Sorption equilibrium and kinetic studies of Direct Yellow 12 using carbon prepared from bagasse, rice husk and textile waste cloth

103-110This paper reports the sorption study of Direct Yellow12 (DY) to describe the suitability of low cost adsorbents prepared from sugar mill waste bagasse, rice mill waste rice husk and textile industry waste cloths for its effective removal. The adsorption studies have been performed by varying parameters such as adsorbent dosage, pH of the dye solution, contact time and temperature. A significant increase in percentage removal of DY with increase in dosage of all the carbons is observed. The maximum removal of dye is obtained under acidic conditions, in particular, at pH 4. The equilibrium adsorption data obtained are used to calculate Freundlich and Langmuir isotherms and thermodynamic parameters such as ∆Go, ∆Ho, ∆So, Ea and S* are calculated in order to understand the nature of sorption process. The sorption process is found to be controlled by pseudo-second-order and pore diffusion models

Synergistic Effect of Chitosan and Titanium Dioxide on the Removal of Toxic Dyes by the Photodegradation Technique

The photodegradation of three different types of dyes like an anionic dye, a cationic dye, and a zwitterionic dye, namely, Reactive Red 2 (RR), Methylene Blue (MB), and Rhodamine B (RB), respectively, have been carried out using chitosan/TiO₂ composite (CTC). The as-synthesized CTC was characterized by Fourier transform infrared (FTIR) spectral studies, scanning electron microscopy (SEM), energy dispersive analysis of X-ray (EDAX), BET, X-ray diffraction (XRD), and thermal analysis (thermogravimetric analysis (TGA) and differential thermal analysis (DTA)). The enhanced photocatalytic activity of CTC for the degradation of the dyes was attributed to the synergistic effect of TiO₂ and chitosan (CS). The photodegradation experiments were carried out by varying different parameters such as irradiation time, dosage, pH, initial dye concentration, coexisting ions, hydrogen peroxide, and light intensity. The kinetic behavior was described in terms of the Langmuir–Hinshelwood model. The confirmation of mineralization of dyes has been studied by measuring chemical oxygen demand (COD)