【摘要】：氯代苯甲酸作為一種重要化工原料和中間體被廣泛使用,由于具有致癌、致畸、致突變“三致效應(yīng)”,其排放使地表水體生態(tài)環(huán)境受到嚴(yán)重污染。光化學(xué)轉(zhuǎn)化是有機(jī)污染物在水體環(huán)境中去除的重要方式。本文針對(duì)地表水體嚴(yán)重的富營(yíng)養(yǎng)化現(xiàn)象,研究水體中氮、磷對(duì)氯代苯甲酸光化學(xué)降解轉(zhuǎn)化的影響具有重要意義。本文采用TiO2光催化氧化技術(shù)降解鄰氯苯甲酸,主要包括以下幾個(gè)部分：(1)首先采用凝膠溶膠法制備TiO2,考察制備過(guò)程中各個(gè)因素的影響。運(yùn)用XRD和TG對(duì)催化劑進(jìn)行表征,并用亞甲基藍(lán)測(cè)試其光催化活性；(2)利用自制TiO2與商業(yè)P25型TiO2在相同實(shí)驗(yàn)條件下光催化降解鄰氯苯甲酸,根據(jù)其去除率來(lái)比較兩種催化劑的光催化性能,采用催化性能較好的TiO2來(lái)進(jìn)行后續(xù)試驗(yàn)�？疾旃饨忄徛缺郊姿徇^(guò)程中初始濃度、催化劑投加量和溶液pH值的影響,確定最佳降解條件；(3)在水體N、P富營(yíng)養(yǎng)化的情況下考察鄰氯苯甲酸的光解效果；(4)利用醇類(lèi)做為羥基自由基的捕獲劑,初步檢驗(yàn)羥基自由基理論；(5)采用液質(zhì)聯(lián)用來(lái)檢測(cè)鄰氯苯甲酸光解的中間產(chǎn)物,以推斷鄰氯苯甲酸的光解過(guò)程。實(shí)驗(yàn)結(jié)果顯示：(1)自制TiO2的晶型受煅燒溫度影響顯著,其中450-600℃煅燒制備的TiO2為銳鈦礦型,對(duì)亞甲基藍(lán)光催化降解2.5小時(shí)后降解率高達(dá)95%左右；(2)在相同實(shí)驗(yàn)條件下商業(yè)P25型TiO2比自制的TiO2對(duì)鄰氯苯甲酸光解4小時(shí)后,其降解效果差距較大,相對(duì)比之下最終選擇P25型TiO2作為后續(xù)實(shí)驗(yàn)的催化劑,確定了光解鄰氯苯甲酸的最佳條件,當(dāng)溶液初始濃度為30 mg/L時(shí)催化劑投加量為0.1g/L、溶液初始pH值為3.5；(3)在最佳光解條件下當(dāng)水體中N、P呈現(xiàn)不同程度的富營(yíng)養(yǎng)化狀態(tài)時(shí),均會(huì)對(duì)鄰氯苯甲酸的光解產(chǎn)生抑制作用。其中,溶液中5 mg/L的NO3-使2-CBA的去除率下降了近27%,0.5 mg/L的H2P04-使2-CBA的去除率下降了近25%。(4)實(shí)驗(yàn)體系中加入異丙醇導(dǎo)致2-CBA的去除效率明顯降低,表明2-CBA光解過(guò)程中起主要作用的是羥基自由基,初步驗(yàn)證了羥基自由基理論。(5)通過(guò)液質(zhì)聯(lián)用的檢測(cè)結(jié)果得知2-CBA光解中間產(chǎn)物為鄰氯苯酚,初步推斷出2-CBA降解過(guò)程為先脫羧而后羥基化。本實(shí)驗(yàn)研究為鹵代芳香酸類(lèi)在水體環(huán)境中的遷移轉(zhuǎn)化,尤其是在富營(yíng)養(yǎng)化水體中的光解轉(zhuǎn)化機(jī)理提供了重要依據(jù)。
[Abstract]:Chlorobenzoic acid, as an important chemical raw material and intermediate, is widely used. Because of its carcinogenic, teratogenic and mutagenic effects, the discharge of chlorobenzoic acid has seriously polluted the ecological environment of surface water. Photochemical transformation is an important way to remove organic pollutants in water environment. In view of the serious eutrophication of surface water bodies, it is of great significance to study the effects of nitrogen and phosphorus on the photochemical degradation and transformation of chlorobenzoic acid. In this paper, the degradation of o-chlorobenzoic acid by TiO2 photocatalytic oxidation is described. The main contents are as follows: (1) TiO2 was prepared by gel sol method, and the influence of various factors in the preparation process was investigated. XRD and TG were used to characterize the catalyst and methylene blue was used to test its photocatalytic activity. (2) the photocatalytic degradation of o-chlorobenzoic acid was carried out under the same experimental conditions using self-made TiO2 and commercial P25 type TiO2. According to the removal rate, the photocatalytic performance of the two catalysts was compared, and the TiO2 with better catalytic performance was used to carry out the follow-up test. The effects of initial concentration, catalyst dosage and pH value of the solution during photolysis of o-chlorobenzoic acid were investigated, and the optimum degradation conditions were determined. (3) the photolysis effect of o-chlorobenzoic acid was investigated under the condition of eutrophication. (4) the hydroxyl radical theory was preliminarily tested by using alcohols as the trapping agent of hydroxyl radical, (5) the intermediate product of photolysis of o-chlorobenzoic acid was detected by liquid-quality coupling to infer the photolysis process of o-chlorobenzoic acid. The results showed that: (1) the crystal type of TiO2 was significantly affected by calcination temperature. The TiO2 prepared by calcination at 450-600 鈩，

本文編號(hào)：2171169