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Physico-Chemical Study of the Adsorption of Carotenoids from Carrots on Raw and Modified Kaolinites

Advances in Chemical Engineering and Science 2023年第2期13卷 132-148页

作者： orléans ngomo Etienne Dongo Joseph Sieliechi Department of Organic Chemistry Faculty of Sciences University of Yaoundé I Yaounde Cameroon Department of Applied Chemistry The National School of Agro-Industrial Sciences University of Ngaoundere Ngaoundere Cameroon

This study focuses on the adsorption at temperatures below 70℃, of carotenoids from carrots on clay materials such as kaolinite in the raw state, activated with a 0.5 M HCl solution or treated with a sodium solution of Al+. The kinetic study of carotenoid adsorption shows that equilibrium is reached after 30 minutes and the temperature has little influence on carotenoid adsorption. On the other hand, the quantities adsorbed at equilibrium increase with the initial concentration of carotenoids. The kinetic model that best describes the experimental data is that of the pseudo-second order, adsorption is made in two time. For the carotenoid adsorption isotherms, the best correlation is obtained with the Freundlich model. The low values of the Freundlich constants indicate that the adsorption is probably of a physical type. This conclusion is confirmed by the effective desorption of carotenoids observed during desorption experiments.

关键词： Kaolinite Carrots Antioxidant Cosmetic Adsorption

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Assessment of the Selective Properties and Optimization of Mesh Size of Pelagic Trawl Codends, Used for Fishing Mackerel (Trachurus Spp) in the Gulf of Guinea

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Open Journal of Marine Science 2013年第2期3卷 103-111页

作者： Njomoue Pandong Achille Ebeku ngomo Christopher Tcham Leopold Department of Fisheries Faculty of Industrial Engineering University of Douala Douala Cameroon

Over the past few decades, it has become widely recognized that the management strategies of world fisheries must ensure sustainability of target species. The intervening years have seen many improvements to the concept of gear selectivity and methods for measuring the selectivity of fishing towed gears. Improved understanding of the principles of the selection of fish by gears has changed the list of parameters which are known to have a significant effect upon selection. The recent development of new mathematical models and the increased availability of powerful computers have resulted in improvements in the analysis procedures for the data produced to measure a gear’s selectivity. The catch of mackerel in the gulfofGuineahas steeply declined during the last two decades, and resource management is clearly required. Therefore, the need for evaluation of trawl codends used in this fishery and the potential improvements to their selectivity are of prime importance. In this paper, we use semi-empirical models to define selective properties of pelagic trawl codends targeting black mackerel (Trachurus spp) in theGulfofGuinea. These properties are determined using the experimental and theoretical methods of assessing the parameters of the selectivity curve, and by plotting the curve. Selection parameters were obtained by fitting a logistic equation using a maximum likelihood method. Trawl codend selectivity is estimated for 17 internal diamond mesh sizes in the range 47 - 79 mm. Using the basic selectivity equations, we determine the needed mesh size A = 58 mm for fishing mackerel in the gulf of Guinea. This nominal mesh size gives room for nj = 0.1 catch of juveniles, which not exceeds the allowable proportion [nj] = 0.1. To provide resource conservation, there is the need to make amendments in the fishery regulations for more rational exploitation of mackerel stoks, because the currently use nominal mesh size A = 56 mm is rather unselective.

关键词： Codend Selectivity Mesh Size Gulf of Guinea Selectivity Models

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Composite Activated Carbon from Canarium schweinfurthii/Polyethylene Terephthalate: Adsorption Test of Rhodamine B Dye Removal in Aqueous Solution

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Journal of Materials Science and Chemical Engineering 2023年第11期11卷 75-105页

作者： Gadjui Youatou Boris Ankoro Naphtali Odogu Lekene Ngouateu René Blaise Kouotou Daouda Ndi Julius Nsami ngomo Horace Manga Ketcha Joseph Mbadcam Applied Physical and Analytical Chemistry Laboratory Department of Inorganic Chemistry Faculty of Science University of Yaoundé I Yaoundé Cameroon Department of Chemistry Faculty of Science University of Buea Buea Cameroon

