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1.
The kinetics of ferrate(VI) (Fe VIO 4
2−, Fe(VI)) oxidation of an antiphlogistic drug, ibuprofen (IBP), as a function of pH (7.75–9.10) and temperature (25–45°C) were investigated to see the applicability of Fe(VI) in removing this drug from water. The rates decrease with an increase in pH and the rates are related to protonation of ferrate(VI). The rates increase with an increase in temperature. The E
a of the reaction at pH 9.10 was calculated as 65.4±6.4 kJ mol −1. The rate constant of the HFeO 4
− with ibuprofen is lower than with the sulphur drug, sulfamethoxazole. The use of Fe(VI) to remove ibuprofen is briefly discussed. 相似文献
2.
We prepared a carbonaceous sorbent for Cr(VI) from the culm of Sasa
kurilensis by dehydration with concentrated H 2SO 4. The removal of Cr(VI) by the sorbent was highly solution pH dependent and mainly governed by physicochemical sorption. The
equilibrium data fit well in the Langmuir isotherm model and indicate the endothermic nature of the Cr(VI) sorption. The desorption
experiments suggest that the Cr(VI) sorption is generally irreversible, owing to strong interaction of HCrO 4− with the active sites of the sorbent. 相似文献
3.
Performance of autohydrogenotrophic bacteria for bio-reduction of selenate (Se(VI)) under anaerobic conditions was investigated with batch experiments. Results showed Se(VI) was bio-reduced to selenite (Se(IV)) as an intermediate product, and then to elemental selenium (Se 0). Reduction kinetics could be described by the pseudo-first-order model. In particular, the influences of pH value and temperature on Se(VI) reduction by autohydrogentrophic organisms were examined. The high degradation rate was achieved at pH 7.0 to 8.0; and the best reduction temperature was between 25°C and 35°C. This study is of help for treating groundwater with selenium contamination by autohydrogenotrophic bacteria as well as its reactor development. 相似文献
4.
A multicommutated flow system was designed and evaluated for the determination of total arsenic and selenium by Hydride Generation
Atomic Absorption Spectrometry (HG-AAS). It was applied to the determination of arsenic and selenium in samples of natural
and drinking water. Detection limits were 0.46 and 0.08 μg l −1 for arsenic and selenium, respectively; sampling frequency was 120 samples h −1 for arsenic and 160 samples h −1 for selenium. Linear ranges found were 1.54–10 μg l −1 ( R = 0.999) for arsenic and 0.27–27 μg l −1 ( R = 0.999) for selenium. Accuracy was evaluated by spiking various water samples and using a reference material. Recoveries
were in the range 95–116%. Analytical precision ( s
r
(%), n = 10) was 6% for both elements. Compared with the Standard Methods, APHA, 3114B manual method, the system consumes at least
10 times less sample per determination, and the quantities of acid and reducing agent used are significantly lower with a
reduction in the generation of pollutants and waste. As an additional advantage, the system is very fast, efficient and environmentally
friendly for monitoring total arsenic and selenium levels in waters. 相似文献
5.
Selenium was determined from 25 topsoils and 25 plants in the semi-arid Central Spain where large extents of soils are developed
on evaporitic materials. Some species of vegetation associated with them are of the genera Astragalus, Salsola, Mercurialis, Phlomis, Thymus and Atriplex. Total selenium in soils was determined and its bioavailability assessed by chemical sequential fractionation. Se content
in soils was adequate (in the range 0.17–0.39 mg kg −1) or large (in the range 0.50–4.38 mg kg −1) and appeared in highly and/or potentially available forms. Several plant species showed high Se levels (in the range 5–14.3 mg kg −1), which can be a potential risk of toxicity to animals. Data obtained from the study area can be used as a guide to the range
of values in soils and plants of the European Mediterranean area that are relatively unpolluted from industrial sources, allowing
comparison with more polluted areas. 相似文献
6.
Growth and development rates were determined for nauplii of Calanus finmarchicus (Gunnerus) in the near-shore waters of a western Norwegian fjord from in situ mesocosm incubations. The major food source
for the nauplii was diatoms, but Phaeocystis sp., dinoflagellates and ciliates were also part of the diet. At local temperatures ranging from 4.8 to 5.2 °C the cumulative
median development time from hatching to Nauplius VI was 19 d. The time taken to molt to the next naupliar stage was approximately
constant (3 d) from Stages IV to VI, but Stage III needed the longest development time (5 d). The instantaneous growth rate
in terms of body carbon was negative from hatching to Nauplius Stage II, but as high as 0.25 to 0.30 d −1 from Stage III to V. Enhancement of food resources by nutrient addition led to no significant change in specific growth rates.
