Titanium dioxide mediated photocatalytic degradation of 17beta-estradiol in aqueous solution

Photocatalytic degradation of 17beta-estradiol (E2) in aqueous medium mediated with titanium dioxide (TiO(2)) was studied. Moreover, effect of TiO(2) dosage on the degradation efficiency was investigated. Particular attention was paid to the identification of intermediates and analysis of photocatalytic degradation mechanism of E2 under neutral and alkaline conditions. The degradation efficiency of E2 increased with increasing concentration of TiO(2) but decreased due to light scattering as TiO(2) concentration was greater than 0.5mgml(-1). Several intermediates were formed during photocatalytic degradation of E2. However, only a few of the compounds could be identified and confirmed by LC-MS and LC-MS/MS. Six intermediates were observed by photocatalytic oxidation under alkaline conditions, namely 2-hydroxyestradiol, 10epsilon-17beta-dihydroxy-1,4-estradien-3-one (DEO), 10epsilon-hydroperoxide-17beta-hydroxy-1,4-estradien-3-one and three kinds of dicarboxylic acids formed by the opening of aromatic ring. In addition to the six intermediates mentioned above, 17beta-hydroxy-1,4-estradien-3-one (EO) was observed under neutral conditions and in the presence of methanol. Based on these intermediates, which were hardly degraded even after E2 was fully degraded, the mechanism of E2 degradation by TiO(2) photocatalysis was elucidated.     

Factors controlling the biodegradation of 17beta-estradiol, estrone and 17alpha-ethinylestradiol in different natural soils

We conducted a series of laboratory microcosm incubations with [(14)C]-labeled 17beta-estradiol (E2), estrone (E1) and 17alpha-ethinylestradiol (EE2) in 17 different natural soils to characterize hormone mineralization. A significantly higher mineralization was observed for E1 (2.0-37.6%) and E2 (4.2-50.2%) than for EE2 (0.5-2.6%) in all test soils after 21 days. Soil physical or chemical parameters were not related to estrogen mineralization. Although sorption parameters varied greatly for E2 (K(F)=21.9-317.5 mL g(-1)), for E1 (K(F)=46.0-517.5 mL g(-1)) and for EE2 (K(F)=29.9-326.1 mL g(-1)) this apparently did not control estrogen bioavailability since it showed no effects on hormone mineralization. In order to elucidate the controlling factors, experiments with combined additions of radiolabeled estrogens and different substrates were conducted. Additions of ammonium nitrate or alanine to soil samples generally increased EE2 mineralization, thus indicating N-limitation. Additions of glucose induced higher E2 and EE2 degradation in comparison to control samples which is attributed to co-metabolism. Additions of saw dust, catechol or streptomycin influenced the microbial population in the test soils and affected the mineralization of E2 and EE2. Thus, we clearly demonstrate that different microbial communities are responsible for E2 and EE2 degradation in soils. We suggest that EE2 is mineralized by white-rot fungi and E2 by bacteria.     

Photodegradation of 17alpha-ethynylestradiol in aqueous solution exposed to a high-pressure mercury lamp (250 W)

The photodegradation of 17alpha-ethynylestradiol (EE(2)) induced by high-pressure mercury lamp (lambda> or =313, 250 W) in aqueous solution of EE(2) was investigated initially. The affecting factors on the photodegradation were studied and described in details, such as EE(2) initial concentration, Fe(3+), algae, exposure time, and so on. The concentration of EE(2) in distilled water was mainly determined using fluorescence spectrophotometer. The photodegradation of EE(2) in aqueous solution exposed to high-pressure mercury lamp was evident and could be accelerated by Fe(3+) or algae (e.g. Anabaena cylindrica) in general. With the algae concentration increasing, photodegradation rate increased. In this paper, the mechanism of photocatalytic degradation of EE(2) by Fe(3+) or algae is discussed primarily.     

