Impact Factors of p-Nitrophenol Treatment by Hydraulic Cavitation due to Circular Orifices Plates

With the rapid development of modern industry, both the shortage of water resources and threat to human health (due to the water pollution) have become a worldwide problem. Hydraulic cavitation, as an advanced water treatment technology, is being studied and discussed by many researchers. The circular orifices plates were used in the hydraulic cavitation device in this paper. P-Nitrophenol (P-NP) was degraded under different hydraulic conditions respectively. And free hydroxyl radicals were captured by Methylene Blue (MB). It was using UV spectrophotometer to analyze P-NP concentration and free hydroxyl radical concentration before and after the treatment. Effect of pH value, water temperature, back pressure (of experimental device), initial concentration and opening rate (of orifices plate) on P-NP degradation were analyzed based on the variation in concentration. The results showed that the temperature increases, the P-NP degradation of hydraulic cavitation treatment increases constantly too. It becomes the biggest one when reaching a certain temperature (35-40 degrees C). Processing efficiency reduces gradually after exceeding this temperature. It can get optimal effect of degradation in neutral wastewater conditions. The back pressure should be 0.08MPa in order to receive stable and ideal data easily. As the initial concentration increases, the degradation of P-NP first increases and then decreases, the concentration of P-NP reaches the maximum value in the range of 25-50mg/L. Along with the opening rate of orifices plate increases, the degradation first increases and then decreases as well. In this experiment of the orifices plate, it is found that the processing effect of 3mm in diameter, 49 in number is best.