Additionally, the cohorts from different nutrient regimes showed almost equal development time, size and body carbon within
stages. Length–weight relationships of nauplii from the two different food resources were: W
low resources = 4.17 × 10 −6 × L
2.03 ( r
2 = 0.84) and W
high resources = 4.29 × 10 −6 × L
2.05 ( r
2 = 0.92), where weight ( W) is in micrograms of C and body length ( L) in micrometers. The natural body morphology of naupliar stages I to VI is illustrated with digital images, including the
final molt from Nauplius VI to Copepodid Stage I. In general, development of the nauplii was faster than that of the copepodids
of C. finmarchicus, and structural growth was exponential from naupliar stages III to VI. This study validates our earlier results that nauplii
of C. finmarchicus can obtain high growth and nearly maximal developmental rates at relatively low food levels (∼50 μg C l −1), suggesting that nauplii exhibit far less dependence on food supply than copepodids.
Received: 30 July 1999 / Accepted: 7 March 2000 相似文献
7.
The objective of this document is to report on the early success for sequestering 129I. Sorption coefficients ( K
d) for I − and IO 3
− onto delafossites, spinels and layered metal hydroxides were measured and compared for their applicability to sequester 129I. The studies were performed using a dilute fluid composition representative of groundwater indigenous to the Yucca mountain
area. Delafossites generally exhibited relatively poor sorption coefficients (<35 mL/g). In contrast, the composition of the
layered hydroxides significantly affects their ability to sorb I. Cu/Al and Cu/Cr layered hydroxide samples exhibit K
d’s greater than 1000 mL/g for both I − and IO 3
−. 相似文献
8.
The influence of naturally occurring uraniferous black shales on cadmium, molybdenum and selenium concentrations in soils
and plants is examined. The possible implications of element concentrations to animal and human health are considered for
the Deog-Pyoung area.
Geochemical surveys have been undertaken within 13 river tributary valleys in the area underlain by uraniferous black shales
and black slates or grey chlorite schists. Sampling of rocks, soils and plants has been carried out along transect lines within
each valley. Samples were analysed for trace elements by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES)
and for uranium by Neutron Activation Analysis (NAA). Soil pH, cation exchange capacity, loss on ignition and particle size
distribution have been measured for selected samples.
Average trace element concentrations of the Okchon uraniferous black shales were 6.3 μg g −1 Cd, 136 μg g −1 Mo and 8.6 μg g −1 Se. Soils derived from these rocks tend to reflect their extreme geochemical composition. Trace element concentrations in
alluvial soils derived in part from these black shales averaged 1.2 μg g −1 Cd, 20 μg g −1 Mo and 1.5 μg g −1 Se. Trace element concentrations in plants were found to be influenced by those of soils. Cadmium accumulated in tobacco
leaves up to 46 μg g −1 (D.M.) and leafy plants such as lettuce contain up to 0.5 μg g −1 Se (D.M.).
In addition to total concentrations in soils, soil pH is a major factor influencing uptake of Mo into crop plants and soil
texture for Se. Concentrations of trace elements in plants also varied between plant species. The relative concentrations
of Cd were found to vary in the order tobacco > lettuce > red pepper > rice grain.
Elevated concentrations of Cd in crop plants and in tobacco may possibly have deleterious effects on human health in this
area. The low Cu:Mo ratio in rice stalk of 2.65:1 may be associated with disturbed Cu metabolism in ruminant animals which
regularly consume this material. 相似文献
9.
Adsorption of vanadate(V) from aqueous solution onto industrial solid ‘waste’ Fe(III)/Cr(III) hydroxide was investigated.
HCl treated Fe(III)/Cr(III) hydroxide was found to be more efficient for the removal of vanadate(V) compared to untreated
adsorbent. The adsorption follows second-order kinetics. Langmuir and Freundlich isotherms have been studied. The Langmuir
adsorption capacity ( Q
0) of the treated and untreated adsorbents was found to be 11.43 and 4.67 mg g −1, respectively. Thermodynamic parameters showed that the adsorption process was spontaneous and endothermic in the temperature
range 32–60°C. Maximum adsorption was found at system pH 4.0. The adsorption mechanism was predominantly ion exchange. Effect
of other anions such as phosphate, selenite, molybdate, nitrate, chloride, and sulfate on adsorption of vanadium has been
examined. 相似文献
10.
