Pyrite cinder as a cost-effective heterogeneous catalyst in heterogeneous Fenton reaction: decomposition of H2O2 and degradation of Acid Red B

2014 ◽  
Vol 70 (9) ◽  
pp. 1548-1554 ◽  
Author(s):  
Deli Wu ◽  
Yanxia Liu ◽  
Dong Duan ◽  
Luming Ma

Pyrite cinder (PyC) was employed as a heterogeneous Fenton-like catalyst, and its catalytic activity was evaluated in view of the effects of catalyst dosage, pH and leaching metal ions. PyC showed significant reactivity, and the pseudo-first-order kinetic rate constant for decomposition of H2O2 and degradation of Acid Red B (ARB) were 3.4 and 14.89 (10−3 min−1) respectively when pH = 5. When 20 g/L PyC was added into 10 mM H2O2 solution in neutral pH, H2O2 could be completely degraded within 4 h, and more than 90% ARB was removed. Leaching metal ions from PyC were found to have little effect on decomposition of H2O2 or on degradation of ARB. PyC still had high catalytic activity after five successive runs. The decomposition mechanism of H2O2 was analyzed and the Haber–Weiss mechanism was employed in this paper. The electron spin resonance image showed •OH was produced and increased between 3 and 5 min in the PyC catalyzing H2O2 reaction, which demonstrated that PyC had a durable ability to produce •OH.

2010 ◽  
Vol 150-151 ◽  
pp. 1710-1713
Author(s):  
Ying Jie Zhang ◽  
Yue Xiao Tian ◽  
Da Peng Li ◽  
Guo Rui Liu ◽  
Li Zhang ◽  
...  

A new Fenton-like catalyst was prepared to degrade Orange IV in water by catalytic decomposition of H2O2. The optimal preparation conditions were discussed. The catalytic activity of catalyst was evaluated by the degradation of Orange IV and the decomposition of H2O2. The results show that solid super acid (S2O82-/FexOy) soaked in (NH4)2S2O8 is the most effective catalyst among the synthesized iron oxides soaked in other oxidants. The optimal conditions for solid super acid preparation are calcined at 500 for 2 h in the air.


2014 ◽  
Vol 53 (47) ◽  
pp. 12855-12859 ◽  
Author(s):  
Ping Jiang ◽  
Qian Liu ◽  
Yanhui Liang ◽  
Jingqi Tian ◽  
Abdullah M. Asiri ◽  
...  

Author(s):  
Ganapati D. Yadav ◽  
Shashikant B Kamble

Alkylation of mesitylene with tert-butyl alcohol in the presence of novel mesoporous superacidic catalysts, namely, UDCaT-4, UDCaT-5 and UDCaT-6 was investigated. The catalysts are modified versions of zirconia showing high catalytic activity, stability and reusability in the presence of water as compared to conventional sulfated zirconia. The catalytic activity is in the order: UDCaT-5 (most active) > UDCaT-6 > UDCaT-4 > sulfated zirconia (S-ZrO2) (least active). The synergistic effect of the very high sulfur content present (9% w/w S) and the preservation of the tetragonal phase in UDCaT-5, in comparison with sulfated zirconia (4% w/w S), were responsible for higher catalytic activity. A catalyst ensuring the production of 2-tert-butyl-mesitylene (2-TBMT) with 98% selectivity and 94% conversion of tert-butanol (TBA) was developed under optimum reaction conditions. The formation of products is correlated with the acidity of the catalyst. The reactions were conducted in liquid phase at relatively low reaction temperatures (120–150 °C). A systematic investigation of the effects of various operating parameters was accomplished and a mathematical model is developed to describe the reaction pathway and validated with experimental results. The reaction was carried out without using any solvent in order to make the process cleaner and greener. An overall second order kinetic equation was used to fit the experimental data, under the assumption that both mesitylene and tert-butanol are weakly adsorbed. An independent dehydration study of tert-butanol (TBA) was also done.


Author(s):  
Z. Y. Yao ◽  
G. X. Zhu ◽  
T. L. Lu ◽  
Y. Z. Zhan

Abstract Using the bulk g-C3N4 as a precursor, four g-C3N4 nanosheets were further prepared by ultrasonic, thermal, acid, and alkali exfoliation. The structures of these materials were characterized by various techniques such as X-ray powder diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-Ray spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The synergistical Fenton catalysis of these materials with Cu2+ was evaluated by using rhodamine B as a simulated organic pollutant. The results showed that there existed a significant synergistical Fenton catalysis between Cu2+ and g-C3N4. This synergistic effect can be observed even when the concentration of Cu2+ was as low as 0.064 mg L−1. The properties of g-C3N4 strongly influenced the catalytic activity of the Cu2+/g-C3N4 system. The coexistent of Cu2+ and the alkali exfoliated g-C3N4 showed the most excellent catalytic activity. Hydroxyl radicals as oxidizing species were confirmed in the Cu2+/g-C3N4 system by electron paramagnetic resonance spectrum. The synergistic catalysis may be attributed to the easier reduction of Cu2+ adsorbed on the g-C3N4. This study provided an excellent Fenton catalytic system, and partly solved the rapid deactivation of heterogeneous Fenton catalysts caused by the leaching of metal ions. HIGHTLIGHTS There exists a significant synergistical Fenton catalysis between trace Cu2+ and g-C3N4. The Cu2+ concentration is lower than the maximum acceptable limit in drinking water. This study partly solved the rapid deactivation caused by the leaching of metal ions. This study reminds researchers to pay attention to the possible synergistic catalysis between leached ions and supports.


