- Electrochemical and Photocatalytic Decomposition of Perfluorooctanoic acid with a hybrid reactor using a boron-doped diamond electrode and TiO2 photocatalyst
-
The efficient decomposition of environmentally persistent perfluorooctanoic acid (PFOA) was achieved by a hybrid of electrolysis and photocatalysis. The rate constant of PFOA decomposition in the hybrid system was larger than the sum of the constants in electrolysis-only and photocatalysis-only systems. The hybrid system was able to accelerate the PFOA decomposition by complementally support of two kinds of reaction kinetics. These results could be useful for development of a new continuous system for practical treatment of waste water containing perfluorinated acids.
- Ochiai, Tsuyoshi,Moriyama, Hirofumi,Nakata, Kazuya,Murakami, Taketoshi,Koide, Yoshihiro,Fujishima, Akira
-
-
Read Online
- SYNTHESE D'ACIDES PERFLUOROALCANE CARBOXYLIQUE ET SULFINIQUE PAR REDUCTION ELECTROCHIMIQUE D'IODURES DE PERFLUOROALKYLE SUR CATHODE EN FIBRES DE CARBONE DANS LE SOLVANT N,N-DIMETHYLFORMAMIDE. APPLICATION A LA SYNTHESE DE PERFLUORO α,ο DIACIDES
-
The electrochemical reduction of C6F13I on a carbon fibre cathode in DMF as solvent and in the presence of SO2 is studied.Depending on the water content of the solvent, perfluorohexyl sulfinic acid C6F13SO2H or perfluoropentyl carboxylic acid C5F11COOH are obtained.These reactions are applied to 1,4-diiodoperfluorobutane; by varying the composition of the solvent it has been possible to obtain the two diacidic compounds : HO2S(CF2)4SO2H and HO2S(CF2)3COOH.
- Benefice-Malouet, Sylvie,Blancou, Hubert,Calas, Patrick,Commeyras, Auguste
-
-
Read Online
- Ozonolysis of perfluoroalkenes and perfluorocycloalkenes
-
Ozonolysis of 1-methoxyperfluorocyclobutene in Freon-113 followed by hydrogenation of the reaction products gave methyl hydrogen perfluorosuccinate. Under similar conditions, perfluorooct-1- and -2-enes and 4-trifluoromethyl-1,1,1,2,3,4,5,5,5-nonafluoropent-2-ene were converted into perfluorinated heptanoic, hexanoic, and isobutyric acids, respectively.
- Odinokov,Akhmetova,Savchenko,Bazunova,Fatykhov,Zapevalov
-
-
Read Online
- Photocatalytic amidation and esterification with perfluoroalkyl iodide
-
The successful generation of perfluoroalkyl radicals (Rf˙) through photoredox catalysis has inspired us to investigate the preparation of various organofluorine species. In this work, visible light-induced photocatalytic reactions for the preparation of perfluoroalkyl amides and esters from the corresponding amines and alcohols using different types of triplet emitters as photocatalysts have been studied. The effects of the excited-state characteristics and redox potentials of the photocatalysts have been elucidated. Under optimized reaction conditions, these reactions can be performed successfully with different types of amines or alcohols and perfluoroalkyl iodides. Detailed mechanistic studies based on emission quenching experiments have been performed to study the photocatalytic cycles as well as the role of the different reagents. The proposed mechanism has also been examined by DFT calculations.
- Xiao, Yelan,Chun, Yuen-Kiu,Cheng, Shun-Cheung,Ng, Chi-On,Tse, Man-Kit,Lei, Ngai-Yu,Liu, Ruoyang,Ko, Chi-Chiu
-
p. 556 - 562
(2021/02/09)
-
- Electrocatalytic degradation of perfluorooctanoic acid by LaNixY1-xO3 (Y = Fe, Cu, Co, Sr) gas dispersion electrode
-
Perfluorooctanoic acid (PFOA), as a refractory organic pollutant, seriously harms the environment and damages human health. Here, the electrocatalytic method was selected to degrade PFOA. In this work, perovskite catalysts doped with different elements, and corresponding gas diffusion electrodes (GDE) were prepared by the gel-sol method and citric acid complexation method. The crystal structure, microscopic morphology, and electrochemical properties of the LaNixY1-xO3 (Y = Fe, Cu, Co, Sr) perovskite catalyst electrode were analyzed by XRD, TEM, and CV. Moreover, the electrocatalytic performances of the as-prepared electrodes were assessed by the degradation of PFOA, and the Sr-doped GDE exhibited the highest degradation rate of PFOA. The optimum degradation conditions, such as the current density, pH, and initial concentration were also investigated. It was observed that when the current density was 20 mA/cm2, pH was 5, and initial concentration was 0.25 mmol/L, the Sr-doped GDE had the best degradation and defluorination efficiency of PFOA reached 90.0 % and 75.1 %, respectively. High performance liquid chromatography-mass spectrometry (HPLC-MS) was used to analyze the intermediate products of PFOA degradation and obtain the degradation pathway. With the combined action of [rad]OH and O2, PFOA was degraded by stepwise removal of CF2 groups, which were ultimately degraded into F? and CO2.
