Volume 54, Issue 6

The inhibition of calcium phosphate (Ca/P) precipitation by natural organic polyelectrolytes, bio- and hybrid polymers, homo- and co-polymers of acrylic acid and maleic acid containing different functional groups was examined in aqueous solution. Additionally, commonly used phosphonates were also evaluated as Ca/P inhibitors. It has been found that performance of additive (polymeric and non-polymeric) as Ca/P inhibitor depends upon additive concentration, ionic charge, and molecular weight. Based on the inhibition data, the ranking in terms of decreasing effectivess is: biopolymer > hybrid polymer > natural organic polyelectrolytes. Among synthetic polymers the ranking order is: terpolymer > co-polymer > homopolymer. Results on phosphonates evaluation reveal that compared to synthetic polymers, phosphonates show poor performance as Ca/P inhibitors.

A novel double-hydrophilic copolymer (acrylic acid-isoprenyl polyethoxy carboxylate, AA-TPEL) is synthesized and the structural properties are identified by FT-IR, 1 HNMR and GPC analyses. The inhibitory behavior of the copolymer is determined by using a static scale inhibition method. It is shown that AA-TPEL exhibits an excellent ability to control the formation of CaCO 3 scale with an inhibition efficiency of 88.67 % at the 8 mg L –1 , and it still maintains a superior efficiency even at increasing solution temperature, pH, and Ca 2+ concentration. Weight loss test, potentiodynamic polarization and electrochemical impedance spectroscopy are applied to investigate the inhibition efficiency on mild steel corrosion. All measurements show that, AA-TPEL acts as an efficient corrosion inhibitor and also displays a superior ability to prevent the corrosion of mild steel with approximately 83.21 % inhibition efficiency at the low level of 10 mg L –1 . Scanning electron microscopy (SEM) and X-ray powder diffraction (XRD) are used to characterize the surface morphology of CaCO 3 and steel.

The low grade potash ores contain large amount of fine water insoluble minerals, which was defined as slime here. The removal of the slime from the low grade of potash ores (KCl < 10 %; slime > 40 %) from the Mahai Basin, Qinghai Province, PRC, was investigated using flotation. The characteristics of the slime sample, which was extracted from the potash ores sample, were examined by X-Ray Fluorescence Spectrometry and X-Ray Diffraction. It was found that more than 70 % of the slime was aluminum silicate minerals including feldspar, clay (phyllosilicates), silt, as well as gypsum and carbonate minerals. In this study the flotation response of the slime minerals was evaluated. It was found that a higher slime flotation recovery of the slime was obtained when the MR-1 surfactant (polyoxyethylene fatty acid ester)-kerosene-water emulsion was used as collector. Fourier Transform Infrared Spectrometry (FTIR Spectrometry), oil spreading, and contact angle results indicated that the MR-1 surfactant is selectively adsorbed on slime minerals surfaces and facilitates the spreading of kerosene.

The corrosion inhibition ability of ester based pyridinium Gemini surfactants (GS) with different hydrophobic character (14-Py and 16-Py) towards mild steel (MS) in 1 M HCl solution was investigated at various concentrations and temperatures (303–333 K). Potentiodynamic polarization, electrochemical impedance spectroscopy, weight loss, surface analysis (SEM/EDAX and AFM) and FT-IR were combined to investigate the corrosion inhibition behaviour of the surfactants. 14-Py and 16-Py were found to be efficient, mixed type inhibitors. The inhibition efficiencies increased with increasing concentration, hydrophobicity and solution temperature. The existence of a protective film of the adsorbed inhibitors on the MS surface was confirmed by SEM/EDX/AFM.

New salts combining a benzalkonium cation and chiral amino acid anions were synthesized and characterized. The identification was performed by NMR spectroscopy. Properties such as temperature of phase transformation, specific rotation, thermal stability and surface activity and antimicrobial activity were determined and compared with that of benzalkonium chloride. Benzalkonium amino acids salts can be used as conditioners in cosmetics. It has been shown they have weak impact on symbiotic microorganisms which occupy a wide range of skin, and this confirms that they do not disturb the biological balance of human skin.

