應用高重力旋轉填充床反應器於觸媒臭氧處理程序以去除水中之鄰苯二甲酸二甲酯

Application of High-gravity Rotating Packed Bed for Catalytic Ozonation of Dimethyl Phthalate in Aqueous Solution

張家驥(Chia-Chi Chang)

指導教授 ： 張慶源

國立臺灣大學/工學院/環境工程學研究所/博士(2009年)

https://doi.org/10.6342/NTU.2009.02623

摘要

本研究使用高重力旋轉填充床(high-gravity rotating packed bed, HGRPB)做為氣-液接觸裝置提臭氧之氣-液質量傳送效率對水中溶解性有機物進行臭氧化反應。氣-液質量傳送效率為決定臭氧化系統氧化效率之主要限制因子。HGRPB相較於傳統之氣-質量傳送裝置其質量傳送效率較高。本研究並利用其高混合效率之特性，填入鉑觸媒(Pt/γ-Al2O3)做為觸媒接觸床以催化臭氧自解產生更高氧化能力之氫氧自由基，以提升系統整體氧化效能。系統分為旋轉填充床及光化學反應槽兩部分，以半批次式(semi-batch type)操作 ，並以酚(phenol)為測試物種進行HGRPB之操作測試，求取最適化之系統操作條件。其後，進一步針對生物難分解之環境賀爾蒙物種鄰苯二甲酸二甲酯(dimethyl phthalate, DMP)以臭氧相關之高級氧化程序(advanced oxidation processes, AOPs)加以處理，探討DMP之高級氧化之反應性與處理效果並建立其臭氧化分解反應機制。本研究以高重力臭氧化(high-gravity ozonation, HG-OZ)程序為基礎搭配觸媒及紫外光進行有機物高重力催化臭氧化分解，所比較程序包含高重力臭氧化反應(HG-OZ)、高重力觸媒催化臭氧化(HG catalytic OZ, HG-Pt-OZ)、高重力光催化臭氧化(HG photolysis OZ, HG-UV-OZ) 及高重力觸媒光催化臭氧化(HG-UV-Pt-OZ)。
研究結果顯示HGRPB達高重力狀態轉速(rotating speed, Nr)須在600 rpm (23.76 G)以上。臭氧之氣-液質量傳送係數(kLa)隨Nr增加而提昇。當Nr = 1,200 rpm時，其kLa = 0.0148 s-1。DMP之對臭氧之反應性雖然較phenol差，但以HG-OZ處理DMP在DMP初始濃度(CDMP0)為100 mg L-1、反應液體體積(VL)為1L、Nr為1,200 rpm及臭氧添加劑量(ozone applied dosage, mA,in)為1,500 mg L-1-sample時亦可將DMP完全分解。以HG-OZ處理DMP時可得Nr與DMP相對於mA,in之降解反應速率常數(kDMP)之關係為kDMP = 2 ×10-6 Nr + 0.0005。在HG-OZ處理DMP之系統中，於中性(以緩衝鹽控制pH = 7)時，其降解反應最為迅速，kDMP = 0.0042 (mg l-1)-1;然其總有機物(total organic carbon, TOC)分解則在鹼性(以緩衝鹽控制pH= 10)時礦化分解速率最為迅速，其kTOC = 0.0004 (mg l-1)-1。於HGRPB填充Pt/γ-Al2O3觸媒之HG-Pt-OZ系統，其DMP降解可進一步提升，pH = 7時其kDMP = 0.0067 (mg l-1)-1。而合併使用UV-C光源進行照射之HG-UV-Pt-OZ系統，可進一步分解水中殘留之溶解性臭氧形成氫氧自由基加速水中DMP及TOC分解。DMP之臭氧化降解以phthalate acid (PA)為主要中間產物，進一步臭氧化分解形成mucomic acid、glyoxalic acid、glyoxal、及formic acid等副產物。

關鍵字

臭氧 ； 臭氧催化 ； 觸媒 ； 旋轉填充床 ； 酚 ； 鄰苯二甲酸二甲酯

並列摘要

In this study, a high-gravity rotating packed bed (HGRPB) was used as a gas-liquid mass transfer equipment as well as ozonation reactor to decompose persistent organic pollutants (POPs). Ozonation is limited by its selective reactivity and gas-liquid mass transfer rate while HGRPB is an effective gas-liquid mixing equipment can increasing ozone mass transfer coefficient. The system consists of photoreactor and HGRPB and was carried out via semi-batch type operation. The platinum-containing catalyst (Pt/γ-Al2O3) packed in the HGRPB in conjunction with ozonation (HG-Pt-OZ) can enhance the self-decomposition of molecular ozone in liquid to form high reactive radical species and promote the oxidation ability of ozone in HG-OZ system. Phenol was firstly used to simulate the organic pollutant in HG-OZ based advanced oxidation processes (AOPs) to realize the operation characteristics of the HG system. Then the ozonation efficiency and mechanism of dimethyl phthalate (DMP) were further stuided. Different combinations of HG-OZ with Pt/γ-Al2O3 and UV for the degradation of DMP were tested. These include HG-OZ, HG catalytic OZ (HG-Pt-OZ), HG photolysis OZ (HG-UV-OZ) and HG-UV-Pt-OZ. The O3 gas-liquid mass transfer in HGRPB was also discussed in this study.
The results indicate that the rotating speed (Nr) needs to be higher than 600 rpm (23.76 G) for reaching the well high-gravity condition. The gas-liquid mass transfer coefficient (kLa) increases with Nr for which kLa = 0.0148 s-1 at Nr = 1,200 rpm. The resistance for ozonation of DMP is higher than that of phenol. However it is decomposed completely in all HG-OZ based AOPs at ozone applied dosage (mA,in) of 1,500 mg L-1-sample (with the conditions: intial concentration of DMP CDMP0 = 100 mg L-1, volume of liquid sample VL = 1 L, Nr = 1,200 rpm). The correlation relationship of Nr and DMP decomposition rate (kDMP) is kDMP = 2 ×10-6 Nr + 0.0005. In neutral condition (pH = 7), DMP has the best decomposition rate with kDMP = 0.0042 (mg l-1)-1. However, the total organic carbon has the signest mineralization rate in alkaline solution (pH = 10) with kTOC = 0.0004 (mg l-1)-1. The combined use of Pt/γ-Al2O3 in HG-OZ process (HG-Pt-OZ) can promote the decomposition of DMP with kDMP = 0.0067 (mg l-1)-1 at pH = 7. The UV-C irradiation in photoreactor can further decompose the residual dissolved ozone to form hydroxyl radicals to reduce DMP and TOC. Phthalate acid (PA) is the main intermediate in the beginning of DMP ozonation and further decomposed into mucomic acid, glyoxalic acid, glyoxal and formic acids in the course of ozonation.

並列關鍵字

Ozonation ； catalytic ozonation ； catalyst ； high-gravity rotating packed bed (HGRPB) ； phenol ； dimethyl phthalate (DMP)

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