硅藻土/泥炭藓复合调湿材料温湿度调节效果研究

通过试验研究了硅藻土/泥炭藓复合调湿材料的制备及其强度、耐水性和调湿性能,选择较优配比的调湿材料进行密闭状态和与外界有换气条件下的小室温湿度调节效果研究,根据扫描电镜分析及材料的吸附/解吸理论研究材料调节机理。研究表明,综合考虑材料强度、耐水性和调湿性能,合理的泥炭藓用量宜为5%～13%,此时材料的抗压强度、软化系数和调湿性能均较好。密闭状态下,喷涂厚度为0.5 mm和1 mm的硅藻土/泥炭藓调湿材料小室的单位空间最大吸湿量为1.48 g/m~3和2.21 g/m~3,最大放湿量为1.88 g/m~3和3.27 g/m~3;与外界有换气条件下,随着预留缝隙增大,材料对小室内湿度调节效果逐渐减弱,但对温度仍有一定调节作用。硅藻土和泥炭藓的毛细孔道效应、表面物理吸附和化学吸附,加之泥炭藓强持水性,两者共同作用使硅藻土/泥炭藓复合调湿材料具有优异的调湿调温效果。     

g-C3N4光催化剂的改性及制备

石墨相氮化碳(g-C3N4)是种非常具有发展前景的光催化剂,较好的光催化性和稳定性,已成为学者研究的焦点.但是其光生电子-空穴对非常容易复合,光生载流子寿命比较短,使得量子效率非常低,进而导致g-C3N4的光催化性能降低,同时限制了光响应范围,致使g-C3N4的应用范围和前景折损.本文通煅烧三聚氰胺(C3N6H6)制备g-C3N4,然后进行半导体(TiO2)复合改性的方法,在不同条件下将g-C3N4和TiO2混合后进一步煅烧制备g-C3N4/TiO2复合光催化剂.对g-C3N4/TiO2复合光催化剂进行光降解氮氧化物试验,通过亚甲基蓝降解和thermo氮氧化物分析进行评价.     

TiO2光催化降解甲醛气体的研究

以玻璃纤维为载体,用溶胶-凝胶法自制锐钛矿型TiO2光催化材料,分别对400℃、450℃、500℃不同温度下制备的纳米TiO2进行X衍射(XRD)、电镜扫描(SEM)分析,并用在不同温度下制备的TiO2光催化材料进行降解甲醛的实验,结果表明450℃下制备的TiO2光催化材料具有最佳的光催化活性。     

MnO2/g-C3N4纳米复合材料的合成及其光催化性能

通过Na₂SO₄进行形貌调控和MnO₂掺杂对石墨类氮化碳(g-C₃N₄)改性,采用水热法制备多形貌的MnO₂/g-C₃N₄复合光催化剂(MCN),探讨最佳合成条件;研究不同形貌MCN的微观结构、光吸收能力以及对甲基橙(MO)的光催化降解性能。结果表明,MCN的最佳制备条件如下：Na₂SO₄、g-C₃N₄、KMnO₄投加量分别为 0.04、0.6、0.12 g/L,反应温度为 80 ℃,反应时间为 4 h。MnO₂掺杂可显著提高g-C₃N₄的光催化活性。MCN对MO的光催化降解率高达97.34%,而g-C₃N₄仅为54.39%;MCN具有较强的可见光响应活性,最大吸收边带为 486 nm,禁带宽度(...     

g-C3N4/TiO2复合汽车尾气光催化剂的组成设计与性能评价

随着汽车尾气对空气质量的负面影响日益严重,光催化技术在环保领域的应用逐渐受到重视。因此,基于二氧化钛(Ti O₂)和石墨相氮化碳(g-C₃N₄)的光催化性能,制备了一种g-C₃N₄/Ti O₂复合光催化剂,旨在提高汽车尾气的降解效率,即：选用三聚氰胺(C₃H₆N₆)、双氰胺(C₂H₄N₄)和尿素(CH₄N₂O)作为前驱体制备g-C₃N₄,通过质量损失和尾气降解实验分析筛选出最佳前驱体,并设计了不同质量比的g-C₃N₄/Ti O₂复合光催化剂;通过对比分析单体和复合光催化剂的光催化性能,确定了复合光催化剂的最佳质量比。实验结果表明：制备g-C₃N_...     

