Application of Two-and Three-Parameter Isotherm Models: Biosorption of Acid Red 88 onto<i>Azolla microphylla</i>

Abstract

ABSTRACT Biosorption potential of Azolla microphylla for acid red 88 from aqueous solution was investigated under laboratory conditions as a function of initial pH and temperature. The algal biomass exhibited the highest dye sorption capacity at optimum conditions of pH 3 and temperature 30°C. The experimental isotherms were analyzed using five two-parameter models (Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, and Flory-Huggins) and five three-parameter models (Redlich-Peterson, Sips, Khan, Radke-Prausnitz, and Toth). Three error analysis methods were used to evaluate the experimental data: correlation coefficient, residual root mean square error (RMSE), and chi-square test to find the best fitting isotherm. In particular, Langmuir (two-parameter) and Khan (three-parameter) models described the dye biosorption isotherm data well at all pH and temperature conditions examined.