Kinetics and Thermodynamic Study of Acid Red 73 Dye Removal on HCl- Water Hyacinth Stems Biomass

DYE containing waste water can cause serious water pollution problems by hindering light penetration and photo synthesis and toxicity from heavy metals associated with dyes. The ability of HCl-water hyacinth stems (HCl-WHS) biomass powder to adsorb acid red 73 (AR73) dye, from aqueous solutions has been investigated through batch experiments. The dye removal was found to be dependent on adsorbent dosage, initial dye concentration, mixing speed, contact time and adsorbent particle size. All batch experiments were carried out at constant pH and temperature of 3.0 and 289K respectively. Pseudo-first-order and pseudo-second-order models have been used to represent the process kinetics and obtain the main kinetic parameters. The results show that the pseudo-first order model is the one that best describes the biosorption of the AR73. The experimental isotherm was analyzed using the Langmuir and Freundlich equations. The maximum adsorption capacity was found 50 mg AR73 per g HCl-WHS powder. The thermodynamic study indicated that the adsorption of AR73 onto HCl-WHS surface was favorable, spontaneous and endothermic.