H3PW12O40-TiO2/膨润土光催化降解甲基橙的催化性能

通过溶胶凝胶制得H3PW12O40Ti(OH)4凝胶,并柱撑于膨润土层间制备了复合光催化剂H3PW12O40TiO2/膨润土。由XRD、SEM、EDS对制备的复合光催化剂进行表征测试表明,固载的H3PW12O40TiO2使膨润土层状结构发生明显变化,柱撑体H3PW12O40TiO2呈弥散状态,且TiO2为锐钛结构,催化剂为颗粒粒径大小不一、分布松散的复合材料。对甲基橙的H3PW12O40TiO2/膨润土光催化降解应用表明,掺杂的杂多酸使所制备的复合催化剂光催化活性得到了极大提高,在光催化体系下有较广的pH适应范围,且制备的催化剂具有良好的催化稳定性。在表征分析及应用实验的基础上,提出了H3PW12O40TiO2/膨润土的强化催化作用原理。     

蒸汽相水解法制备磁性光催化剂Fe_3O_4/SiO_2/TiO_2及其光催化性能

采用蒸汽相水解法,以Fe3O4纳米磁性颗粒为磁核,在其表面包覆一层SiO2来阻止光腐蚀,然后将锐钛矿相纳米氧化钛沉积在Fe3O4/SiO2颗粒表面,从而制得核壳结构的Fe3O4/SiO2/TiO2磁性复合光催化材料。用X射线粉末衍射仪(XRD)、场发射扫描电镜(FE-SEM)、高分辨率透射电子显微镜(HR-TEM)、探针式震动磁强计等手段对所制备的产物的结构、形貌、磁强度性能进行表征。以300W汞灯为光源,用亚甲基蓝和酸性红模拟污水中的有机染料来评价复合光催化剂的性能。结果表明,磁性纳米微球中TiO2的含量越大,其光催化性能越好,含TiO2质量分数50%的F3O4/SiO2/TiO2磁性纳米微球可在180min内降解亚甲基蓝模拟染料废水,降解率达99%,在80min内降解酸性模拟染料废水,降解率达98%。     

酸处理对TiO2/硅藻土复合材料光催化性能的影响

以四氯化钛为前驱体,用水解沉淀法对酸处理前后的硅藻土表面负载TiO2,制备了硅藻土负载TiO2复合材料.采用SEM和EDX测试手段对复合材料进行了表征。以甲基橙溶液的光催化脱色率对硅藻土负载TiO2复合材料的光催化活性进行了评价。结果表明，用酸处理后的精硅藻土制备的硅藻土负载TiO2材料具有较强的光催化性能，对10mg/L的甲基橙溶液1.5h的脱色率可达99%以上，比相同条件下用硅藻原土制备的TiO2/硅藻土复合材料的脱色率高出近60%。     

光催化对洁净厂房循环风单元中甲醛净化参数的优化研究

为了探讨洁净厂房循环风单元回风净化装置中光催化剂种类、用量、光照强度等参数对降解甲醛效率的影响,以确定光催化净化网参数配置的方案。采用酚试剂分光光度法测定甲醛浓度,在60 m~3的模拟洁净厂房内,通过正交试验筛选回风净化装置中光催化净化网对甲醛15 min降解效率的最优参数组合。试验结果表明,光催化剂用量对甲醛降解效率有显著性差异。直接分析发现净化参数对甲醛降解效率的影响大小顺序为光催化剂用量光照强度光催化剂种类。综合分析得出光催化净化网最佳参数配置为纳米TiO_2、光催化剂用量三遍(30 g/m~2)、紫外灯20 W。光催化净化网的最佳参数配置能够提高光催化净化网对洁净厂房中甲醛的降解效率。     

