Photodegradation Of Naproxen In Aquatic System

Naproxen (NPX) is a kind of typical non-steroidal anti-inflammatory drug(NSAIDs),used to relieve antipyretic, analgesic and ankylosing reaction caused by arthritis,dysmenorrhea and other illnesses. Because of the extensive use and emissions, naproxenhas been continuously detected in many environmental water. Studies shows thatlong-term intake can cause cardiovascular disease and stroke, and the existence ofnaproxen in water has great biological impact, but the treatment process cannot effectivelyremove naproxen, and photodegradation is an important way in water environment, so it isessential to study the photochemical behavior in aqueous environments. As Fe(III),oxalate, citric and humic substances are widespread in environments, studies indicates thatthey have important implications for the photodegradation of organic pollutants.In this paper, degradating of naproxen is in humic substances system andFe(III)-carboxylate complex system under simulated sunlight, and exploring the kinetcand its photocatalytic mechanism. The main substances and conclusions of theexperimental study are as follows:Under the simulated sunlight, The photodegradation of naproxen by humus systemwas studied. The impact of initial substrate concentration of naproxen, pH value, humus,irradiation intensity and wavelength were studied. Results suggested:(1)The reaction rateof naproxen increased with rising initial concentration.(2)In the low initial concentrationof naproxen(10μM), Fulvic acid(FA) has the promoting effect, with the furtherincreasing of Naproxen, FA becomes into inhibition, Humici (HA) is inhibitionThroughout.(3)The photodegradation efficiency decreased with increasing pH within therange of3.09.0.(4)The removal rate of naproxen increased with the rising of FA, anddecreased by rising concentration of HA.(5)The reaction rate of naproxen increased withincreasing irradiation intensity.(6)The photodegradation efficiency decreased withincreasing filter wavelength within the range of260400nm.(7)The photolysis ofnaproxen was considered via two pathways: the direct photodecomposition of the tripletexcited-state naproxen(3NPX); the indirect degradation by the resultant of1O2underaerated conditions and the energy transfer of3FA*under deaerated conditions. In the Fe(III)-carboxylate complex system, exploring the ratio of Fe(III)-carboxylalt,pH and various aqueous media in the degradation system. Results suggested:(1)Thephotodegradation of Naproxen droped with increasing pH at fixed Fe(III)-ox ratio andfollow the order of pH7.05.03.0; the photodegradation efficiency changed withvariable pH at fixed Fe(III)-citrate and follow the order of pH7.03.05.0, Thephotodegradation efficiency decreased with increasing pH at fixed Fe(III)-cit-ox ratio andfollow the order of pH9.07.03.05.0.(2)Adding oxalate in Fe(III)-citrate canincreased the photodegradation, but a high concentration of oxalate can reduce theefficiency of naproxen degradation.(3)The photodegradation of naproxen has been alsostudied in different types of waters, the efficiency follow the order of purified water>Liangzi Lake> Yangtze> East Lake> Sea.(4) OH is the main factor of the naproxenindirect photodegradation in the Fe(III)-cit-ox system.