1,720,972 research outputs found
Fe(III) homogeneous photocatalysis for the removal of 1,2-dichlorobenzene in aqueous solution by means UV lamp and solar light
No full textBezafibrate removal by means of ozonation: Primary intermediates, kinetics, and toxicity assessment
No full textBezafibrate (BZF) is a lipid regulator largely used for the treatment of hyperlipidaemia. As a result of its wide use, unmetabolized BZF is released in the environment with potential toxic effects for aquatic living organisms. The results obtained in this work show that ozonation is an efficient method to degrade BZF: after 10 min of treatment (corresponding to a dose of 0.73 mmol L-1 of ozone), the complete BZF abatement is achieved, starting from an initial concentration of 0.5 mmol L-1. However, only a small part of the substrate is mineralized.Two different experimental approaches (absolute and competition method) are adopted to estimate the second-order kinetic constants for the ozone attack at pH = 6.0, 7.0 and 8.0. A good agreement was observed between the two kinetic methods adopted.The identification of main intermediates, attempted by high-performance liquid chromatograph (HPLC)-MS technique, indicates that the oxidation of BZF develops through both the hydroxylation of the aromatic ring and the attack of ozone on the unchlorinated aromatic one.The assessment of by-products biodegradability and acute toxicity demonstrates that ozonation is a suitable technique to improve the biodegradability and reduce the toxicity of waters containing BZF
Kinetic investigation of Cu(II) ions photoreduction in presence of titanium dioxide and formic acid
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A Kinetic Investigation on the Ozonation of Glycerol and its Oxygenated Derivatives
No full textThe ozonation of glycerol and its main oxygenated derivatives is studied aiming at evaluating the possibility to convert them into valuable products. The direct ozonation of glycerol results into a mixture of its oxygenated derivatives. In some cases the use of ozone to convert them into valuable products proceeds with good selectivity. A kinetic study to estimate the kinetic constants of ozone attack to the main glycerol oxygenated intermediates is carried out. The data found well agree with the few values found in the literature for alcoholic groups by ozo
Removal of Ofloxacin and Propranolol from Water by means of ozonation and H2O2/UV system
No full textLincomycin solar photodegradation, algal toxicity and removal from wastewaters by means of ozonation
No full textAntibiotic molecules have been reported among the xenobiotics present at trace levels in sewage treatment plant (STP) effluents and aquatic environment. Lincomycin, one of the most used in clinical practices whose presence in the STP effluents has been often documented, is submitted to an extensive investigation to assess its persistence in the environment and toxicity towards different algal strains. The possibility to remove the lincomycin from water by means of ozonation is demonstrated and a reduction of toxicity of ozonated solutions on S. leopoliensis, with respect to untreated solutions containing this compound, is obtained even just for 1 h of treatment. Kinetic constants for the attack to lincomycin of ozone (from 1.53×105 M−1 s−1 at pH=3.0 and 4.93×105 M−1 s−1 at pH=6.7) and OH radicals (4.37×109 M−1 s−1 at pH=5.5 and 4.59×109 M−1 s−1 at pH=7.5) are also evaluated
Effect of combined physico-chemical processes on the phytotoxicity of olive mill wastewaters
No full textA pool of laboratory experiments is planned with the aim of evaluating the possibility to reduce the phytotoxicity of olive mill wastewater (OMW) with combined physico-chemical processes (centrifugation-ozonation, centrifugation-solar photolysis, centrifugation-solar modified photoFenton, centrifugation-solar modified photoFenton-ozonation). A moderate COD removal of an OMW is reached by using ozonation or solar modified photoFenton separately or solar modified photoFenton/O-3 combined process even for prolonged treatment times. The O-3-treated OMWs are still toxic towards algal growth (Pseudokirchneriella subcapitata) and only for dilutions equal to or higher than 1:160 a stimulation of algal growth is observed. The sole ozonation does not reduce significantly the phytotoxicity of tested OMW measured through the GI calculation of Raphanus sativus L., Cucumis sativus L. and Lactuca sativa L. A marked reduction of OMW inhibition, higher than 50%, is evidenced for 1:8 dilution OMW samples ozonated for 2 h. The long-term storage of OMW associated with solar irradiation without or with Fe(III) ions under continuous aeration is less efficient than ozonation, and the combined action of the two former treatments does not significantly contribute to enhance both COD removal and germination index.Better results are obtained on seed germination and root elongation of plantlets of the three selected species, which germinated on OMW-free solidified medium and were then transferred on a solidified culture medium containing O-3-treated OMW diluted 1:2 and 1:4. The operating costs are estimated for the solar modified photoFenton-ozonation process
Kinetic and safety assessment for salicylic acid nitration by nitric acid/acetic acid system.
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