High adsorption capacity of thermally treated solid olive wastes to treat olive mill wastewater

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.