Revue des sciences chimiques

Hydrogen sulfide contaminates the geothermal brines that are encountered in the drilling of wells. It promotes the corrosion of the drilling equipment, pipelines, vessels, forms sulfide scales, which plug tubulars, and degrades the quality of the produced oil. This work aims to study the feasibility of electrochemical removal of H2S from such brines by anodic oxidation. Porous graphite electrode was used to achieve electrochemical oxidation of sulfide ions in chloride brines in an autoclave under high temperature and pressure. The X-ray photoelectron spectroscopy (XPS) and Energy Dispersive Spectroscopy (EDS) proved that sulfur was identified as the final reaction product under various potentials and temperatures. In low temperature, the sulfur was detected on the electrode surface, while in high temperature the resulting sulfur flows out in the electrolyte so that it is not detected on the electrode surface. The rate of sulfide oxidation depends on the potential, temperature and the sulfide concentration. The obtained limiting currents are lower than those predicted from mass transfer correlations, which result from the effects of the deposited sulfur on the internal surface of the porous graphite electrode. The large internal surface area of the used electrodes improved the removal efficiency of sulfide ions and this is very clearly noticed from the current transient's results. In high temperature, the limiting current is re-increased due to the liberation of sulfur from the electrode surface, which reactivates electrode surface and the rate of oxidation is increased again.

Some substituted 3,5-diphenyl-2-pyrazoline-1-carboxamide derivatives were synthesized from appropriate substituted 1,3-diphenylprop-2-en-1-one (chalcone) on reaction with semicarbazide hydrochloride. The final compounds were structurally elucidated on the basis of IR, 1H-NMR & mass spectral data and microanalyses. The final compounds were evaluated for anticonvulsant activity by the maximal electroshock seizure (MES) method. The neurotoxicity was determined by rotorod toxicity test on male albino mice. The preliminary results showed that all of the tested compounds were protective against MES at 100-300 mg/kg dose levels. The compounds numbered 4d-4e, 4j-4k, and 4m-4t were most protective against MES even at 30 mg/kg dose levels.

The adsorption of Ni(II) and Cd(II) ions onto rice straw was investigated. The effects of pH, initial adsorbent concentration, initial metal ion concentration, contact time and temperature were studied in batch experiments. The Langmuir and Freundlich models were applied and the adsorption equilibrium followed the two adsorption isotherms. The maximum adsorption capacities for Ni(II) and Cd(II) were 35.08 and 144.19 mg/g, respectively. Thermodynamic parameters such as free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°) have been calculated on the basis of Langmuir constants. The negative values of ΔG° were indicative of the spontaneity of the adsorption process. The negative values of ΔH° revealed the exothermic nature of the adsorption process whereas the positive ΔS° reflected an irregular increase of the randomness at the adsorbent/solution interface during the sorption of metal ions.

The terpenoids, sometimes referred to as isoprenoids, are a large and diverse class of naturally occurring organic chemicals similar to terpenes, derived from five-carbon isoprene units assembled and modified in thousands of ways. Most are multicyclic structures that differ from one another not only in functional
groups, but also in their basic carbon skeletons. These lipids can be found in all classes of living things, and are the largest group of natural products. The features of mass spectra of mono-, bi- and tri-cyclic terpenoids: 1-isopropyl-4-methyl-1, 3-cyclohexadiene (I) terpilene; 1-methyl-4-(1-methylethylidene)-1-
cyclohexene (II) terpinolene; 4-methyl-3-(1-methylethylidene)-1-cyclohexene (III); 1,5,5-trimethyl 3-methylene-1-cyclohexene (IV); 2,6,6-trimethylbicyclo\\\\\\\\\\\\\\\\ [3.1.1]-2-heptene (V)  -pinene; 2,2,6-trimethylbicyclo [3.1.1]-2-heptene (VI)  -pinene; 2,2-dimethyl-3-methylenebicyclo [2.2.1]-heptane (VII) camphene;1-isopropyl-4-methylbicyclo [3.1.0]-2-hexene (VIII)  -thugene; 5-isopropyl-2-methylbicyclo [3.1.0]-2-hexene (IX)  -thugene; 1-methyl-6-(1-methylidene) bicycle [3.1.0] hexane (X); 3,7,7-trimethylbicyclo [4.1.0]-3-heptene (XI)  -3-carene; 4,7,7-trimethylbicyclo [4.1.0]-2-heptene (XII) (+)-4-carene; 3,7,7- trimethylbicyclo [4.1.0]-2-heptene (XIII) (+)-2-carene; 1,7,7-trimethyltricyclo [2.2.1.0(2.6)]-heptane (XVI) tricyclene; 1,3,3-trimethyltricyclo [2.2.1.0(2.6)]- heptane (XVII) cyclofenchene extracted from natural raw materials and comprising a number of drugs were investigated. The mass spectra for: cyclohexene- 3-(tretbutyl) peroxide (XIV) and 3-isopropyl-1-cyclohexene (XV) were investigated as well. It was established that the mass spectra of these compounds are absolutely identical in mass values of peaks of fragment ions, where their relative intensities have minor differences. In the spectra of all compounds the observed characteristic ions were [M-CH (CH3)2] and [M-CH (CH3)2 –H2]. The latter has a structure with m/z 91 that is attributed to pathing. All fragment ions correspond to even-electron cations. The identity of mass spectra of the studied tepenoids is explained by isomerization of molecular ions, similar to isomerization of terpenes in chemical transformations under the action of acids, also under the influence of other catalysts, temperature and light

