Quaternary Ammonium Chloride Research Articles

Resistance of two temperate Lactobacillus paracasei bacteriophages to high pressure homogenization, thermal treatments and chemical biocides of industrial application

Temperate bacteriophages ф i Lp84 and ф i Lp1308, previously isolated from mitomycin C-induction of Lactobacillus paracasei strains 84 and CNRZ1308, respectively, were tested for their resistance to several physical and chemical treatments applied in dairy industry. Long-term survival at 4 °C, −20 °C and −80 °C, resistance to either thermal treatments of 63 °C, 72 °C and 90 °C, high pressure homogenization (HPH, 100 MPa) or classic (ethanol, sodium hypochlorite and peracetic acid) and new commercial sanitizers, namely A (quaternary ammonium chloride), B (hydrogen peroxide, peracetic acid and peroctanoic acid), C (alkaline chloride foam), D (p-toluensulfonchloroamide, sodium salt) and E (ethoxylated nonylphenol and phosphoric acid), were determined. Phages were almost completely inactivated after eight months of storage at 25 °C, but viability was not affected at 4 °C, −20 °C or −80 °C. Both phages tolerated well HPH treatments. Phage i Lp1308 showed higher thermal resistance than ф i Lp84, but neither resisted 90 °C for 2 min. Best chemical inactivation was accomplished using peracetic acid or biocides A, C and E, whereas biocides B and D were completely ineffective. These results help to improve selection of chemical agents and physical treatments to effectively fight against phage infections in dairy plants.

Development and characterization of polymer inclusion membranes for the separation and speciation of inorganic As species

This study involves the preparation and optimization of polymer inclusion membranes (PIMs) based on the polymer cellulose triacetate and the extractant (carrier) Aliquat 336 (a mixture of quaternary ammonium chlorides) for the transport of inorganic As species (arsenite and arsenate) from their aqueous solutions. The influence of the composition of the membranes on its extraction and transport properties was investigated. Better membrane performance was obtained when the membranes did not contain plasticizer and the concentration of the extractant was high. Under these conditions arsenate (As(V)) could be quantitatively separated from As(III) within 5 h even in the presence of common anions (i.e. chloride, phosphate, nitrate, sulfate and carbonate) often encountered in natural waters and industrial and domestic wastewaters. Electrical impedance spectroscopy measurements allowed the determination of the dielectric constant and conductivity values of the PIMs of interest. These results suggested that the extracted As(V) species was HAsO 4 2− which was further transported across the membrane by a hopping mechanism, counter currently to the transport of the chloride anions present at a high concentration in the stripping solution. The overall performance of the proposed PIM in terms of stability, selectivity and permeability compared favorably to those of an Aliquat 336 based supported liquid membrane and a commercial multi-valent anion exchange membrane.

Development, Characterization and Performance Evaluation of Positively-Charged Thin Film-Composite Nanofiltration Membrane Containing Fixed Quaternary Ammonium Moieties

Thin film composite (TFC) type positively-charged nanofiltration membranes, bearing fixed quaternary ammonium moieties, have been developed and studied. Branched polyethyleneimine (PEI) was functionalized by reaction with glycidyl trimethyl ammonium chloride (GTACl) to introduce quaternary ammonium chloride. Positively-charged TFC membranes were prepared by in situ interfacial polymerization of functionalized PEI and terephthaloyl chloride. The effects of variation of chemical compositions and other experimental conditions such as curing temperature and duration of curing on the performances of the membrane were studied. ATR FT-IR spectroscopy was done to establish the presence of charge-bearing groups in the membrane. The membranes were tested using single solute feed solutions of NaCl, Na2SO4, CaCl2, and MgSO4. Positive charges on the membranes were estimated in terms of their ion-exchange capacities (IEC). The values were also correlated to the solute-rejection properties of the membranes.

