Search

The aim of this study was to develop a chromatographic method for 4-NP determination in anaerobic batch reactors using low amount of organic solvents and also evaluate 4-NP degradation in the presence of different co-substrates. Chromatographic parameters was improved for stationary phase (C-8 column), mobile phase (acetonitrile/water solution 90:10, v:v), column temperature (40 ºC), eluent flow (0.8 mL min-1), injection volume (100 µL) and wavelengths in fluorescence detector (FLD) (λex=225 nm and λem=305 nm). Solid phase extraction (SPE) was performed for sample purification with smaller amount of solvents (methanol - 2 mL and ethanol - 1 mL) than previously reported. Reduction in reagent consumption was about 5.5 times for HPLC and about 19 times for SPE, according to previously reported. Method was validated according to the linearity (0.9951), selectivity and limits of detection and quantification were 15.7 µg L-1 and 55.6 µg L-1, respectively. The 4-NP removal in anaerobic batch reactors was higher than 50% (4-NP initial concentration of 398 µg L-1). Fumarate was a better co-substrate to favor methanogenesis in the presence of 4-NP, which provided higher organic matter removal, higher methane production speed and shorter start-up time for methane production.

Alkyl (octyl, decyl and dodecyl; C8,C10 and C12) benzene sulphonyl chloride was used in the preparation of a novel series of nonionic surfactants (IV-VI)a-c, (VII-IX) a-c and (X-XII)a-c. The preparations were completed by reacting each alkyl (C8,C10 and C12) benzene sulphonyl chloride with ethanolamine to give (I-III) respectively. The resulting products were reacted separately with ethylene oxide in the presence of different (base KOH, Lewis acid SnCl4 and k10 clay) catalysts to produce different moles of nonionic surfactants (5, 7 and 9) in sequence corresponding to (IV-VI)a-c, (VII-IX) a-c and (X-XII)a-c respectively. The chemical structures of prepared nonionic surfactants were elucidated by IR and 1HNMR spectra. The surface activity, biodegradability and biological activities of the prepared compounds were investigated. The obtained data show that these compounds have good surface and biological activities as well as reasonable biodegradability properties.

In this work, the feasibility of employing micelle-mediated extraction for selective separation of homologous or isomeric organic compounds is demonstrated. Firstly, the main parameters controlling extraction performances, such as surfactant concentration and temperature were varied. A Scheffé-type experimental design was demonstrated as a novel and useful method to characterize the various experimental factors. At each point selected in the two-phase domain and for a given solute, extraction percentage (E%), concentration ratio, phase volume ratio, and equilibrium partition coefficient (K C) were determined. The values of E% and K C decrease in the following order: phenol > 1-phenylethanol ~ 2-phenylethanol > benzyl alcohol.

In this work the linear viscoelastic behaviour of micelar and liquid-crystalline phases in a polyoxy-ethylene glycol nonylphenyl ether (EOa=10)/water system was studied. A linear viscoelastic characterization using small amplitude oscillatory tests was carried out. The Maxwell and Generalized Maxwell models fit the linear viscoelastic functions of micellar and hexagonal phases respectively, fairly well. On the other hand, the lamellar phase shows a plateau region characteristic of highly structured systems. As may be deduced from the experimental results, dynamic measurements constitute an effective method to study the structural changes occurring in phase diagrams.