Novel metal modified diatomite, zeolite and carbon xerogel catalysts for mild conditions wet air oxidation of phenol: Characterization, efficiency and reaction pathway

Investigations on Cationic Dye Degradation Using Iron-Doped Carbon Xerogel

“…More energetically Lorentzian band at 886 cm −1 was ascribed to stretching vibration of C−H bonds, which seems to have similar length and surroundings within the rigid structure of carbon xerogel [31,43]. Two intense vibrations located at 1375 and 1443 cm −1 and a shoulder at 1473 cm −1 connected to the last vibration belong all to bonds linked to aromatic rings [5,44]. After iron doping, all the above-mentioned bands disappeared under a broad infrared envelope.…”

“…This more energetic spectral domain is composed of two signals, one located at 782 cm −1 and the other one at~818 cm −1 . The [650-850] cm− 1 spectral domain was attributed to the aromatic ring in particular to C-H bond vibrations [5,31]. More energetically Lorentzian band at 886 cm −1 was ascribed to stretching vibration of C−H bonds, which seems to have similar length and surroundings within the rigid structure of carbon xerogel [31,43].…”

“…The bands at 2852 and 3002 cm −1 were associated with asymmetric and symmetric vibrations of aliphatic and aromatic structures [46]. Infrared bands, which build up the broad band with a metacenter at 2294 cm −1 , were assigned to −C≡C− triple bond [5].…”

“…Iron-doped carbon xerogel samples were prepared using a sol-gel method modified (washing steps) after Plesa Chicinas et al, 2018 [5]. The main steps involved in the process were as follows: (1) Potassium-2,4-dihydroxybenzoate was obtained from 2,4-dihydroxybenzoic acid and K2CO3, (2) polycondensation reaction with formaldehyde was conducted using K2CO3 as a catalyst, (3) organic gel obtained was washed with ethanol, (4) K + ions from the organic gel were replaced with Fe 3+ ions, (5) iron-doped gel was dried in air, and finally (6) iron-doped gel was pyrolyzed in inert atmosphere.…”

“…In contrast, WAO in presence of a solid catalyst, catalytic wet air oxidation (CWAO), decreases the severity of the operating conditions, increases efficiency, and reduces the cost of the process [2][3][4]. Although conducted under milder conditions, majority of the CWAO studies report usage of temperatures and pressures up to 250 • C and 8 MPa, respectively, and use pure oxygen or high purity air as oxidizing agent [2,5]. Classic WPO, homogeneous Fenton, uses Fe 2+ and H 2 O 2 to efficiently reduce the organic load of wastewaters.…”