Short-term effects of temperature and irradiance on oxygenic photosynthesis and O 2 consumption in a hypersaline cyanobacterial mat were investigated with O 2 microsensors in a laboratory. The effect of temperature on O 2 fluxes across the mat–water interface was studied in the dark and at a saturating high surface irradiance (2162 μmol photons
m −2 s −1) in the temperature range from 15 to 45 °C. Areal rates of dark O 2 consumption increased almost linearly with temperature. The apparent activation energy of 18 kJ mol −1 and the corresponding Q
10 value (25 to 35 °C) of 1.3 indicated a relative low temperature dependence of dark O 2 consumption due to mass transfer limitations imposed by the diffusive boundary layer at all temperatures. Areal rates of
net photosynthesis increased with temperature up to 40 °C and exhibited a Q
10 value (20 to 30 °C) of 2.8. Both O 2 dynamics and rates of gross photosynthesis at the mat surface increased with temperature up to 40 °C, with the most pronounced
increase of gross photosynthesis at the mat surface between 25 and 35 °C ( Q
10 of 3.1). In another mat sample, measurements at increasing surface irradiances (0 to 2319 μmol photons m −2 s −1) were performed at 25, 33 (the in situ temperature) and 40 °C. At all temperatures, areal rates of gross photosynthesis saturated
with no significant reduction due to photoinhibition at high irradiances. The initial slope and the onset of saturation ( E
k = 148 to 185 μmol photons m −2 s −1) estimated from P versus E
d curves showed no clear trend with temperature, while maximal photosynthesis increased with temperature. Gross photosynthesis
was stimulated by temperature at each irradiance except at the lowest irradiance of 54 μmol photons m −2 s −1, where oxygenic gross photosynthesis and also the thickness of the photic zone was significantly reduced at 40 °C. The compensation
irradiance increased with temperature, from 32 μmol photons m −2 s −1 at 25 °C to 77 μmol photons m −2 s −1 at 40 °C, due to increased rates of O 2 consumption relative to gross photosynthesis. Areal rates of O 2 consumption in the illuminated mat were higher than dark O 2 consumption at corresponding temperatures, due to an increasing O 2 consumption in the photic zone with increasing irradiance. Both light and temperature enhanced the internal O 2 cycling within hypersaline cyanobacterial mats.
Received: 30 November 1999 / Accepted: 11 April 2000 相似文献
11.
The abundance and biomass of Corophium multisetosum Stock, 1952 were determined from benthic corer samples collected monthly over 1 yr in the upper reaches of Canal de Mira
(Ria de Aveiro, Portugal). Both density and biomass over the sampling period were negatively correlated with water temperature
and positively correlated with chlorophyll a concentration in the sediment. C. multisetosum density was significantly negatively correlated with plant biomass and positively correlated with salinity. The nature of
the sediment, favourable environmental conditions, high availability of food and low interspecific competition allowed the
population to reach a maximal density of 200 × 10 3 individuals m −2 and a maximal biomass (ash-free dry wt, AFDW) of 62 g AFDW m −2. The population was highly productive, especially during the autumn/winter period. Production, estimated by two different
methods (Hynes method: 251 g AFDW m −2 yr −1; Morin–Bourassa method: 308 g DW m −2 yr −1), was much higher than the values reported for other Corophium species. The annual P:Bˉ ratio (10) was high, but similar to values reported for Swedish populations of C. volutator and lower than the values estimated from Mediterranean populations of C. insidiosum.
Received: 8 October 1999 / Accepted: 22 June 2000 相似文献
12.
