ABSTRACT
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.
ABSTRACT
Bisphenol A (BPA; 4-[2-(4-hydroxyphenyl)propan-2-yl]phenol) is a substance typically used in the plastic industry. It is used in the production of epoxy resins, polycarbonate, or fire retardants or as a stabilizer and an antioxidant in numerous types of plastics. Bisphenol A is introduced into the environment via municipal and industrial wastewater. Because of its hydrophobic properties, BPA has the potential for sorption on activated sludge during the biological wastewater treatment processes. This study investigated the degradation of BPA by means of UV-radiation and in the UV/H2O2 process with the presence and absence of hydrocarbonate ions (HCO3(-)) as hydroxyl radicals (OH*) scavengers. The calculated value of quantum yield was equal to 0.18, and the value of BPA rate constant with hydroxyl radicals was equal to 3.3 x 10(9) M(-1) s(-1).
Subject(s)
Hydrogen Peroxide/chemistry , Phenols/chemistry , Ultraviolet Rays , Benzhydryl Compounds , Free Radical Scavengers/chemistry , Hydroxyl Radical/chemistry , Spectrophotometry, UltravioletABSTRACT
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.
Subject(s)
Air Pollutants/chemistry , Environmental Restoration and Remediation/trends , Nitrogen Oxides/chemistry , Air Pollutants/analysis , Air Pollution/prevention & control , Air Pollution/statistics & numerical data , Environmental Restoration and Remediation/methods , Nitrogen Oxides/analysis , Ozone/chemistryABSTRACT
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.
Subject(s)
Parabens/chemistry , Estrogens/pharmacology , Humans , Models, Molecular , Parabens/pharmacology , Parabens/radiation effects , Photochemistry , Preservatives, Pharmaceutical/chemistry , Rose Bengal/chemistry , Singlet Oxygen/chemistry , Skin/drug effects , Spectrophotometry , Spectrophotometry, Ultraviolet , WaterABSTRACT
The decomposition of 2-chlorophenol (2CP) in an aqueous solution by means of photosensitized oxidation using rose bengal has been studied. The influence of initial 2CP concentration, pH of reaction mixture and oxygen content on reaction rate has been observed. The reaction of 2CP with singlet oxygen (type II of photooxidation) appeared the most important pathway of degradation. The rate constants of singlet oxygen quenching and reaction with 2CP were determined and the rate constant of excited rose bengal quenching by 2CP was also estimated. An attempt was made to identify the main photooxidation products.
Subject(s)
Chlorophenols/metabolism , Light , Photosensitizing Agents/chemistry , Rose Bengal/chemistry , Chlorophenols/radiation effects , Hydrogen-Ion Concentration , Kinetics , Oxidation-Reduction , Photochemistry , Singlet Oxygen/metabolism , Singlet Oxygen/radiation effects , Solar System , WaterABSTRACT
The toxicity of benzo[a]pyrene, chrysene, and fluorene and their decomposition products formed by advanced oxidation processes (AOPs) was investigated using biotests with Escherichia coli and Vibrio fischeri. The polycyclic aromatic hydrocarbons (PAHs) were not highly toxic to either bacterial strain; the toxicity of their degradation products depended on the method of chemical processing. Inhibition of more than 27% was observed with products formed by oxidation of the PAHs, by AOP methods without hydrogen peroxide. Toxicity as high as 100% was observed after the combined action of hydrogen peroxide and other oxidizing agents.