EFFECT OF COAGULATING SKIM NR PARTICLES AS NR–CLAY NANOCOMPOSITE: PROPERTIES AND STRUCTURE

Abstract New materials of skim NR–clay nanocomposites were prepared by a coagulating method using several organoclays, i.e., dodecyl ammonium–montmorillonite, Cloisite 15A, Cloisite 20A, and Cloisite 25A, which were modified by dodecyl ammonium chloride, dimethyl dehydrogenated tallow quaternary ammonium chloride, dimethyl dehydrogenated tallow quaternary ammonium chloride, and dimethyl hydrogenated tallow 2 ethylhexyl quaternary ammonium methyl sulfate, respectively. X-ray diffraction revealed that the intercalated nanocomposites were formed depending on the type and content of organoclays, and the excellent dispersion of clay in rubber matrix could be confirmed by transmission electron microscopy micrographs. In addition, thermal stability of the coagulated skim rubber–organoclay nanocomposites was improved as shown by the thermogravimetric analysis. The mechanical properties and dynamic-mechanical thermal analysis revealed that hardness and storage modulus of nanocomposites were improved and the glass transition temperature of nanocomposites increased as compared with that of the pure skim NR. Thus, not only recovery of this significant fraction of the lost rubber material but also reinforced skim rubber particles were obtained by the use of a coagulating method using several organoclays.

EFFICACY OF SODIUM HYPOCHLORITE AND QUATERNARY AMMONIUM COMPOUNDS ON YEASTS ISOLATED FROM APPLE JUICE

ABSTRACTIn this work, we evaluated the effectiveness of sodium hypochlorite and a commercial quaternary ammonium compound against four wild yeast strains in their different growth forms: planktonic, sessile and forming microcolonies. These yeasts had been isolated from apple juice processing plant, and appropriate environmental conditions were employed throughout the work. For planktonic cells, 4 log reduction was obtained using the lowest concentration of sodium hypochlorite (200 ppm) on all tested strains. However, quaternary ammonium chloride was effective only on Zygosaccharomyces sp. in all in‐use concentrations tested, and only the stronger in‐use concentration (1:30) was effective on Rhodotorula mucilaginosa. Because of the above results, the disinfection on sessile yeast cells was performed only with sodium hypochlorite solutions. In cells attached in batch conditions, the highest concentration of sodium hypochlorite (500 ppm) was necessary to get 4 log reduction. In order to obtain a 3 log reduction on Zygosaccharomyces sp. microcolonies formed in laminar flow conditions, the combined action of 0.5% w/v NaOH and 500 ppm sodium hypochlorite was required. We concluded, thus, that cells forming microcolonies under laminar flow conditions were less susceptible to disinfectants than those suspended or attached in batch conditions. These results also indicated that attachment and colonization of autochthonous yeasts must be properly identified to evaluate the effectiveness of disinfectants used in apple juice processing plants.PRACTICAL APPLICATIONSBiofilm formation is a serious hygienic problem in food industry. In fruit processing plants, the microbial attachment causes serious engineering problems such as decreases in permeate flow in membrane processes, greatly reducing operating efficiency of ultrafiltration process. Moreover, the presence of microorganisms attached to food contact surfaces could increase the fluid frictional resistance of surfaces, increases the corrosion rate of surfaces leading to energy and production losses and compromises the hygienic quality of the final product causing significant economic losses. Our results show that the evaluation of the effectiveness of a disinfectant on biofilms should be performed using a method where the adhesion and colonization of cells was carried out in flow conditions similar to those of the environment where the disinfectant is applied. We observed that even when using new surfaces, and performing both cleaning and sanitizing under optimal conditions, the risk that the number of viable cells remaining on the surface can generate a new biofilm subsists.