The toxicity of fenitrothion was determined in larvae (nauplii, Zoeae 1 to 3, Mysis 1 to 3), postlarvae (PL stages) and juvenile
shrimp ( Penaeus japonicus Bate), in two media, seawater (SW) and diluted seawater (DSW) (1100 and 550 mos M kg −1, ≃ 37 and 19‰ S). The effects of fenitrothion on the osmoregulatory capacities (OC) of juveniles were recorded. A gill and
epipodite histopathological study was also conducted. For larvae in seawater, 24 and 48 h LC 50s ranged from 32.9 μg l −1 (Zoeae 2) to 10.7 μg l −1 (Mysis 3), and from 3.9 μg l −1 (Zoeae 3) to 2.0 μg l −1 (Mysis 3), respectively; 48 and 96 h LC 50s in postlarvae (PL) at the same salinity ranged from 1.8 μg l −1 (PL1) to 0.6 μg l −1 (PL5), and from 0.3 μg l −1 (PL7) to 0.4 μg l −1 (PL15). In juveniles, 96 h LC 50s were 0.8 μg l −1 in seawater and 1.5 μg l −1 in diluted seawater. From hatching to juvenile stages, the overall trend was a rapid decrease (from nauplii to PL5–PL7) followed
by a slight increase (from PL7 to PL15 and juveniles) in the shrimp's ability to tolerate the insecticide. In juveniles kept
in seawater and in diluted seawater, fenitrothion decreased the osmoregulatory capacity (OC = difference between the hemolymph
osmotic pressure and the osmotic pressure of the medium) at both lethal and sublethal concentrations. This effect was time-
and dose-dependent. In SW, the decrease in hypo-OC was ˜ 25% at sublethal concentrations and ˜ 35% at the 96 h LC 50. In DSW, the decrease in hyper-OC was ˜ 10 to 15% at sublethal concentrations. In SW, shrimp were able to recover their OC
in less than 48 h when transferred to water free of pesticide. In DSW, recovery at 48 h was only possible after exposure to
the lowest tested sublethal concentration. Haemocytic congestions (thrombosis) of the gills, lamellae necrosis and other alterations
of gills and epipodites (breakage of the cuticle, reduction of the hemolymph lacunae) were noted in juveniles exposed to lethal
and sublethal concentrations of fenitrothion.
Received: 7 October 1996 / Accepted: 13 November 1996 相似文献
13.
Artemia franciscana was grown on Isochrysis galbana Green (clone T. Iso) at saturated food concentrations (13 to 20 mg C l −1) for 11 d at 26 to 28 °C, and 34 ppt salinity. Three groups of brine shrimp were used in the feeding experiments: metanauplius
III and IV (Group 1), post-metanauplius II and III (Group 2) and post-metanauplius VIII (Group 3), corresponding to 4-, 7-
and 11-d-old animals, respectively. The ingestion rate, clearance rate and carbon balance were estimated for these stages
at different concentrations of 14C-labeled I. galbana ranging from 0.05 to 30 mg C l −1. The handling time of algae was determined for all three groups. The ingestion rate ( I, ng C ind −1 h −1) increased as a function of animal size and food concentration. In all three groups, the ingestion rate increased to a maximum
level ( I
max) and remained constant at food concentrations ≥10 mg C l −1 (saturated food concentrations). The clearance rate ( CR, μl ind −1 h −1) increased with increasing food concentration up to a maximum rate ( CR
max), after which it decreased for even higher food concentrations. The functional response of A. franciscana was most consistent with Holling's Type 3 functional response curve (sigmoidal model), which for the two oldest groups (Group 2
and 3) differed significantly from a Type 2 response ( p < 0.05). The gut passage time for the three groups of A. franciscana, feeding on saturated food concentration (20 mg C l −1), varied between 24 and 29 min. As the nauplii developed to pre-adult stage the handling time of the algae increased as a
function of animal size. The assimilation rate (ng C ind −1 h −1) in the youngest stages (Group 1 and 2) increased with increasing food concentrations, reaching a maximum level close to
10 mg C l −1. At higher food concentrations the assimilation rate decreased, and the proportions of defecated carbon increased, reaching
60 to 68% in the post-metanauplius stages (Group 3). The assimilation efficiency (%) was high at the lowest food concentrations
in all three groups (89 to 64%). At higher concentrations, the assimilation efficiency decreased, reaching 56 to 38% at the
highest concentrations.
Received: 2 February 2000 / Accepted: 25 March 2000 相似文献
14.
Effects of low dissolved oxygen on early development and swimming behaviour of veliger larvae of the scavenging gastropod
Nassarius festivus were studied. Embryonic development was significantly delayed when dissolved oxygen level was reduced to 3.0 mg O 2 l −1 and no embryo hatched successfully at 0.5 mg O 2 l −1. Veliger larvae hatched at 4.5 mg O 2 l −1 had significantly smaller velar lobe, shell length and shell width. Median 48-h LC 50 value of the veliger larvae was estimated at 1.25 mg O 2 l −1 with lower swimming speed (swimming velocity and dispersal velocity) being recorded for the survivors exposed to reduced
oxygen levels. The percentage of veliger larvae that developed into crawling juveniles was significantly reduced and metamorphosis
was delayed at 4.5 mg O 2 l −1 whereas all larvae at 3.5 mg O 2 l −1 died before they underwent metamorphosis. Juveniles developed at 4.5 mg O 2 l −1 were also smaller than those at 6.0 mg O 2 l −1. Results indicated that dissolved oxygen levels well above hypoxia levels (2.8 mg O 2 l −1) have already had significant impact on the hatching success and larval development in gastropods, which may lead to long-term
decreases in population growth. 相似文献
15.
