探討二氧化鈦及鈦酸鹽奈米管摻入金屬物質 以光催化降解染料之研究

Study on photocatalysis rates of methylene blue using the doped titanium dioxide and titanium dioxide nanotubes by metal ions

蘇子紜(ZI-YUN SU)

指導教授 ： 趙煥平

中原大學/工學院/環境工程學系/碩士(2022年)

https://doi.org/10.6840/cycu202201488

摘要

光催化目前已被廣泛研究於如何處理廢水中難分解的有機物，在過去二氧化鈦是最常被使用的光催化劑，經過能量激發後，二氧化鈦能夠產生電子躍遷，利用氫氧自由基進行氧化還原反應以分解污染物，但由於電子-電洞對結合快速降低了TiO2降解效果，為了提升TiO2使用上的效率，本研究以摻入或複合其他元素的方式提升TiO2和以TiO2所合成之鈦酸鹽奈米管作為光催化劑降解不同pH溶液中的陽離子染料亞甲基藍。
首先將TiO2利用水熱法合成製備TNT，並使用氯化鋅及硫酸亞鐵在水熱合成法下對TiO2及TNT進行摻雜合成不同金屬摻之催化劑TiO2-Zn、TiO2-Fe及TNT-Fe，藉由BET、SEM、EDS、FTIR、XRD、Zeta potential等分析技術，對催化劑之結構與成分加以鑑定。本實驗不同酸鹼值下，使用0.1克之光催化於50ppm濃度下之亞甲基藍染料(MB)進行吸附及降解測試，利用完全黑暗及照射紫外光兩種方式觀察光催化劑在不同酸鹼值下之降解效果，探討不同環境條件對各光催化劑之效果。
實驗結果顯示，由XRD分析可以得知五種樣品之晶型皆為銳鈦礦，TNT-Fe除了銳鈦礦還有些許金紅石；FTIR分析可得知合成之光催化劑表面皆具有OH官能基團，此官能基有助於光催化之氧化還原反應；EDS分析可知材料中催化劑主要元素為C、O及Ti，水熱合成後之TNT則多了Na元素，金屬摻雜之催化劑皆有發現相對應之特徵峰。在五種催化劑中，以TNT-Fe催化劑之吸附與光催化效果較為顯著，在所有酸鹼值中都可達到高去除效率。與完全黑暗的環境下相比，利用紫外光照射有助於光催化效果，提升光催化效率，在不同的pH值溶液中，以pH3下有最好的光催化效果，最大去除量從120分鐘縮短至60分鐘。

關鍵字

光催化 ； 水熱合成法 ； 二氧化鈦奈米管 ； 金屬摻雜

並列摘要

Photocatalysis has been widely used on the treatment of wastewater containing unbiogradable organic substances. Titanium dioxide (TiO2) is a most common material to be used in the photocatalysis process. Titanium dioxide excited through light energy can generate electronic transitions and hydroxyl radicals to carry out redox reaction to decompose pollutants. However, the electron-hole pairs might combine rapidly, which inhibit the degradation of organic pollutants by TiO2. In this study, TiO2 was doped or compounding other elements. Moreover, the doped TiO2 and titanate nanotubes (TNT) synthesized by TiO2 were used as photocatalysts to degrade the cationic dye methylene blue in the different pH solutions.
TNT was synthesized by TiO2 through the hydrothermal method. Then TiO2 and TNT were doped with zinc chloride and ferrous sulfate through the hydrothermal process to produce the catalysts of TiO2-Zn, TiO2-Fe and TNT-Fe. The produced materials were characterized by BET, SEM, EDS, FTIR, XRD, zeta potential and other analytical techniques. 0.1 g of photocatalyst was added in different pH solution containing 50ppm methylene blue dye (MB) for the adsorption and degradation experiments. To distinguish the removal rates by adsorption or photocatalysis, the experiments were carried out under the darkness or ultraviolet light condition with pH ranged from 3 to 9. The removal rates of MB by adsorption photocatalysis were elucidated based on the environmental conditions.
The experimental results showed that the five samples are classified as anatase phase from XRD analysis. TNT-Fe has not only anatase phase but also has rutile one. FTIR spectra demonstrated that the synthesized photocatalysts have OH functional groups on the surface, and this functional group contributes to the photocatalytic redox reaction. EDS analysis exhibits that the main elements of the catalysts contain C, O and Ti. After the hydrothermal synthesis, Na element is found in TNT. The elemental composition in all catalysts can correspond with expected results. Among the five catalysts, the TNT-Fe is the best one for the photocatalytic and adsorption in all pH solutions. Compared the results in dark with those in the ultraviolet light, the ultraviolet light can produce a good photocatalytic effect and improve the photocatalytic efficiency. It can be found the optimum photocatalytic reaction was found in pH3, and the period in the maximum degradation rate is shortened from 120 to 60 minutes.

並列關鍵字

Photocatalysis ； hydrothermal synthesis ； titanium dioxide nanotubes ； metal doping

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