Swelling of Brazilian Organoclays in Some Solvents with Application in the Petroleum Industry

Brasgel clay has been modified via cation exchange reaction using quaternary ammonium chlorides (stearyl dimethylammonium chloride, Praepagen). Basal spacing, interlamellar structure clay have been characterized using X-ray diffraction (XRD) technique. The organoclay was characterized by the Foster Swelling test. The results indicated that the quaternary ammonium salts were intercalated between the layers of clay. The Foster Swelling Test results indicated that the affinity of stearyl dimethylammonium chloride, Praepagen occurred in the treated clay tested in all organic solvents (diesel, gasoline, toluene and p-xylene), without and with agitation. the treated sample presented a high swelling capacity (with and without agitation) when tested in gasoline. On the other hand, when inserted in diesel oil without agitation, the treated samples presented low swelling capacity, but when the assay was performed under agitation, it yielded an intermediate swelling capacity. In Toluene, the samples presented intermediate swelling, both without and with agitation. In p-xylene, the samples presented low swelling, without and intermediate swelling, with agitation. Therefore, this clay can be used for the removal of oils and greases from polluted aqueous effluents of the petroleum industry.

Rifampin-Isoniazid Oligonucleotide Typing: an Alternative Format for Rapid Detection of Multidrug-Resistant Mycobacterium tuberculosis

A reverse line blot DNA hybridization format for rapid detection of multidrug-resistant tuberculosis was developed. Simultaneous detection of rifampin and isoniazid resistance in clinical isolates of Mycobacterium tuberculosis was based on the same amplification/reverse hybridization principle of the widely used spoligotyping. The test involved probing nine DNA regions that are targets of common drug resistance-associated mutations in the genes rpoB, katG, and inhA. Addition of quaternary amine tetramethyl ammonium chloride to the hybridization buffer promoted multiple hybrid formations at a single annealing temperature irrespective of the different GC contents of probes. The assay was standardized using 20 well-documented strains from the Institute of Tropical Medicine (Belgium) and evaluated blindly in a central laboratory with 100 DNA samples that were obtained from cultured clinical isolates and shipped dried from three other countries. Compared with drug susceptibility testing, both sensitivity and specificity for rifampin resistance detection were 93.0% while for isoniazid the values were 87.7% and 97.7%, respectively. Compared with sequencing and GenoType MTBDRplus methods, sensitivity and specificity reached 96.4% and 95.5% for rifampin and 92.7% and 100% for isoniazid. Altogether, 40/45 (89%) multidrug-resistant isolates were correctly identified. Advantages of this in-house development include versatility, capacity to run up to 41 samples by triplicate in a single run, and reuse of the membrane at least 10 times. These features substantially reduce cost per reaction and make the assay an attractive tool for use in reference laboratories of countries that have a high burden of multidrug-resistant tuberculosis but that cannot afford expensive commercial tests because of limited resources.

Effect of surface modification of montmorillonite on the properties of rigid polyurethane foam composites

This study investigated the influence of various organically modified montmorillonites (organoclays) on the structure and properties of rigid polyurethane foam (RPUF) nanocomposites. The organoclays were modified with cetyltrimethyl ammonium bromide (CTAB), methyl tallow bis(2-hydroxyethyl) quaternary ammonium chloride (MT2ETOH) and tris(hydroxymethyl)aminomethane (THMA) and denoted as CMMT, Cloisite 30B and OMMT, respectively. MT2ETOH and THMA contain hydroxyl groups, while THMA does not have long aliphatic tail in its molecule. X-ray diffraction and transmission electron microscopy show that OMMT and Cloisite 30B can be partially exfoliated in the RPUF nanocomposites because their intercalating agents MT2ETOH and THMA can react with isocyanate. However, CMMT modified with nonreactive CTAB is mainly intercalated in the RPUF matrices. At a relatively low filler content, the RPUF/CMMT composite foam has a higher specific compressive strength (the ratio of compressive strength against the apparent density of the foams), while at relatively high filler contents, RPUF/Cloisite 30B and RPUF/OMMT composites have higher specific compressive strengths, higher modulus and more uniform pore size than the RPUF/CMMT composite.

