Enhancing decolorization of Eriochrome Blue Black R during nano-size zero-valent iron treatment using ultrasonic irradiation

Abstract

The effectiveness of nano-size zero-valent iron (NZVI) particles for treatment of Eriochrome Blue Black R (EBBR), a representative azo dye, under ultrasonic irradiation was determined. The influence of experimental variables such as, initial solution pH, NZVI dosage, irradiation time, initial dye, NaCl, and Na2CO3 concentrations on removal efficiency of color were investigated. It was found that the kinetic rate constant of sonocatalytic destruction of EBBR in presence of NZVI was significantly enhanced under acidic conditions. The degradation rate constants of dye increased by increasing of NZVI dose and irradiation time, but decreased by increasing the initial dye concentration. Although, increasing NaCl concentration from 0.1 to 1% (w/v) improved the kinetic removal rate from 0.16 to 0.29 min−1 but, presence of Na2CO3 had no significant effect on the degradation rate. The UV–vis spectrum showed that complete decolorization of synthetic solutions contain 100 ppm EBBR by 0.3 g/L NZVI at initial pH solution 3, occurred at 20 min ultrasonic irradiation.