Chemically Treated Orange Peels as a Bio-absorbent for Various Dyes

Abstract

In this study, the decolorization capability of various synthetic dyes using the chemically treated orange peel (CTOP) is highly effective. An uncomplicated consecutive chemical treatment process by sodium hydroxide and iso-propanol promotes enhanced adsorption capacity of the raw orange peel for cationic dyes and enables high removal efficiencies in a wide range of pH conditions. The highest removal efficiency of the CTOP for the dyes in the pH range of 3-9 follows the order, safranin (99 %, pH 3) > methylene blue (97 %, pH 5) > methyl violet (91 %, pH 9) > rhodamine B (37 %, pH 3) > Congo red (20 %, pH 5). The adsorption capacity of CTOP for methylene blue calculated from the Langmuir model ( ?? 2 > 0.99) is remarkably high at 294 mg/g, which is almost 1.5 times higher than that of the untreated orange peels. These results demonstrate the great potential of low-cost, effective CTOP for application in the purification of dye-contaminated water. The selective removal of certain groups of toxicants from contaminated water using bio-peels can be achieved via tailoring their surface properties as removing essential oils on surface peels to increase the pore, appearing dendrimer-like microspores.