Removal of Malachite green dye (MG) from water by using Residual Tea Leaves (RTL) as adsorbent

Abstract

The present study is related to the removal of colorants. Adsorption of
Malachite green dye on residual tea leaves was studied as a function of temperature,
amount of adsorbent and pH.
A spectrophotometer technique was used for measuring the extent of
adsorption. The data were fitted with Langmuir and Freundlich, isotherm equations
and their corresponding constants were calculated from the slopes and intercepts of
their respective lines.
The measured adsorption isotherms at the different temperatures 298 K, 308 K
and 318 K were found that adsorption increase as the temperature increase within this
range. from the measured adsorption isotherms at different pHs 3, 5 and 7it was
found that the adsorbed amount of MG dye increases with increased acidity.
Thermodynamic parameters such as standard enthalpy change (ΔHo), standard
Gibbs energy change (ΔGo), and standard entropy change (ΔSo) of adsorption were
calculated, and were explained in the mean of the chemical structure of the adsorbate.
Results are showed that the adsorption process is endothermic.