A COMPARATIVE STUDY OF REMOVAL OF MALACHITE GREEN USING ZVI (ZEROVALENT IRON) AND ZVI/US (ZEROVALENT IRON-ULTRASOUND)

In this study, removal of MG (malachite green), a toxic dye, by ZVI (zerovalent iron) and ZVI/US (combining use of zerovalent iron and ultrasound) was comparatively studied. The result shows that MG could be removed by ZVI, and a combined use of ZVI and ultrasonic enhanced MG degradation. MG degradation by ZVI and ZVI/US treatment followed the first-order kinetic equation. The first-order rate constant for MG degradation by ZVI was enhanced by a factor of about 2 under ultrasonic irradiation, at initial pH ranging from 2 to 10. MG degradation percentage by ZVI increased significantly as the initial pH of solution increased from 2 to 4. For ZVI treatment, initial pH of the solution had little effect on MG degradation when it was above 4. For ZVI/US treatment, MG degradation percentage increased significantly with initial pH from 2 to 7, but increased slightly with initial pH from 7 to 10. MG degradation percentage increased as ZVI dosage increased both for ZVI treatment and ZVI/US treatment. MG de radation percentage by ZVI and ZVI/US treatment and the corresponding degradation rate decreased when initial MG concentration increased. An increase in ultrasonic power intensity from 0.5 to 2.0 W ml(-1) resulted in higher MG degradation percentage and rate, whereas a further increase in ultrasonic power intensity resulted in a decrease in MG degradation.