Photodegradation Behavior Of Some Selected Pharmaceuticals In Aqueous Environment

In recent years, the potential adverse effects of the pollutants of pharmaceuticals on public health and aquatic environment, including aquatic toxicity, pathogen resistance, genetic toxicity and endocrine disrupting activity has been widespread concern. They are widely used for treatment of human diseases, effectively protect the life and health of the human.Besides, they are also used in a number of animal husbandry and aquaculture in prevention and treatment of infectious diseases, and used as antimicrobial growth promoters to accelerate the growth of animals.Photodegradation of pollutants is very important abiotic degradation pathway in water environment.This paper selects several kinds of antibacterial anti-inflammatory drugs and antibiotics, to study the photodegradation kinetics, discusses the effect of different factors on the photodegradation of various pharmaceuticals and detection the photodegradation products of the part of the pharmaceuticals to speculate the possible photodegradation pathways, refers to provide scientific basis for pollution controls and risk evaluation of this kind of emerging contaminants.Research contents and main conclusions are as follows:Tetracycline,Oxytetracycline and Erythromycin are the widespread used antibiotics, especially in animal husbandry and aquaculture production.In this paper, selected to investigate the degradation kinetics by identifying and determining the concentrations of antibiotics residues in water with solar simulator(1.7KW xenon lamp, 300nm≤λ≤400nm). The results indicated that photodegradation can occur for the three antibiotics under simulated sunlight irradiation conditions. The kinetic analysis indicated that the pseudo-first-order kinetic models were well described their degradation equilbrium processes, and their degradation rate constants(k) are 0.0064min-1, 0.0138min-1 and 0.0155min-1, respectively, and their half-life(t1/2) are 108.30 min, 50.23 min and 44.72 min, respectively. In addition, the byproducts from three antibiotics photolysis had been analyzed using high-performance liquid chromatography mass spectrometry(LC-MS), and the possible degradation pathways of the tested antibiotics were proposed.Acetaminophen is the most common non anti-inflammatory antipyretic analgesics. Natural water and drinking water are often detected, but also in the process of chlorine disinfection in drinking water to generate more toxic substances. In this paper,we research the dynamics of the degradation of it in simulated sunlight(1.7 KW xenon lamp, 300nm≤λ≤400nm) and in mercury lamp(100W, illumination 155.8×103lx, 265.2nm≤λ≤265.5nm).Explores the effects of the photolysis of acetaminophen with H2O2, p H and five kinds of metal ions,such as Cu2+, Fe3+, Mn2+, Mg2+, Co2+.Results show that:the acetaminophen is degraded in simulated sunlight and mercury lamp,its degradation rate in 90 min are 13.9% and 99.8%.Degradation of acetaminophen in mercury lamp meet level 1 dynamics and its rate constant(k) is 0.05689min-1.Speculation acetaminophen’s slowly degradation in simulated daylight illumination from its absorption spectrum that:in xenon lamp 300nm≤λ≤ 400 nm illumination waviness, acetaminophen only in the 300 nm to 310 nm has the absorption degree, but in entire 265.2nm≤λ≤ 265.5nm light waves has a greater degree of absorption peaks.When adding H2O2 acetaminophen completely degrade significantly shorter, that almost completely degraded in 20 min.Five metals ions in the degradation reaction of acetaminophen, first to accelerate the reaction, and later inhibit.Raising or lowering the p H are conducive to the degradation of the acetaminophen under ultraviolet.HA inhibited the photodegradation of acetaminophen. Finally, using LC-MS to identify the major photolysis products of paracetamol in aqueous solution under ultraviolet, and put forward three possible photolysis ways.Cephalosporins is very important to the clinical use of anti infective drugs. In this paper,we research the dynamics of the degradation of them in mercury lamp(100W, illumination 155.8×103lx, 265.2nm≤λ≤265.5nm).Discusses the effect of p H value of the solution, Fe3+, Mn2+ metal ions on photodegradation of the ceftriaxone and cefotaxime sodium.The results showed that:ceftriaxone and cefotaxime sodium is degraded in mercury lamp irradiation. The degradation rate constant were 0.111 and 0.104 min-1, R2 were respectively 0.9598 and 0.9638;Increased or decreased of the p H is beneficial to the degradation of ceftriaxone and cefotaxime sodium under UV light;Fe3+ were promoted the reaction of photolysis of ceftriaxone and cefotaxime sodium, and the concentration is higher, the promoting is stronger; Mn2+ were inhibit the reaction of photolysis of ceftriaxone and cefotaxime sodium, and the concentration is higher, the inhibition is stronger.