Formulation of an antiseptic topical cream based on chitosan extracted from the scales of the Nile tilapia (Oreochromis niloticus).

The Nile tilapia is a widely consumed fish, its scales dumped in nature as waste have been recovered in the formulation of antiseptic creams because of its high content in chitin, precursor of chitosan. Creams have the advantage of being more comfortable on the skin and allow prolonged administration of the active ingredient. Chitosan is obtained with a yield of 21.2%. FTIR analysis of chitosan showed numerous bands of phase groups present and a successful deacetylation assessed on the intensity of the bands at 1650 cm-1 and 1315 cm-1 and confirm by SEM analysis with an abundance of Carbone followed by EDS analysis. Solubilisation of chitosan in 2% acetic acid at 96% and the antibacterial activity test revealed antibacterial activity on Escherichia coli. The viscosity and the optimum spreading capacity of the cream base has been obtained at 14.65% for sesame oil, 9.08% for lanette and 1.26% for glycerine.

Characterization of the Acid-Base Character of Burned Clay Ceramics Used for Water Decontamination.

The paper presents the results of ample investigations performed on industrial and traditional ceramics of fired clay used in processes of water potabilization in the last stage of filtration, after that of active charcoal. Using the data obtained through the scanning electron microscope coupled with energy dispersive X-ray analysis (SEM-EDX) and pH analyses, on the basis of the atomic composition and free concentration of hydronium ions, the normal caustic (Si/Al) and summative [(Si+Ti+FeIII+Cl)/(Al+Ca+Mg+Na+K)] modules were assessed, which were correlated with the free acidity and, respectively, the capacity of absorption and ionic exchange of the Fe3+ and Al3+ ions. The study allowed the selection, on the basis of the caustic module, of the ceramics with high capacity for ionic exchange.

Peroxymonosulfate improved photocatalytic degradation of atrazine by activated carbon/graphitic carbon nitride composite under visible light irradiation.

The photocatalytic degradation of atrazine by activated carbon/graphitic carbon nitride composites with peroxymonosulfate (PMS) was investigated under visible light irradiation. The photocatalysts were prepared at different activated carbon (AC) loaded percentages and characterized by XRD, FT-IR, BET surface area, SEM, UV-Vis absorbance, photocurrent response and EIS. Several parameters which might influence the degradation efficiency were studied including PMS concentration, solution pH, catalyst dosage, initial atrazine concentration as well as water matrix effect. The results indicated that incorporation of AC contributes effectively in suppressing the recombination of electron-holes pairs and enhancing the photocatalytic performance of graphitic carbon nitride. More significantly, the degradation efficiency of atrazine showed remarkable improvement with PMS addition under visible light irradiation. The reaction rate constant of the 10% AC/g-C3N4/Vis/PMS system (0.0376 min-1) was approximately 2.9 times higher than that of g-C3N4/Vis/PMS system (0.0128 min-1). Results from quenching tests revealed that both sulfate and hydroxyl radicals were involved in the degradation of atrazine, while the latter is the main contributor. This paper constitutes an insight for the metal-free catalyst activation of PMS by photocatalysis for environmental remediation.

Effects of first-row transition metals and impregnation ratios on the physicochemical properties of microwave-assisted activated carbons from wood biomass.

