TITLE:
Removal of Acid Yellow 25 from Aqueous Solution by Chitin Prepared from Waste Snow Crab Legs
AUTHORS:
Chin-Chuan Wei, Inoka K. Pathiraja, Emily Fabry, Kyle Schafer, Nick Schimp, Tuo-Ping Hu, Lawrence P. Norcio
KEYWORDS:
Acid Yellow 25, Chitin, Adsorption Kinetics, Adsorption Isotherm
JOURNAL NAME:
Journal of Encapsulation and Adsorption Sciences,
Vol.8 No.3,
July
25,
2018
ABSTRACT: Acid Yellow 25
(AY25) is used in the textile industry for dyeing of natural and synthetic
fibers, and is also used as a coloring agent in paints, inks, plastics, and
leathers. Effluents from such industries are major sources of water pollution. Hence, it is important to find simple, efficient,
and inexpensive ways to remove these dyes from wastewater. Here, we determined
the suitability of chitin extracted from waste crab legs as an adsorbent for
removing AY25 dye. The adsorption kinetics was modeled using pseudo-first
order, pseudo-second order, and intraparticle diffusion equations to
determine the rate controlling step. Results showed that the pseudo-second
order adsorption mechanism is predominant, and the overall rate of the dye
adsorption process is therefore controlled by an adsorption reaction. Adsorption
isotherms were analyzed by utilizing the Langmuir, Freundlich,
Dubinin-Radushkevich (D-R) and Temkin isotherm models at 23℃, with data
collected by using various initial dye concentrations with different chitin
dosages. Our results show the highest correlation with the Langmuir model,
consistent with the fact that chitin contains both a monolayer and homogeneous
adsorption sites. Based on the D-R model, the adsorption of AY25 dye onto
chitin is via chemisorption. Furthermore, we have concluded that the rate
constants of both pseudo-second order adsorption and film diffusion are
correlated to the initial dye concentrations and chitin dosages. In conclusion,
chitin from waste crab legs is a very suitable adsorbent material that is
capable of rapidly removing up to 95% of the initial concentration of AY25 dye
at a pH of 2 and room temperature.