High adsorption capacity of thermally treated solid olive wastes to treat olive mill wastewater: Treated solid olive wastes for depollution

Abstract

In this study, solid olive wastes were suggested as adsorbents for olive mill wastewater (OMWW) clean-up. These solid olive wastes underwent thermal treatment by two-step process: carbonization at 300°C and 400°C, then physical activation at 800°C and 1000°C. Characterizations were determined by FTIR, TGA/DTA, and N2 Adsorption-Desorption techniques. The efficiency of these new bio-adsorbents was verified on OMWW. Adsorption kinetics experiments were realized at room temperature and diluted OMWW (1/100 v/v). Evaluation of obtained activated carbons (ash, iodine value, and moisture) shows a good activity and stability in weight according to the thermogravimetric analysis. Moreover, the textural results of BET surface area showed a high area for activated carbons prepared from olive stones at 300°C/800°C (SBET = 208 ± 0.3 m2/g) and olive flesh at 400°C/1000°C (SBET = 77 ± 0.8 m2/g). The adsorption rates of OMWW were 91% after 120 min and 95.3% after 60 min contact time at pH = 2.0, respectively. At the end, the pH increased to neutral value. Thus, these bio-adsorbents from solid waste of olive industry can be efficient adsorbents for their liquid effluent clean-up.