金黄色葡萄球菌、枯草芽孢杆菌、蜡样芽孢杆菌的抑菌性能,结果表明杂多酸季铵盐对枯草芽孢杆菌的抑菌能力最好,并且钒原子所占比例越高,抑菌效果越好.     

季铵盐型抗菌纤维素纤维的辐射接枝聚合

固相表面接触抗菌材料应用于水的表面接触消毒是一项新的水处理技术,提高材料表面抗菌基团含量将有利于抗菌性能的提高。本研究采用直接辐射接枝和预辐射接枝两种方法,在纤维素纤维表面引入具有抗菌功能的季铵盐聚合物,详细探讨了两种辐射接枝聚合技术以及温度、时间、单体浓度、辐射剂量等具体辐射接枝聚合工艺参数对接枝聚合反应的影响。利用红外光谱（FTIR）、扫描电子显微镜（SEM）对接枝纤维素纤维进行了表征。结果表明,采用预辐射接枝技术可制得接枝率55%以上的高接枝率抗菌纤维素纤维。     

季铵盐链长及用量对CnTA+/蒙脱石纳米复合物吸附PAEs的影响

用具有相同结构但不同烷基碳链长度的系列季铵盐制得C_nTA⁺/蒙脱石纳米复合物,并对水溶液中邻苯二甲酸酯进行吸附实验。探讨了季铵盐烷基碳链链长和用量对制得的C_nTA⁺/蒙脱石纳米复合物吸附水溶液中PAEs效果的影响。结果表明:C_nTA⁺/蒙脱石纳米复合物能有效地吸附溶液中的PAEs,季铵盐烷基碳链链长及用量均对C_nTA⁺/蒙脱石纳米复合物的吸附效果产生影响。当季铵盐用量较低时,随着季铵盐烷基链长的增加,PAEs的吸附去除率增加;增大季铵盐用量,随着季铵盐烷基链长的增加,PAEs的吸附去除率先增大后减小。     

Polysiloxanes With Quaternary Ammonium Salt Biocidal Functions and Their Behavior When Incorporated Into a Silicone Elastomer Network

Polysiloxanes of various structures having biocidal quaternary ammonium salt (QAS) groups pendant to the polymer chain were prepared. Their antibacterial activities were compared in aqueous solution. Selected polysiloxanes were linear polydimethylsiloxanes having 20% siloxane units substituted at silicon by 3(dimethyl-n-octylammonio)propyl chloride or 3(dimethyl-n-hexadecylammonio)propyl chloride and terminated by silanol functions at both chain ends. They were crosslinked and also incorporated by co-crosslinking into an RTV (room temperature vulcanized) silicone elastomer. Bacteriocidal activities of surfaces of the crosslinked biocidal polysiloxanes and of the elastomers having incorporated these polymers were determined by the colony count method. Thousand-fold reduction of Staphylococcus aureus in contact with the dimethyl-n-octylammonio substituted polymer was achieved in 2 min and in contact with the elastomer containing 20 wt% of this polymer in 15 min, although the density of the QAS was as low as 0.36 mmol/g. The surface structure and properties of the elastomers were studied by XPS, contact angle, AFM and model human serum protein (HSA) adsorption. Water sorption by this material was also studied. The concentration of QAS groups on the elastomer surface depended strongly on the material surroundings. No QAS was found on the surface in ultrahigh vacuum, while a strong enhancement of QAS presence on the surface was observed when it was in contact with water or water vapor. Hydrophobicity of the elastomer surface was little affected by the incorporated biocidal QAS-containing polysiloxane when the elastomer was kept in air. This material showed little ability to adsorb the HSA protein from its aqueous solution.     

Biocidal polyurethane and its antibacterial properties

The antimicrobial finishes on the cotton fabrics has been known and reported recently. Particularly, the reactive-antimicrobial finishes are the most attractive. In this study, we synthesized three types of polyurethane (PU) polymers; type A (molecular weight of polytetramethylene glycol (PTMG) is 2000), type B (molecular weight of PTMG is 1000), and type C (molecular weight of PTMG is 650). Firstly, the PU prepolymers were prepared by reacting PTMG with 4,4′-diphenylmethane diisocyanate (MDI), then were extended with diethylenetriamine (DETA) (or DETA/hydrazine mixture) to form the PU polymer. The polymer was then grafted with epichlorohydrin and further reacted with different amounts of biocide (QAS) to form biocidal active PU quaternary ammonium salts. The biocidal properties of the PU films were evaluated by the agar plate and the shake flask method. From the experimental results, it demonstrates that these films and finished fabrics exhibit a high biocidal activity against Staphylococcus aureus. The biocidal activity is found to increase with the amount of QAS. After rinsing with water, the biocidal characteristics of these films and finished fabrics remain. From IR spectra, PU films with covalent bond of QAS show an absorption peak at 2300 cm⁻¹, which corresponds to the presence of silicon in QAS. For the mechanical properties, the PU films with QAS sustain the mechanical properties in spite of the increasing amount of grafted QAS.     

