Jacek S. Miller

Trends in NOx abatement: a review.

Implementation of stringent regulations of NO(x) emission requires the development of new technologies for NO(x) removal from exhaust gases. This article summarizes current state of NO(x) abatement strategy. Firstly, the influence of NO(x) on environment and human health is described. The main focus is put on NO(x) control methods applied in combustion of fossil fuels in power stations and mobile vehicles, as well as methods used in chemical industry. Furthermore the implementation of ozone and other oxidizing agents in NO(x) oxidation is emphasized.

The aqueous photosensitized degradation of butylparaben

The photosensitized oxidation of butyl p-hydroxybenzoate (butylparaben, BP), the endocrine disrupting compound, in aqueous solution using rose bengal (RB) and aluminium phthalocyanine chloride tetrasulfonic acid (PC) as sensitizers was examined. A xenon lamp simulating solar radiation was used as a light source. The influence of pH of the reaction mixture, oxygen content, irradiation intensity and initial sensitizers and BP concentration on the reaction rate was studied. Based on the kinetic model, the rate constants of singlet oxygen quenching and reaction with BP as well as the rate constant of excited sensitizer quenching by BP were determined.

Oxidation of PAHs in water solutions by ultraviolet radiation combined with hydrogen peroxide

The destruction of three polycyclic aromatic hydrocarbons (PAHs): benzo(a)pyrene, chrysene and uorene in aqueous solution using advanced oxidation process H2O2/UV was investigated. The inuence of pH, initial hydrogen peroxide and radical scavenger concentrations on the reaction rate was studied. The oxidation reactions most rapidly run in neutral and acidic solution at optimal hydrogen peroxide concentra- tion (ca. 0.01M). The degradation of benzo(a)pyrene and chrysene follows radical reaction, for uorene the mechanism is not clear. The rate constants of the hydroxyl radicals and selected PAHs reaction were found to be 2:531010 ,9 :82109 and 2:77109 M 1s 1 for benzo(a)pyrene, chrysene and uorene, respectively.

Ozonation of Polycyclic Aromatic Hydrocarbons in Water Solution

ABSTRACT The degradation of three polycyclic aromatic hydrocarbons (PAHs): benzo[a]pyrene (BAP), chrysene (CHR), and fluorene (FLU) in aqueous solution using ozone was investigated. The influence of pH of the reaction mixture, ozone concentration, and the presence of a radical scavenger on the reaction rate was determined. The highest rate of PAHs disappearance was achieved in acidic solutions. The radical scavenger, tert-butanol, effectively inhibited the rate of PAHs destruction. The rate constants of direct reaction of PAHs with ozone were calculated and they were equal to (3.32 ± 0.21) × 104; (1.10 ± 0.15) × 104 and 44.8 ± 1.1 M−1s−1 for BAP, CHR, and FLU, respectively. The contributions of direct ozonolysis, and radical reaction to PAHs oxidation in ozonation processes, were evaluated.

Photosensitised oxidation of a water pollutant using sulphonated porphyrin

Photodegradation of endocrine disrupting butylparaben (BP) in aerated aqueous solutions was studied using 4,4′,4″,4‴-(porphine-5,10,15,20-tetrayl)tetrakis(benzenesulphonic acid) (TPPS4), as a sensitiser. Influence of various parameters, such as initial sensitiser and BP concentration, pH of the reaction solution and oxygen content in the reaction solution, on the photosensitised oxidation was examined. It was found that the dominant pathway of BP degradation occurred in the reaction with molecular singlet oxygen 1O2, i.e. via photosensitised oxidation mechanism of type II. Kinetic parameters of the BP reaction with 1O2 were estimated.

