TITLE:
Adsorption of Malachite Green from Aqueous Solutions onto Rice Husks: Kinetic and Equilibrium Studies
AUTHORS:
V. M. Muinde, J. M. Onyari, B. Wamalwa, J. Wabomba, R. M. Nthumbi
KEYWORDS:
Adsorption, Malachite Green, Rice Husks, Isotherm, Cationic Dye
JOURNAL NAME:
Journal of Environmental Protection,
Vol.8 No.3,
March
10,
2017
ABSTRACT: A study was done to evaluate the removal of a
cationic dye from simulated waste water onto rice husks (RH). Spectroscopic
methods such as FTIR and SEM/EDX were used for adsorbent characterization. Experimental
dependency on solution pH, initial dye concentration, agitation speed,
adsorbentparticle size, temperature of the solution and contact time was
evaluated. The adsorption data was tested using both Langmuir and Freundlich
isotherms. The data fitted well into Langmuir isotherm model with a monolayer
adsorption capacity of 6.5 mg/g. Further, the separation factor (RL) value was less than unity
indicating a favorable adsorption process. Adsorption kinetics was determined
using pseudo-first-order, pseudo-second-order and intra-particle diffusion
models. The results showed that the adsorption of malachite green onto rice
husks followed pseudo-second-order model with a determination coefficient of
0.986. This work has revealed that rice husks have a great potential to
sequester cationic dyes from aqueous solutions and therefore it can be utilized
to clean contaminated effluents.