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71.
Background, Aim and Scope
Due to their large potential for manifold applications, the use of nanoparticles is of increasing importance. As large amounts
of nanoparticles may reach the environment voluntarily or by accident, attention should be paid on the potential impacts on
the environment. First studies on potential environmental effects of photocatalytic TiO2 nanoparticles have been performed
on the basis of widely accepted, standardized test systems which originally had been developed for the characterization of
chemicals. The methods were adapted to the special requirements of testing photocatalytic nanoparticles.
Materials and Methods:
Suspensions of two different nanoparticles were illuminated to induce their photocatalytic activity. For testing, the growth
inhibition test with the green alga Desmodesmus subspicatus and the immobilization test with the daphnid Daphnia magna were
selected and performed following the relevant guidelines (algae: ISO 8692, OECD 201, DIN 38412-33; daphnids: ISO 6341, OECD
202, DIN 38412-30). The guidelines were adapted to meet the special requirements for testing photocatalytic nanoparticles.
Results:
The results indicate that it is principally possible to determine the ecotoxicity of nanoparticles. It was shown that nanoparticles
may have ecotoxicological effects which depend on the nature of the particles. Both products tested differ in their toxicity.
Product 1 shows a clear concentration-effect curve in the test with algae (EC50: 44 mg/L). It could be proven that the observed
toxicity was not caused by accompanying contaminants, since the toxic effect was comparable for the cleaned and the commercially
available product. For product 2, no toxic effects were determined (maximum concentration: 50 mg/L). In the tests with daphnids,
toxicity was observed for both products, although the concentration effect-curves were less pronounced. The two products differed
in their toxicity; moreover, there was a difference in the toxicity of illuminated and non-illuminated products.
Discussion:
Both products differ in size and crystalline form, so that these parameters are assumed to contribute to the different toxicities.
The concentration-effect curves for daphnids, which are less-pronounced than the curves obtained for algae, may be due to
the different test organisms and/or the differing test designs. The increased toxicity of pre-illuminated particles in the
tests with daphnids demonstrates that the photocatalytic activity of nanoparticles lasts for a period of time.
Conclusions:
The following conclusions can be drawn from the test results: (I) It is principally possible to determine the ecotoxicity
of (photocatalytic) nanoparticles. Therefore, they can be assessed using methods comparable to the procedures applied for
assessing soluble chemicals. - (II) Nanoparticles may exert ecotoxicological effects, which depend on the specific nanoparticle.
- (III) Comparable to traditional chemicals, the ecotoxicity depends on the test organisms and their physiology. - (IV) The
photocatalytic activity of nanoparticles lasts for a relevant period of time. Therefore, pre-illumination may be sufficient
to detect a photocatalytic activity even by using test organisms which are not suitable for application in the pre-illumination-phase.
Recommendations and Perspectives:
First results are presented which indicate that the topic 'ecotoxicity and environmental effects of nanoparticles' should
not be neglected. In testing photocatalytic nanoparticles, there are still many topics that need clarification or improvement,
such as the cause for an observed toxicity, the improvement of the test design, the elaboration of a test battery and an assessment
strategy.
On the basis of optimized test systems, it will be possible to test nanoparticles systematically. If a potential risk by specific
photocatalytic particles is known, a risk-benefit analysis can be performed and, if required, risk reducing measures can be
taken. 相似文献
72.
近二十年来发展起来的光催化技术可利用太阳光能对水体中的多种有机污染物进行降解.这符合可持续发展的长远需要,具有诱人的发展前景。光催化技术利用可再生的清洁资源,氧化能力强.适用于广谱有机物,能使难被一般氧化剂氧化、又难生物降解的污染物降解.是当前太阳能利用及水污染控制方面开辟的前沿领域.在治理环境污染方面具有明显的发展优势。本文以溶胶-凝胶法、金属有机化学气相淀积、煅烧沉淀法等多种方法制备光活性二氧化钛膜。 相似文献
73.
74.
75.
分别研究了纳米TiO2 在主波长为 364nm的汞灯光照下催化氧化i C3H7OH和CH3COCH3水溶液的反应速率 .通过XRD ,TEM ,BET和FT IR PAS对催化剂进行表征 ,粉末的晶型主要为锐钛矿型 .平均粒径在 1 5nm左右 ,比表面积为 1 0 1 0± 0 2m2 ·g- 1 ,FT IR PAS的检测结果表明 ,CH3COCH3是i C3H7OH光催化氧化的中间产物 ,其光催化氧化反应为 :i C3H7OH [O]CH3COCH3[O]CH3COOH[O]…[O]CO2 H2 O 相似文献
76.
Zr/TiO2纳米颗粒的制备及其光催化活性 总被引:1,自引:1,他引:1
以钛酸丁酯,乙醇为原料,用固相合成法制备了Zr/TiO2纳米颗粒,用XRD、TEM对其组成、颗粒大小、形貌进行了表征.通过对罗丹明B的降解反应,考察了Zr/TiO2的光催化活性.结果表明,Zr/TiO2为纳米颗粒,平均粒径为12.7 nm左右,且颗粒均匀;掺杂金属离子Zr提高了TiO2光催化效率,掺杂2.0%Zr的催化剂活性最高.Zr/TiO2的光催化反应,首先是反应物在Zr/TiO2表面发生吸附作用,然后进一步发生光催化降解. 相似文献
77.
光催化降解制浆漂白废水试验条件的优化 总被引:1,自引:0,他引:1
制浆漂白废水的主要成分之一氯代愈创木酚在TiO2作催化剂、254nm波长的紫外光作光源时,发生光催化降解反应,苯环特征峰在反应过程中逐渐消失。采用正交试验得到较佳的试验条件,结果表明,有机物的初始浓度是一个关键因素,其次是溶液的酸碱度,降解时间的延长可以提高光催化降解效果,同时还要考虑催化剂的用量和反应器的循环流量等工艺参数。在初始浓度为0.05mmol/L、循环流量20L/h、催化剂用量250mg/L、pH值10、反应180min时,降解率达到99%。 相似文献
78.
多相光催化过程是近年来日益引起重视的污染治理新技术,具有适用范围广、可使污染物彻底破坏、适用于低浓污染物治理等优点,本文对国外近年有关多相光催化在水污染治理中应用的研究结果进行了总结,包括各种有机污染物的氧化及各种无机离子的治理,并讨论了多相光催化过程的优点及实用性。 相似文献
79.
微波无极灯:一种具有前景的高效光催化光源 总被引:3,自引:0,他引:3
微波无极灯具有制造容易、价格低廉、能耗小和光强大等优点.作为光催化氧化的光源时,由于微波的协同作用可有效提高光催化活性,并能简化反应器.从发光机理、微波协同作用、优缺点和影响因素等方面,对微波无极灯在光催化领域的研究进行详细阐述. 相似文献
80.