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991.
Semiconductor-assisted photocatalytic degradation of reactive dyes in aqueous solution 总被引:21,自引:0,他引:21
This work reports the semiconductor-assisted photochemical degradation of reactive dyes. In an oxygenated-UV-ZnO system almost total decolorization of Remazol Brilliant Blue R, Remazol Black B, Reactive Blue 221 and Reactive Blue 222 was observed in reaction times of about 60 min. Extending the photochemical treatment up to 120 min, mineralization higher than 80% for all the dyes was observed. During the same period, the residual acute toxicity was significantly reduced only for Remazol Black B. A systematic optimization study carried out by factorial design showed that for the reactive dyes tested, the ZnO semiconductor exhibits a better efficiency than that observed with anatase TiO2. A synergistic effect in the coupled TiO2-ZnO system was not observed. 相似文献
992.
Beltrán FJ García-Araya JF Rivas J Alvarez PM Rodríguez E 《Journal of environmental science and health. Part. B》2000,35(4):439-454
Comparison of the effects and kinetics of UV photolysis and four advanced oxidation systems (ozone, ozone/hydrogen peroxide, ozone/UV radiation and UV radiation/hydrogen peroxide) for the removal of simazine from water has been investigated. At the conditions applied, the order of reactivity was ozone < ozone/hydrogen peroxide < UV radiation < ozone/UV radiation and UV radiation/hydrogen peroxide. Rate constants of the reactions between ozone and simazine and hydroxyl radical and simazine were found to be 8.7 M-1s-1 and 2.1 x 10(9) M-1s-1, respectively. Also, a quantum yield of 0.06 mol.photon-1 was found for simazine at 254 nm UV radiation. The high value of the quantum yield corroborated the importance of the direct photolysis process. Percentage contributions of direct reaction with ozone, reaction with hydroxyl radicals and direct photolysis were also quantified. 相似文献
993.
Mateo R Martínez-Vilalta A Guitart R 《Environmental pollution (Barking, Essex : 1987)》1997,96(3):335-341
Lead (Pb) poisoning has been found to be a serious problem for waterfowl in some southern European countries, but few studies have been conducted in Spain. In order to obtain these data, studies were made in the Ebro delta, a Spanish Ramsar site, during 1992 and 1993. Lead shot densities in the first 20 cm of sediment ranged from < 8 900 to 2 661 000 shot ha(-1). A similar proportion of birds had lead shot in the gizzard and elevated liver lead (> 5 microg g(-1) DW) concentrations. Northern pintail and common pochard (both with declining populations in Europe) showed the highest levels of shot ingestion, with 70.8 and 69.2%, respectively. Body condition index in the northern pintail was negatively correlated with the number of pellets in the gizzard and liver Pb concentration. Levels of exposure were higher than in other northern countries of the western Palearctic flyway, where lead shot have been banned recently. 相似文献
994.
The lichen Punctelia subrudecta (Nyl.) Krog was transplanted to 22 biomonitoring sites in a northwestern area of Córdoba city, Argentina and tested for chlorophyll a, chlorophyll b, phaeophytin a, soluble protein, hydroperoxy conjugated dienes (HPCD), malondialdehyde (MDA) concentration and sulphur accumulation. A pollution index (PI) was calculated for each biomonitoring site. The biomonitoring sites were set according to (1) traffic levels, (2) industrial density and (3) distance of the power station close to each site. The biomonitor's chemical response was associated with industries as well as power stations. Significant differences were observed in sulphur content, MDA concentration and PI values in lichen material transplanted to sites with different industrial densities. The higher values for these parameters were found at sites with high industrial levels. At the same time, significant differences were detected for sulphur content in samples at different distances from the power station, with higher accumulation in samples located far from the power plant. For MDA concentration, effect of different levels of industrial density was observed only at points close to the power station, probably because of higher levels of humidity near the power plant. For PI significantly higher values were observed in samples at points far from the power station and with high industrial density. This shows the additive effect of the principal emission sources that act on the response of P. subrudecta to air pollutants. 相似文献
995.
Ana B. Payá-Pérez Mohammed S. Rahman Helle Skejø-Andresen Bo R. Larsen 《Environmental science and pollution research international》1996,3(4):183-188
The soil/water partition coefficient (Kd) of hexachlorobenzene (HCB) ranged from 220 1/kg to 1800 1/kg for eight soils having a wide range of physico-chemical properties. Kd normalised to soil organic carbon (Koc) was found to be 28000 ± 4800 1/kg. Anionic surfactant dodecylsulphate (DS) present at concentrations above the critical micellar concentration (CMC) caused reductions in the apparent soil/water partition coefficient (Kd *) in the range of 3–26 times for most soils and up to 36–91 times for sandy soils. Below CMC, at environmentally relevant surfactant concentrations, Kd * was reduced by a factor of 1–13. For clay and calcareous soils significant adsorption/complexation/precipitation of DS occurred. At the lowest DS concentration this produced a two-fold increase in Kd *. At increasing DS concentrations this effect was shielded by the solubihzing effect from DS. Monomer (Kmn) and micellar (Kmc) surfactant/water partition coefficients for HCB were determined to be, 980 ± 190 1/kg and 21000 ± 1600 1/kg, respectively. 相似文献
996.
