Studies on the potential use of activated carbon from guava seeds (AC-GS) as a prospective sorbent for the removal of Cr(VI) from aqueous acidic medium

Abstract

ABSTRACT The aim of this study is to use guava seeds as a source of activated carbon (AC-GS) as eco-friendly and low-cost adsorbent for the removal of toxic Cr(VI) from aqueous solutions. Parameters affecting the adsorption process were investigated and characterisation of the prepared AC using (SEM) and FT-IR was carried out. The physical properties such as the yield (Y %), ash%, moisture% and particle size of the prepared (AC-GS) from guava seeds were calculated and found to be 30%, 1.5%, 2% and 75 µm, respectively. Based on the regression coefficient values, the pseudo-second-order was found to be more suitable than the first-order kinetic model; in addition, the value of qe (exp.) is more close to the calculated value qe.(cal.). The maximum sorption capacity of (AC-GS) was found to be 244 mg/g at pH = 1 and V/m = 0.16 L/g after four sorption cycles. The values of ∆H, ∆G and ∆S were found to be −31 k J/mole, −3 k J/mole and −93 J /mole. K, respectively, which indicates that the adsorption process is exothermic. Adsorption isotherm of Cr(VI) ions on the AC-GS could be fitted by the four isotherm models in the order: Freundlich > Temkin >D-R > Langmuir. Comparison between AC-Gs and other related AC from different materials indicates that AC-GS is more efficient and sustainable adsorbent for the removal of Cr(VI) from aqueous solution. AC-GS efficiently removed Cr(VI) from simulated wastewater solution of galvanising industry with % removal = 99%.