CdTe nanocrystal–polymer composite thin film without fluorescence resonance energy transfer by using polymer nanospheres as nanocrystal carriers

A series of positively charged polystyrene (PS) nanosphere emulsions were prepared by copolymerization of quaternary ammonium chloride cationic monomer with styrene via emulsifier-free emulsion polymerization. The average diameter of the nanospheres was tuned in the range of 35–100 nm by adjusting the recipe. The PS nanospheres were used as carriers of aqueous CdTe nanocrystals (NCs) by adsorbing them on the surface through static interaction. After attached to the nanospheres, NCs’ stability against pH change and UV light irradiation was enhanced. The CdTe–PS composite nanospheres were blended with compatible poly (vinyl alcohol) (PVA) matrix to prepare fluorescent thin film by spin coating. CdTe–PS nanospheres had homogenous distribution in the thin film and their light scattering performance was largely reduced after solvent evaporated, as a result, the composite thin film was highly transparent. In the meantime, the immobilization effect of PS nanospheres prevented NCs from aggregation, thus they preserved original high fluorescence without fluorescence resonance energy transfer. The CdTe–PS/PVA composite solution has potential applications in light emitting devices by inkjet printing.

Temperate and virulent Lactobacillus delbrueckii bacteriophages: Comparison of their thermal and chemical resistance

The aim of this work was to study the efficiency of diverse chemical and thermal treatments usually used in dairy industries to control the number of virulent and temperate Lactobacillus delbrueckii bacteriophages. Two temperate (Cb1/204 and Cb1/342) and three virulent (BYM, YAB and Ib3) phages were studied. The thermal treatments applied were: 63 °C for 30 min (low temperature – long time, LTLT), 72 °C for 15 s (high temperature – short time, HTST), 82 °C for 5 min (milk destined to yogurt elaboration) and 90 °C for 15 min (FIL-IDF). The chemical agents studied were: sodium hypochlorite, ethanol, isopropanol, peracetic acid, biocides A (quaternary ammonium chloride), B (hydrogen peroxide, peracetic acid and peroctanoic acid), C (alkaline chloride foam), D (p-toluensulfonchloroamide, sodium salt) and E (ethoxylated nonylphenol and phosphoric acid). The kinetics of inactivation were drew and T 99 (time necessary to eliminate the 99% of phage particles) calculated. Results obtained showed that temperate phages revealed lower resistance than the virulent ones to the treatment temperatures. Biocides A, C, E and peracetic acid showed a notable efficiency to inactivate high concentrations of temperate and virulent L. delbrueckii phages. Biocide B evidenced, in general, a good capacity to eliminate the phage particles. Particularly for this biocide virulent phage Ib3 showed the highest resistance in comparison to the rest of temperate and virulent ones. On the contrary, biocide D and isopropanol presented a very low capacity to inactivate all phages studied. The efficiency of ethanol and hypochlorite was variable depending to the phages considered. These results allow a better knowledge and give useful information to outline more effective treatments to reduce the phage infections in dairy plants.

Removal of Zn(II) from chloride acidic solutions with hydrophobic quaternary salts

Removal of Zn(II) from chloride acidic solutions with hydrophobic quaternary salts The equilibrium of zinc(II) extraction from hydrochloric acid solutions with phosphonium and ammonium quaternary salts and their application as carriers in polymer inclusion membranes were studied. The most efficient was the extraction of zinc with the use of chlorides and bromide of ammonium and phosphonium salt (more than 90%). Quaternary ammonium and phosphonium chlorides and bromide are efficient extractants of zinc(II) from hydrochloric acid solutions. Two-fold molar excess of extractant over Zn(II) is necessary for efficient extraction (100%). Solvent extraction power of the extractants studied decreases with increasing hydrophobicity of the anion in the following sequence: QPCl > QPBr > QPBis > QACl > QABF4 > QPBF4 > QPPF6 > QPNtf2. A solution of 1 M H2 SO4 is chosen as the best stripping phase from the technological and economical point of view. Transport across polymeric inclusion membrane enables concentration of the stripping solution; however it takes a very long time.

