KINETIC, ISOTHERMS AND THERMODYNAMIC MODELING FOR ADSORPTION OF ACID BLUE 92 (AB92) FROM AQUEOUS SOLUTION BY MODIFIED AZOLLA FILICOLOIDES

Dyes are the important contaminants of the environment. The dyes are often toxic, carcinogenic and mutagenic and can lead to allergies and skin problems. Therefore, it is necessary to treat the colorfull effluents before discharging into the environment. The aim of this research was to evaluate the Azolla filicoloides ability in removal of AB92 dye from aqueous solution. The Azolla biomass was dried in the sunlight and then it was crushed and sieved to particle sizes in range of 1-2 mm. After that, it was treated with 0.1M HCl for a period of 5h. The residues concentration of AB92dye was measured by spectrophotometer in [gamma]max of 571 nm. The effect of pH, contact time, initial AB92 dye concentration, biosorbent dosage, kinetic and isotherm models of AB92 adsorption were investigated. The pH value of 3, contact time of 90 min, adsorbent dosage of 7 g/L and dye concentration of 10 mg/L were determined as optimum conditions for the adsorption process. The maximum Acid Blue 92 dye removal efficiency by modified Azolla filicoloides was 99% which it obtained in optimum conditions. The equilibrium data is best fitted on Langmuir isotherm and the adsorption kinetic model follows pseudo-second model. Thermodynamic parameters showed that biosorption of Acid Blue 92 was spontaneous and endothermic. This study showed that Azolla could be used as an efficient sorbent for the removal of dyes from aqueous solution.