The present work deals on one hand with the valorization of wastes plastics, polyethylene terephthalate (PET) and Canarium schweinfurthii (CS) for the preparation of polyethylene terephthalate activated carbon (PETAC) and Canarium schweinfurthii/polyethylene terephthalate activated carbon (CS/PETAC). These adsorbents, on the other hand, were used for removal Rhodamine B (RhB) in an aqueous solution. PET and CS precursors were subjected to thermogravimetric analysis (TGA) and differential scanning colorimetry (DSC). Meanwhile PETAC and CS/PETAC were characterized using scanning electron microscopy-energy dispersive spectrometry (SEM-EDS), X-ray fluorescence (XRF), Fourier transformed infrared spectroscopy (FT-IR) and nitrogen adsorption/desorption (N2-BET). The N2-BET results revealed an increase of the specific surface area from 6.75 m2/g to 1282.0 m2/g for PETAC and CS/PETAC. The results of characterization indicated the key role played by plastic wastes to enhance the structural and functional properties of CS/PETAC. The RhB removal from the aqueous solution onto PETAC and CS/PETAC was found to be independent of pH, with an optimal contact time of RhB removal within 10 min for materials. The non-linear adsorption isotherm data for the adsorption process showed that the Langmuir and Freundlich models best fitted the RhB adsorption onto PETAC meanwhile only the Freundlich adsorption isotherm gave the best fit for CS/PETAC according to the correlation coefficient value closed to unity. The pseudo-first and pseudo-second-order kinetic models best described the RhB dye removal on both adsorbents. Additionally, the Elovich model confirmed that chemisorption was the main mechanism followed. These findings proved that CS seeds and PET wastes are low-cost precursors that should be given an added value by transforming them into an outstanding carbon material for dye removal in liquid effluent.

关键词： Activated Carbon Rhodamine B Canarium schweinfurthii Plastics Wastes Pollution Wastewaters

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Adsorption of Tartrazine onto Activated Carbon Based Cola Nuts Shells: Equilibrium, Kinetics, and Thermodynamics Studies

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Open Journal of Inorganic Chemistry 2021年第1期11卷 1-19页

作者： Dantio Nguela Christian Brice ngomo Horace Manga Bénédoué Serge Arnold Kouotou Daouda Abega Aimé Victoire Ndongo Ndongo Alain Giresse Che Randy Nangah Ndi Julius Nsami Laboratory of Applied Physical and Analytical Chemistry Department of Inorganic Chemistry Faculty of Science University of Yaoundé I Yaoundé Cameroon

The uptake of tartrazine from its aqueous solution by powdered activated carbon prepared from cola nut shells chemically activated with potassium hydroxide (ACK) and phosphoric acid (ACP) has been investigated using kinetics models. Batch isotherm data were analysed with the pseudo-first order, pseudo-second order model as well as the intraparticle diffusion model. For structural elucidation, the materials were characterized using FTIR, XRD and SEM. These analyses revealed that the activated carbons (ACK and ACP) were predominantly mesoporous with several oxygen-containing functional groups dispersed on their surface. The reaction was systematically investigated under various experimental conditions such as contact time, adsorbent dose and pH. For the two adsorbents, the quantity adsorbed of 19.256 mg/g and 18.196 mg/g respectively for ACP and ACK at respective contact times of 5 and 10 min were obtained. The adsorption data were tested with the Langmuir, Freundlich models. Langmuir model was found to best describe the adsorption of tartrate ions with maximum monolayer adsorption capacities of 24.57 and 21.59 mg/g for ACP and ACK, respectively. Results analysis indicated clearly that the pseudo-second order kinetic rate model best fitted the experimental data and therefore was the adsorption controlling mechanism for both adsorbents. Thermodynamic studies revealed that the adsorption process was spontaneous and exothermic for ACP with increased randomness at the solid solution interface, then exothermic but non-spontaneous for ACK. The results show that these activated carbons could be an alternative for more costly adsorbents for the purpose of tartrate ions elimination.

关键词： Cola Nuts Shells Activated Carbon Adsorption Tartrazine

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