In this work, activated carbons (ACs) prepared by chemical activation of garcinia cola nut shell impregnated with H 3 PO 4 (CBH 2/1) and KOH (CBK 1/1) were used to study the kinetics, equilibrium and thermodynamics of the adsorption of thymol blue from aqueous solution. The characterization of ACs showed the BET measurements gave surface area and total pore volume respectively of 328.407 m 2 •g −1 and 0.1032 cm 3 •g −1 for CBH 2/1 and 25.962 m 2 •g −1 and 0.03 cm 3 •g −1 for CBK 1/1 ; elemental analysis showed a high percentage of carbon in both ACs. Influence of parameters such as initial pH, contact time, adsorbent mass, initial concentration, ionic strength and the effect of temperature on the removal of thymol blue from aqueous solution were studied in batch mode. The studies showed that equilibrium adsorption was attained after 60 minutes for the two ACs, adsorption capacity increased with increasing concentration of thymol blue, and maximum adsorption capacity was obtained at an acidic environment with pH 2. Avrami's non-linear kinetic expression was the best suited for describing the adsorption kinetics of thymol blue onto ACs, while equilibrium data showed that the three-parameter isotherms better described the adsorption process since R 2 > 0.96, and the error functions were lowest for all of them.

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Waste cooking oils are an agro-food waste with adverse effects on the health of living organisms and the environment. The main objective of this work is to valorize waste cooking oil for the synthesis and physicochemical characterization of biodiesel. The method used is based on the transesterification reaction of the oils using methanol and a basic homogeneous catalyst. In this study we employ waste from refined palm oil used for frying doughnuts. After optimization a reaction time of 2 hours, KOH catalyst, and a molar ratio of 9:1 were selected to obtain a good quality biodiesel. Physicochemical characterization was performed on the biodiesel to obtain its density, viscosity, calorific value, acid number, saponification index and IR spectral features. The analysis shows that the biodiesel obtained after transesterification has physicochemical characteristics similar to those of diesel and is consistent with American standards.

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