TiO2光催化氧化脱除模拟烟气中的NOx

采用P25纳米TiO2为催化剂,对NOx浓度360 mg/m3的模拟烟气进行了光催化氧化实验研究,以期为此种方法在电厂烟气脱硝方面的应用提供依据。经SEM、XRD等表征手段,探讨了催化剂晶型尺寸对光催化的作用。实验考察了光催化反应过程规律以及负载量、光照度、NO初始浓度、O2含量、相对湿度和停留时间对光催化氧化效率的影响。结果表明,光催化反应是瞬态到稳态的过程,其催化效率与上述影响因子有密切关系。实验最优条件下NOx的脱除率为46%,但只需适当提高氧化效能,便能达到理想的效果。     

天然有机物对混凝效果影响机制及絮体特性分析

混凝是降低水体中天然有机物浓度的有效手段.本研究旨在了解天然有机物的存在对混凝效果及絮体特性产生的影响.实验以PACl25作为混凝剂来模拟含有一定量天然有机物的典型代表物质腐殖酸或柠檬酸配水的水处理混凝过程.分析了混凝过程中这两种有机物的存在对絮体颗粒大小、分形维数、Zeta电位和水中剩余铝浓度的影响.结果表明,在一定浓度范围内,随着溶液中腐殖酸、柠檬酸浓度的增加,絮体颗粒的大小及其成长速率、Zeta电位以及分形维数均呈现出下降的趋势(腐殖酸质量浓度从0 mg·L-1增加到10 mg·L-1、柠檬酸浓度从0μmol·L-1增加到7μmol·L-1,破碎前絮体大小分别降低34.2%、53.1%;絮体Zeta电位从10 mV左右分别下降到-10 mV及-2.5 mV左右;絮体成长速率分别下降了42.6%、77.5%;分形维数分别降低了0.08和0.094),表明有机物占据了微絮体表面从而导致絮体活性及致密性的降低;而在此有机物浓度范围内溶液中剩余铝的浓度却不因絮凝能力的下降而变化.     

Price perceptions in water demand

Economists advocate for using the price mechanism to manage water scarcity, but complex nonlinear rate structures prevalent in markets for municipal water obscure price signals. We conduct a randomized field experiment that jointly elicits knowledge about the cost of water and examines the impact of improved information on demand by linking a survey to water billing records. Half of our sample of 30,000 single family homeowners are randomly sent an invitation to a survey that asks questions about the water bill and the costs of water-use activities (e.g. the cost of taking a shower), and subsequently provides personalized accurate information. Results show that consumers have poor information about the marginal price of water and overestimate the costs of using water. Respondents are relatively better informed about their total bill and water consumption. In aggregate, respondents increase water use in response to the survey, potentially due to learning that water is cheaper than they previously thought. Increased consumption is concentrated among low users who are more likely to over-estimate the costs of using water.     

利用糖蜜废水生产微生物絮凝剂及条件优化和效果实验研究

用糖蜜废水取代葡萄糖作为发酵培养基中的碳源和能源培养微生物絮凝剂产生菌Pseudomonas alcaligenesPS-25。通过单因素试验和正交试验得到该菌株产絮凝剂的最佳培养条件:糖蜜废水COD浓度5 000 mg/L、培养基初始pH值6.5、接种量5%(体积比)、温度30℃、培养时间为72 h、摇床转速160 r/min,在此条件下,PS-25所产絮凝剂对高岭土悬浊液絮凝率达96.75%,并且对多种废水都有较好的净化效果,对废水中浊度和色度的去除率分别在90%和80%以上,COD去除率在73.60%～91.10%。研究表明,用糖蜜废水培养PS-25生产微生物絮凝剂处理废水是完全可行的,从而实现废物的资源化利用。     

g-C3N4-P25/光合细菌复合材料降解偶氮染料废水的机理

采用海藻酸钙将g-C3N4-P25和光合细菌进行共固定,合成了光催化-微生物复合材料,并进行了降解模拟偶氮染料废水的研究.结果表明,光催化-微生物复合材料的染料(活性艳红X-3B)脱色率和COD去除率分别为94%和84.7%,远远大于固定光催化剂与固定光合细菌.利用UV-Vis、FT-IR及GC-MS对反应残留物进行表征,根据结果可推测:由光催化产生的自由基和光合细菌共同破坏X-3B的偶氮结构,生成的苯胺类化合物经过一系列的水解、氧化还原作用生成多种具有苯环结构的化合物,然后自由基破坏苯环结构产生长链烷烃,减少芳香烃化合物的累积对光合细菌活性的影响.光合细菌及时利用光催化生成的长链烷烃,产生分子量较小的物质,最后矿化为CO2和H2O.     

