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abstract: Abstract A new two phase swirl flow monolithic type reactor was designed to study the kinetics of heterogeneous photocatalytic processes on semiconductor catalysts. Most of the earlier work investigated the effects of various parameters on the initial degradation rate (or the formation of CO2) of the pollutants. In the present study, photomineralization of 4 nitrophenol (4 NP) sensitized by Degussa P25 TiO2 in aqueous solution has been investigated as a function of the following different experimental parameters: initial concentration of pollutant (CS0) light intensity (Ia) partial pressure of oxygen (pO2) catalyst concentration, pH, chloride ion and temperature. The kinetic expression obtained can be described by the following formula rs=k0 exp E/RT)IabKO2pO2/(1+KO2pO2)KsCs/(1+KsCs0) The apparent overall activation energy for 4 NP obtained was 7.42 kJ mol 1 by fitting the above equation with experimental data and the values for b, KO2 and Ks were 0.84, 9.98 atm 1 and 0.075 ppm 1 respectively. The kinetic equation can predict the concentration of 4 NP during the entire degradation process at pH value of 4.3 and TiO2 concentration of 2 g l 1, and is therefore, more meaningful. It can be used in the development of large scale photocatalytic reactor and optimization of experimental conditions for any particular studies. Furthermore, the photodegradation of 4 NP on two different catalysts (P25 and UV100) was compared and the photonic efficiency of the process has also been investigated.
author_names: Dingwang Chen

Ajay K Ray
title: Photodegradation kinetics of 4 nitrophenol in TiO2 suspension
year: 1998

abstract: The kinetics of the photocatalytic degradation of 4 nitrophenol (4 NP) in the presence of TiO2 has been investigated experimentally and theoretically. The effects of the catalyst loading, the initial concentration of 4 NP, H2O2 and the added Cu2+ ions on the degradation rate have been examined. A pseudo first order kinetic model has been used to describe the results. A linear dependence of the rate constant upon the reciprocal of the initial 4 NP concentration has been obtained. The addition of H2O2 increases the reaction rate while Cu2+ ions has a detrimental effect. With the intention of predicting the primary intermediates, geometry optimizations of the reactants, the products and the transition state complexes have been performed with the semi empirical PM3 method. The molecular orbital calculations have been carried out by an SCF method using RHF or UHF formalisms. Based on the results of the quantum mechanical calculations, the rate constants of the two possible reaction paths have been calculated by means of the transition state theory, and 1,2 dihydroxy 4 nitro cyclohexadienyl radical which then forms 4 nitrocatechol has been determined as the most probable primary intermediate by the application of three different theoretical shortcut methods.
author_names: Nevim San

Arzu Hatipoglu

Gulin Kocturk

Zekiye Cinar
title: Photocatalytic degradation of 4 nitrophenol in aqueous TiO2 suspensions: Theoretical prediction of the intermediates
year: 2002

abstract: An internally irradiated annular photoreactor has been used to investigate the oxidative degradation of aqueous 4 nitrophenol with titania as the photocatalyst. Reaction runs were performed over a 3 h period and in practically all cases, complete degradation was possible within about 2 h. The kinetics was determined as a function of nitrophenol concentration, oxygen partial pressure, catalyst loading, pH, temperature and light intensity. The reaction was characterised by a relatively low activation energy of 7.83 kJ mol 1 although transport intrusions were negligible. Rate decreased almost exponentially with pH while a quadratic (maximum) behaviour with respect to both oxygen pressure and nitrophenol concentration is symptomatic of self inhibition possibly due to the formation of intermediates which competitively adsorb on similar sites to the reactants. Increased catalyst dosage also improved the reaction rate although the possible effects of light scattering and solution opacity caused a drop at loadings higher than about 1.20 g dm 3. Rate, however, has a linear dependency on light intensity, suggesting that hole electron recombination processes were negligible at the conditions investigated. (c) 2001 Society of Chemical Industry
author_names: Jimmy Lea