Kidney stones (urinary calculi) have become a global scourge since it has been recognized as one of the most painful medical problems. Primary causative factors for the formation of these stones are not clearly understood, though they are suspected to have a direct relationship to the composition of urine, which is mainly governed by diet and drinking water. Sixty nine urinary calculi samples which were collected from stone removal surgeries were analyzed chemically for their Na, K, Ca, Mg, Cu, Zn, Pb, Fe and phosphate contents. Structural and mineralogical properties of stones were studied by XRD and FT-IR methods. The mean contents of trace elements were 1348 mg kg −1 (Na); 294 mg kg −1 (K); 32% (Ca); 1426 mg kg −1 (Mg); 8.39 mg kg −1 (Mn); 258 mg kg −1 (Fe); 67 mg kg −1 (Cu); 675 mg kg −1 (Zn); 69 mg kg −1 (Pb); and 1.93% (PO 43−). The major crystalline constituent in the calculi of Sri Lanka is calcium oxalate monohydrate. Principal component analysis was used to identify the multi element relationships in kidney stones. Three components were extracted and the first component represents positively correlated Na-K-Mg-PO 43− whereas the␣second components represent the larger positively weighted Fe–Cu–Pb. Ca–Zn correlated positively in the third component in which Mn–Cu correlated negatively. This study indicates that during the crystallization of human urinary stones, Ca shows more affinity towards oxalates whereas other alkali and alkaline earths precipitate with phosphates.Contribution from the Environmental Geology Research Group (EGRG), Department of Geology, University of Peradeniya, Sri Lanka. 相似文献
16.
On the eastern shore of Nova Scotia late summer atmospheric systems cause upwelling of shelf water; the associated temperature
variations of 10 °C with a 6 to 8 d period are comparable in magnitude to the seasonal variation. A laboratory study was undertaken
to assess the effects of these temperature fluctuations on sea scallop ( Placopecten magellanicus) growth and metabolism. In a factorial design, scallops were subjected to constant (10 °C) or a variable (6 to 15 °C) 8 d
temperature cycle, and either a low (seston in filtered seawater) or high (seston supplemented with cultured phytoplankton)
food diet. During the 48 d experiment scallop mortality was low and growth positive in all treatments. Shell and total tissue
growth rate did not differ between temperature treatments, but growth in the high food treatments was 40 to 50% higher than
in the low food treatments. However, soft tissue (excluding adductor) growth did show a temperature treatment effect; growth
rates were significantly higher in the fluctuating temperature treatment, due in part to greater gonad development. Weight-standardized
rates of scallop oxygen consumption ( V
sO 2 , μmol O 2 g −1 h −1) were 20 to 25% higher in high food than in low food treatments, consistent with the expected increase in respiration due
to the higher growth rates. Scallop metabolism did not acclimate to the fluctuating temperature cycle; V
sO 2 and ammonium excretion ( V
sNH +
4, μmol O 2 g −1 h −1) remained dependent on ambient temperature throughout the experiment. V
sNH +
4 Q 10 (2.77) was higher than V
sO 2 Q 10 (2.01) which was reflected in a decrease in the O:N ratio at 15 °C, indicating a shift toward increased protein catabolism
and a stressed state. At 10 °C, V
sO 2 and V
sNH +
4 in the variable temperature treatments were 15 to 18% lower than in the constant temperature treatments, a difference that
was not detected in growth measurements. Results demonstrate that the metabolism of Placopecten magellanicus, unlike some bivalve species, is tightly coupled to fluctuations in ambient temperature. Although an absence of compensatory
acclimation had a minimal effect on growth in this study, if high temperatures were combined with low food conditions a reduction
in scallop production could result.
Received: 23 June 1998 / Accepted: 8 February 1999 相似文献
17.