- Chen, Yongyang,Guo, Dan,Dong, Xiaochun,Li, Yahui,Huang, Yixuan,Chen, Hao,Li, Shanping
-
-
- The effect of oxygen in the photocatalytic oxidation pathways of perfluorooctanoic acid
-
The influence of oxygen in the photocatalytic oxidation of perfluorooctanoic acid (PFOA) promoted by a commercial nano-sized titanium dioxide was studied by testing the reaction in different conditions: static air, oxygen flux, nitrogen flux and pre-saturated nitrogen flux. The reaction was monitored by Total Organic Carbon (TOC) analysis and Ionic Chromatography (IC). Shorter chain perfluorocarboxylic acids (PFCAs; Cn, n = 1-7) intermediate degradation products were quantitatively determined by High-Performance Liquid Chromatography combined with Mass Spectrometry (HPLC-MS) analysis. The presence of shorter chain PFCAs in solution was also monitored by 19F NMR. The experimental findings are in agreement with two major oxidative pathways: Cn → Cn-1 photo-redox and β-scissions routes mediated by COF2 elimination. Depending on the experimental conditions, the mutually operating mechanisms could be unbalanced up to the complete predominance of one pathway over the other. In particular, the existence of the β-scissions route with COF2 elimination was corroborated by the isolation and characterization of carbonyl difluoride, a predicted fluorinated decomposition by-product.
- Sansotera, Maurizio,Persico, Federico,Rizzi, Valentina,Panzeri, Walter,Pirola, Carlo,Bianchi, Claudia L.,Mele, Andrea,Navarrini, Walter
-
p. 159 - 168
(2015/11/10)
-
- A novel liquid plasma AOP device integrating microwaves and ultrasounds and its evaluation in defluorinating perfluorooctanoic acid in aqueous media
-
A simplified and energy-saving integrated device consisting of a microwave applicator and an ultrasonic homogenizer has been fabricated to generate liquid plasma in a medium possessing high dielectric factors, for example water. The microwave waveguide and the ultrasonic transducer were interconnected through a tungsten/titanium alloy stick acting both as the microwave antenna and as the horn of the ultrasonic homogenizer. Both microwaves and ultrasonic waves are simultaneously transmitted to the aqueous media through the tungsten tip of the antenna. The microwave discharge liquid plasma was easily generated in solution during ultrasonic cavitation. The simple device was evaluated by carrying out the degradation of the perfluorooctanoic acid (PFOA), a system highly recalcitrant to degradation by conventional advanced oxidation processes (AOPs). PFOA is 59% degraded in an aqueous medium after only 90 s of irradiation by the plasma. Intermediates were identified by electrospray mass spectral techniques in the negative ion mode.
- Horikoshi, Satoshi,Sato, Susumu,Abe, Masahiko,Serpone, Nick
-
experimental part
p. 938 - 942
(2012/03/08)
-
- Efficient mineralization of hydroperfluorocarboxylic acids with persulfate in hot water
-
The persulfate (S2O82-)-induced decomposition of hydroperfluorocarboxylic acids (H-PFCAs), that is, HCnF2nCOOH (n = 4, 6, and 8), in hot water was investigated, and the results were compared with the
- Hori, Hisao,Murayama, Misako,Inoue, Naoko,Ishida, Kyoko,Kutsuna, Shuzo
-
experimental part
p. 131 - 136
(2010/08/20)
-
- Photocatalytic decomposition of environmentally persistent perfluorooctanoic acid
-
Perfluorooctanoic acid was photocatalytically decomposed by using TiO 2/Ni-Cu, and a small bias potential (-0.1 V) applied on TiO 2/Ni-Cu electrode greatly enhanced its decomposition. Copyright
- Chen, Jing,Zhang, Pengyi,Zhang, Li
-
p. 230 - 231
(2007/10/03)
-
- PROCESS FOR THE SYNTHESIS OF POLYFLUOROCARBOXYLIC ACIDS
-
The invention relates to a process for the preparation of the acids of formula: Rf(CX2CF2)m-1CX2COOH by reaction of the sulphinates of formula: Rf(CX2CF2)m SO2Na with a radical initiator, in which formulae m is an integer from 2 to 6, Rf is a linear or branched perfluoroalkyl group comprising from 1 to 6 carbon atoms, X= F or H. According to one advantageous form, Rf is a linear or branched perfluoroalkyl group comprising from 2 to 4 carbon atoms. According to another advantageous form, m is an integer from 3 to 5.
