Modeling and Optimization of M-cresol Isopropylation for Obtaining N-thymol: Combining a Hybrid Artificial Neural Network with a Genetic Algorithm

The application of a hybrid framework based on the combination, artificial neural network-genetic algorithm (ANN-GA), for n-thymol synthesis modeling and optimization has been developed. The effects of molar ratio propylene/cresol (X1), catalyst mass (X2) and temperature (X3) on n-thymol selectivity Y1 and m-cresol conversion Y2 were studied. A 3-8-2 ANN model was found to be very suitable for reaction modeling. The multiobjective optimization, led to optimal operating conditions (0.55 ≤X1≤0.77; 1.773 g ≤ X2 ≤1.86 g; 289.74 °C ≤ X3 ≤291.33 °C) representing good solutions for obtaining high n-thymol selectivity and high m-cresol conversion. This optimal zone corresponded to n-thymol selectivity and m-cresol conversion ranging respectively in the interval [79.3; 79.5]% and [13.4 %; 23.7]%. These results were better than those obtained with a sequential method based on experimental design for which, optimum conditions led to n-thymol selectivity and m-cresol conversion values respectively equal to 67%and 11%. The hybrid method ANN-GA showed its ability to solve complex problems with a good fitting

Lead concentrations in sediments and mollusc gastropod from Vridi Canal, Côte d’Ivoire

Lead (Pb) is one of the most frequent and toxic contaminant in the environment. It can be bioaccumulated by marine organisms through contaminated sediments as well as their food chains. The current study aimed at investigating Pb occurrence in the sediments and gastropod P. haemastostoma from Vridi Canal. Sediment samples were taken using a Van Veen steel grab of 0.02 m2 area, sealed in plastic bags and transported to the laboratory at 4 °C. Gastropod P. haemastostoma species were collected manually using gloves, and then placed in polyethylene plastic bags. The different concentrations were determined using atomic absorption spectrometer Varian AA 20. The results showed seasonal variability of Pb concentrations in sediments and P. haemastostoma. In the both matrices, Pb exhibited the same trend in the distribution between the seasons. This study also mentioned that sediments were highly  contaminated by Pb (54.27-134.71 mg/kg). Vridi Canal was found to be one of the most contaminated seaport area. Pb levels  (49.55-104.19 mg/kg) in P. haemastostoma exceeding the maximum permitted levels according to the United Nations Food and Agriculture Organization (FAO). This research demonstrated that sediments having lower ecological risk may be resulting in lower tissue Pb of P. haemastostoma. Keywords: Metal Pb, sediment, P. haemastostoma, seasonal variatio

Economic and environmental strategies for process design

This paper first addresses the definition of various objectives involved in eco-efficient processes, taking simultaneously into account ecological and economic considerations. The environmental aspect at the preliminary design phase of chemical processes is quantified by using a set of metrics or indicators following the guidelines of sustainability concepts proposed by . The resulting multiobjective problem is solved by a genetic algorithm following an improved variant of the so-called NSGA II algorithm. A key point for evaluating environmental burdens is the use of the package ARIANE™, a decision support tool dedicated to the management of plants utilities (steam, electricity, hot water, etc.) and pollutants (CO2, SO2, NO, etc.), implemented here both to compute the primary energy requirements of the process and to quantify its pollutant emissions. The well-known benchmark process for hydrodealkylation (HDA) of toluene to produce benzene, revisited here in a multiobjective optimization way, is used to illustrate the approach for finding eco-friendly and cost-effective designs. Preliminary biobjective studies are carried out for eliminating redundant environmental objectives. The trade-off between economic and environmental objectives is illustrated through Pareto curves. In order to aid decision making among the various alternatives that can be generated after this step, a synthetic evaluation method, based on the so-called Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) (), has been first used. Another simple procedure named FUCA has also been implemented and shown its efficiency vs. TOPSIS. Two scenarios are studied; in the former, the goal is to find the best trade-off between economic and ecological aspects while the latter case aims at defining the best compromise between economic and more strict environmental impact