Oxidation of PAHs in water solution by ozone combined with ultraviolet radiation

The oxidation of three polycyclic aromatic hydrocarbons (PAHs): benzo(a)pyrene (BAP), chrysene (CHR) and fluorene (FLU) in aqueous solution using ozone assisted by UV radiation was investigated. The influence of pH of the reaction mixture, ozone concentration and the presence of a radical scavenger on the reaction rate was determined. The highest rate of PAHs disappearance was achieved in acidic solutions. The radical scavenger-tert -butanol, effectively inhibited the rate of BAP and CHR destruction but had a slight influencein thecaseof FLU. Therateconstants of direct reaction of PAHs with ozonewerecalculated using our earlier investigations and they were equal to 6.8 × 104 ;6 .9 × 103 and 62 M−1s−1 for BAP, CHR and FLU, respectively. The contributions of direct ozonolysis, photolysis and radical reaction to PAHs oxidation in O3/UV system were evaluated.

Effectiveness of nitric oxide ozonation

Attempts to develop new technologies of NOx (NO + NO2) emission reduction are still carried out all around the world. One of the relatively new approaches is the application of ozone injection into the exhaust gas stream followed by the absorption process. Ozone is used to transform NOx to higher nitrogen oxides which yield nitric acid with better effectiveness. The main objective of this paper was to study the influence of mole ratio (MR) O3/NO used in the ozonation process of NOx on the effectiveness of NOx oxidation to higher oxides. The ozonation process was carried out in a flow reactor for concentrations of nitric oxide in the range of 1.5 × 10−5−7.7 × 10−5 mol dm−3 and varying O3/NO mole ratios. Measurements were conducted with the use of a FTIR spectrometer. The results obtained prove that for MR higher than 1, the oxidation effectiveness of nitric oxides generally reaches 95 %, whereas for MR higher than 2, oxidation of NOx to higher nitrogen oxides is completed.

Kinetics of nitric oxide oxidation

Nitrogen oxides are nowadays a subject of global concern. Several types of nitrogen oxides exist in the environment: N2O, NO, NO2, N2O3, N2O4, N2O5. The abbreviation NOx usually relates to nitric oxide NO, nitrogen dioxide NO2, and nitrous oxide N2O. The first two are harmful pollutants for both environment and human health, whereas the third is one of the greenhouse gases. Implementation of stringent NOx emission regulations requires the development of new NOx removal technologies from exhaust gases. One of many proposals for NOx emission reduction is the application of an oxidizing agent which would transform NOx to higher nitrogen oxides with higher solubility in water. The main objective of the paper was to present the rate constant of nitric oxide oxidation, determined in our studies.

2-Chlorophenol photooxidation using immobilized meso-tetraphenylporphyrin in polyurethane nanofabrics

The photosensitized oxidation of 2-chlorophenol (2-CP) in aqueous solution using immobilized meso-tetraphenylporphyrin (TPP) in polyurethane nanofabrics was studied. The influence of various parameters on the reaction efficiency was investigated, i.e., 2-CP concentration, oxygen content and pH of the reaction solution and the stability of immobilized photosensitizer at the multiple use. The resistance of the structure of the photosensitizer carrier toward the solutions of various pH was also studied. The participation of molecular singlet oxygen ((1)O(2)) in the photooxidation was tested using NaN(3) and imidazole quenchers of (1)O(2). The kinetics of the process was described using Langmuir-Hinshelwood model.

Nitrogen Oxides Ozonation as a Method for NOx Emission Abatement

Attempts to develop new technologies of reduction of NOx emission are still carried out all around the world. However, most of them as literature survey suggests is focused on NOx emission control from power plants and mobile vehicles. Fewer investigations are conducted on the NOx emission abatement from the chemical industry. One of the relatively new approaches is the application of ozone injection into exhaust gas stream followed by an absorption process. Ozone is used to transform NOx to higher nitrogen oxides that are more soluble in water, and therefore the higher yield of nitric acid is expected. The main objective of this article is to present results of our studies in which the effectiveness of the ozonation process, as well as the dependence of the conversion rate and the selectivities of NO ozonation into NO2, N2O5 and HNO3 on the residence time of reagents in the reactor space were studied. Results of laboratory investigations were confirmed during ozonation experiments with real exhaust gases from a nitric acid pilot plant in Fertilizers Research Institute in Pulawy, Poland.