a b s t r a c tSolvent Free Microwave Extraction (SFME) of oil from French maritime pine bark waste and its antioxidant activity were investigated and compared to classical hydrodistillation (HD) method (Clevenger apparatus). A central composite design combined with response surface methodology was applied to evaluate the simultaneous influences of irradiation power and irradiation time. A maximal extraction yield of 3.48% (g/100 g dry bark) was achieved under optimal extraction time of 92.4 min and an irradiation power of 803.5 W compared 2.2% obtained for the conventional method (HD). Gas chromatography coupled to mass spectrometry (GCeMS) analysis showed that SFME extract is richer in oxygenated compounds (~40%) compared to HD extract with 26%. The results also showed that the two independent variables had a statistical significant effect on the considered responses namely oil yield, total phenolic compounds (TPC) and antioxidant activity assessed by 2,2-diphenyl-1-picrylhdrazyl (DPPH). Under optimized conditions, the amount of TPC was 139.15 mg GAE/g extract largely higher than that obtained for HD extraction (14.28 15 mg GAE/g extract) suggesting that SFME represents an interesting alternative technology for production of recoverable oil from waste of French Maritime pine bark. The percentage inhibition was also higher for SFME extraction technique (71.91%) than for HD (56.51%) indicating a higher antioxidant activity.

Response surface methodology (RSM) is used to optimize the electrocoagulation/electro-flotation process applied for the removal of turbidity from surface water in an internal loop airlift reactor. Two flat aluminium electrodes are used in monopolar arrangement for the production of coagulants. The central composite design is used as a second-order mathematical model. The model describes the change of the measured responses of turbidity removal efficiency and energy consumption according to the initial conductivity (X1), applied voltage (X2), treatment time (X3) and inter-electrode distance (X4). The evaluation of the model fit quality is done by analysis of variance (ANOVA). Fisher's F-test is used to provide information about the linear, interaction and quadratic effects of factors. Multicriteria methodology, mainly the desirability function (D), is used to determine optimal conditions. The results show that, for a maximal desirability function D = 0.79, optimal conditions estimated are X1 = 1,487 μS/cm, X2 = 5 V, X3 = 6.5 min, X4 = 14 mm. The corresponding turbidity removal rate and energy consumption are 84.15% and 0.215 kWh/m3 respectively. A confirmation study is then carried out at laboratory scale using the optimal conditions estimated. The results show a turbidity removal rate of 72.05% and an energy consumption of 0.210 kWh/m3.

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The present study focuses on the optimization of the parameters to extract phenolic products by decoction and the quantification of these compounds from grape pomace, using a central experimental design. The antioxidant activity of methanolic extracts from grape skin grown in Morocco was evaluated. The grapes variety is “Michael Paleiri”, it is a black variety with pips, and they are from the region of Benslimane. The total phenolic compounds contents were determined by the Folin-Ciocalteu method. The optimization suggested that extraction with methanol for 29 min, at 60°C were the best solutions for this combination of variables.The largest amount obtained was 1042.06 mg EGA/g DW. The antioxidant activity is carried out by the radical scavenging method 1,1-diphenyl-2-picryl hydrazyl (DPPH°) and the ferric iron reduction capacity (FRAP). The DDPH inhibition capacity reached 20.78%, compared with 15.22% of a BHT solution at 0.001 g/L. A significant relationship between antioxidant capacity and total phenolic content is evident (R2=0.994). These results demonstrate that methanol extracts from the waste from grapes grown in Morocco could be used as potential sources of natural extracts rich in phenolic compounds and endowed with significant antioxidant activity.

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