新型旋流式涡流空化器的流场仿真及该空化器对废水中土霉素的去除效果

为有效去除废水中的残留抗生素，设计了一种由涡流腔与螺旋线流道相组合的新型旋流式涡流空化器。运用ANSYS流场计算软件仿真该涡流空化器核心部件流场的绝对压力；研究了不同溶液初始pH值、土霉素初始质量浓度、降解时间及温度控制范围等条件下该旋流式涡流空化器对水中土霉素的去除效果；用亚甲基蓝法检测该旋流式涡流空化器产生的羟基自由基质量浓度，初步推断其降解土霉素的机理。结果表明：本研究中设计的新型旋流式涡流空化器在局部区域可形成远低于饱和蒸汽压的低压区域，具有较明显的涡流空化效应；酸性和中性条件有利于涡流空化器中土霉素的降解，但总体上，溶液初始pH值对降解率影响不大；随土霉素初始浓度的增大，土霉素的降解率相应下降；在最初10 min内土霉素的降解速率较快，随后变慢，至50 min时初始质量浓度2 mg·L⁻¹的土霉素溶液的降解率为76.45%；控制溶液温度在25~50 ℃时，对土霉素的降解更有利；该旋流式涡流空化器产生的羟基自由基质量浓度为4.58 μmol·L⁻¹，由此可推断，土霉素的降解可能主要在羟基自由基的强氧化作用下完成。涡流空化法降解抗生素技术可为废水中抗生素的去除提供一种新的途径。

Flow field simulation in a novel swirling vortex cavitator and its performance on oxytetracycline removal from wastewater

To effectively remove antibiotics residues in wastewater, a novel swirling vortex cavitator composed of vortex cavity and spiral channel was designed. ANSYS software was used to simulate the absolute pressures of flow fields in the vortex cavitator core components. Under the different conditions including initial solution pH values, initial concentrations of oxytetracycline, degradation times and temperature control ranges, the removal efficiencies of oxytetracycline in wastewater were examined. The concentrations of hydroxyl radical were determined by methylene blue method, and the mechanism of oxytetracycline degradation was deduced. The results showed that the local area in the vortex cavitator can form a low-pressure area with far lower pressure than the saturated vapor pressure, and has an obvious vortex cavitation effect. The acidic and neutral pHs were conducive to oxytetracycline degradation in the vortex cavitator. However, the initial pH value of the solution had slight effect on the degradation efficiency. The degradation efficiencies decreased with the increase of oxytetracycline concentration. The degradation rate was fast within 10 minutes, and then slowed down. The degradation efficiency of 2 mg·L−1 oxytetracycline solution reached 76.45% at 50 minutes. 25~50 ℃ for the solution temperature was conducive to oxytetracycline degradation. The concentration of hydroxyl radical produced by the swirling vortex cavitation device was 4.58 μmol·L−1. It was concluded that the possible oxytetracycline degradation pathway was mainly the oxidation of hydroxyl radicals. This provides a new way for antibiotics treatment by the swirling vortex cavitation degradation technology.