Adsorption Tests of Humic Substances on Raw Clay from Bikougou (Gabon)

The presence of organic material of natural origin is characteristic of surface waters. Humic substances (HS) are generally the largest category in these waters. The objective of this work was to evaluate the adsorption performance of raw clay from Bikougou (Gabon) for the removal of humic substances. During the experimental study, the batch equilibration technique was used to follow the kinetics of adsorption of humic substances on clay. The influence of reaction parameters such as the initial concentration, the pH of the solution and the presence of inorganic salts (calcium or magnesium ions) was also observed. Optimum removal is obtained for low values of initial concentrations. pH variation showed that acidic medium (pH 4) can achieve good yields retention of humic substances. The presence or absence of mineral salts in the medium appears as one of the most critical parameters. Indeed, the impact of water mineralization has resulted in a significant improvement in removal efficiency of humic substances, taking as reference the results obtained in demineralized water. The promoting effect of cations such as calcium and magnesium may be the cause of this improvement. This let suggest a mechanism based on adsorption bridging clay-cation-SH. The kinetic study also showed that the adsorption equilibrium is reached after more than ten hours of reaction, whatever the dilution medium humic substances. Keywords: Clay, adsorption, humic substance

Simultaneous phosphates and nitrates removal from waste-waters by electrochemical process: Techno-economical assessment through response surface methodology

In this study, a new multiobjective optimization of the simultaneous removal of phosphates and nitrates by electrocoagulation was studied using the Box-Behnken design. Ten aluminium electrodes, connected in a monopolar configuration in a batch reactor, were immersed in synthetic wastewater and then in real wastewater. The optimal conditions and the effects of parameters (current intensity, electrolysis time and initial pH) on phosphate and nitrate removal, the formation of by-products, and the operating cost were assessed in the case of synthetic wastewater. This optimization allowed to eliminate 89.21 % of phos­phates, 69.06 % of nitrates with an operating cost of 3.44 USD m-3 against 13.67 mg L-1 of ammonium generated. Optimal conditions applied to real domestic wastewater made it possible to remove 93 % of phosphates and 90.3 % of nitrates with an ammonium residual of 30.9 mg L-1. The addition of sodium chloride reduced the residual ammonium content to 2.95 mg L-1. Further, XRD analysis of the sludge showed poor crystal structure and the FTIR spectrum suggested that the phosphate is removed by adsorption and co-precipitation

CARACTERISATION BIOCHIMIQUE ET FONCTIONNELLE DES GRAINES DE SEPT CULTIVARS DE VOANDZOU [VIGNA SUBTERRANEA (L.) VERDC. FABACEAE] CULTIVES EN CÔTE D'IVOIRE

Seeds of Bambara groundnut [Vigna subterranea (L.) Verdc.] were collected from seven cultivars in the locality of Ouangolodougou, north Côte d'Ivoire. The seeds biochemical composition was evaluated in order to determine the nutritional value of Bambara groundnut. The results showed that the moisture content varied between 7.35 to 9.02%, ash content 2.55 to 2.98 %; crude fiber 2.57 to 4.08 % and the protein content 14.61 to 20.74%. Seeds lipid composition was varying between 7.69 to 8.55 %, while the content of carbohydrate was between 54.05 to 64.50 %. Energy value was found to range from 370.02 to 388.80 Kcal per 100 g of flour. The content of phenolic compound varied from 142.43 to 205.92 mg per 100 g EG. For the functional properties, the water absorption capacity was between 199.26 to 239.75 ml per 100 g of flour, while the oil absorption capacity was between 2 to 2.12 ml / g flour. The study showed that Bambara seeds grown in that area could be a good source of nutrients. Therefore, the judicious use of Bambara seeds could be a source of additional nutrients in the diet of vulnerable population