Adesoji A Adesina
title: Oxidative degradation of 4 nitrophenol in UV illuminated titania suspension
year: 2001

abstract: A set of TiO2 and Pt TiO2 polycrystalline samples were prepared by sol gel method hydrolysing a modified alkoxide titanium precursors under acidic conditions. The Pt TiO2 samples gave an homogeneous nanometric metal dispersion after drying heat treatment forming platinum particles in the range 2 4 nm. All the samples have been characterised using several techniques, namely thermogravimetric analysis, gas chromatography, mass spectrometry, thermogravimetric analysis combined with mass spectrometry or with gas chromatography/mass spectrometry, X ray diffraction coupled with a Rietveld refinement procedure, X ray photoelectron spectroscopy and determination of specific surface area. Moreover, the samples have been employed as catalysts for 4 nitrophenol photodegradation in aqueous suspension used as a "probe" reaction. Characterisation results indicate that the thermal and chemical treatments of the catalysts influenced the photocatalytic activity. In the Pt TiO2 samples both Pt(0) and Pt(II) species are present in the catalyst particles and the most abundant phase is anatase for all of the samples. Doping with Pt beneficially influences the photo oxidant properties of TiO2 while the presence of organic residual species on the surface, deriving from the preparation procedure of the catalyst particles interferes negatively in the kinetics of the photocatalytic process.
author_names: Giacomo Facchin

Giovanni Carturan

Renzo Campostrini

Stefano Gialanella

Luca Lutterotti

Lidia Armelao

Giuseppe Marci

Leonardo Palmisano

Antonino Sclafani
title: Sol Gel Synthesis and Characterisation of TiO2 Anatase Powders Containing Nanometric Platinum Particles Employed as Catalysts for 4 Nitrophenol Photodegradation
year: 2000

abstract: p Nitrophenol (PNP) is a difficultly decomposed organic pollutant under solar light in the absence of strong oxidants. This study shows that under artificial solar light PNP can be effectively degraded by a Cu(2)O/TiO(2) p n junction network which is fabricated by anodizing Cu(0) particles loaded TiO(2) nanotubes (NTs) The network is composed of p type Cu(2)O nanowires on the top surface and Cu(2)O nanoparticles on the inner walls of the n type TiO(2) NT arrays. The Cu(2)O/TiO(2) network shows much higher degradation rate (1.97 mg/min cm(2) than the unmodified TiO(2) NTs (0.85 mg/min cm(2) The enhanced photocatalytic acitivity can be attributed to the extended absorption in the visible resulting from the Cu(2)O nanowire networks and the effective separation of photogenerated carriers driven by the photoinduced potential difference generated at the Cu(2)O/TiO(2) p n junction interface.
author_names: Lixia Yang

Shenglian Luo

Yue Li

Yan Xiao

Qing Kang

Qingyun Cai
title: High efficient photocatalytic degradation of p nitrophenol on a unique Cu2O/TiO2 p n heterojunction network catalyst.
venue: Environmental science technology
year: 2010

abstract: A set of polycrystalline TiO2 photocatalysts loaded with various ions of transition metals (Co, Cr, Cu, Fe, Mo, V, and W) were prepared by using the wet impregnation method. The samples were characterized by using some bulk and surface techniques, namely X ray diffraction, BET specific surface area determination, scanning electron microscopy, point of zero charge determination, and femtosecond pump probe diffuse reflectance spectroscopy (PP DRS) The samples were employed as catalysts for 4 nitrophenol photodegradation in aqueous suspension, used as a probe reaction. The characterization results have confirmed the difficulty to find a straightforward correlation between photoactivity and single specific properties of the powders. Diffuse reflectance measurements showed a slight shift in the band gap transition to longer wavelengths and an extension of the absorption in the visible region for almost all the doped samples. SEM observation and EDX measurements indicated a similar morphology for all the parti.
author_names: Agatino Di Paola

Giuseppe Marci

Leonardo Palmisano

Mario Schiavello

Kohei Uosaki

Shigeru Ikeda

Bunsho Ohtani
title: Preparation of Polycrystalline TiO2 Photocatalysts Impregnated with Various Transition Metal Ions: Characterization and Photocatalytic Activity for the Degradation of 4 Nitrophenol
year: 2002

abstract: Photocatalytic degradation of 4 nitrophenol was investigated using Fe doped (1, 3, 5 and 8 wt. Fe) TiO(2) catalysts under UV light irradiation in aqueous dispersions in the presence of H(2)O(2) Photocatalysts with the lowest Fe content (1% showed a considerably better behavior with respect to the unloaded TiO(2) and the catalysts with higher Fe contents. Photocatalytic degradation was studied under different conditions such as amounts of 1% Fe TiO(2) catalyst, H(2)O(2) dose and initial pH of 4 NP solution. The results indicated that about 67.53% total organic carbon of a solution containing 20 mg L( 1) 4 NP was removed at pH 6.17 by using 4.9 mM of H(2)O(2) and 0.4 g L( 1) of the catalyst in a 2 L batch photo reactor, the complete degradation of 4 NP occurring after 60 min. It was also observed that catalytic behavior could be reproduced in consecutive experiments without a considerable decrease of the UV/Fe TiO(2)/H(2)O(2) process efficiency.
author_names: Binxia Zhao

