Efficient sequester of hexavalent chromium by chemically active carbon from waste valorization (Phoenix Dactylifera)

Abstract This research assessed the adsorption of hexavalent chromium Cr(VI) on chemically active carbon (AC) produced from Phoenix Dactylifera fronds (PF) through batch experiments. To determine the optimum conditions for the synthesis process, the effect of different parameters such as impregnation ratio (1:2 ‒ 8:2), activation time (90 ‒ 270 min) and ramp rate (5 ‒ 30 °C min-1) on the BET surface areas, pore volumes, and percent yield of the prepared Phoenix Dactylifera fronds active carbons (PFACs) were studied. The PF, PF charcoal (PFC) and PFACs were characterized by nitrogen adsorption Brunauer-Emmett-Teller (BET), Thermogravimetric analysis (TGA) and Fourier Transform infrared spectroscopy (FTIR) were used for surface functional groups. Morphology analysis was done by Scanning Electron Microscopy (SEM), Transmission electron microscopy (TEM) for particle size analysis and Energy Dispersive X-ray (EDX) was utilized for elemental analysis. The optimal preparation conditions for the highest BET surface area 1901 m2 g-1, mesopore surface area 1835 m2 g-1, total pore volume 0.756 cm3 g-1 and particle size 0.785 nm of the PFAC were found to be 6:2 impregnation ratio, activation temperature 400 °C for 180 min activation time and heating ramp rate of 5 °C min-1. The adsorption properties of PFAC have inspected through the chromium Cr(VI) ions adsorption from aqueous solutions. The effect of different adsorption factors such as contact time, pH, adsorbent dose, shaking rate and temperature, to adsorb Cr(VI) on its capacity was examined under batch conditions. The maximum adsorption of 98% Cr(VI) at optimizing conditions of PFAC was 0.06 g adsorbent dose, contact time 6 hours, pH 6, at 25 °C temperature and with 150 rpm shaking speed was found.