沸石负载TiO_2光催化水泥基材料的制备与性能研究

光催化技术在污水处理方面具有成本低、效率高和环境友好等特点,是近年来环境领域重点开发的新技术。以钛酸四丁酯为前驱体,通过溶胶-凝胶法制备TiO_2溶胶,采用浸润法制备TiO_2/沸石光催化剂,采用XRD表征光催化剂的化学组成。将TiO_2/沸石光催化剂均匀洒布于水泥基材料上制备光催化水泥基材料,并研究其光催化性能。研究煅烧温度、TiO_2负载量、p H值对亚甲基蓝降解效率的影响。结果表明:煅烧温度为200℃时,制备的TiO_2光催化性能最佳;TiO_2负载量越高,亚甲基蓝溶液p H值越低,光催化效率越好;沸石负载TiO_2后两者相结合产生了协同效应,起到了"超叠加"效果,极大地提高了光催化降解效率。     

Numerical modelling of two stoping methods in two Indian mines using degradation of c and mobilization of φ based on Q-parameters

Two Indian mines are the subject of a comparative study of a strain-softened Hoek–Brown and FLAC 3D modelling, and a novel ‘c then tan φ’ strain-softening-strain-mobilization approach, using Q-system based input data. This approach is also used with FLAC 3D, using identical stope geometries. The parameters CC and FC, denoting the cohesive component and frictional component of shear strength, are extracted directly from the Q-logging and knowledge of UCS, and are the source of the peak values. Measured deformations, or the strains recorded over the total length of pre-mining installed MPBX, are compared and effectively calibrate the models, in view of the very similar deformations obtained from empirical formulations based on Q using the competence factor approach, as in SRF. The ‘c then tan φ’ approach appears to give the most realistic match to observations in the mines, including the modelling of a shear band within the back or roof of a stope, rather than at the surface of the stope. The Q-based approach also uses a depth-dependent modulus, and this is perhaps the reason why the strain-softened Hoek–Brown model, without this stiffening with depth, shows ‘global failure’ in a second mine having a wider range of depths within one model, and many openings, since modulus is not increased in standard-method approaches.     

Greywater treatment by UVC/H2O2

Greywater treatment by UVC/H₂O₂ was investigated with regard to the removal of chemical oxygen demand (COD). A COD reduction from 225 to 30 mg l⁻¹ (overall removal of 87%) was achieved after settling overnight and subsequent irradiation for 3 h with 10 mM H₂O₂. Most of the contaminants were removed by oxidation since only 13% COD was removed by settlement.The removal of COD in the greywater followed a second-order kinetic equation, r = 0.0637[COD][H₂O₂], up to 10 mM H₂O₂. A slightly enhanced COD removal was observed at the initial pH of 10 compared with pH 3 and 7. This was attributed to the dissociation of H₂O₂ to O₂H⁻. The treatment was not affected by total concentration of carbonate (c_T) of at least 3 mM, above which operation between pH 3 and 5 was essential. The initial biodegradability of the settled greywater (as BOD₅:COD) was 0.22. After 2 h UVC/H₂O₂ treatment, a higher proportion of the residual contaminants was biodegradable (BOD₅:COD = 0.41) which indicated its potential as a pre-treatment for a biological process.     