Photodegradation of alachlor with the TiO(2) film immobilised on the glass tube in aqueous solution

Alachlor photodegradation was performed using TiO(2), which was synthesized by a modified sol-gel method. The thickness of a TiO(2) film immobilised by a 5-time dip-coating was 174 nm and the average diameter of TiO(2) particles was about 10-15 nm in SEM images. The crystal structure of a TiO(2) film calcinated at 300 degrees C for 1 h was observed as a typical anatase type. The stability of a TiO(2) film by a modified sol-gel method was 4% better than TiO(2) by a typical sol-gel method.The removal rate of alachlor with both Fe(3+) and UV radiation in the absence of TiO(2) was 0.28 mg/l/h in 10 h and the removal rate of alachlor with Fe(3+)/UV in the presence of TiO(2) was 0.32 g/l/h, which was higher by 14% than that with Fe(3+)/UV system. TOC concentration during the alachlor degradation with both TiO(2) and UV radiation in the absence of added Fe(3+) decreased from 100%, through 81% and 51%, to 44% with time elapses of 4, 8, and 10 h, respectively, while TOC concentration with both added Fe(3+) and UV radiation in the absence of TiO(2) decreased from 100% to 70% in 10 h.     

UV及UV/US降解对二氯苯水溶液的研究

使用紫外光（UV）和超声波（US）降解水溶液中的对二氯苯（p-DCB）。考察了p-DCB初始浓度,初始pH、腐殖酸和H2O2的存在对p-DCB光解的影响。结果表明,较低的初始浓度或弱酸性pH有利于p-DCB降解。溶液中存在20 mg/L的腐殖酸可使p-DCB的反应速率常数提高32.6%。加入氧化剂H2O20=0.1 mmol/L,［H2O20=0.1 mmol/L,pH0=5.8,反应180 min条件下,p-DCB的降解率为95.5%。超声波对p-DCB的降解速率（14.6×10-3/min）大约是紫外光（4.3×10-3/min）的3.4倍,紫外光 超声波耦合时的降解速率（20.6×10-3/min）大于两者单独降解速率的加合。在各种实验条件下,p-DCB的降解均遵循表观一级动力学。     

Photodegradation of 4-tert octylphenol in aqueous solution promoted by Fe(III)

4-Tert-octylphenol (4-t-OP), a kind of endocrine-disrupting compounds, is widely distributed in natural water surroundings but can hardly be biodegraded. The advanced oxidation processes (AOPs) have been proved to be an efficient method to degrade 4-t-OP. In this study, the photodegradation of 4-t-OP in aqueous solution promoted by Fe(III) and the photooxidation mechanism were investigated. The ferric perchlorate was added into the aqueous solution for the production of hydroxyl radical. The efficiency of mineralization was monitored by total organic carbon analyzer, and photooxidation products were determined by high-performance liquid chromatography and liquid chromatography-mass spectrometer. 4-t-OP (2.4?×?10^?5 M) in aqueous solution was completely degraded after 45 min in the presence of Fe(III) (1.2?×?10^?3 M) under UV irradiation (λ?=?365 nm). The optimal pH was 3.5. Higher Fe(III) concentration or lower initial 4-t-OP concentration led to increased photodegradation efficiency of 4-t-OP. The reaction was almost completely inhibited in the presence of 2-propanol. About 70 % mineralization of the solution was obtained after 50 h. The photooxidation product was supposed to be 4-tert-octyl catechol. 4-t-OP in aqueous solution can be degraded in the presence of Fe(III) under the solar irradiation. The photoinduced degradation is due to the reaction with hydroxyl radicals. It shows that the 4-t-OP is mineralized by the inducement of Fe(III) aquacomplexes, which exposes to solar light. Therefore, the results would provide useful information for the potential application of the AOPs to remove 4-t-OP in water surroundings.     

水中四环素类化合物在不同光源下的光降解

研究了模拟太阳光和实际室外太阳光下四环素类化合物在水溶液中的光降解。结果表明,四环素类化合物(TCs)在模拟太阳光照射下均能发生直接光降解,且其降解速率随pH不同变化很大。四环素(TC)、土霉素(OTC)、金霉素(CTC)和多西环素(DTC)的光降解速率随溶液pH升高明显加快,而米诺环素(MTC)在水中的光降解速率随溶液pH升高略有下降。天然水体pH范围内,模拟太阳光照下四环素类化合物表观光降解速率常数在0.004～0.026 min-1范围内,降解半衰期在26～136 min范围内。在室外实际太阳光照下,四环素类化合物光降解反应速率与太阳光强成正比例关系。晴朗无云天气下,四环素类化合物降解半衰期在春冬季节较长、夏季节较短;四环素在东江实际水体中表观光降解速率很快,在冬季晴天天气下,其平均半衰期仅为8.2 min。     

Photochemistry and environment IV- Photochemical behaviour of monochlorophenols in dilute aqueous solution

The photochemical behaviour of chlorophenols is different to that of non-halogenated phenols. In the former, the first step is a C-Cl bond scission, which is not influenced by oxygen. Chlorine is converted into hydrochloric acid. For monochlorophenols, the position of the chlorine on the ring strongly influences the transformation. In the molecular form, 2-chlorophenol is converted into pyrocatechol. In the anionic form however, it is reduced in a cyclopentadienic acid which dimerizes according to a Diels-Alder reaction. The irradiation of 3-chlorophenol leads to resorcinol whatever the pH. This would appear to suggest a photohydrolysis mechanism. With 4-chlorophenol, the photochemical conversion is not so specific. Hydroquinone is formed (mainly in aerated solution), along with polyphenolic oligomers. A radical mechanism is proposed.     