UV-LED/P25-based photocatalysis for effective degradation of isothiazolone biocide

• UV-LED with shorter wavelength was beneficial for photocatalytic degradation. • SRNOM dramatically inhibit the degradation. • ·OH acts as the active radical in photocatalytic degradation. • Degradation mainly undergoes oxidation, hydrolysis and chain growth reactions. In this work, LED-based photocatalysis using mixed rutile and anatase phase TiO₂ (P25) as the photocatalyst could effectively remove 5-chloro-2-methyl-4-isothiazolin-3-one (CMIT) and methylisothiazolone (MIT) simultaneously, with removal efficiencies above 80% within 20 min. The photocatalytic degradation of both CMIT and MIT could be modeled using a pseudo-first-order rate equation. The photocatalytic degradation rates of CMIT and MIT under LED280 illumination were higher than under LED310 or LED360 illumination. At concentrations below 100 mg/L, the degradation rate of CMIT and MIT under LED illumination significantly increased with increasing catalyst dosage. Additionally, the effects of the chloride ion concentration, alkalinity and dissolved organic matter on the photocatalytic degradation reaction were also investigated. The ·OH free radicals were determined to play the primary role in the photocatalytic degradation reaction, with a degradation contribution of >95%. The photocatalytic degradation of CMIT and MIT mainly occurred via oxidation, hydrolysis, and chain growth reactions. Finally, the possible photocatalytic degradation pathways of CMIT and MIT over LED/P25 are proposed.     

环境空气PM_(2.5)和PM_(10)监测分析质量保证及其评价

为保证四城市ＰＭ２５和ＰＭ１０的监测数据准确,具有可比性,本研究规定了滤膜的选择、称量操作步骤的要求和滤膜称量的质控指标。研究结果表明,粗细颗粒物样品的采集和称量操作可行,监测数据准确、可靠,具有可比性。     

Air pollution in Athens basin and health risk assessment

An inventory of air pollution sources within the Athens basin is carried out for the years 1989, 1992 and 1998 and the results areinputted in a climatological model for predicting ambient concentrations. Despite of the significant growth in the numberof road vehicles and the deteriorating traffic, the emissions andambient concentrations of fine particulates, CO, NO_x and VOCappear to remain reasonably constant over for the period 1989 to 1998, while these of SO₂ and Pb are reduced, mainly due to the renewal of vehicle fleet, the use of catalytic technologies and the improved quality of the used fuel. The results further indicate that for CO, NO_x and VOC the major source is road traffic, while for PM_2.5 and SO₂ both space heating andtraffic share responsibility. The air pollutant concentrations monitored by the network of 11 stations are reviewed and statistics related to air quality guidelines are presented. As fine particulate levels are not monitored, approximate PM_2.5and PM₁₀ concentrations are derived from black smoke ones on basis of experimentally determined conversion factors. The computed and monitored air pollution levels are compared and found in reasonable agreement. The results of the above analysisshow that the levels of all `classical' pollutants, with the exception of SO₂ and Pb, exceed significantly the WHO guidelines and are thus expected to exert a significant healthimpact. The latter could be quantified in relation to the PM_2.5 or PM₁₀ levels on the basis of risk assessment information developed by the World Health Organization (WHO). The results show that the existing levels of fine particle concentrations in Athens increase significantly the mortality and morbidity, and reduce the average longevity of the entirepopulation from 1.3 to 1.7 years.     

基于移动监测的隧道内部PM_(2.5)与PM_(10)质量浓度分布研究

以上海市5条隧道为研究对象,采用车载移动监测的方式监测记录各条隧道沿程颗粒物(PM_(2.5)和PM_(10))的质量浓度,结合隧道自身特点,探究隧道内部颗粒物分布规律和成因。结果表明:隧道内颗粒物质量浓度分布主要与隧道自身的通风方式、结构特点和通过的车辆及其形成的活塞风有关。通过平行比较5条隧道的通风效果,发现翔殷路隧道通风效果较好,人民路隧道北线污染较为严重。     

Bi（25）FeO40-g-C3N4磁性催化剂的制备及其可见光催化性能

采用水热法制备了铁酸铋(Bi25FeO40),将其与类石墨相氮化碳(g-C3N4)复合得到Bi25FeO40-g-C3N4磁性光催化剂,用X-射线衍射(XRD)、扫描电子显微镜(SEM)、BET比表面积分析、UV-Vis光谱和磁滞回线对该磁性光催化剂进行了表征.考察了Bi25FeO40-g-C3N4复合催化剂对亚甲基蓝的可见光催化降解效果.结果表明,Bi25FeO40-g-C3N4复合催化剂对亚甲基蓝的可见光催化降解效率远高于Bi25FeO40.此外,Bi25FeO40-g-C3N4表现出顺磁性,可通过磁选分离并回收.