Indoor and outdoor PM2.5 and PM10 concentrations in the air during a dust storm

Asian dust storms (ADS) originating from the arid deserts of Mongolia and China are a well-known springtime meteorological phenomenon throughout East Asia. The ventilation systems in office utilize air from outside and therefore it is necessary to understand how these dust storms affect the concentrations of PM_2.5 and PM₁₀ in both the indoor and outdoor air. We measured dust storm pollution particles in an office building using a direct-reading instrument (PC-2 Quartz Crystal Microbalance, QCM) that measured particle size and concentration every 10 min for 1 h, three times a day. A three-fold increase in the concentrations of PM_2.5 and PM₁₀ in the indoor and outdoor air was recorded during the dust storms. After adjusting for other covariates, autoregression models indicated that PM_2.5 and PM₁₀ in the indoor air increased significantly (21.7 μg/m³ and 23.0 μg/m³ respectively) during dust storms. The ventilation systems in high-rise buildings utilize air from outside and therefore the indoor concentrations of fine and coarse particles in the air inside the buildings are significantly affected by outside air pollutants, especially during dust storms.     

Glyphosate degradation in water employing the H2O2/UVC process

Glyphosate is the organophosphate herbicide most widely used in the world. Any form of spill or discharge, even if unintentional, can be transferred to the water due to its high solubility. The combination of hydrogen peroxide and UV radiation could be a suitable option to decrease glyphosate concentration to acceptable limits. In this work, the effects of initial pH, hydrogen peroxide initial concentration, and incident radiation in glyphosate degradation were studied. The experimental device was a cylinder irradiated with two tubular, germicidal lamps. Conversion of glyphosate increases significantly from pH = 3-7. From this value on, the increase becomes much less noticeable. The reaction rate depends on the initial herbicide concentration and has an optimum plateau of a hydrogen peroxide to glyphosate molar concentration ratio between 7 and 19. The expected non linear dependence on the irradiation rate was observed. The identification of critical reaction intermediaries, and the quantification of the main end products were possible and it led to propose a plausible degradation path. The achieved quantification of the mineralization extent is a positive indicator for the possible application of a rather simple technology for an in situ solution for some of the problems derived from the intensive use of glyphosate.     

Emission of N2O and CH4 from a constructed wetland in southeastern Norway

The Skjønhaug constructed wetland (CW) is a free surface water (FSW) wetland polishing chemically treated municipal wastewater in southeastern Norway and consists of three ponds as well as trickling, unsaturated filters with light weight aggregates (LWA). Fluxes of nitrous oxide (N₂O) and methane (CH₄) have been measured during the autumn, winter and summer from all three ponds as well as from the unsaturated filters. Physicochemical parameters of the water have been measured at the same localities. The large temporal and spatial variation of N₂O fluxes was found to cover a range of − 0.49 to 110 mg N₂O–N m^− 2 day⁻¹, while the fluxes of CH₄ was found to cover a range of − 1.2 to 1900 mg m^− 2 day^− 1. Thus, both emission and consumption occurred. Regarding fluxes of N₂O there was a significant difference between the summer, winter and autumn, with the highest emissions occurring during the autumn. The fluxes of CH₄ were, on the other hand, not significantly different with regard to seasons. Both the emissions of N₂O and CH₄ were positively influenced by the amount of total organic carbon (TOC). The measured fluxes of N₂O and CH₄ are in the same range as those reported from other CWs treating wastewater. There was an approximately equal contribution to the global warming potential from N₂O and CH₄.     

不同构造环境花岗岩类的Na2O和K2O含量变化特征

结合花岗岩类的构造环境,通过对大量的岩石地球化学数据统计分析,总结了不同类型花岗岩的Na_2O和K_2O的含量变化,认为不同构造类型花岗岩的Na_2O和K_2O的含量变化可以用鲍文反应序列来解释。在一个构造演化越到晚期,岩浆分异程度越高,形成的花岗岩含K矿物越来越多,K_2O含量越高,Na_2O含量越低,反之,形成的花岗岩类K_2O含量越低,Na_2O含量越高。因此,可以认为,在早期大陆裂谷期由于岩石圈壳幔作用强烈,花岗岩分异程度中等,Na_2O含量略小于或约等于K_2O;到大洋形成时期,洋中脊出现,岩浆分异的程度应该非常低,Na_2OK_2O;收缩环境下形成的花岗岩分异程度较低,因此,岛弧环境的花岗岩Na_2OK_2O;大洋闭合陆陆碰撞环境形成的花岗岩分异程度适中,Na_2O≈K_2O;造山环境的花岗岩分异程度较高,Na2_O﹤K_2O。花岗岩的Na_2O和K_2O的含量变化及Na_2O/K_2O值基本可以反映花岗岩的构造环境。     

