三氯乙烯重质非水相液体聚结分离的实验研究

以三氯乙烯(TCE)为模拟污染物,配置非均质介质TCE重质非水相液体(DNAPL),搭建DNAPL聚结分离器,通过实验研究网状和颗粒状材料润湿性、流量、编织孔径、床层厚度及TCE浓度等重要参数对分离性能的影响规律。结果表明:(1)网状材料润湿性越强,聚结分离器的分离效率越高,相应水相出口TCE浓度越少。应选择亲分散相纤维作为聚结介质,网状聚四氟乙烯具有最高的分离效率(96.71%),是填充聚结分离器的优选材料。(2)填充材料的分离效率随流量的变化曲线呈抛物线,流量为80 L/h时聚结分离器具有最高的分离效率。(3)分离效率随编织孔径的减小、床层厚度的增大、TCE浓度的减小而升高。

Construction of 3D flowers-like O-doped g-C_(3)N_(4)-[N-doped Nb2O5/C]heterostructure with direct S-scheme charge transport and highly improved visible-light-driven photocatalytic efficiency

Constructing a suitable heterojunction photocatalytic system from two photocatalytic materials is an efficient approach for designing extremely efficient photocatalysts for a broader range of environmental,medical,and energy applications.Recently,the construction of a step-scheme heterostructure system(hereafter called the S-scheme)has received widespread attention in the photocatalytic field due to its ability to achieve efficient photogenerated carrier separation and obtain strong photo-redox ability.Herein,a novel S-scheme heterojunction system consisting of 2D O-doped g-C_(3)N_(4)(OCN)nanosheets and 3D N-doped Nb_(2)O_(5)/C(N-NBO/C)nanoflowers is constructed via ultrasonication and vigorous agitation technique followed by heat treatment for the photocatalytic degradation of Rhodamine B(RhB).Detailed characterization and decomposition behaviour of RhB showed that the fabricated material shows excellent photocatalytic efficiency and stability towards RhB photodegradation under visible-light illumination.The enhanced performance could be attributed to the following factors:fast charge transfer,highly-efficient charge separation,extended lifetime of photoinduced charge carriers,and the high redox capability of the photoinduced charges in the S-scheme system.Various trapping experiment conditions and electron paramagnetic resonance provide clear evidence of the S-scheme photogenerated charge transfer path,meanwhile,the RhB mineralization degradation pathway was also investigated using LC-MS.This study presents an approach to constructing Nb_(2)O_(5)-based S-scheme heterojunctions for photocatalytic applications.

用于重质非水相液体分离的新型旋流器研究

高效分离地下水中的重质非水相液体已成为地下水修复领域的热点问题。设计了一种内溢流管外侧带有环隙溢流管的新型旋流器,通过数值模拟对比了传统旋流器与新型旋流器的流场特性、短路流量及对重质非水相液体的分离性能。结果表明:(1)新型旋流器的环隙溢流结构降低了内旋流区的切向速度和轴向速度,增大了外旋流区的切向速度,且消除了短路流。(2)新型旋流器在网格数量2470810、最佳入口速度6 m/s时,分离效率最高达到99.91%,在同等分离效率的前提下分离时间缩短为传统旋流器的81%。