Removal of Cr(VI) from alkaline aqueous solutions using chemically modified magnetic chitosan resins

Chitosan was cross-linked using glutaraldehyde in the presence of magnetite. The resin obtained was chemically modified through the reaction with tetraethylenepentamine followed by glycidyl trimethylammonium chlorid to produce chitosan bearing amine (R1) and chitosan bearing both amine and quaternary ammonium chloride moieties (R2), respectively. The quaternary amine resin (R2) showed a higher affinity towards the uptake of Cr(VI) from alkaline medium, where an uptake value of 2.8mmol/g was reported at pH 8 and 25°C. The nature of interaction of R2 with chromate in alkaline medium was clarified. The resin Kinetics at different temperatures and thermodynamic parameters of the uptake process in alkaline medium were obtained. The uptake of Cr(VI) from different electrolyte solutions was studied. Regeneration curves for the desorption of Cr(VI) from R2 were studied. The adsorbed chromate anions was regenerated effectively (desorption ratio ~98%) using a mixture of 2M NaCl and 0.5M NaOH.

Analysis of Relationships Between Structure, Surface Properties, and Antimicrobial Activity of Quaternary Ammonium Chlorides

AbstractThe research concerns analysis of cause‐effect relationships occurring between condition attributes describing structure and surface‐active properties and decision attributes (antimicrobial activity) of alkyl(alkylthiomethyl)dimethylammonium chlorides and alkyl(alkoxymethyl)dimethylammonium chlorides. 72 ammonium chlorides were described by 7 condition attributes concerning structure and 7 condition attributes concerning surface‐active properties. Antimicrobial activity was expressed by minimal inhibitory concentration (MIC) against strains of Pseudomonas aeruginosa ATCC 15442 (classification I) and Candida albicans ATCC 10231 (classification II). The ROSE 2 (Rough Sets Data Explorer) and LEM 2 (Minimal Set Covering Algorithm) software were used to perform the analysis. Attributes with continuous values were discretized. 45 decision rules were generated in the classification I, and 38 rules in the classification II. Those described the most important dependencies between structure, surface‐active properties of analyzed chlorides and their antimicrobial activity. Strong decision rules supported by large number of objects provide guidelines which may facilitate synthesis of new compounds with preferable antimicrobial properties.

Impact of disinfectant and nutrient concentration on growth and biofilm formation for a Pseudomonas strain and the mixed cultures from a fine papermachine system

Biofilm formation in papermaking processes could inflict financial loss by interrupting paper machine operation and pose a potential health hazard. A mixed microbial culture obtained from paper machine slime and a Pseudomonas strain (identified as Pseudomonas putida HB45) which is tolerant to the alkyl dimethyl benzyl ammonium chloride (quaternary ammonium chloride, QAC) were used to investigate the interplay between disinfectants and glucose on bacterial growth and biofilm formation. QAC and 2,2-dibromo-3-nitrilopropionamide (DBNPA) were found to be effective at concentration lower than isothiazolone in both standardized Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) tests. Crystal violet staining technique demonstrated that biofilm formation of P. putida HB45 and the mixed culture could be controlled by modest dosage of DBNPA and QAC; however, they could be barely eliminated due to high MBC to MIC ratios. In simulated papermaking processing water, glucose was shown to increase the average biofilm formation rates during stationary phase for both P. putida HB45 and the mixed culture under the presence of biocides. Complexity and population diversity of biofilm of the paper machine slime was observed by in-situ cryo-scanning electron microscopy. Confocal laser scanning microscopy (CSLM) was employed to show qualitative and partial quantitative biofilm formation under various circumstances. The results of this study could assist improving strategy for controlling biofilm formation in papermaking processes.

Chemical and Hot Water Treatments to Control Rhizoctonia AG P Infesting Stem Cuttings of Azalea

