Open Access Original Research Article

Oxidative Dehydrogenation of Propane over Vanadium Catalyst Supported on Alkali-Modifiedx-Al2O3

Vinicius M. Crivelaro, Sayuri Okamoto, Gilberto G. Cortez

Chemical Science International Journal, Page 1-15
DOI: 10.9734/CSJI/2021/v30i930250

The propane oxidative dehydrogenation (ODH) reaction has been considered as an alternative method for propene production owing to its exothermic nature, which renders it environmentally friendly. The use of alkaline promoters for supported V catalysts can increase propene selectivity and partially inhibit the formation of CO and CO2. Our goal was to evaluate the promoting effect of K and Na and the support effect using gibbsite as precursor for the propane ODH reaction. Catalysts were prepared via co-impregnation of V and alkali metals on a previously prepared alumina support and were characterized using N2 adsorption-desorption, X-ray diffraction, temperature-programmed reduction, and isopropanol decomposition tests to evaluate their acid-base properties. The activity of the synthesized catalysts for the propane ODH reaction was evaluated at the O2:C3H8:He molar ratios of 5:2:4, 6:1:4, and 4:3:4. The addition of alkali metals to the V catalysts increased propane conversion and propene selectivity; moreover, both parameters increased with increasing molar fraction of O2 in the reactants. K doping increased the propene selectivity of the doped catalysts, because it inhibited a large fraction of catalytic surface acidic sites. A high molar fraction of O2 in the reactants facilitated the regeneration of the catalyst, whereas a high reoxidation rate improved catalytic activity and propene selectivity.

Open Access Original Research Article

Analysis of Agmatine by UV-Visible Absorption Spectrophotometry and Detailed Interference Study on Biogenic Amines and Salts: Grape Application

Khémesse Kital, Moussa Mbaye, Adama Dione, Latyr Dione, Diéry Diouf, Diéne D. Thiaré, Lamine Cisse, Abdourahmane Khonté, Mame D. Gaye-Seye, Atanasse Coly, Francois Delattre, Alphonse Tine

Chemical Science International Journal, Page 16-29
DOI: 10.9734/CSJI/2021/v30i930251

The aim of this work is to develop a new method for the analysis of agmatine from UV-Visible absorption spectra. The optimization of the analytical parameters shows that the stoichiometry of the orthophthalaldehyde-agmatine complex is 1:1, the optimal pH is equal to 11 and the stability time is about 10 minutes. The analytical performances obtained are satisfactory with very low limit of detection (LOD) and limit of quantification (LOQ) respectively equal to 0.121 µg/mL and 0.405 µg/mL. The relative standard deviation (RSD) obtained of 2.1% shows the good reproducibility of the measurements. Interference effects show that the aromatic biogenic amines interfere less than linear ones, excepted serotonine. Similarly, a more marked interference is found for chloride salts. Finally, a recovery rate of between 99.4% and 111.7% was found in the grape extract studied, showing the effectiveness of the method.

Open Access Original Research Article

Essential Oil from Lemon Peel (Citrus lumion) and application in Skin-Care Lotion

Oragwu Ifeoma Perpetua, C. U. Ugwu Shadrack

Chemical Science International Journal, Page 30-38
DOI: 10.9734/CSJI/2021/v30i930252

Essential oil from peels of lemon (Citrus Lumion) fruit had been evaluated for its physiochemical, phytochemical compositions and application in skin-care product.  Lemon peel oil,  which is one of the under-utilized essential oil was  isolated from the matured fruits  peel using petroleum ether by soxhlet extraction method. The percentage  yield of 3.7 %,  for air-dried peels and 2.30 %, for fresh peels  are acceptable  for most plants essential oils. The ash content of both the dried and fresh peels were 1.42 ± 0.001 and 4.007±0.003. Some phytochemicals like, saponins, flavonoids, terpenes, carbohydrates, tannins, were determined using  standard methods.  The lemon-peel-oil skin-lotion formulation was  carried out by  mixing  5 ml   of the peel oil  sample  with corresponding  mass of basic lotion compositions, in water base-tank,  and homogenously mixed  in oil base-tank under 700 C.  The pH range(6.30), viscosity, spreadability,  and  properties  of the lotion were compared to the  non-lemon-oil lotion and to  a commercial grade skin lotion. 

Open Access Original Research Article

Evaluative Study of River Birim in Denkyembuor, Ghana, Using Water Quality Indices

Victus Bobonkey Samlafo, Desmond Adakwah

Chemical Science International Journal, Page 39-51
DOI: 10.9734/CSJI/2021/v30i930253

Aim: To evaluate water quality of the river Birim after a two-year ban as a result of illegal mining activities in the catchment areas of the river.

Methodology: Samples were taken during wet and dry seasons in acid-washed plastic containers. Two water quality indices were adapted for the river under study and used in the evaluation. These were Water Quality Index (WQI) and Heavy Metal Pollution Index (HPI). Twelve physicochemical parameters, such as pH, turbidity, conductivity, total suspended solids, total dissolved solids, total hardness, alkalinity, sulphate, phosphate, nitrate, Fluoride, and chloride which were life-threatening and generally acceptable in water quality were used to evaluate the water quality index. The computed WQI was 439.168, which fell within the unfit for drinking category with turbidity and total suspended solids positively influencing the index.  Iron, (Fe), As, Mn, and Hg were used to evaluate HPI, with an index value of 39.49, which was excellent considering a critical value of 100 set, below which the water is fit for good drinking water.

Conclusion: Except for heavy metal pollution, the river Birim is unfit for drinking without chemical treatment and that, the two-year ban on artisanal small-scale mining was not enough for the river to recover fully from previous pollution episodes and hence did not have any impact on water quality of the river Birim.

Open Access Original Research Article

Chemical Characterisation and Biological Effects of Essential Oils of Four Gabonese Medicinal Plants

Elvis Jolinom Mbot, Cédric Sima Obiang, Maximilienne Ascenssion Nyegue, Bill Raphaël Bikanga, Huguette Agnaniet, Chantal Menut

Chemical Science International Journal, Page 52-60
DOI: 10.9734/CSJI/2021/v30i930254

Aims: The objective of this work is to determine the chemical composition and in vitro evaluation of the antibacterial activities of essential oils of four species of aromatic plants of Gabonese origin obtained by hydrodistillation.

Methods: All the samples were examined by chromatographic analyzes and by GC / MS coupling. Antimicrobial activity was assessed by diffusion and microdilution methods.

Results: The most common compounds found in essential oils were terpene hydrocarbons and oxygenates. The major constituents are β-phellandrene (56.3%), β-pinene (11%) and myrcene (10.4%). The three bacterial strains used are sensitive to essential oils. However, some essential oils stood out with greater spectra of action compared to others, such as Maranthes gabunensis and Mammea africana which showed activity against all strains. The inhibition parameters (MIC and CMB) are between 0.78 and 25 mg / mL. Some oils have shown bacteriostatic and / or bactericidal activity on the targeted strains.

Conclusion: The essential oils studied present a diversity of chemical compositions and good antibacterial activities.