Preparation the Esters of Oleic Acid-Maleic Anhydride Copolymer and Their Evaluation as Flow Improvers for Waxy Crude Oil

Five comb-like copolymers derived from oleic acid-maleic anhydride were prepared and then esterified by long-chain fatty alcohol (POMA C_n), where n = 18, 20, 22. These polymers were characterized by FTIR and ¹H NMR analysis. The molecular weight was determined by using gel permeation chromatography (GPC). The prepared copolymers were investigated as flow improvers and pour point depressants (PPD) for crude oil. From the evaluation, it was found that, the maximum depression of PP was obtained by (POMA₂ C₂₂) with long-chain alcohol (C₂₂–OH) from 27°C to 15°C (ΔPP_3000ppm = ?12°C). On the other side, it was remarked that no depression obtained by (POMA₂ C₁₈), which esterified by alcohol (C₁₈–OH) at the same condition. The depression of pour point effectiveness was discussed on the light of polymers structure, molecular weights, and their concentrations. By analysis the results of the rheological flow properties, it was found that the POMA₂ C₂₂ enhanced the Bingham yield values (τ_β). The τ_β for crude oil without additives against 15, 27, and 39°C were 0.286, 0.131, and 0.075 Pa respectively, whereas the τβ for the treated crude oil with POMA₂ C₂₂ were 0.027, 0.022 and 0.010 Pa at 3000 ppm at the same temperatures. By using the photomicrography analysis, it was found that, the wax morphology was greatly modified to fine dispersed crystals of compact size.     

Micellization and Clouding Phenomenon of Phenothiazine Drug Promethazine Hydrochloride: Effect of NaCl and Urea Addition

Herein we report the micellization and clouding behavior of promethazine hydrochloride (PMT) in absence and presence of NaCl/ureas. The critical micelle concentration (CMC) of PMT is measured by conductivity method and the values decrease with increasing the NaCl concentration. With increasing the temperature, the CMC first increases then decreases. At 25°C, the maximum CMC values were obtained (with or without NaCl). The thermodynamic parameters are evaluated which indicate more stability of the PMT solution in presence of NaCl. PMT shows phase separation also. The cloud point (CP) of PMT decreases with increase in pH due to deprotonation of the drug molecules. Ureas decreased the CP and the behavior is explained on the basis of removal of water from the head group region.     

Synthesis of Some Additives and Study Effect of Gas Oil Composition on Flow Properties

Nine additives were prepared by esterification of dibasic acid (succinic, adipic, sebacic acid) and polyethylene glycol (Mol.wt.=600, 1000, 4000). These additives were characterized by infrared spectral analysis, average molecular weight and polydispersity index. Their influence on the depression of pour point for two type of paraffin gas oils (G1 and G2) were investigated, blends of paraffin gas oils G1 and G2 by different ratio, when their untreated and treated by additives were evaluated as pour point depressant in comparison with the original paraffin gas oils G1 and G2.

The effect of additive type and gas oil composition on wax crystal modification were studied using the photo micrographic analysis. Diethoxylate (eo=182) sebacate with blend gas oil No. 3 has achieved the best performance as pour point depressant. The photo micrographic analysis showed that, the wax morphology was greatly modified to fine dispersed crystals of compact size. A correlation between the pour point depression and the extent of wax modification was detected.     

Polymers-Copolymer as Flow Improvers for Fuel Oils and Their Electrical Conductivity

In order to find efficient cold flow improvers for fuel oil, polymethylmethacrylate (PMMA), polystyrene (PS), and a copolymer [styrene (S)–methylmethacrylate (MMA) were prepared. The structure of these polymers and the copolymer were characterized by infrared spectral analysis and their molecular weights were measured. These polymers-copolymer were used as additives for fuel oils in order to lower their pour point. Accordingly, they were evaluated as flow improvers for fuel oil. The results indicated that PMMA possesses less performance as pour point depressant. While the addition of PS and the copolymer (S–MMA) yield excellent pour point depressants for fuel oil. Upon studying the prepared additives and their properties, it was found that the electrical properties of the copolymer were changed due to the presence of polar ion in MMA effect on the electrical properties. The highest electrical conductivity was found when styrene:MMA molar ratio was 1:1.     

The Effect of Added Salts and Organics on the Cloud Point of TX‐114

Herein we report the effect of additives (salts and organics) on the cloud point (CP) of nonionic surfactant Triton X‐114 (TX‐114) aqueous solutions. CP showed a concentration dependent variation in the absence of any added compound. Addition of quaternary ammonium (or phosphonium) bromides to 0.8 mM TX‐114 solutions increased the CP. It was found that long chain alcohols and amines decreased the CP of 0.8 mM TX‐114 +80 mM Bu₄AmB aqueous system, while it either remained constant or increased in the presence of short chain additives. The effect of first group additives (long chain) can be explained by considering that these additives solubilize in interfacial region and assist in micellar growth. Short chain additives remain in aqueous phase and affect the micelle hydration by affecting the solvent. Pentylamine behaved differently than pentanol: pentylamine increased the CP (like short chain additives) while pentanol decreased the CP. In pentylamine, the hydrophilicity of NH₂ group and its dissociation into NH₃ ⁺ dominates over the hydrophobicity of its alkyl chain. Aliphatic hydrocarbons first decreased and then increased the CP. The overall behavior depended upon the chain length of the hydrocarbon. With decane, the CP decreasing region disappeared completely.     