Low-cost activated carbon for adsorption and heterogeneous ozonation of phenolic wastewater

This work is aimed at elaborating an innovative material from palm tree waste that can be used in industrial applications for adsorption and catalytic oxidation. This low-cost activated carbon, elaborated from Borassus palm tree waste (bpAC) showed textural and chemical properties comparable with common activated carbon. Moreover, it demonstrated interesting behaviour when it was coupled with ozone to remove a phenolic compound, 2,4-dimethylphenol (2,4-DMP). This refractory model molecule was removed two times faster in the presence of bpAC and was achieved in only 7 min. The total organic carbon (TOC) removal by only adsorption on bpAC was satisfactory with a value of 93.8% after 8 h. Nevertheless, the most interesting result concerned the TOC removal during catalytic ozonation which increased from 26% (single ozonation, i.e., without bpAC) to 91% in the presence of bpAC. The addition of a radical scavenger (tert-butanol) showed that hydroxyl radicals were involved during ozonation with bpAC. Moreover, a kinetics study highlighted that both radical and molecular mechanisms were acting in heterogeneous reaction. All the results were finally validated by treating real wastewater spiked with 2,4-DMP, confirming the ability of this bpAC to enhance the treatment of phenolic wastewaters

Removal of Gentian Violet by activated carbon from mango kernel shells (Adams)

This study aims to Gentian Violet (G.V) removal using activated carbon (AC). The AC was obtained by chemical activation of mango kernel shells (Adams) with potassium hydroxide (AC-BK), at 600°C and for 2h. AC-BK has been characterized by physico-chemical analyses such as: specific surface area, zero charge point pH, surface functions and morphology. With a specific surface area of 534 m2.g-1, AC-BK was used to remove Gentian Violet (G.V) in batch mode and under magnetic stirrer at 150 rpm. Thus, the effect of contact time, initial concentration, pH and temperature of the reaction medium was studied. The maximum abatement rate for G.V was 96.5 % at temperature of 25 °C and pH = 6. Among the models discussed, the Freundlich model seems to better reflect the elimination of G.V. by AC-BK with a coefficient of determination very close to 1 (R2 > 0.99). In addition, this reaction is well fitted by pseudo-second order kinetics with a regression coefficient of 0.99. The adsorption of G.V by AC-BK is characterized by a multilayer on the surface of the AC. These results suggest that AC-BK was effective in removing of G.V with a maximum adsorption capacity of 160. 10 mg.g-1 and could therefore be tested for the remediation of dye-laden industrial effluents

CARACTERISATION BIOCHIMIQUE ET FONCTIONNELLE DES GRAINES DE SEPT CULTIVARS DE VOANDZOU [VIGNA SUBTERRANEA (L.) VERDC. FABACEAE] CULTIVES EN CÔTE D'IVOIRE

Seeds of Bambara groundnut [Vigna subterranea (L.) Verdc.] were collected from seven cultivars in the locality of Ouangolodougou, north Côte d'Ivoire. The seeds biochemical composition was evaluated in order to determine the nutritional value of Bambara groundnut. The results showed that the moisture content varied between 7.35 to 9.02%, ash content 2.55 to 2.98 %; crude fiber 2.57 to 4.08 % and the protein content 14.61 to 20.74%. Seeds lipid composition was varying between 7.69 to 8.55 %, while the content of carbohydrate was between 54.05 to 64.50 %. Energy value was found to range from 370.02 to 388.80 Kcal per 100 g of flour. The content of phenolic compound varied from 142.43 to 205.92 mg per 100 g EG. For the functional properties, the water absorption capacity was between 199.26 to 239.75 ml per 100 g of flour, while the oil absorption capacity was between 2 to 2.12 ml / g flour. The study showed that Bambara seeds grown in that area could be a good source of nutrients. Therefore, the judicious use of Bambara seeds could be a source of additional nutrients in the diet of vulnerable population