Antonio García MT Martinez-Conde E Corpas Vazquez I 《Environmental pollution (Barking, Essex : 1987)》1988,54(2):89-96
Tissue lead data are presented for populations of feral pigeons (Columba livia) from three locations in Madrid (Spain). The lead present in the lungs and digestive tract of pigeons increased progressively with traffic density and in parallel with atmospheric and ground lead values. The contribution of the respiratory route of Pb intake to the pigeons was about three times greater than the digestive route. The highest Pb values were found in bones. It is suggested that the pigeons gave a greatly magnified picture of lead pollution in cities than indicated by atmospheric lead concentrations. 相似文献
997.
Relationships between catchment characteristics of 31 alpine lakes and observed trends in lake water concentrations of nitrate were evaluated in the Tatra Mountains. Nitrate concentrations increased from background levels <4 microeql(-1) in the 1930s to maxima (up to 55 microeql(-1)) in the 1980s, after which they declined to 4-44 microeql(-1) by the late 1990s. In-lake nitrate concentrations correlated negatively with parameters characterising catchment-weighted mean pools (CWM; kgm(-2)) of soil, i.e. with percent land cover with meadow and soil depth, and positively with grade of terrain, annual precipitation, and the highest elevation in the catchment. The CWM pool of soil and annual precipitation explained together 65% of the current spatial variability in nitrate concentrations. Denitrification and direct N deposition on surface area explained 14% of the variability. Increased atmospheric N deposition and declining net N retention in soils were responsible for long-term changes in nitrate concentrations. Long-term decline in %N retention in soils decreased along with the estimated decline in C:N ratios (from 21 to 18 on average during the last 70 years). An empirical model linking nitrate concentrations in different types of alpine Tatra Mountain lakes to four independent variables (CWM soil pool, annual precipitation, increased N deposition, and average trend in soil C:N ratios) explained 80% of the observed spatial and temporal nitrate variability over the period 1937-2000. 相似文献
998.
The present study investigated the ability of the non-pathogenic fungus Fusarium lateritium to either degrade or modify aromatic substances in olive-mill dry residue (DOR) and to reduce its phytotoxicity. The 80% reduction of ethylacetate extractable phenols in DOR colonized by the fungus for 20 weeks appeared to be due to polymerization reactions of phenol molecules as suggested by mass-balance ultrafiltration and size-exclusion chromatography experiments. Several lignin-modifying oxidases, including laccase, Mn-peroxidase and Mn-inhibited peroxidase were detected in F. lateritium solid-state cultures. Tests performed with tomato seedlings in soils containing 6% (w/w) sterilized non-inoculated DOR showed that the waste was highly phytotoxic. By contract, F. lateritium growth on DOR for 20 weeks led to a complete removal of the waste toxicity and to a higher shoot dry weight of tomato plants than that obtained in the absence of DOR. 相似文献
999.
The investigation presented here focussed on the electrochemical decolourisation of a commercial, textile indigo dye, in an undivided electrochemical cell using graphite electrodes. The decolourisation values obtained employing halide salts--sodium chloride, potassium bromide and potassium iodide--and a reductive agent--sodium meta-bisulphite--as electrolytes are higher than those attained when no electrolyte was used. The highest decolourisation value at a low level of electric power consumption was obtained with sodium chloride. Besides, this electrolyte is usually found in the coloured wastewaters of textile industry. Thus, a detailed study was carried out to determine the influence of electrolyte--sodium chloride--and dye concentration on the efficiency of the process expressed in terms of energy consumption and extension of the decolourisation reaction. The scale-up of the treatment with sodium chloride was satisfactorily tested in a 20 l cell. 相似文献
1000.
Pereira FA de Assunção JV Saldiva PH Pereira LA Mirra AP Braga AL 《Journal of the Air & Waste Management Association (1995)》2005,55(1):83-87
To evaluate the possible influence of air pollutants on the incidence of respiratory tract neoplasm we studied 12 S?o Paulo City districts where air pollution is observed. We collected data on pollutants from 1981-1990 and correlated it with the incidence of larynx and lung neoplasms in 1997. Ozone was the pollutant that best correlated with the incidence of neoplasm. The correlation coefficients were 0.7234 (p=0.277) and 0.9929 (p=0.007) for lung and larynx cancer, respectively. There may be a relationship between air pollution and the incidence of respiratory tract neoplasm. This study, however, does not allow us to conclude that there is a causal relationship. 相似文献