No abstract

This study compares three types of activated carbon (AC) prepared from agri-food waste: olive pomace (ACOP), date pits (ACDP) and argan shells (ACAS), collected from different regions of Morocco, for the removal of the organic pollutant methyl orange (MO) from aqueous solutions. The three ACs were used after carbonization of their precursors at 900°C for 2 hours followed by chemical activation with phosphoric acid (H3PO4) with a weight ratio of 1:2. A quantity of 0.06g of each prepared activated carbon in contact with MO solution with a concentration of 10mg/L for 30 minutes respectively showed a removal efficiency of 93.87% for ACAS followed by 91.83% for ACDP and finally 89.79% for ACOP. This could be attributed to the BET specific surface area of the prepared activated carbons which is 475 m²/g for ACAS, 440 m²/g for ACDP and 361 m²/g for ACOP, as well as to the physicochemical analyses by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) which showed the presence of rough surfaces with more pores for ACAS and chemical bonds O-H, C-O, C = O, CO-O-CO and C-C on the three activated carbons. The kinetic study and isothermal analysis indicated that the adsorption data follow a pseudo-second order model and the adsorption results follow the Langmuir model.