Adsorption Of Selected Dyes By Chemically Modified Uncaria Gambir Extract
Loading...
Date
2012
Authors
Achmad, Azraa
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Uncaria gambir extract was chemically modified to develop a novel adsorbent for the adsorption of Methylene Blue (MB), Sunset Yellow FCF (SY), and Direct Red 23 (DR 23) from aqueous solution. It was revealed that the ethyl acetate extraction of gambir showed highest total phenolic and total flavonoid contents. The gambir extract was subjected to pretreatment with formaldehyde and hydrochloric acid to produce the modified gambir adsorbent (MGA) which was then characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscope (SEM) with energy dispersive X-ray (EDX) spectroscopy, Brunauer-Emmett-Teller (BET) surface area, and pH zero point of charge (pHzpc). Adsorption tests were conducted in batch reactors under various conditions where the effect of pH, adsorbent dosage, contact time, and dye initial concentration were studied. The adsorption experimental data of MB, SY and DR 23 were well described by the Langmuir isotherm and the maximum adsorption capacity at 303 K was found to be 149.3 mg g-1, 6.4 mg g-1 and 26.3 mg g-1, respectively. The adsorption process for all dyes was followed by pseudo-second order kinetic model. Thermodynamic study had showed that the adsorption process of MB, SY and DR 23 onto MGA were endothermic and spontaneous. Maximum desorption study of MB was obtained in pH 2 aqueous solution meanwhile for SY and DR 23 were achieved in pH 10 aqueous solution. Based on the isotherm, thermodynamic and desorption studies, the adsorption of MB, SY and DR 23 onto MGA was chemical and physical adsorption processes. The research indicated that Uncaria gambir extract has a potential to be employed as an adsorbent for the removal of dyes from aqueous solutions.
Description
Keywords
Uncaria gambir extract was chemically modified , for the adsorption of Methylene Blue