First-row transition metals (Co, Ni, Cu and Zn) were successfully used in the preparation of activated carbons from wood biomass via microwave-assisted irradiation. Physical-chemical properties of the produced materials (MWAC) were studied by nitrogen adsorption-desorption curves, SEM, FTIR, UV-vis DRS and synchronous fluorescence spectroscopy, CHN elemental analysis, TGA/DTG, pHzpc, hydrophobic properties, and total acidity and basicity groups. Results showed that the metals were bound successfully in different amounts with surface functional groups of the wood biomass through ion exchange and surface complexation interaction during the impregnation step. Zn2+ and Cu2+ formed the most complexes. MWAC impregnated with Zn2+ showed higher pore volumes and surface areas, followed by Cu2+, Co2+ and Ni2+, independently of the ratio used. As the metal : biomass ratio was increased from 0.5 to 2, the surface area of MWAC increased from 300 to 620m2g-1 for Co-MC, 260 to 381m2g-1 for Ni-MC, 449 to 765m2g-1 for Cu-MC and from 572 to 1780m2g-1 for Zn-MC. The samples showed high values of carbon contents and oxygen-containing groups. An adsorption experiment revealed that samples prepared using ZnCl2 showed the highest sorption capacities (qe) for the tested adsorbates, followed by CuCl2, CoCl2 and NiCl2. These results matched with the surface areas and pore volumes trends, which were found to follow atomic number and melting point trends-Ni(II)bisphenol A>hydroquinone>4-nitro phenol>2-naphtol>paracetamol>caffeine>resorcinol.

Speciation of phosphorus in Lake Dang of Ngaoundere-Cameroon.

In this study, we investigated the nature of phosphate phase present in sediment of Lake Dang. The phosphate speciation was determined by sequential extraction method. The concentration of phosphate in solution was measured by the ammonium molybdate method with ascorbic acid as the reducing agent. Water and sediment (surface and bottom) were sampled at eight points around the lake by taking into account activities around the lake during dry and rainy seasons. The results showed five forms of phosphorus presents in the sediments. The rank order obtained was Res-P < P-L < P-OM < P-Ca < P-Fe with the prevalence of inorganic phosphorus (P-L + P-Ca + P-Fe) than organic phase. The average phosphorus (P) content was 133, 86, and 52 µg g(-1) for the surface layer (A, 0-5 cm), medium layer (B, 5-10 cm), and bottom layer (C, 10-15 cm), respectively. This P-content depletion with depth can be explained mainly by oxygen depletion with depth which enhance P desorption. Except P-L form, the P contents were higher in rainy season compared to the dry season. The results of principal component analysis indicate that inorganic phosphorus (P-L + P-Ca + P-Fe) were linked and were provided mainly by car-washing. It appears clearly that phosphorus content vary significantly during the seasons. These results showed also that the amount of (P-Fe) is higher than the others whatever the season. This P form is easily labile and bioavailable which suggest that it can unfortunately enhance greatly the eutrophication of Lake Dang.

Speciation of phosphorus in the sediments of Lake Bini (Ngaoundere-Cameroon).

In this study, spatial and seasonal variations of phosphorus fractions in Lake Bini sediments were evaluated using a sequential extraction method. The sampling of water and sediments (surface and coring) was carried out at seven sites around the lake during the dry season and the rainy season. The results showed that phosphorus is mainly in the inorganic form (L-P+Ca-P+Fe-P) in the sediments whatever the season may be. The rank order of phosphorus extracts obtained was Fe-P>Ca-P>OM-P>L-P>Res-P. The maximum values of phosphorus (sum of each fraction) were obtained in the rainy season at the sites D6 (298.12 +/- 12.37 microg P/g) and D4 (244.93 +/- 11.06 microg P/g) located beside water source 2 and farmland 2, respectively. The average values of the phosphorus content vary from 05.29 +/- 1.05 microg P/g to 102.58 +/- 4.62 microg P/g for the upper layer (0-5 cm depth); 04.67 +/- 0.66 microg P/g to 70.06 +/- 2.82 microg P/g for the medium layer (5-10 cm depth) and finally 04.63 +/- 0.98 microg P/g to 55.24 +/- 5.17 microg P/g for the deep layer (10-15 cm depth). The results of principal component analysis showed that processes which enhance Ca-P and Fe-P accumulation are probably related to the same factor and the origin of P depends on the source of pollution. The nature of the season plays a significant role in the geochemical composition of the sediments in phosphorus and on the eutrophication level of Lake Bini.