Preparation and antimicrobial activity of terpene-based polyurethane coatings with carbamate group-containing quaternary ammonium salts

A series of novel carbamate group-containing quaternary ammonium salts (QASs) have been synthesized, which were subsequently used as antimicrobial agent and incorporated into polyurethane coatings through crosslinking with terpene-based polyol and polyisocyanate. The chemical structures of QASs were characterized by FT-IR, ¹H NMR, and ¹³C NMR. The effects of QASs on the properties of coatings were investigated. The results showed that the resulting coatings exhibited significant antimicrobial activity against both Staphylococcus aureus and Escherichia coli by introducing QASs into the polyurethane networks. Furthermore, with the increasing of QAS content, the antimicrobial activity and adhesion of the coatings were enhanced, while the pencil hardness, water resistance and thermal stability of the coatings were decreased.     

Synthesis, Characterization and Properties of New Lauryl Amidopropyl Trimethyl Ammoniums

A new lauryl amidopropyl trimethyl ammonium methyl carbonate with the formula CH₃(CH₂)₁₀CONH(CH₂)₃N⁺(CH₃)₃CH₃CO₃ ^? was synthesized via a high pressure process with tertiary amines and dimethyl carbonate, and its chemical structure was confirmed using ¹H-NMR spectra, mass spectral fragmentation, and FTIR spectroscopic analysis. In addition, several quaternary ammonium salts with new counterions X^? (X^?=HCO₃ ^?, HCOO^?, CH₃COO^?, CH₃CH(OH)COO^?) were also synthesized by the ion exchange reaction of methyl carbonate quaternary ammoniums with corresponding acids. The surface activities of these compounds were measured, including surface tension (??), critical micelle concentration and minimum surface area (A _min) at 25?°C. Adsorption and micellization free energies of these quaternary ammonium salts in their solutions showed a good tendency towards adsorption at interfaces. The antimicrobial activities are reported for the first time against representative bacteria and fungi for lauryl amidopropyl trimethyl ammoniums. It was found that the antimicrobial potency was Gram-positive bacteria?>?fungi?>?Gram-negative bacteria.     

Novel Synthesized Gemini Surfactant as Corrosion Inhibitor for Carbon Steel in HCl Solution

A quaternary ammonium gemini surfactant containing an ester spacer, namely (diethylhexanedioate)diyl‐α,ω‐bis(dimethyl myristyl ammonium bromide) ( 14‐DEHA‐14 ) was synthesized using a two‐step procedure with dimethyl hexanedioate, dimethylaminoethanol, and 1‐bromotetradecane. The chemical structure of the compound was confirmed by infrared (IR) spectrum, ¹H nuclear magnetic resonance (NMR), and elemental analysis. The critical micelle concentration was determined by conductivity and tensiometry measurements, and its inhibition effect on corrosion of carbon steel in dilute (1.0 M) hydrochloric acid solution was investigated by weight loss measurements. The results show that the synthesized gemini surfactant acts as an excellent corrosion inhibitor in 1.0 M HCl solution. The adsorption of the inhibitor via chemical adsorption onto the carbon steel surface obeyed the Langmuir adsorption isotherm. A possible corrosion mechanism of the compound is discussed in relation to the calculated thermodynamic parameters and adsorption isotherm.     

The Stability of the Adsorption of Some Anions on Chemical Manganese Dioxide

The stability of the adsorption of three anions (nitrate, bromide, and chloride) on chemical manganese dioxide (CMD) was studied using a two‐variable, two level factorial design. The two variables were the concentration and pH of the solutions of the sodium salt of the anions. The concentration CMD was varied from 1 M–0.001 M and the pH from 3.5–2.5. 84, 67, and 54 % variations in the adsorption of Br^–, NO₃^–, and Cl^– on CMD, respectively, were obtained. Independently, the concentration and pH affected the electric surface charge. However, their combined influence has a negative and low effect. The surface response plots of the model equations, which did not show the optimum values for concentration and pH, reinforced this observation. The highest stability of the anions was observed when concentration and pH were at their minimum values of 0.001 M and 2.5, respectively.     

