Catalytic ozonation of p-chloronitrobenzene over pumice-supported zinc oxyhydroxide

2013 ◽  
Vol 68 (8) ◽  
pp. 1895-1900 ◽  
Author(s):  
Lei Yuan ◽  
Jimin Shen ◽  
Zhonglin Chen

The catalytic ozonation of p-chloronitrobenzene (pCNB) in an aqueous solution using pumice-supported zinc oxyhydroxide (ZMP) as the catalyst was investigated. ZMP significantly enhanced the degradation efficiency in the heterogeneous catalytic ozonation compared with ozonation alone. The decomposition rate of the aqueous ozone increased 2.84-fold in the presence of ZMP. Catalytic ozone decomposition showed that pCNB is oxidized primarily by hydroxyl radicals (•OH) in ozonation/ZMP processes. This modification increases the density of surface hydroxyl groups as well as the pH at the point of zero charge (pHPZC) of pumice, resulting in the appearance of new ZnO and Zn(OH)2 crystalline phases. An investigation of the underlying mechanism confirms that ZnOOH loading promotes •OH initiation, which enhances the degradation of pCNB.

2014 ◽  
Vol 242 ◽  
pp. 348-356 ◽  
Author(s):  
Qiangqiang Sun ◽  
Laisheng Li ◽  
Huihua Yan ◽  
Xiaoting Hong ◽  
K.S. Hui ◽  
...  

2012 ◽  
Vol 15 (2) ◽  
Author(s):  
Héctor Valdés ◽  
Héctor P. Godoy ◽  
Claudio A. Zaror

AbstractIn this work, the influence of volcanic sand surface hydroxyl groups (Me-OH


2012 ◽  
Vol 557-559 ◽  
pp. 448-455 ◽  
Author(s):  
Fa Min Shi ◽  
Lei Wang ◽  
Si Mo Shi ◽  
Han Fei Zhang ◽  
Chang Qing Dong ◽  
...  

A DFT study of the catalytic properties of CuO/CNT and CuO@CNT complexes for the heterogeneous catalytic ozonation has been performed. We illustrated the atomistic details of CuO/CNT and CuO@CNT with a quantitative and qualitative discussion within such an electronic structure characteristics. Ozone was catalytically decomposed into an atomic oxygen species and oxygen molecule on both the surface inner and outer CuO@CNT complex, while ozone can only decompose over CuO on the outer surface of CuO/CNT, with partial electrons transfer from CuO/CNT and CuO@CNT complexes to the adsorbate. Then the atomic oxygen reacted with the water molecule to form two hydroxyl groups on the surface, promoting the reaction chain for the generation of•OH which, in turn, lead to an increase in the catalytic ozonation efficiency. Results show synergetic confinement effect of metal oxide nanoparticles inside CNT could also lead to an acceleration of ozone decomposition and the generation of •OH on the inner and outer surface of carbon-nanotube containing catalytic particles.


2019 ◽  
Vol 41 (6) ◽  
pp. 521-530 ◽  
Author(s):  
Qiushi Zhu ◽  
Wei Yao ◽  
Haibo Ye ◽  
Shuofan Li ◽  
Mengmeng Si ◽  
...  

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Liqiang Yan ◽  
Jishuai Bing ◽  
Hecheng Wu

Abstract A transformation process of ozone on different iron oxides suspensions, including α-Fe2O3, α-FeOOH, Fe3O4, was carried out using FTIR of adsorbed pyridine, ATR-FTIR and electron paramagnetic resonance (EPR) spectra with isotope 18O3. It was verified that on the surface isolated hydroxyl groups and the surface hydroxyl groups without acid sites of these iron oxides, ozone was electrostatically adsorbed and did not interact with the surface of these oxides, stably existed as ozone molecule. In contrast, ozone could replace the surface hydroxyl groups on Lewis acid sites of oxides, and directly interacted with the surface metal ions, decomposing into reactive oxygen species (ROS) and initiating the surface metal redox. The results indicate that Lewis acid sites were active center while the electronic cycle of the Fe2+/Fe3+ is advantageous to promote ozone decomposition into O2•− and •OH radicals. The mechanism of catalytic ozonation in different surface acid sites of iron oxides aqueous suspension was proposed on the basis of all experimental information.


2020 ◽  
Vol 12 (24) ◽  
pp. 10503
Author(s):  
Savvina Psaltou ◽  
Efthimia Kaprara ◽  
Kyriaki Kalaitzidou ◽  
Manassis Mitrakas ◽  
Anastasios Zouboulis

In order to enhance the efficiency of heterogeneous catalytic ozonation, the effect of thermal treatment on three commonly used and inexpensive minerals, i.e., zeolite, talc and kaolin (clay), which present different physicochemical properties as potential catalysts, has been examined for the removal of para-chlorobenzoic acid (p-CBA). p-CBA is considered a typical micro-pollutant, usually serving as an indicator (model compound) to evaluate the production of hydroxyl radicals in ozonation systems. The catalytic activity of selected solid catalysts was studied for different pH values (6, 7 and 8) and different temperatures (15 °C, 25 °C and 35 °C). The mechanism of radicals’ production was also verified by the addition of tert-butyl alcohol (TBA). The respective thermal behavior study showed that the point of zero charge (PZC) of these minerals increased with the increase of applied treatment temperature, as it removed crystalline water and hydroxyls, thus improving their hydrophobicity. Circa-neutral surface charge and the presence of hydrophobicity were found to favor the affinity of ozone with solid/catalytic surfaces and the subsequent production of hydroxyl radicals. Therefore, zeolite and talc, presenting PZC 7.2 and 6.5 respectively, showed higher catalytic activity after thermal treatment, while kaolin with PZC equal to 3.1 showed zero to moderate catalytic efficiency. The degradation level of p-CBA by oxidation was favored at 25 °C, while the pH value exerted positive effects when it was increased up to 8.


1986 ◽  
Vol 51 (7) ◽  
pp. 1430-1438 ◽  
Author(s):  
Alena Reissová ◽  
Zdeněk Bastl ◽  
Martin Čapka

The title complexes have been obtained by functionalization of silica with cyclopentadienylsilanes of the type Rx(CH3)3 - xSi(CH2)nC5H5 (x = 1-3, n = 0, 1, 3), trimethylsilylation of free surface hydroxyl groups, transformation of the bonded cyclopentadienyl group to the cyclopentadienyl anion, followed by coordination of (h5-cyclopentadienyl)trichlorotitanium. The effects of single steps of the above immobilization on texture of the support, the number of free hydroxyl groups, the coverage of the surface by cyclopentadienyl groups and the degree of their utilization in anchoring the titanium complex have been investigated. ESCA study has shown that the above anchoring leads to formation of the silica-supported bis(h5-cyclopentadienyl)dichlorotitanium(IV) complex.


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