- -
-
Page/Page column 6-7
(2008/06/13)
-
- A [2 + 2] cycloaddition route to dimethylaminomethylene vinamidinium salts
-
(figure presented) Trifluoropropanoic acid reacts with 1 equiv of POCl3 in DMF to generate the trifluoromethyl enamine (7). At this stage, two reaction manifolds are available. The expected reaction with additional POCl3 generates the 2-trifluoromethyl vinamidinium salt (3c). However, thermally driven loss of fluoride generates an iminium ion, which sets the stage for a [2 + 2] cycloaddition to ultimately generate the dimethylaminomethylene vinamidinium salt (1).
- Davies, Ian W.,Tellers, David M.,Shultz, C. Scott,Fleitz, Fred J.,Cai, Dongwei,Sun, Yongkui
-
p. 2969 - 2972
(2007/10/03)
-
- Synthese de 3-perfluoroalkylprop-1-enes RF-CH2-CH=CH2
-
The reactions of perfluoroalkyl iodides with allylbromide or chloride, in the presence of solid potassium hydroxide KOH give 3-perfluoroalkylprop-1-enes RFCH2CH=CH2 in good yields under mild conditions. This reaction represents a synthetically viable and convenient route to such compounds.
- Rubio,Blancou,Commeyras
-
p. 171 - 175
(2007/10/03)
-
- Reaction of Perfluoroalkanesulfinates with Allyl and Propargyl Halides. A Convenient Synthesis of 3-(Perfluoroalkyl)prop-1-enes and 3-(Perfluoroalkyl)allenes
-
The reaction of perfluoroalkanesulfinates, RfCF2SO2Na, with allyl and propargyl halides, in the presence of (NH4)2S2O8, gave 3-(perfluoroalkyl)prop-1-enes (RfCH2CH=CH2) and 3-(perfluoroalkyl)allenes (RfCH=C=CH2), respectively, in good yield.Evidence is presented for a radical addition-elimination mechanism for the reaction.The reaction represents a synthetically viable and convenient route to such compounds.
- Hu, Chang-Ming,Qing, Feng-Ling,Huang, Wei-Yuan
-
p. 2801 - 2804
(2007/10/02)
-
- REACTIONS OF PERHALOCARBONS. PART IX. CONVERSION OF PER(POLY)FLUOROALKYL HALIDES INTO THE CORRESPONDING CARBOCYCLIC ACIDS WITH A REDOX SYSTEM
-
The conversion of per(poly)fluoroalkylhalides into the corresponding carbocyclic acids with a redox system-(NH4)2S2O8/HCO2Na is described.The reaction provides a convenient method for the synthesis of various per(poly)fluorocarboxylic acids under mild conditions.
- Hu, Chang-Ming,Qing, Feng-Ling,Zhang, Hong-Gen
-
p. 275 - 280
(2007/10/02)
-
- A NEW METHOD FOR THE PREPARATION OF PERFLUOROCARBOXYLIC ACIDS
-
The reaction of both primary perfluoroalkyl iodides and bromides containing 3-12 carbon atoms with a rongalite-NaHCO3 reagent in aqueous dipolar aprotic solvents, such as DMF or DMSO, has been investigated.The reaction gave sodium perfluorocarboxylates in 51-86percent yields, and these were transformed to the respective perfluorocarboxylic acids by treatment with sulfuric acid.This provides a new method for the synthesis of perfluorocarboxylic acids.
- Huang, Bing-Nan,Haas, A.,Lieb, M.
-
-
- SYNTHESE D'ACIDES PERFLUORES DE HAUTS POIDS MOLECULAIRES
-
Perfluorinated olefins of general formula CF3-(CF2)p-CF=CF-(CF2)m-CF3 (3 /= m + p /= 25) are oxidized by potassium permanganate or ruthenium tetroxide.The linear high molecular weight perfluorinated carboxylic acids so obtained are characterized by 19F N.M.R. spectroscopy.
- Battais, A.,Boutevin, B.,Pietrasanta, Y.,Sierra, P.
-
-