Low environmental sensitive antistatic material based on poly(vinyl chloride)/quaternary ammonium salt by blending with poly(ethylene oxide)

A quaternary ammonium salt (QAS) was synthesized and characterized by ¹H NMR. A low environmental sensitive antistatic plasticized poly(vinyl chloride) (PPVC) was prepared by blending with QAS and poly(ethylene oxide) (PEO). The structure and properties of PPVC/QAS/PEO blend were studied by scanning electronic microscope (SEM), surface resistivity, and mechanical properties tests. The results show that the surface resistivity of PPVC/QAS/PEO (100/4.5/0) blend without PEO component can be reduced to less than 3.0 × 10⁸ Ω at 65% environmental humidity, which satisfied the antistatic property requirement related to MT113‐1995 of China. However, QAS, similar to other commercial antistatic agents, is much sensitive to environmental humidity. When a small amount of PEO is added, the surface resistivity of PPVC/QAS/PEO blend has a quite low sensitivity to environmental humidity and further reduces. An excellent antistatic property of PPVC/QAS/PEO blend under low humidity can be achieved. Its tensile strength and elongation at break are also improved with PEO addition. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Poly(sulfobetaine)s and corresponding cationic polymers. XI. Synthesis and aqueous solution properties of a cationic poly(methyl iodide quaternized ethyl vinyl ether/N,N‐dimethylaminopropyl maleamidic acid) copolymer

A copolymer prepared by the copolymerization of ethyl vinyl ether and maleic anhydride underwent amidoacidation with N,N‐dimethylaminopropylamine. The obtained ethyl vinyl ether/dimethylaminopropyl maleamidic acid copolymer was then reacted with methyl iodide to yield poly(methyl iodide quaternized ethyl vinyl ether/N,N′‐dimethylaminopropyl maleamidic acid) (MIQEDMAPMA). The greatest difference from other polyelectrolytes was the carboxylic group on the polymer chain unit of MIQEDMAPMA. Its aqueous solution properties in various salts and at various pH values were studied by measurements of the reduced viscosity and intrinsic viscosity. The reduced viscosity and intrinsic viscosity of this cationic polyelectrolyte were related to the types and concentrations of the added salts. The tendency of the salt effect was similar to that of other polyelectrolytes; that is, soft salt anions were more easily bound to the quaternary ammonium (R₄N⁺) of MIQEDMAPMA than hard salt anions. Some salt ions strongly attracted the quaternary ammonium of the cationic polymeric side chain for the agglomeration of the polymers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2261–2269, 2003     

Quaternary Ammonium Salts (QAS) Modified Polysiloxane Biocide Supported on Silica Materials

Three types of silica particles modified with vinyl groups were obtained: (i) xerogel formed by hydrolytic polycondensation of the mixture of tetramethoxysilane (TMOS) and 1,1,1,7−tetramethoxy-3,5,7-trimethyl-3,5,7-trivinyltetrasiloxane, (ii) mesoporous silica obtained from the same precursors in the presence of the cetyltrimethylammonium bromide (CTAB), and (iii) commercial Fluka silica gel 60A with a vinyltriethoxysilane-treated surface. Vinyl groups on these silica materials were transformed into silyl chloride by hydrosilylation with HMe₂SiCl. These groups were used to graft living polysiloxane that was synthesized by anionic ring-opening polymerization of 2,4,6-tri(3-chloropropyl)-2,4,6-trimethylcyclotrisiloxane and initiated by BuLi. Chloropropyl groups on the grafted polymer were used to quaternize N,N-dimethyl-n-octylamine. Silica particles with grafted polysiloxane having quaternary ammonium salt (QAS) groups pendant to polymer chains were obtained. Silica material with QAS groups directly attached to the surface were generated by the action of N,N-dimethyl-n-octylamine on particles obtained by the sol–gel process involving tetraethoxysilane (TEOS) with 3-chloropropyltriethoxysilane. The bacteriocidal properties of all these materials were tested in water suspension against five representative strains for Gram-positive and Gram-negative bacteria. Some of the silica–polysiloxane hybrid materials have good antibacterial properties against Gram-positive strains, but not as good as the non-tethered QAS-substituted polysiloxane in water solution. The QAS groups that are directly bonded to the silica material surface are inactive.     

新型蓖麻油基季铵盐的合成及其抑菌性能研究

以蓖麻油酸甲酯为起始原料,与N,N-二甲基-1,3-丙二胺和溴化苄、溴乙烷通过酰胺化反应和季铵化反应生成了新型蓖麻油基季铵盐,其结构经FTIR、1HNMR、13CNMR及ESI-MS进行了确证。采用抑菌圈直径法对目标产物的抑菌性能进行了测试,结果表明,两种季铵盐均有一定的抑菌活性,N,N-二甲基-N-乙基-蓖麻油酸酰胺丙基溴化铵的抑菌活性略强于N,N-二甲基-N-苄基-蓖麻油酸酰胺丙基溴化铵。