Atmospheric NH3 and NO2 concentration and nitrogen deposition in an agricultural catchment of Eastern China

To assess the atmospheric environmental impacts of anthropogenic reactive nitrogen in the fast-developing Eastern China region, we measured atmospheric concentrations of nitrogen dioxide (NO₂) and ammonia (NH₃) as well as the wet deposition of inorganic nitrogen (NO₃⁻ and NH₄⁺) and dissolved organic nitrogen (DON) levels in a typical agricultural catchment in Jiangsu Province, China, from October 2007 to September 2008_. The annual average gaseous concentrations of NO₂ and NH₃ were 42.2 μg m⁻³ and 4.5 μg m⁻³ (0 °C, 760 mm Hg), respectively, whereas those of NO₃⁻, NH₄⁺, and DON in the rainwater within the study catchment were 1.3, 1.3, and 0.5 mg N L⁻¹, respectively. No clear difference in gaseous NO₂ concentrations and nitrogen concentrations in collected rainwater was found between the crop field and residential sites, but the average NH₃ concentration of 5.4 μg m⁻³ in residential sites was significantly higher than that in field sites (4.1 μg m⁻³). Total depositions were 40 kg N ha⁻¹ yr⁻¹ for crop field sites and 30 kg N ha⁻¹ yr⁻¹ for residential sites, in which dry depositions (NO₂ and NH₃) were 7.6 kg N ha⁻¹ yr⁻¹ for crop field sites and 1.9 kg N ha⁻¹ yr⁻¹ for residential sites. The DON in the rainwater accounted for 16% of the total wet nitrogen deposition. Oxidized N (NO₃⁻ in the precipitation and gaseous NO₂) was the dominant form of nitrogen deposition in the studied region, indicating that reactive forms of nitrogen created from urban areas contribute greatly to N deposition in the rural area evaluated in this study.     

Temporal variation of nitro-polycyclic aromatic hydrocarbons in PM10 and PM2.5 collected in Northern Mexico City

With the aim to determine the presence of individual nitro-PAH contained in particles in the atmosphere of Mexico City, a monitoring campaign for particulate matter (PM₁₀ and PM_2.5) was carried out in Northern Mexico City, from April 2006 to February 2007. The PM₁₀ annual median concentration was 65.2 μg m^− 3 associated to 7.6 μg m^− 3 of solvent-extractable organic matter (SEOM) corresponding to 11.4% of the PM₁₀ concentration and 38.6 μg m^− 3 with 5.9 μg m^− 3 SEOM corresponding to 15.2% for PM_2.5. PM concentration and SEOM varied with the season and the particle size. The quantification of nitro-polycyclic aromatic hydrocarbons (nitro-PAH) was developed through the standards addition method under two schemes: reference standard with and without matrix, the former giving the best results. The recovery percentages varied with the extraction method within the 52 to 97% range depending on each nitro-PAH. The determination of the latter was effected with and without sample purification, also termed fractioning, giving similar results. 8 nitro-PAH were quantified, and their sum ranged from 111 to 819 pg m^− 3 for PM₁₀ and from 58 to 383 pg m^− 3 for PM_2.5, depending on the season. The greatest concentration was for 9-Nitroanthracene in PM₁₀ and PM_2.5, detected during the cold-dry season, with a median (10th-90th percentiles) concentration in 235 pg m^− 3 (66-449 pg m^− 3) for PM₁₀ and 73 pg m^− 3 (18-117 pg m^− 3) for PM_2.5. The correlation among mass concentrations of the nitro-PAH and criteria pollutants was statistically significant for some nitro-PAH with PM₁₀, SEOM in PM₁₀, SEOM in PM_2.5, NO_X, NO₂ and CO, suggesting either sources, primary or secondary origin. The measured concentrations of nitro-PAH were higher than those reported in other countries, but lower than those from Chinese cities. Knowledge of nitro-PAH atmospheric concentrations can aid during the surveillance of diseases (cardiovascular and cancer risk) associated with these exposures.     

