ADSORPTIVE REMOVAL OF DYES FROM SYNTHETIC WASTEWATER USING ACTIVATED CARBON FROM TAMARIND SEED

Abstract

Activated carbon prepared from seed (Tamarindus indica) was utilized for the removal of orange G and safranin O dyes from aqueous solution. Chemical activation using orthophosphoric acid (H3PO4) was employed for the preparation of activated carbon. The effect of various factors namely; particle size, pH, adsorbent dosage, ion concentration, and contact time was studied to identify the adsorption capacity of the tamarind seed. The percentage of dye adsorbed was found to be dependent on these factors. The Langmuir, Freundlich, and Temkin isotherm models are fitted into the graphs, but the Freundlich isotherm model is best-fitted into the experimental data. The pseudo-first order, pseudo-second order, Elovich, and Bhattacharya-Venkobachor kinetic models were also fitted into the graphs, but pseudo-second order is best fitted into the experimental data. The thermodynamic parameters such as enthalpy, entropy, and free energy were evaluated using the Van’t Hoff equations. The negative free energy (∆G) and negative enthalpy (∆H) indicate the feasibility and exothermic nature of the adsorption process. The positive entropy (∆S) shows the increased randomness of the solid/solution interface during the adsorption process. The chemical functional groups, crystalline nature, and the surface morphology of the carbon adsorbents were studied by Fourier Transform Infrared (FTIR) spectroscopy, X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Characteristics of the activated carbons were determined using standard methods.