The natural selenium poisoning due to toxic Se levels in food chain had been observed in humans and animals in Lower Cambrian outcrop areas in Southern Shaanxi, China. To find out the distribution pattern of selenium and other hazardous elements in the plant, soil and water of Lower Cambrian in Southern Shaanxi, China, and their possible potential health risk, a total of 30 elements were analyzed and the health risk assessment of 18 elements was calculated. Results showed that the soil, plant and natural water of Lower Cambrian all had relatively high Se levels. In Lower Cambrian, the soil was enriched with Se, As, Ba, Cu, Mo, Ni, Zn, Ga, Cd and Cr (1.68 < Igeo < 4.48, Igeo; geo-accumulation index). In same plants, the contents of Se, Cd and Zn (except Cd in corn and rice, Zn in potato and corn) of Lower Cambrian were higher than that of the other strata. Ba and Ga in natural water were higher than that of the other strata, while K and Cs were opposite. The health risk assessment results showed that the people living in outcrop areas of Lower Cambrian had both high total non-carcinogenic risk of 18 elements (HI = 16.12, acceptable range: < 1) and carcinogenic risk of As (3.98E−04, acceptable range: 10−6–10−4). High contents of Se, As, Mo and Tl of Lower Cambrian may pose a health risk to local people, and food intake was the major pathway. For minimizing potential health risk, the local inhabitants should use the mix-imported food with local growing foods. 相似文献
18.
Efficiency of metabisulfite and a commercial steel wool as reducing agents in the removal of Cr(VI) from wastewaters was evaluated.
Chromium(VI) was converted to Cr(III), precipitated with NaOH, and removed by filtration. A reduction of more than 1.0 × 10 5 and 4.0 × 10 5 fold in total Cr and the Cr(VI) concentrations, respectively, was observed by employing steel wool masses as low as 0.4420 g
to 30-mL solutions of wastewater. Chromium(III) hydroxide obtained after the treatment was recycled and used as marker in
cattle nutrition studies. The liquid residue obtained after the treatment was reused as precipitation agent replacing NaOH. 相似文献
19.
A wide range of pharmaceutical compounds have been identified in the environment, and their existence is a topic of growing
concern, both for human and ecological health. The work described here has investigated the photolytic properties of L(+)-α-phenylglycine
(L-α-PG-H) in aqueous solution as it can be degraded by photo-catalysis. In 266 nm laser flash photolysis of aqueous solution
of L-α-PG-H saturated with nitrogen, two transient absorption bands are observed at 280–330 nm and 450–800 nm, respectively,
due to L-α-PG-H radical cation and hydrated electrons (e aq−). Then e aq− reacts with L-α-PG-H to form the L-α-PG-H radical anion. Decaying rate constants of e aq− observed at 720 nm is to be 8.9 × 10 8 dm 3 mol −1 s −1. The rate constant for oxidation of L-α-PG-H by SO 4
− is calculated as 4.5 × 10 8 and 4.3 × 10 8 s −1 mol −1 dm 3, respectively. The dissociation constants (pKa) of L-α-PG-H is 3. Excited triplet of L-α-PG-H in solution is formed by laser
flash photolysis. The quench rate constant of L-α-PG-H excited triplet ( k
s) is determined to be 1.3 × 10 7 dm 3 mol −1 s −1 and k
0 is equal to 1.7 × 10 5 s −1. 相似文献
20.
Advanced oxidation processes, such as photocatalysed oxidation, provide an important route for degradation of wastes. In this
study, the lowest excited state ( 3MLCT) of Ru(bpy) 32+ is used to break down chlorophenol pollutant molecules to harmless products. This has the advantage of using visible light
and a short-lived catalytically active species. Photolysis of deaerated aqueous solutions of a variety of mono- and poly-substituted
chlorophenols has been followed in the presence of Ru(bpy) 32+/S 2O 82− with near visible light (λ > 350 nm) by UV/visible absorption spectroscopy, luminescence, potentiometry, NMR and HPLC techniques.
Upon irradiation, a decrease is observed in the chlorophenol concentration, accompanied by the formation of Cl −, H + and SO 42− ions as the main inorganic products. Benzoquinone, phenol, dihydroxybenzenes and chlorinated compounds were the dominant
organic products. As the ruthenium(II) complex is regenerated in the reaction, the scheme corresponds to an overall catalytic
process. The kinetics of the rapid chlorophenol photodechlorination has been studied, and are described quite well by pseudo-first
order behaviour. Further studies on this were made by following Cl − release with respect to the initial Ru(bpy) 32+ and S 2O 82− concentrations. A comparison is presented of the photodechlorination reactivity of the mono and polychlorophenols studied
at acidic and alkaline pH. 相似文献
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