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201.
The generation of reactive species in an aqueous goethite suspension, under room light and aeration conditions, was investigated using the electron paramagnetic resonance (EPR) technique employing spin trap agents. The trap reagents, including 5,5-dimethylpyrroline N-oxide (DMPO) and 2,2,6,6-tetramethylpiperidine (TEMP), were used for the detection of OH radicals (OH) and singlet oxygen (1O2), respectively. On the addition of DMPO to the goethite suspended solution, a DMPO-OH adduct was formed, which was not decreased, even in the presence of the OH scavenger, mannitol. This result implied a false positive interpretation from the DMPO-OH EPR signal. In the presence of TEMP reagent, a TEMP-O signal was detected, which was completely inhibited in the presence of the singlet oxygen scavenger, sodium azide. With both DMPO-OH and TEMP-O radicals in the presence and absence of radical scavengers, singlet oxygen was observed to be the key species formed in the room-light sensitized goethite suspension. In the goethite/H2O2 system; however, both OH and singlet oxygen were generated, with significant portions of DMPO-OH resulting from both OH and singlet oxygen. In fact, the DMPO-OH resulting from OH should be carefully calculated by correcting for the amount of DMPO-OH due to singlet oxygen. This study reports, for the first time, that the goethite suspensions may also act as a natural sensitizer, such as fulvic acids, to form singlet oxygen. 相似文献
202.
Chemical oxidation of cable insulating oil contaminated soil 总被引:2,自引:0,他引:2
Leaking cable insulating oil is a common source of soil contamination of high-voltage underground electricity cables in many European countries. In situ remediation of these contaminations is very difficult, due to the nature of the contamination and the high concentrations present. Chemical oxidation leads to partial removal of highly contaminated soil, therefore chemical oxidation was investigated and optimized aiming at a subsequent bioremediation treatment. Chemical oxidation of cable oil was studied with liquid H2O2 and solid CaO2 as well as permanganate at pH 1.8, 3.0 and 7.5. Liquid H2O2 most effectively removed cable oil at pH 7.5 (24%). At pH 7.5 poor oil removal of below 5% was observed with solid CaO2 and permanganate within 2 d contact time, whereas 18% and 29% was removed at pH 1.8, respectively. A prolonged contact time of 7 d showed an increased oil removal for permanganate to 19%, such improvement was not observed for CaO2.Liquid H2O2 treatment at pH 7.5 was most effective with a low acid use and was best fit to a subsequent bioremediation treatment. To further optimize in situ chemical oxidation with subsequent bioremediation the effect of the addition of the iron catalyst and a stepwise liquid H2O2 addition was performed. Optimization led to a maximum of 46% cable oil removal with 1469 mM of H2O2, and 6.98 mM Fe(II) chelated with citric acid (H2O2:FeSO4 = 210:1 (mol mol−1). The optimum delivery method was a one step addition of the iron catalyst followed by step wise addition of H2O2. 相似文献
203.
改性粉煤灰与过氧化氢联合作用深度处理皂素生产废水的研究 总被引:1,自引:0,他引:1
利用改性粉煤灰与过氧化氢(H2O2)联合的方法对二次处理过的皂素生产废水进行深度处理,研究了pH、改性粉煤灰投加量、H2O2投加量、反应时间对皂素生产废水脱色率和COD去除率的影响,分析了其作用机制.结果表明,试验最佳条件为:pH=6、反应时间60 min、改性粉煤灰投加量10 g/L、H2O2投加量4 mL/L.在最... 相似文献
204.
通过纯水条件下的模拟研究,考察NH4+和H2O2在单独和联用时对臭氧氧化过程中溴酸盐形成的抑制效能。结果表明,单独投加NH4+能显著降低溴酸盐的生成量,并对水中臭氧浓度衰减无明显影响;投加H2O2大于0.20 mmol/L时,能在一定程度上抑制溴酸盐的形成,但加快了水中臭氧浓度的衰减;同时投加过量H2O2和NH4+时,相对单独投加过量H2O2条件进一步抑制了溴酸盐的形成,但相对单独投加NH4+条件却促进了溴酸盐的形成。 相似文献
205.
206.
The ability of calcium peroxide (CaO2) to immobilize As of contaminated soil was studied using pot and field experiments. In pot experiment, CaO2 applied at 2.5 and 5 g kg−1 significantly increased celery shoot weight and decreased shoot As accumulation, which was ascribed to the formation of stable crystalline Fe and Al oxides bound As and the reduction of labile As fractions in the soil. The labile As fractions were pH dependent and it followed a “V” shaped profile with the change of pH. In field experiment, the dose of CaO2 application at 750 kg ha−1 was optimal and at which the celery was found to produce the highest biomass (63.4 Mg ha−1) and lowest As concentration (0.43 mg kg−1). CaO2 probably has a promising potential as soil amendment to treat As contaminated soils. 相似文献
207.