In the southern and eastern United States, azalea stems cut during the spring for propagation may be infested with Rhizoctonia spp. Multiple methods were evaluated in a series of laboratory experiments for the purpose of eliminating Rhizoctonia from stem cuttings of Rhododendron L. ‘Gumpo White’ [‘Gumpo White’ (Satsuki) azalea] to prevent spread of azalea web blight during the propagation phase of nursery production. Leafless stem sections were inoculated with an isolate of binucleate Rhizoctonia anastomosis group P (AG P). Disinfestants (sodium hypochlorite, hydrogen dioxide, and quaternary ammonium chloride) or fungicides (chlorothalonil + thiophanate-methyl and flutolanil) applied at several rates (below, at, and above label rates) did not eliminate Rhizoctonia AG P from stem sections. Recovery of Rhizoctonia AG P was not reduced by submersing stem pieces in 45 °C water, but was eliminated at water temperatures of 50 °C or greater. Mortality of Rhizoctonia infesting azalea stem pieces was best explained by a cubic regression model. Mortality increased with increasing time (0, 1.5, 3, 4.5, 6, 7.5, 9, 10.5, 12, 15, 18, and 21 min) in water at 50 and 55 °C and with increasing temperatures (52, 55, 58, 61, 64, 67, and 70 °C) when stem pieces were submerged for 30 and 60 s. The duration of hot water treatment at which 99% of stem pieces were predicted to be free of Rhizoctonia was 20 min 16 s at 50 °C and 5 min 19 s at 55 °C. The average water temperature at which 99% of the stem pieces were predicted to be free of Rhizoctonia was 60.2 and 56.9 °C when stem pieces were submerged for 30 and 60 s, respectively. Only minor leaf damage occurred on terminal, leafy stem cuttings when submerged in 50 °C water after 40 min. Severe leaf damage did occur if cuttings were submerged long enough in water of 55 °C or greater. Leaf damage was predicted to exceed a proportional leaf damage value of 0.25 (indicating severe damage) when leafy stem cuttings were submerged in 55 °C water for longer than 13 min 54 s or for 30 and 60 s with water temperature greater than 57.4 and greater than 56.8 °C, respectively. Of the methods tested, submersion in hot water has the greatest potential for eliminating Rhizoctonia AG P from azalea stem cuttings. Submerging stem pieces in 50 °C water for 21 min eliminated Rhizoctonia and provided the least risk for development of severe leaf damage.

Synthesis and thermotropic properties of novel double-chained quaternary ammonium chlorides with symmetric and asymmetric hydrocarbon chain length

A series of novel double-chained quaternary ammonium chlorides with symmetrical and asymmetrical hydrocarbon chain length R 1–O–CH 2–CH(OH)–CH 2–N +(CH 3) 2–R 2·Cl − (R 1, R 2: C 12H 25, C 14H 29, C 16H 33) have been synthesized by the reaction of 1- O-alkyl glycidyl ether with N, N-dimethylalkylamine and N, N-dimethylalkylamine hydrochloride. Their chemical structures have been characterized through FT-IR, 1H NMR, MS and elementary analysis. Their thermotropic properties have been examined by differential scanning calorimetry (DSC), polarizing light microscopy (PLM) and X-ray diffraction (XRD). It has been found that the compounds with longer hydrocarbon chain length and being higher asymmetry in hydrocarbon chain length exhibit lower melting point ( T m) , isotropization temperature ( T i) and narrower mesophase temperature range. However, the hydrocarbon chain length and the symmetry in the hydrocarbon chain length have little influence on the type of liquid crystals. All compounds form cholesteric liquid crystal.

Removal of Reactive Black 5 from aqueous solutions using magnetic chitosan resins

Chitosan was cross-linked using glutaraldehyde in the presence of magnetite. The resin obtained was chemically modified through the reaction with tetraethylenepentamine followed by glycidyl trimethylammonium chloride, to produce chitosan/amino resin (R1) and chitosan bearing both amine and quaternary ammonium chloride moieties (R2), respectively. The uptake of Reactive Black 5 (RB5) from aqueous solutions using R1 and R2 resins was studied using batch and column methods. The resins showed high affinity for the adsorption of RB5 where an uptake value of 0.63 and 0.78 mmol/g was reported for resins R1 and R2, respectively at 25 °C. Both kinetics and thermodynamic parameters of the process were estimated. These data indicated an endothermic spontaneous adsorption process and kinetically followed the pseudo-second order model. Breakthrough and regeneration curves for the removal of RB5 were studied. The adsorbed dye was eluted from the investigated resins effectively.

