Synthesis-activated carbon based on various agri-food wastes for highly efficient removal of an anionic dye before analysis by UV-Vis spectrometry

Abstract

This study aims to valorize three agricultural-food (agri-food) wastes: Argan husks, dates seeds, and olive stones collected from various regions of Morocco to produce three types of activated carbons (ACah),(ACds) and (ACos) respectively. These activated carbons were used to compare their effectiveness in removing methyl orange, an organic pollutant in aqueous solutions. The precursor materials were carbonized at a temperature of T=900°C for 2 hours and subsequently chemically activated using phosphoric acid (H3 PO4) in a weight ratio of 1:2. The obtained samples were characterized by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and BET-analysis to determine the specific surface area. The analysis revealed that (ACah) displayed a rough surface with more pores and O-H chemical bonds, indicating its superior adsorption properties. This finding corresponds to the BET-specific surface areas obtained, which were 476 m2g-1 for ACah, 441 m2g-1 for ACds, and 362 m2g-1 for ACos. In all methyl orange adsorption experiments (10 mg L-1), 60 mg of each activated carbon was used for 30 minutes, resulting in removal efficiencies of 93.87% for ACah, 91.83% for ACds, and 89.79% for ACos. The examination of adsorption kinetics and isotherm analysis demonstrated a strong alignment of the adsorption data with both the pseudo-second-order and Langmuir models across various materials.