Novel Bubble Column Design Constructed for Catalytic Ozonation – Effectiveness Assessment by Hydrodynamics and Kinetic Regime Determination

This article introduces an innovative design for a bubble column tailored for catalytic ozonation. A semi-batch reactor was employed with strategically positioned baffles to accommodate catalysts throughout the column. These baffles, constructed with a specially designed mesh-type material, not only served as catalyst supports but also provided an additional active surface for efficient mass transfer on both macro and micro scales. This groundbreaking approach has advanced heterogeneous catalysis by utilizing a multi-structured scaffold enriched with chemically active species. The dual role of the baffles was envisioned to enhance the physical absorption of ozone gas into the liquid and catalytic action in the production of reactive oxygen species (ROS) through ozone decomposition. However, it is crucial to note that any alteration in the column’s geometry can influence the mass transfer resistance. The primary objective of this study was to assess the efficiency of the newly constructed bubble column by determining hydrodynamic parameters. For the column without mesh, the volumetric mass transfer coefficient (k_La) ranged between 0.007 and 0.009 1/s. Upon the incorporation of the mesh, k_La increased to values between 0.007 and 0.01 1/s. Simultaneously, the overall interphase surface rose from 42.16 ± 6.2 1/m to 53.29 ± 7.9 1/m, and the film mass transfer coefficient (k_L) improved from (1.68 ± 0.1) × 10⁻⁴ to (2.13 ± 0.2) × 10⁻⁴ m/s after the mesh installation. This novel column design was specifically engineered for the treatment of textile wastewater. Dye degradation experiments demonstrated a higher rate of color removal when the mesh was inserted, surpassing traditional ozonation methods. Furthermore, the Hatta number increased from 3 to 5 with mesh usage, and the enhancement factor (E) shifted from 2.6 to 4. These enhanced Hatta values and improvement factors suggest that the new column construction successfully transitioned the operating regime from moderate to high speed.

本文介绍了一种专为催化臭氧化工艺设计的创新型鼓泡塔（bubble column）。该装置采用半间歇反应器（semi-batch reactor）结构，通过塔内优化布置的挡板实现全塔催化剂的承载。这些挡板采用特制网状材料制成，既可作为催化剂载体，又可额外提供活性表面，实现宏观与微观尺度下的高效传质。该开创性方案通过使用负载化学活性物种的多结构支架，推动了非均相催化（heterogeneous catalysis）领域的发展。挡板的双重功能旨在强化臭氧气体向液相的物理吸收，以及通过臭氧分解产生活性氧物种（reactive oxygen species, ROS）的催化反应过程。但需注意，鼓泡塔几何结构的任何改动均会影响传质阻力，这一点至关重要。本研究的核心目标为，通过测定流体力学参数，评估该新型鼓泡塔的性能。未安装网状挡板时，体积传质系数（volumetric mass transfer coefficient, k_La）介于0.007~0.009 s⁻¹；加装网状挡板后，该系数提升至0.007~0.01 s⁻¹。与此同时，总相界面积从42.16±6.2 m⁻¹提升至53.29±7.9 m⁻¹；液膜传质系数（film mass transfer coefficient, k_L）则从(1.68±0.1)×10⁻⁴ m/s提升至(2.13±0.2)×10⁻⁴ m/s。该新型鼓泡塔专为纺织废水处理工艺设计。染料降解实验结果表明，加装网状挡板后脱色速率更高，性能优于传统臭氧化工艺。此外，加装网状挡板后，八田数（Hatta number）从3提升至5，增强因子（enhancement factor, E）从2.6升至4。上述八田数与增强因子的提升表明，新型鼓泡塔成功将操作工况从中等速率切换至高速率工况。