BASIC BLUE 41 DYESTUFF ADSORPTION ONTO PURIFIED SEPIOLITE: ISOTHERMS, KINETIC-THERMODYNAMIC STUDIES AND ERROR ANALYSIS

Abstract

Sepiolite, which was found to have a dolomitic structure by XRD analysis, was utilized as an adsorbent to remove the cationic Basic Blue 41(BB41) mono azo dye from wastewater. The physicochemical parameters of purified sepiolite in accordance with the eluate criteria were investigated using pHpzc, XRF, FTIR, SEM-EDS and BET techniques. The adsorption process was optimized with pH 9.0, 0.03 g/45 mL adsorbent dose, 80 minutes equilibrium time and initial dye concentration in the range of 30-120 mg/L. While the maximal adsorption capacity was determined to be 153.85 mg/g, the D-R isotherm (R2=0.9652) provided the best correlation coefficient among the isotherm models investigated. Based on the error analysis methodologies applied, the Sips isotherm was considered to be the best appropriate model. The most suitable kinetic model has been identified as the pseudo-second-order kinetic model. The adsorption energy [E= 0.0177 kJ/mol] and the calculated ΔG° values ranging from -3.12 kJ/mol to -7.35 kJ/mol for varying concentrations support physical and spontaneous adsorption. The exothermic nature of adsorption results in ΔH° values ranging from -10.4 kJ/mol to -12.6 kJ/mol for various doses.