The kinetic adsorption of p-cresol from aqueous solution onto mesoporous activated carbon was investigated for 100, 500 and 1000 mg L-1 initial concentrations, at constant 295 K temperature. The kinetic of the adsorption process was discussed using three kinetic models, i.e., pseudo-first order kinetic model, pseudo-second order kinetic model, and Avrami fractionary order kinetic model. In order to provide a mathematically rigorous method for evaluating the kinetic parameters using the original form of the kinetic models, the nonlinear regression was selected as most viable algorithm. The common statistical tools was employed to check the accuracy of fit measure, namely, sum of the squares of the errors SSE, reduced sum of the squares of the errors Red-SSE, coefficient of determination R2, adjusted coefficient of determination Adj R2 and standard deviation SD.

This study aims to investigate NieMo/gAl 2 O 3 and NieLa/Zn-ZSM-5egAl 2 O 3 catalysts, which convert methyl esters into various compounds with a similar composition to those found in diesel fuels. The catalysts were synthesized by impregnation using two different routes and characterized by atomic absorption spectrometry, BrunauereEmmetteTeller, and scanning electron microscopy. The acid strength distribution indicates a relatively high concentration of weak acid centers for both materials. The disposal of the catalysts into the reactor system is an important factor for driving the process toward the desired reaction products. The hydrodeoxygenation becomes important and paraffins are formed as intermediaries when NieMo/gAl 2 O 3 is first disposed into the reactor, whereas hydrocracking is poor and the dehydrocyclization does not occur in the case of NieLa/Zn-ZSM-5egAl 2 O 3 as first layer. Triple-layered catalytic systems enhance the production of n-paraffins with high carbon number, mainly C17 and C18, which are important as diesel component. The effect of temperature was also studied and it was found that aromatics are mainly formed over double-layered catalytic systems by varying the temperature. In the case of triplelayered catalysts, the change in the product composition from saturated hydrocarbons with 12e18 carbon atoms to aromatics was observed by increasing the temperature from 420 to 445 C. An interesting finding by the addition of n-octane in the feed was observed and the considerable increase in C8 aromatics involved the dehydrocyclization that occurred faster than hydrocracking.

The present paper studies biodiesel samples preparation by transesterification and compares their physical and chemical properties (biofuels prepared from different raw materials - vegetable oils: sunflower oil, crocus oil and soya bean oil) and the biodegradability degree, as well as the possibilities of the integration of such production unit in industrial diagram of auto fuels production.

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