Decolourization of C.I. Direct blue 78 aqueous solution in presence of exfoliated graphite under ultrasound irradiation

Abstract

This paper reports an efficient and convenient removal of C.I. Direct blue 78 dye from aqueous solution by the combination of ultrasound and exfoliated graphite. The effects of various factors such as <i>p</i>H, temperature, dosage of exfoliated graphite and initial concentration of dye were studied. The results show that ultrasound irradiation significantly improves removal of C.I. Direct blue 78 from aqueous solution in presence of exfoliated graphite. A removal of 98% was achieved within 20 min using 1.0 g/L exfoliated graphite at <i>p</i>H 1 and 25^oC for 50 mg/L Direct blue 78 aqueous solution. Direct blue 78, solution was discoloured nearly 100% at 45°C. The maximum adsorption capacity of exfoliated graphite towards the dye was found to be 152.9 mg/g. Langmuir isotherm equation fits better than Freundlich isotherm equation for describing the isotherm data for the present system. The adsorption of Direct blue 78 over exfoliated graphite follows first-order kinetics.