Wastewater treatment using local available materials such as gravel and charcoal was investigated. The removal of TDS from roughing filters was evaluated for roughing filtration treatment system. Achieved results showed that roughing filters could be considered as a major pretreatment process for wastewater, since they efficiently separate fine solids particles over prolonged periods without addition of chemicals. A pilot plant was designed at delcoal. The wastewater used was from delcoal. The design and sizing of the pilot plant was guided by wegelin design criteria. Gravel was used as a control medium since it is one of the most commonly used roughing filter media and because it was used in developing these criteria. In order to improve the performance of roughing filters, this process has been modified by applying local available material such as charcoal as an alternative filter media. The pilot plant was monitored for a continuous 90 days from commissioning. The overall function of the filter in removing parameters such as TDS is accepted using charcoal as an alternative filter media. Achieved results in this study showed that roughing filters might be considered as an efficient pretreatment process for mine water. It was also observed that in general performance, charcoal performed better than gravel. This observation could have resulted from the reason that charcoal has a slightly higher specific surface area and porosity respectively to enhance sedimentation and other filtration processes like adsorption, compared to gravel.

A number of new diazonium salt derivatives of 7-chloro-5-phenyl-3-(phenyl-n-substituted)-diazo-1,3-dihydro-benzo[e][1,4]-diazepin-2-one (IVa-l) from 7-chloro-5-phenyl-1,3-dihydro-benzo[e]-[1,4]-diazepin-2-one (III) with diazonium salts (phenyl diazo salt derivatives) were prepared and tested for anticonvulsant activity. The compounds provided significant protection against maximal electroshock induced seizures (MES) and seizures indicated by sc pentetrazole administration (sc PTZ) at 300 mg/kg after 0.5 h. The compounds IVb, IVd, and IVf were active in MES and sc PTZ indicated seizure. A conformational study of these derivatives was undertaken to explore the mechanistic details of the mode of action and their interlinked, interconvertible and energetically favored geometrical configurations acting on the receptor site.

In this study, soil and sediment samples from known sources (sewage treatment plants, chicken farms, paddy fields and palm oil plantations) were analyzed for selected organic compounds (polycyclic aromatic hydrocarbons (PAHs), chlorpyrifos, cypermethrin and sterols). Samples were extracted using pressurized liquid extraction (PLE) techniques. The data sets obtained were subjected to chemometric techniques namely cluster analysis (CA), discriminant analysis (DA) and principal component analysis (PCA). Based on CA, two clusters were generated; cluster 1 consisting of PAHs, chlorpyrifos and cypermethrin while cluster 2 consisting of coprostanol, cholesterol, stigmasterol, stigmastanol, and β- sitosterol. DA plot rendered clear discrimination between the samples from different sources of contaminations. PCA analysis, applied to the data sets resulted in four latent factors explaining 63.8% of the total variance. The varifactors obtained from PCA indicated that the parameters responsible for source variations are sterols (coprostanol, cholesterol, stigmasterol, -sitosterol and stigmastanol), which are strongly correlated to sewage and chicken farm samples, PAHs (naphthalene, acenaphtene, pyrene, benzo[a]anthracene and benzo[a]pyrene) and pesticides (chlorpyrifos and cypermethrin) which are comparatively correlated to samples from agricultural activities (paddy fields and palm oil plantations). The application of chemometric on selected organic compounds provides useful and promising techniques in tracing sources of contaminants as well as to reduce the complexity of the data interaction without lost of much important information.