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

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 q_e (exp.) is more close to the calculated value q_e.(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%.

KEYWORDS:

• Natural sorbent
• chromium(VI)
• low cost
• galvanising

Disclosure statement

The authors declare that they have no conflict of interest.

Additional information

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.