Solution Behavior of Poly(n-Isopropylacrylamide) in Water: Effect of Additives

The effect of different kinds of additives (electrolytes, nonelectrolytes, hydrotropes, and surfactants) on the cloud point (CP) of low molecular weight and narrow dispersed poly(n-isopropylacrylamide) (PNIPAM) synthesized via reversible addition-fragmentation chain transfer (RAFT) controlled radical polymerization was examined. The CP showed a concentration dependent variation and it is greatly modified in the presence of additives. The size of the random polymer coil at 30°C obtained from dynamic light scattering (DLS) measurements is often influenced by the presence of additives. We have explained the effects of different additives on PNIPAM in terms of their interaction with polymer and resultant changes in the coil structure.     

Novel Sulfanilamide as Potent Surfactants and Antibacterial Agents

Sulfanilamide derivatives of the type RØSO₂NHR in which substitution at both the amino and amido nitrogen have been synthesized where R = NHCOCH:CHCOOH, NHCOCH₂CH₂COOH, NHCH₂CH(OH)CH₂SO₃Na, N⁺(CH₃)₃I^? and NHCH₂CH(OH)CH₂N⁺(C₂H₅)₃Cl^? and R′ = butyl, cyclohexyl, and decyl. The unique structural features of these sulfanilamides were confirmed by infrared, proton magnetic resonance and elemental analysis. Most of these compounds exhibited good water solubility and surface activity. Wetting ability and tendency of enhancing oil/water emulsification were related to the structure of the substituents in sulfanilamide molecule. Furthermore, the peculiar of molecular structure of these sulfanilamide surfactants imparts distinguished antimicrobial activity to these molecular species against some Gram positive and Gram negative bacteria.     

Cloud point extraction for the determination of cadmium and lead employing sequential multi-element flame atomic absorption spectrometry

A cloud point extraction procedure for pre-concentration and determination of cadmium and lead in drinking water using sequential multi-element flame atomic absorption spectrometry is described. 4-(2-thiazolylazo)-orcinol (TAO) has been used as complexing agent and the micellar phase was obtained using the non-ionic surfactant octylphenoxypolyethoxyethanol (Triton X-114) and centrifugation. The conditions for reaction and extraction (surfactant concentration, reagent concentration, effect of incubation time, etc) were studied and the analytical characteristics of the method were determined. The method allows the determination of cadmium and lead with quantification limits of 0.30?µg?L^?1 and 2.6?µg?L^?1, respectively. A precision expressed as relative standard deviation (RSD, n?=?10) of 2.3% and 2.6% has been obtained for cadmium concentrations of 10?µg?L^?1 and 30?µg?L^?1, respectively, and RSD of 1.3% and 1.7% for lead concentrations of 10?µg?L^?1 and 30?µg?L^?1, respectively. The accuracy was confirmed by analysis of a natural water certified reference material. The method has been applied for the determination of cadmium and lead in drinking water samples collected in the cities of Ilhéus and Itabuna, Brazil. Recovery tests have also been performed for some samples, and results varied from 96 to 105% for cadmium and 97 to 106% for lead. The cadmium and lead concentrations found in these samples were always lower than the permissible maximum levels stipulated by World Health Organization and the Brazilian Government.     

Cloud point extraction of aluminum (III) in water samples and determination by electrothermal atomic absorption spectrometry,flame atomic absorption spectrometry and UV-visible spectrophotometry

Cloud point extraction was applied as a preconcentration step for the determination of trace level of Al(III) in water samples with electrothermal atomic absorption spectrometry (ETAAS), flame atomic absorption spectrometry (FAAS) and UV-visible spectrophotometry. The aluminum was extracted as aluminum-Eriochrome Cyanine R (ECR) complex, at pH 6 by micelles of the non-ionic surfactant octylphenoxypolyethoxyethanol (Triton X-114). The investigations showed that the same CPE procedure can be used for different detection techniques. The results obtained from these techniques were evaluated. Under the optimal conditions, limit of detection obtained with ETAAS, FAAS and UV-visible spectrophotometry were 0.03 ng mL^?1, 0.06 µg mL^?1 and 0.01 µg mL^?1, respectively. The accuracy of the procedure was tested by analysing certified reference material. The method was successfully applied to determination of aluminum in water samples and dialysis fluid.     

Enthalpy–Entropy Compensation Combined with Cohesive Free‐Energy Densities for Tuning the Melting Temperatures of Cyanobiphenyl Derivatives

This work illustrates how minor structural perturbations produced by methylation of 4′‐(dodecyloxy)‐4‐cyanobiphenyl leads to enthalpy–entropy compensation for their melting processes, a trend which can be analyzed within the frame of a simple intermolecular cohesive model. The transformation of the melting thermodynamic parameters collected at variable temperatures into cohesive free‐energy densities expressed at a common reference temperature results in a novel linear correlation, from which melting temperatures can be simply predicted from molecular volumes.