Effect of 17beta-estradiol on the reproduction of Japanese medaka (Oryzias latipes)

Estrogenic compounds such as 17beta-estradiol (E2) and its analogs are present in the aquatic environment and can adversely affect the reproductive systems of aquatic organisms. Although E2 has been detected at a maximum concentration of 64 ng/l in effluents of sewage treatment works (STWs), few reports address the associated effects on reproduction in fish. Therefore, we exposed adult medaka (Oryzias latipes) to mean measured E2 concentrations of 29.3, 55.7, 116, 227, and 463 ng/l for 21 d and assessed the effects on the egg number and fertility of paired medaka during the exposure period. In addition, we determined the hepatic vitellogenin (Vtg) concentration and histologically assessed the gonads of these fish. The number of egg produced and fertility of the paired medaka exposed to 463 ng/l E2 were significantly less compared with those of the control fish. Males in all treatment groups had developed testis-ova. Males treated with E2 concentrations = 55.7 ng/l contained relating great concentrations of hepatic Vtg. Therefore, although only the greatest E2 concentration tested in our study affected fecundity and fertility, effects of E2 were observed on induction of Vtg and testis-ova in male medaka exposed to environmentally relevant concentrations of E2.     

Occurrence and photochemical degradation of 17alpha-ethinylestradiol in Acushnet River Estuary

17alpha-Ethinylestradiol (EE2), a major constituent of common contraceptive pills, and three other estrogenic hormones, estrone (E1), 17beta-estradiol (E2) and mestranol (MeEE2) have been determined in Acushnet River Estuary seawater using a GC-MS technique. Among three estrogenic compounds detected, EE2 has the highest concentration, up to 4.7 ng/l, at which EE2 may affect lobster and other fish abundance in the coastal seawater due to its high biological activity on fish feminization. Two natural estrogenic hormones, E1 and E2 have also been found in the estuary at concentrations up to 1.2 ng/l and 0.83 ng/l, respectively. Although EE2 is persistent to microbial degradation, it can undergo a rapid photodegradation in estuarine seawater under natural sunlight irradiation, with a half-life of less than 1.5 days in spring sunny days.     

Photodegradation of Oryzalin in aqueous isopropanol and acetonitrile

The phototransformation of Oryzalin was studied under UV light (λ_max ≥ 290 nm) and sunlight (λ_max ≥ 250 nm) in aqueous isopropanol and acetonitrile solution in absence and presence of TiO₂ as sensitizer. The rate of photodegradation of Oryzalin in different solvent system followed first-order kinetics, and calculated half-lives were found to be in the range of 23.52-53.75 h for UV light and 41.23-61.43 h for sunlight. From this study, total 12 photoproducts were identified and characterized on the basis of column chromatography and Q-Tof micromass spectral data. The plausible mechanism of phototransformation involved was hydrolysis, breaking of sulfonic bond, and loss of amino and sulfonic acid group.     

Photodegradation of the novel fungicide fluopyram in aqueous solution: kinetics,transformation products,and toxicity evolvement

The aqueous photodegradation of fluopyram was investigated under UV light (λ?≥?200 nm) and simulated sunlight irradiation (λ?≥?290 nm). The effect of solution pH, fulvic acids (FA), nitrate (NO₃ ^?), Fe (III) ions, and titanium dioxide (TiO₂) on direct photolysis of fluopyram was explored. The results showed that fluopyram photodegradation was faster in neutral solution than that in acidic and alkaline solutions. The presence of FA, NO₃ ^?, Fe (III), and TiO₂ slightly affected the photodegradation of fluopyram under UV irradiation, whereas the photodegradation rates of fluopyram with 5 mg L^?1 Fe (III) and 500 mg L^?1 TiO₂ were about 7-fold and 13-fold faster than that without Fe (III) and TiO₂ under simulated sunlight irradiation, respectively. Three typical products for direct photolysis of fluopyram have been isolated and characterized by liquid chromatography tandem mass spectrometry. These products resulted from the intramolecular elimination of HCl, hydroxyl-substitution, and hydrogen extraction. Based on the identified transformation products and evolution profile, a plausible degradation pathway for the direct photolysis of fluopyram in aqueous solution was proposed. In addition, acute toxicity assays using the Vibrio fischeri bacteria test indicated that the transformation products were more toxic than the parent compound.     

