The results demonstrated that oats straw and agave baggasse contain carboxyl and hydroxyl functional groups. Chromium (III) removed by acid washed OS and AB was 2.48 and 9.85 mg/g, respectively. Based on chromium (III) removed and ions released (mainly H+ and Ca2+) during the sorption process, it was suggested that the main sorption mechanism was ion exchange: for each mol of CrOH2+ adsorbed 1 mol of Ca2+ and 2 mol of H+ were released to the solution. On the other hand, the highest chromium desorption was obtained by using an EDTA solution at 55°C.
Agro-waste materials such as oats straw and agave baggasse are capable of removing cations from aqueous solution. Preliminary results show that chromium (III), as CrOH2+, is exchanged by Ca2+ and H+ during the sorption process. In addition, an EDTA solution could be used to regenerate chromium loaded biosorbents.
Keywords: Oats straw, Agave baggasse, Chromium (III), Sorption, Mechanism.