Removal of Mo(VI) as oxoanions from aqueous solutions using chemically modified magnetic chitosan resins

Chitosan was cross-linked using glutaraldehyde in the presence of magnetite. The resin obtained was chemically modified through the reaction with tetraethylenepentamine followed by glycidyl trimethylammonium chloride to produce chitosan bearing amine (R1) and chitosan bearing both amine and quaternary ammonium chloride moieties (R2), respectively. The removal of Mo(VI) as molybdate anions from aqueous solution was studied using batch and column methods. R1 works efficiently towards the removal of molybdate in acidic medium. Whilst R2 works efficiently in all pH ranges (acidic/neutral/basic). The nature of interaction of the resins obtained with molybdate was clarified. The resins showed a higher affinity towards the uptake of Mo(VI). Kinetics and thermodynamic parameters of the uptake process were obtained. Breakthrough and regeneration curves for the removal of Mo(VI) were also studied. The adsorbed molybdate anions were found to be effectively eluted from the investigated resins.

Lubrication of Inconel 600 with ionic liquids at high temperature

The friction and wear behavior of Inconel 600 against AISI 52100 steel have been studied in the presence of three ionic liquid (IL) lubricants, two imidazolium derivatives, 1-methyl-3-octylimidazolium tetrafluoroborate (L108) and 1-methyl-3-hexylimidazolium hexafluorophosphate (L-P106), and the quaternary ammonium chloride AMMOENG ™101 (AM-101), and compared with a mineral base oil at room temperature. The IL lubricants have been studied at high temperature. While the ammonium derivative has been used at 100 and 200 °C, the higher thermal stability of the imidazolium derivatives allows them to be used up to 300 °C. The results show that the imidazolium derivatives are the best lubricants at all temperatures. A temperature increase from 100 to 200 °C reduces wear rates for all ILs due to a transition form abrasive to adhesive wear and formation of a tribolayer on the Inconel wear track. At 300 °C, the hexafluorophosphate derivative produces tribocorrosion attack on the steel ball and severe wear of Inconel 600 due to decomposition of the IL. The wear mechanisms and surface interactions are discussed in terms of IL-metal surface interactions from SEM, EDX and XPS data.

Alcohol Cosurfactants in Hydrate Antiagglomeration

Because of availability, as well as economical and environmental considerations, natural gas is projected to be the premium fuel of the 21st century. Natural gas production involves risk of the shut down of onshore and offshore operations because of blockage from hydrates formed from coproduced water and hydrate-forming species in natural gas. Industry practice has been usage of thermodynamic inhibitors such as alcohols often in significant amounts, which have undesirable environmental and safety impacts. Thermodynamic inhibitors affect bulk-phase properties and inhibit hydrate formation. An alternative is changing surface properties through usage of polymers and surfactants, effective at 0.5 to 3 weight % of coproduced water. One group of low dosage hydrate inhibitors (LDHI) are kinetic inhibitors, which affect nucleation rate and growth. A second group of LDHI are antiagglomerants, which prevent agglomeration of small hydrate crystallites. Despite great potential, work on hydrate antiagglomeration is very limited. This work centers on the effect of small amounts of alcohol cosurfactant in mixtures of two vastly different antiagglomerants. We use a model oil, water, and tetrahydrofuran as a hydrate-forming species. Results show that alcohol cosurfactants may help with antiagglomeration when traditional antiagglomerants alone are ineffective. Specifically, as low as 0.5 wt. % methanol cosurfactant used in this study is shown to be effective in antiagglomeration. Without the cosurfactant there will be agglomeration independent of the AA concentration. To our knowledge, this is the first report of alcohol cosurfactants in hydrate antiagglomerants. It is also shown that a rhamnolipid biosurfactant is effective down to only 0.5 wt. % in such mixtures, yet a quaternary ammonium chloride salt, i. e., quat, results in hydrate slurries down to 0.01 wt. %. However, biochemical surfactants are less toxic and biodegradable, and thus their use may prove beneficial even if at concentrations higher than chemical surfactants.