[Degradation of reactive red X-3B by ultra sound synergized with zero-valent iron]

The synergistic effects of ultra sound and zero-valent iron were studied by measuring the degradation of X-3B in zero-valent reduction, ultra sound degradation and synergistic systems. The effects of pH, ultra sound power and irradiation time on the synergistic system were explored. The results show that the X-3B is degraded difficultly by ultra sound and the total removal rate is less than 7.75% after 25min ultrasonic irradiation. When pH is 5.0, 7.0 and 9.0, the degradation rate of X-3B in synergistic system is about 1.68, 1.76 and 1.67 times, respectively, than the total removal rate of zero-valent iron reduction plus ultrasound degradation. After 25min ultrasonic irradiation in synergistic system, 99.42% of X-3B is removed at pH7.0. However, the degradation rate of X-3B in zero-valent iron reduction system is much higher than that of synergistic system at pH3.0. The degradation mechanism of X-3B in zero-valent iron reduction system is different from that of synergistic system. The X-3B is degraded into intermediate pollutants in the former, but is degraded completely in the latter. Accordingly, the X-3B can be degraded effectively in the synergistic system of zero-valent iron and ultra sound, when pH is 5.0 approximately 7.0 and the power of ultra sound is 400 approximately 600W.