Cassava starch modified montmorillonite - an efficient material for removal of crystal violet dye from contaminated aqueous solution

Abstract

Because of grave effects on human health and the ecosystem, dye wastewater is exigent to be treated before its access to the environment. Removal of dyes from wastewater is one of the most important steps to eliminate its harmfulness. In this study, montmorillonite (MMT), a clay mineral with numerous applications in catalytic and coating purposes, was modified to form a new adsorbent for the removal of crystal violet (CV) dye from contaminated aqueous solution. Vietnamese cassava starch which is biodegradable, renewable, sustainable and affordable, was used as a modifier for MMT. The modified MMT was characterized by Fourier-transformed infrared (FT-IR) and X-ray diffraction (XRD) spectroscopic methods. Its morphology and structure were observed by Scanning electron microscopy (SEM). In addition, the effects of pH, interaction time, adsorbent concentration and temperature on the physico-chemical adsorption process on the basis surface of the material, have been investigated. Langmuir and Freundlich models were applied to analyze the adsorption values of dye solutions at the time of equilibrium. The results indicated that the modified MMT possessed the spherical shape, with particles on the surface in a wide size range. Investigation on the ideal removal conditions for modified MMT showed that it removed the crystal violet dye with maximum adsorption at pH value of 7 and concentration of 101.1 mg/g after 1 hour of interaction. Moreover, the Langmuir adsorption isotherm model was compatible with all results and the adsorption kinetics followed the pseudo-second-order model. Starch modified MMT should be promising for dye removal from wastewater.