Photodegradation of the herbicide penoxsulam in aqueous methanol and acetonitrile

Penoxsulam is a triazolopyrimidine sulfonamide group of rice herbicide. The phototransformation of penoxsulam was studied under UV light (lambda max >or= 290 nm) and sunlight in aqueous methanol and acetonitrile solvent system using TiO2 as sensitizer. The rate of photodegradation of penoxsulam in different solvent systems followed first-order kinetics and calculated half-lives was found to be in the range of 51.89-73.41 h and 62.70-97.09 h for UV light and sunlight respectively in the presence or absence of sensitizer. From this study, a total of six photoproducts were identified and characterized on the basis of Q-Tof micromass spectral data. The plausible mechanism of phototransformation involved were hydrolysis, photo oxidation of the sulfonamide group, breaking of sulfonamide bond, loss of amino and sulfonic acid group.     

Influence of NO2 and dissolved iron on the S(IV) oxidation in synthetic aqueous solution

The influence of dissolved NO₂ and iron on the oxidation rate of S(IV) species in the presence of dissolved oxygen is presented. To match the conditions in the real environment, the concentration of iron in the reaction solution and trace gases in the gas mixture was typical for a polluted atmosphere. The time dependence of HSO₃⁻, SO₄²⁻, NO₂⁻ and NO₃⁻ and the concentration ratio between Fe(II) and total dissolved iron were monitored. Sulphate formation was the most intensive in the presence of an SO₂/NO₂/air gas mixture and Fe(III) in solution. The highest contribution to the overall oxidation was from Fe-catalysed S(IV) autoxidation. The reaction rate in the presence of both components was equal to the sum of the reaction rates when NO₂ and Fe(III) were present separately, indicating that under selected experimental conditions there exist two systems: SO₂/NO₂/air and SO₂/NO₂/air/Fe(III), which are unlikely to interact with each other. The radical chain mechanism can be initiated via reactions Fe(III)–HSO₃⁻ and NO₂–SO₃²⁻/HSO₃⁻.     

Suppression of sexual behavior in male Japanese medaka (Oryzias latipes) exposed to 17beta-estradiol

Mating pairs of Japanese medaka (Oryzias latipes) received 17beta-estradiol (E2; dose, 3 and 30 microg/g body weight daily) in their diet and E2-free diet (control) for two weeks. The effect on reproductive success was assessed in the mating pairs, and sexual and nonsexual behaviors in the male were quantified. The fecundities of the E2-treated groups were reduced significantly (p < 0.05) compared with those of control, and the sexual behaviors (following, dancing, floating, and crossing) of male fish in response to prostaglandin F2alpha (PG)-injected E2-unexposed females were suppressed dramatically. While the fertility of spawned eggs and the frequencies of the nonsexual behaviors of resting and swimming in a straight line performed by male were unchanged in E2-exposed groups. Therefore, sexual behavior in male may be linked with reproductive success in mating pair of madaka exposed to E2. This assay for sexual behavior using PG may provide a useful tool for assessing the effect of endocrine-disrupting chemicals.     

Degradation and photodegradation of tetraacetylethylenediamine (TAED) in the presence of iron (III) in aqueous solution

The dark degradation of tetraacetylethylenediamine (TAED) was investigated. It is a slow process which is favored in acidic medium. There is a hydrolysis of an imide group with the scission of the C---N bond giving rise to the triacetyl derivative (TAED'). When allowed to stand for longer times a second acetyl group is eliminated with the formation of the symetric diacetyl derivative (DAED). The degradation of TAED photoinduced by iron (III) was also investigated. It appears a faster degradation which does not lead to the same products. The process only involves ^•OH radicals formed upon photolysis of aquocomplex of iron (III). They preferentially abstract a hydrogen from the methylene group. The degradation is then assisted by oxygen and leads to the formation of carbonylated oxidation products.     