Author(s):  
Данил Александрович Роженцев ◽  
Ренат Русланович Мансуров ◽  
Николай Константинович Ткачев ◽  
Ольга Владимировна Русских ◽  
Александр Александрович Остроушко

Исследованы образцы частично окисленного микро- и нанопористого железа, полученного методом высокотемпературного деаллоинга железо-марганцевого сплава в солевом расплаве. При помощи электронной микроскопии получены данные о морфологии образцов и составе их поверхности, установлено, что уже после отмывки при комнатной температуре на воздухе образовались оксидные фазы железа в виде вискеров толщиной порядка 10 нм. В ходе получения образцов достигалось количественное удаление марганца из исходного сплава. Оценена каталитическая активность полученных образцов в гетерогенной реакции Фентона по окислению красителя метилового оранжевого пероксидом водорода. На первом этапе протекания реакции, описываемой уравнением реакции первого порядка, ее скорость определялась наиболее активной расходуемой частью образцов, далее реакция переходила в стационарный режим. Более высокой каталитической активностью обладали нанопористые образцы. The samples of partially oxidized micro- and nanoporous iron obtained by high-temperature dealloing of an iron-manganese alloy in a molten salt were investigated. The data concerning the structure of the samples and the composition of their surface were obtained by electron microscopy; it was found that after washing at room temperature in air the oxide phases of iron were formed as whiskers with a thickness of about 10 nm. During the preparation of the samples a quantitative removal of manganese from the initial alloy was achieved. The catalytic activity of the obtained samples in the heterogeneous Fenton reaction was estimated by oxidation of methyl orange by hydrogen peroxide. The rate of the first stage of the reaction, which was described by the first-order equation, was determined by the most active spent part of the samples, and then the reaction passed into the stationary mode. The nanoporous samples possessed a higher catalytic activity.


2015 ◽  
Vol 3 (3) ◽  
pp. 1272-1278 ◽  
Author(s):  
Shujun Xu ◽  
Kunpeng Song ◽  
Tao Li ◽  
Bien Tan

Microporous polymers were synthesised using external cross-linked N-heterocyclic carbene and benzene. These materials can serve as ligands to bind metal ions and demonstrated high catalytic activity for efficient Suzuki–Miyaura coupling reactions.


2017 ◽  
Vol 14 (6) ◽  
pp. 361 ◽  
Author(s):  
Zhen Yuan ◽  
Minghao Sui ◽  
Jianrui Yang ◽  
Pan Li ◽  
Zhiran Liu ◽  
...  

Environmental contextNorfloxacin is widely used as a human and veterinary medicine for its broad-spectrum antibacterial activity. It is chemically stable, rendering it difficult to remove from water using the traditional water and wastewater treatment techniques. We investigate the use of iron oxide catalysts for the degradation of norfloxacin in water prior to its release into the environment. AbstractThe catalytic activity of ordered mesoporous Fe2O3 (om-Fe2O3) on H2O2 oxidation of norfloxacin (NOR) under neutral pH conditions in water was investigated. Using non-ordered-mesoporous Fe2O3 as a reference (nom-Fe2O3), om-Fe2O3 with high specific surface area of 176.4m2g−1 and a uniform pore structure exhibited high catalytic activity in the decomposition of H2O2 as well as the degradation of NOR at neutral pH. Compared with nom-Fe2O3, om-Fe2O3 promoted the decomposition of H2O2 differently. The adsorption capacity of om-Fe2O3 for NOR was much higher than that of nom-Fe2O3. The adsorption efficiency of NOR on om-Fe2O3 accounted for 60.2–64.9% of the degradation efficiency in om-Fe2O3/H2O2. tert-Butanol (TBA), which is resistant to adsorption by om-Fe2O3, had no effect on the degradation of NOR by om-Fe2O3/H2O2. However, the presence of tromethamine (TMA), which was favourable to adsorption by om-Fe2O3, inhibited the degradation of NOR significantly. Based on the different effects of TBA and TMA on the degradation of NOR, it is proposed that the catalytic degradation of NOR may occur on the surface of om-Fe2O3. Hydroxyl radicals (·OH) generated may be bound on the surface of om-Fe2O3 without diffusing into aqueous solution. It is proposed that the adsorption of target organic pollutants must be considered when assessing the suitability of the om-Fe2O3/H2O2 process. The mechanism of om-Fe2O3 in promoting H2O2 decomposition into OH was also investigated.


Author(s):  
Junfeng Hua ◽  
Mei Huang

Abstract By providing the key carbon and nitrogen elements needed for eutrophication, the potential toxicity of ethylenediaminetetraacetic acid (EDTA) prompts the exploration of effective treatment methods to minimize the amount of EDTA released into the environment. In this study, Fe3O4 magnetic nanoparticles (MNPs) were prepared and used as catalysts to study the mineralization of EDTA in Fenton-like reactions under neutral pH. Fe3O4 MNPs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and Brunauer–Emmett–Teller (BET). The effects of pH, ferric ion leaching, and H2O2 concentration on chemical oxygen demand (COD) removal of EDTA were investigated. The morphological characterization of the nanoparticles suggests a quasi-spherical structure with small particle size and a surface area of 49.9 m2/g. The results show that Fe3O4 MNPs had good catalytic activity for the mineralization of EDTA under pH 5.0–9.0. The optimum conditions for the COD removal of 45% at pH 7.0 were: 40 mM H2O2, 10 mM Fe3O4, and 1 g/L EDTANa2·2H2O at 303 K. Fe3O4 MNPs maintained high catalytic activity after five cycles of continuous degradation of EDTA. According to reactive oxidizing species measurements obtained by electron spin resonance (ESR), it was confirmed that HO· free radicals, presented in the H2O2/Fe3O4 MNPs heterogeneous Fenton-like reaction, were the primary active group in the removal of EDTA. These features can be considered beneficial to the application of Fe3O4 MNPs towards industrial wastewater treatment.


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