Metal concentration of PM2.5 and PM10 particles and seasonal variations in urban and rural environment of Agra, India

Three monthly 24-hour samples of airborne aerosols (PM₁₀ and PM_2.5) were collected at an urban and a rural site of the North central, semi-arid part of India during May 2006 to March 2008. Seven trace metals (Pb, Zn, Ni, Fe, Mn, Cr and Cu) were determined for both sizes. The annual mean concentration for PM₁₀ was 154.2 µg/m³ and 148.4 µg/m³ at urban and rural sites whereas PM_2.5 mean concentration was 104.9 µg/m³ and 91.1 µg/m³ at urban and rural sites, respectively. Concentrations of PM₁₀ and PM_2.5 have been compared with prescribed WHO standards and NAAQS given by CPCB India and were found to be higher. Weekday/weekend variations of PM₁₀ and PM_2.5 have been studied at both monitoring sites. Lower particulate pollutant levels were found during weekends, which suggested that anthropogenic activities are major contributor of higher ambient particulate concentration during weekdays. Significant seasonal variations of particulate pollutants were obtained using the daily average concentration of PM₁₀ and PM_2.5 during the study period. PM_2.5/PM₁₀ ratios at urban and rural sites were also determined during the study period, which also showed variation between the seasons. Three factors have been identified using Principal Component Analysis at the sampling sites comprising resuspension of road dust due to vehicular activities, solid waste incineration, and industrial emission at urban site whereas resuspension of soil dust due to vehicular emission, construction activities and wind blown dust carrying industrial emission, were common sources at rural site.     

Chemically-speciated on-road PM2.5 motor vehicle emission factors in Hong Kong

PM_2.5 (particle with an aerodynamic diameter less than 2.5 µm) was measured in different microenvironments of Hong Kong (including one urban tunnel, one Hong Kong/Mainland boundary roadside site, two urban roadside sites, and one urban ambient site) in 2003. The concentrations of organic carbon (OC), elemental carbon (EC), water-soluble ions, and up to 40 elements (Na to U) were determined. The average PM_2.5 mass concentrations were 229 ± 90, 129 ± 95, 69 ± 12, 49 ± 18 µg m^− 3 in the urban tunnel, cross boundary roadside, urban roadside, and urban ambient environments, respectively. Carbonaceous particles (sum of organic material [OM] and EC) were the dominant constituents, on average, accounting for ∼ 82% of PM_2.5 emissions in the tunnel, ∼ 70% at the three roadside sites, and ∼ 48% at the ambient site, respectively. The OC/EC ratios were 0.6 ± 0.2 and 0.8 ± 0.1 at the tunnel and roadside sites, respectively, suggesting carbonaceous aerosols were mainly from vehicle exhausts. Higher OC/EC ratio (1.9 ± 0.7) occurred at the ambient site, indicating contributions from secondary organic aerosols. The PM_2.5 emission factor for on-road diesel-fueled vehicles in the urban area of Hong Kong was 257 ± 31 mg veh^− 1 km^− 1, with a composition of ∼ 51% EC, ∼ 26% OC, and ∼ 9% SO₄⁼. The other inorganic ions and elements made up ∼ 11% of the total PM_2.5 emissions. OC composed the largest fraction (∼ 51%) in gasoline and liquid petroleum gas (LPG) emissions, followed by EC (∼ 19%). Diesel engines showed higher emission rates than did gasoline and LPG engines for most pollutants, except for V, Br, Sb, and Ba.