Giuseppe Mele

Iolanda Pio

Jun Yu Li

Leonardo Palmisano

Giuseppe Vasapollo
title: Degradation of 4 nitrophenol (4 NP) using Fe TiO2 as a heterogeneous photo Fenton catalyst.
venue: Journal of hazardous materials
year: 2010

abstract: In this study, photo/photocatalytic oxidation of common analgesic and antipyretic drug, paracetamol (acetaminophen) was investigated to determine the optimal operating conditions for degradation in water. UVA (365 nm) radiation alone degraded negligible amount of paracetamol, whereas paracetamol concentration decreased substantially under an irradiation of UVC (254 nm) with marginal changes in total organic carbon (TOC) In the presence of TiO2, much faster photodegradation of paracetamol and effective mineralization occurred; more than 95% of 2.0mM paracetamol was degraded within 80 min. The degradation rate constant decreased with an increase in the initial concentration of paracetamol, while it increased with light intensity and oxygen concentration. The degradation rate also increased with TiO2 loading until a concentration of 0.8 g L( 1) The degradation rate slowly increased between pH 3.5 and 9.5, but significantly decreased with increasing pH between 9.5 and 11.0. Based on the experimental data, a kinetic equation describing paracetamol photocatalytic degradation with various process parameters is obtained.
author_names: Liming Yang

Liya E Yu

Madhumita B Ray
title: Degradation of paracetamol in aqueous solutions by TiO2 photocatalysis.
venue: Water research
year: 2008

abstract: Cardanol, a well known hazardous byproduct of the cashew industry, has been used as starting material for the synthesis of useful differently substituted "cardanol based" porphyrins and their zinc(II) copper(II) cobalt(II) and Fe(III) complexes. Novel composites prepared by impregnation of polycrystalline TiO2 powder with an opportune amount of "cardanol based" porphyrins, which act as sensitizers for the improvement of the photo catalytic activity of the bare TiO2, have been used in the photodegradation in water of 4 nitrophenol (4 NP) which is a toxic and bio refractory pollutant, dangerous for ecosystems and human health.
author_names: Giuseppe Vasapollo

Giuseppe Mele

Roberta Del Sole

Iolanda Pio

Jun Li

Selma Elaine Mazzetto
title: Use of Novel Cardanol Porphyrin Hybrids and Their TiO2 Based Composites for the Photodegradation of 4 Nitrophenol in Water
venue: Molecules
year: 2011

abstract: TiO2/natural hematite supported bentonite (TiNHB) was successfully synthesized as a heterogeneous catalyst for photodegradation of 4 nitrophenol (4 NP) in aqueous solution. Supporting on TiO2/hematite rendered a significant increase in specific surface area of bentonite. X ray diffraction and Fourier transform infrared spectroscopy analyses confirmed the presence of both TiO2 and Fe2O3 nanoparticles in the TiNHB catalyst. The photocatalytic performance of TiNHB was investigated using reduction of 4 nitrophenol (4 NP) as model reaction. The results showed that TiNHB converted nearly 98 of 4 NP under UV254nm irradiation with optimum operating conditions of 0.025 g/L TiNHB, pH 3, and 20 mg/L 4 NP. The reaction kinetics of the photocatalytic reduction of 4 NP were studied by UV Vis spectrophotometry, and the apparent rate constant was determined for comparison with TiO2 Fe2O3. This work is expected to shed new light on the development of new photocatalysts for removal of environmental pollutants.
author_names: Hafida Gaffour

Malika Mokhtari
title: Photocatalytic degradation of 4 nitrophenol using TiO2 Fe2O3 and TiO2/Fe2O3 supported bentonite as heterogeneous catalysts
venue: Research on Chemical Intermediates
year: 2016