Sonolysis of alkylphenols in aqueous solution with Fe(II) and Fe(III)

The sonolytic degradation of alkylphenols (APs), such as butylphenol, pentylphenol, octylphenol, and nonylphenol (NP), in water was investigated at a sound frequency of 200 kHz with an acoustic intensity of 6 W cm(-2) under argon, oxygen, and air atmospheres. The sonolytic degradation rate of the APs under the conditions of the present study depended upon their alkyl chain length. The decrease in the degradation rate by the radical scavenging effect was in the range of about 48-82% for APs in the presence of 3 mM 2-methyl-2-propanol. The free radicals play a significant role in the sonolytic degradation process of the APs. In the presence of Fe(II) and Fe(III), the pseudo-first-order rate constants for the sonolytic degradation of 30 microM NP as a function of the concentration of Fe(II) and Fe(III) were estimated under argon and oxygen. The maximum rate constants were observed at 50 microM Fe(II) (0.139 +/- 0.008 min(-1)) and 100 microM Fe(III) (0.103 +/- 0.001 min(-1)) under oxygen. The total organic carbon concentration (TOC) was investigated under same conditions. TOC decreased in the range of about 50-70% during the sonication in the presence of Fe(II) and Fe(III) under argon and oxygen. The sonochemical effects by the addition of Fe(II) and Fe(III) as catalyst during the sonication under the proper atmosphere result in a remarkable enhancement of degradation and mineralization.     

UV/TiO2光催化降解水体中的邻苯二甲酸二甲酯

酞酸酯是环境中普遍存在的有机污染物(内分泌干扰物)之一。利用UV/TiO2光催化降解水体中的邻苯二甲酸二甲酯(DMP),讨论了溶液pH、TiO2投加量及DMP初始浓度等因素对DMP降解的影响。结果表明,DMP为10mg/L左右时,TiO2投加量为0.2～0.5g/L、pH=7是比较理想的降解条件;DMP初始浓度越高,其降解率则越低。研究了Langmuir-Hinshelwood模式下DMP在TiO2表面的吸附与催化活性的关系,发现DMP主要通过吸附在催化剂的表面而非在溶液本体中发生降解。线性回归计算所得光照条件下的吸附常数远大于无光照条件下的吸附常数,可能是由于UV和TiO2体系之间产生协同效应,提高了UV/TiO2体系对DMP的降解效果。另外,初步分析了可能的降解反应机制。     

3-Chlorophenol elimination upon excitation of dilute iron(III) solution: evidence for the only involvement of Fe(OH)2+

The transformation of 3-chlorophenol (3CP) photoinduced by iron(II) in aqueous solution has been investigated under monochromatic irradiation (lambda(exc) = 365 nm) representative of atmospheric solar emission. Hydroxyl radicals are formed via an intramolecular photoredox process in iron(III) excited hydroxy-complexes. Fe(OH)2+ is the most active complex in terms of HO* formation and according to our experiments and calculations, it appears that Fe(OH)2+ is the only iron(III) species involved in 3CP oxidation process. Hydroxyl radicals react very rapidly with 3CP, which is eliminated from the solution. The primary intermediates do not accumulate in the medium but rapidly degraded to non-absorbing compounds by a subsequent action of hydroxyl radicals.     

Persistence and fate of 17beta-estradiol and testosterone in agricultural soils

Steroidal hormones are constantly released into the environment by man-made and natural sources. The goal of this study was to examine the persistence and fate of 17beta-estradiol and testosterone, the two primary natural sex hormones. Incubation experiments were conducted under aerobic and anaerobic conditions using [4-(14)C]-radiolabeled 17beta-estradiol and testosterone. The results indicated that 6% of 17beta-estradiol and 63% of testosterone could be mineralized to (14)CO(2) in native soils under aerobic conditions. In native soils under anaerobic conditions, 2% of testosterone and no 17beta-estradiol was methanogenized to (14)CH(4). Essentially, no mineralization of either testosterone or 17beta-estradiol to (14)CO(2) occurred in autoclaved soils under aerobic or anaerobic condition. Results also indicated that 17beta-estradiol could be transformed to an unidentified polar compound through abiotic chemical processes; however, 17beta-estradiol was only oxidized to estrone via biological processes. The TLC results also indicated that testosterone was degraded, not by physical-chemical processes but by biological processes. Results also indicated that the assumed risks of estrogenic hormones in the environment might be over-estimated due to the soil's humic substances, which can immobilize majority of estrogenic hormones, and thereby reduce their bioavailability and toxicity.