Six new thiourea-based non-ionic surfactants were prepared from easily existing raw resources in good yield name 1-sec-butyl-3-dodecanoylthiourea, 1-dodecanoyl-3-phenylthiourea, 1,1-dibutyl-3-dodecanoylthiourea, 3-dodecanoyl-1, 1-diphenylthiourea, 1-cyclohexyl-3-dodecanoylthiourea and 1-butyl-3-dodecanoylthiourea. The structural chemistry of these compounds was studied by multinuclear magnetic resonance ( 1 H, 13 C), Infrared spectroscopy and UV-Visible spectrophotometry techniques. Their solubility varies according to temperature. They show a low solubility, which increases with the temperature of the water. However, they are not stable. The are soluble in organic solvent like ethanol. These molecules possess a low critical micelle concentration and due to this it shows that they are moderately hydrophobic. These molecules were studied regarding their antimicrobial activities and their antifungal and antibacterial efficiency was tested against five microoganism strains. In all cases, the new compounds show a significant inhibition growth against the tested five bacterial and fungal strains. Due to these behaviors they can be used as future candidates in cleaning as well as in agriculture features. The corrosion inhibition behavior was also studied using chromium and aluminum metals.

In this study optimization of extraction conditions for saponin from soapnut (Sapindus mukorossi) has been investigated. This investigation showed that a better extraction of saponin can be achieved with increasing the dielectric constant of solvent employed. The best yield was attained in a 50% v/v aqueous ethanol medium. Another objective of the present study is to assess the thermodynamics of the uptake-reduction of hexavalent chromium in contaminated water samples using saponin. Pyrene has been employed to determine the critical micellar concentration (CMC) (in the UV-vis method of determination) of saponin as a spectroscopic probe. Thus, the effectiveness of the bio-surfactant as a self-motivated adsorbent for hexavalent chromium is investigated. Several physico-chemical parameters like contact time, sorbate concentration, pH and temperature have been determined. The findings of the investigation invoked a very efficient uptake of 213.48 mg g −1 of hexavalent chromium from the contaminated water sample at a lower value of pH 2 and temperature 35°C. It is observed that the method followed a pseudo-first order kinetics, where the evaluated ΔG 0 has supported the sorption as a feasible and spontaneous process. The HR-MS, FTIR, steady state Fluorescence spectroscopy, HR-TEM and UV-Vis spectroscopy have been employed for the current scientific studies.

The electrocatalytic hydrogenolysis of different chlorophenolic compounds, namely 2-chlorophenol (2CP) and pentachlorophenol (PCP) was performed on nickel-silica (Ni-SiO 2 ) and nickel-clay (Ni-CY) electrode catalyts. The influence of the catalytic support and the surfactant agent was studied in aqueous media at different pH. Results demonstrated that different regioselectivities were observed according to the used catalytic support. The cyclohexanone was obtained as the major product. In presence of ionic surfactants (SDS and CTAB), the investigated electrodes exhibited a promising dechlorination and hydrogenation potential of aromatic halides with high electrocatalytic activity and good stability.

The enzyme catalyzed synthesis is a environmentally friendly route compared to traditional syntheses. The lipase-catalyzed synthesis of sucrose erucate was achieved in a solvent mixture of t -butanol and dimethyl sulfoxide (4: 1) by esterification of sucrose with erucic acid using the immobilized Thermomyces lanuginosus lipase. Various process parameters like temperature, substrate molar ratio, solvent, time, and enzyme loading were studied. The optimal conditions for the esterification reaction obtained were 10 %(w/w) enzyme loading, a molar ratio sucrose/fatty acid 1: 1, mild reaction conditions (50 °C and atmospheric pressure) and reaction time (40 h with 55.6 % conversion). The sugar esters were characterized for surfactant properties at different concentration. Sucrose erucate showed a surface tension of (32.73 ± 0.01) mN m −1 at a critical micellar concentration of 9.8 × 10 −5 mol L −1 and good emulsification power.

The properties of the surface and the interface of the complex system of hexadecyl/octadecyl alcohol polyoxyethylene ether carboxylate with 3 ethoxy groups and octadecyl dimethyl carboxyl betaine were investigated. The complex system had a good synergistic effect and could reduce the Shengli Oilfield crude oil/water interfacial tension (IFT) to 10 −3 mN m −1 in a wide total surfactant concentration with less amount of hexadecyl/octadecyl alcohol polyoxyethylene ether carboxylate. In addition, we explored the effect of the salinity and divalent ion concentration on the interfacial tension (IFT) of the complex system. The results showed that the complex system can be used in the oil field when the salinity is lower than 50 000 mg · L −1 and the molar ratio of octadecyl dimethyl carboxyl betaine/hexadecyl/octadecyl alcohol polyoxyethylene ether carboxylate is 9: 1.