Activated carbon from grape seeds upon chemical activation with phosphoric acid: Application to the adsorption of diuron from water

The preparation of activated carbon from grape seeds was studied by chemical activation with phosphoric acid. Grape seeds were pretreated with sulfuric acid to improve wettability and impregnated at different grape seed to phosphoric acid ratios (1:1–1:4). The impregnated grape seeds were carbonized in a static horizontal furnace at temperatures between 350 and 550 °C. Microporous activated carbons with some contribution of mesoporosity were obtained. The best results in terms of surface area (1139 m2/g) and mesopore volume (0.24 cm3/g) development were observed for a grape seeds to phosphoric acid ratio of 1:3 and a carbonization temperature of 500 °C. The activated carbon prepared shows granular morphology and an egg shell structure that favors application in liquid phase. The activated carbon was tested in the adsorption of diuron from aqueous phase. The adsorption rate was measured within the temperature range of 15–45 °C. First and second order rate equations and intraparticle diffusion model were checked to fit the kinetic data.

► Preparation of granular activated carbon with “egg-shell” or “hollow core” structure.
► Allocation of most of the material in a outer 200–300 μm layer.
► Enhanced transport thanks to morphology and homogeneous meso- and macro-porosity.
► Adsorption kinetics equivalent to that of powdered activated carbon.