[Show abstract][Hide abstract] ABSTRACT: The photodegradation of clopyralid in pure and surface water under UV and simulated sunlight irradiation, were investigated to guide the treatment of clopyralid contaminated water in a natural environment. Under UV irradiation in pure water, the degradation rate of clopyralid was promoted with the decreasing of initial concentration and the degradation followed pseudo-first-order kinetics. Because of the competition between clopyralid and dissolved organic matters (DOM) for UV adsorption in surface water, the clopyralid degradation rate was lower in surface water than in pure water. The addition of H2O2 significantly enhanced the UV photodegradation of clopyralid; for example, after the addition of 0.2 mM H2O2 and 240 min irradiation nearly 100% degradation was achieved, compared with only 15% degradation without H2O2. To further understand the degradation process of clopyralid, the probable degradation pathway of clopyralid under UV/H2O2 was proposed. The removal of clopyralid was more effective under acidic condition than under neutral and alkaline conditions. Under simulated sunlight irradiation, there was no degradation of clopyralid in pure water, while it could be removed by adding hematoporphyrindihydrochloride (HPDHC) through indirect photodegradation, as HPDHC could generate single oxygen by absorbing the long wavelength sunlight and the single oxygen could facilitate clopyralid degradation. Similarly, a slight decomposition was observed in surface water, which was induced by DOM.
[Show abstract][Hide abstract] ABSTRACT: The seasonal variations and spatial distributions of 4-tert-octylphenol (OP), 4-nonylphenol (NP) and bisphenol A (BPA) in surface waters, suspended solids and surface sediments in the Huangpu River and its tributaries (Suzhou River and Yunzao Brook) were firstly investigated. The mean concentrations of OP, NP and BPA in the three rivers were 10.59, 120.96 and 22.93 ng L(-1) in surface waters, 199.87, 2,300.87 and 84.11 ng g(-1) in suspended solids and 9.49, 119.44 and 7.13 ng g(-1) dry weight in surface sediments, respectively. The concentrations of NP and OP were higher in summer than in winter in the suspended solids and surface sediments, while the reverse was true in surface waters. Similarly, the levels of BPA were lower in summer than in winter in surface sediments, while the opposite was true in surface waters and suspended solids. These seasonal variations might be attributed to temperature and stream flows. High levels of OP, NP and BPA were found in surrounding river intersections, residential and industrial areas. Their concentrations decreased gradually with increasing distance from those areas, while the lowest levels were measured in near less urbanized and agricultural areas. These phenomena might indicate that the stream current and pollutant source were the major factors that affect the spatial distributions of OP, NP and BPA in the three rivers. Ecological risk assessment indicated that NP was the only one of the three pollutants with the potential to influence local aquatic organisms. The results of this study provide scientific support for control of these pollutants.
[Show abstract][Hide abstract] ABSTRACT: The degradation characteristics of clopyralid irradiated by electron beam (EB) was studied in aqueous solutions. The effects
of factors, such as initial clopyralid concentrations, addition of radicals scavenger, initial solution pH and addition of
H2O2, were investigated on clopyralid degradation efficiency and mechanism. It was found that the EB-radiolysis was an effective
way to degrade clopyralid and its degradation rate decreased with the increasing of substrate concentration. In the investigated
initial concentrations range of 100–400mgL−1, the radiolytic degradation of clopyralid followed a pseudo-first kinetic order. The results from addition of radicals scavenger
indicated that both •OH and e
aq− played significant roles in the degradation of clopyralid. Furthermore, the alkaline condition and addition of H2O2 (<10mM) in the solution also slightly enhanced the efficiency of clopyralid degradation. The ion chromatography analysis
showed that some organic acids (formic acid, acetic acid and oxalic acid) were formed, while the completely dechlorination
of the substrate was achieved and organic nitrogen was recovered in the form of ammonium and nitrate ions during the irradiation
Journal of Radioanalytical and Nuclear Chemistry 06/2011; 288(3):759-764. DOI:10.1007/s10967-011-0986-1 · 1.03 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Abstract-The radiolysis of the steroid 17β-estradiol (E2), an endocrine disrupting hormone which is commonly released into aquatic environments, was investigated in aqueous solutions using electron beam. The degradation of E2 was found to follow pseudo-first-order kinetics. Experiments performed with ace toneitrile/water and ethanol/water demonstrated the role of 'OH was predominant in E2 degradation and the reductive species made minor contributions to E2 degradation. Acidic or alkaline conditions were more favorable for the removal of E2 than neutral conditions. At pH 9.1 and 4.9, the degradation value of E2 was 88.3% and 79.4% at the dose of 10 kGy, respectively, while at the same dose, at pH 6.8, a reduction of 53.4% was only achieved. Addition of appropriate amounts of H2O2 also facilitated the degradation of E2.