针对江苏省某化工园区集中式污水处理厂出水COD和TP高于DB32/939—2006《江苏省化学工业主要水污染物排放标准》规定的排放限值的情况,采用Fenton氧化工艺对该污水处理厂装置进行升级改造。小试最佳工艺条件为:初始污水pH 3.0~3.5,H_2O_2(质量分数30%)加入量0.8 m L/L,FeSO_4·H_2O加入量0.8 g/L,反应时间120min,Fenton氧化反应结束后中和反应的适宜pH约为7.0。升级改造工程包括2套并联运行的处理能力各为10 km~3/d的Fenton氧化系统,装置稳定运行后最终控制H_2O_2加入量为150 L/h,FeSO_4·7H_2O溶液加入量为700 L/h,相应的处理后出水COD和TP分别稳定在60 mg/L和0.4 mg/L以下,可达标排放。每吨污水的处理药剂成本约为0.9元。 相似文献
208.
SZU-HUA PAN KWANG VICTOR LO PING HUANG LIAO HANS SCHREIER 《Journal of environmental science and health. Part. B》2013,48(4):451-458
Both the advanced oxidation process (AOP) using a combination of hydrogen peroxide addition and microwave heating (H2O2/microwave), and the microwave heating process were used for solubilization of phosphorus from liquid dairy manure. About 80% of total phosphate was released into the solution at a microwave heating time of 5 min at 170°C. With an addition of H2O2, more than 81% of total phosphate could be released over a reaction period of 49 h at ambient temperature. The AOP process could achieve up to 85% of total phosphate release at 120°C. The results indicated that both the microwave, and the AOP processes could effectively release phosphate from liquid dairy manure. These processes could serve as pretreatments for phosphorus recovery from animal wastes, and could be combined with the struvite crystallization process to provide a new approach in treating animal wastes. 相似文献
209.
Yang Yu Ing W. Lo Ping H. Liao Kwang V. Lo 《Journal of environmental science and health. Part. B》2013,48(8):804-809
The microwave enhanced advanced oxidation process (MW/H2O2-AOP) was used to treat dairy manure for solubilization of nutrients and organic matters. This study investigated the effectiveness of the MW/H2O2-AOP under a continuous mode of operation, and compared the results to those of batch operations. The main factors affecting solubilization by the MW/H2O2-AOP were heating temperature and hydrogen peroxide dosage. Soluble chemical oxygen demand (SCOD) and volatile fatty acids (VFA) increased with an increase of microwave (MW) heating temperature; very high concentrations were obtained at 90°C. Insignificant amounts of ammonia and reducing sugars were released in all runs. An acidic pH condition was required for phosphorus solubilisation from dairy manure. The best yield was obtained at 90°C with an acid dosage of 1.0 %; about 92 % of total phosphorus and 90 % of total chemical oxygen demand were in the soluble forms. The MW/H2O2-AOP operated in a continuous operation mode showed pronounced synergistic effects between hydrogen peroxide and microwave irradiation when compared to a batch system under similar operating conditions, resulting in much better yields. 相似文献
210.
Fernando J. Beltrán Javier Rivas Benito Acedo 《Journal of environmental science and health. Part. B》2013,48(3):449-468
Abstract Atrazine (6‐chloro‐N‐ethyl‐N'‐isopropyl‐1,3,5‐triazinedyl‐2,4‐diamine) was treated with ozone alone and in combination with hydrogen peroxide or UV radiation in three surface waters. Experiments were carried out in two bubble reactors operated continously. Variables investigated were the ozone partial pressure, temperature, pH, mass flow ratio of oxidants fed: hydrogen peroxide and ozone and the type of oxidation including UV radiation alone. Residence time for the aqueous phase was kept at 10 min. Concentrations of some intermediates, including deethylatrazine, deisopropylatrazine and deethyldeisopropylatrazine, were also followed. The nature of water, specifically the alkalinity and pH were found to be important variables that affected atrazine (ATZ) removal. Surface waters with low alkalinity and high pH allowed the highest removal of ATZ to be reached. There was an optimum hydrogen peroxide to ozone mass flow ratio that resulted in the highest ATZ removal in each surface water treated. This optimum was above the theoretical stoichiometry of the process. Therefore, to reach the maximum removal of ATZ in a O3/H2O2 process, more hydrogen peroxide was needed in the surface waters treated than in ultrapure water under similar experimental conditions. In some cases, UV radiation alone resulted in the removal of ATZ higher than ozonation alone. This was likely due to the alkalinity of the surface water. Ozonation and UV radiation processes yield different amounts of hydrogen peroxide. Combined ozonations (O3/H2O2 and O3/UV) lead to ATZ removals higher than single ozonation or UV radiation but the formation of intermediates was higher. 相似文献