BiPO_4-BiVO_4复合光催化剂的制备及其光催化性能

采用水热法制备了BiPO_4-BiVO_4复合光催化剂,运用XRD,SEM,UV-Vis DRS技术对其进行了表征,并以亚甲基蓝为目标降解物考察了复合光催化剂在模拟太阳光下的光催化性能。实验结果表明:当BiPO_4与BiVO_4的摩尔比(磷钒比)为2∶8时BiPO_4-BiVO_4的光催化性能最优,光照180 min时对亚甲基蓝(初始质量浓度5mg/L)的降解率达96.20%,反应速率常数为0.018 1 min-1,明显优于单纯BiPO_4和BiVO_4。表征结果显示:单斜相的BiPO_4与BiVO_4晶粒实现了复合生长,BiPO_4-BiVO_4(磷钒比2∶8)的晶粒粒径比单纯BiPO_4和BiVO_4小;复合光催化剂在紫外光和可见光区均具有较好的光响应,且其禁带宽度较BiPO_4明显减小。     

秸秆生物质炭的制备及吸附性能研究

将麦秆、向日葵秆和玉米秆低温热解制备生物质炭。采用傅里叶红外光谱、X射线衍射等仪器对其结构进行了表征。研究了热解温度、溶液p H值、初始浓度、吸附时间以及吸附剂用量等因素对各生物质炭吸附亚甲基蓝效果的影响。实验结果表明,3种生物质炭均含有多孔的微晶炭,表面存在大量的活性-OH,-COOH等基团,对亚甲基蓝有较强的吸附作用;在最佳吸附条件下,玉米秆炭、向日葵秆炭以及麦秆炭对亚甲基蓝的吸附容量分别为26.6,26.2,14.7 mg/g。     

Thermal runaway reaction for highly exothermic material in safe storage temperature

Highly exothermic materials have caused many serious accidents involving storage and transportation, due to being thermally reactive. The safe storage and management of these materials is still a critical problem in many countries. Our aim was to study the thermal hazard of thermal reactive materials, such as a propellant, by employing differential scanning calorimetry (DSC) non-isothermal tests and isothermal tests, and then comparing the kinetic parameters by isothermal and non-isothermal of kinetics. The chosen approach was to obtain reliable thermal decomposition by a safe and effective method, which acquired the kinetic and safety parameters of storage conditions that could be applied as highly exothermic materials' reduction of loss prevention and energy potential for safer design during storage transport and processing operations.     

Biogeochemistry of two types of permeable reactive barriers, organic carbon and iron-bearing organic carbon for mine drainage treatment: Column experiments

Permeable reactive barriers (PRBs) are an alternative technology to treat mine drainage containing sulfate and heavy metals. Two column experiments were conducted to assess the suitability of an organic carbon (OC) based reactive mixture and an Fe⁰-bearing organic carbon (FeOC) based reactive mixture, under controlled groundwater flow conditions. The organic carbon mixture contains about 30% (volume) organic carbon (composted leaf mulch) and 70% (volume) sand and gravel. The Fe⁰-bearing organic carbon mixture contains 10% (volume) zero-valent iron, 20% (volume) organic carbon, 10% (volume) limestone, and 60% (volume) sand and gravel. Simulated groundwater containing 380 ppm sulfate, 5 ppm As, and 0.5 ppm Sb was passed through the columns at flow rates of 64 (the OC column) and 62 (the FeOC column) ml d^− 1, which are equivalent to 0.79 (the OC column) and 0.78 (the FeOC column) pore volumes (PVs) per week or 0.046 m d^− 1 for both columns. The OC column showed an initial sulfate reduction rate of 0.4 µmol g (OC)^− 1 d^− 1 and exhausted its capacity to promote sulfate reduction after 30 PVs, or 9 months of flow. The FeOC column sustained a relatively constant sulfate reduction rate of 0.9 µmol g (OC)^− 1 d^− 1 for at least 65 PVs (17 months). In the FeOC column, the δ³⁴S values increase with the decreasing sulfate concentration. The δ³⁴S fractionation follows a Rayleigh fractionation model with an enrichment factor of 21.6‰. The performance decline of the OC column was caused by the depletion of substrate or electron donor. The cathodic production of H₂ by anaerobic corrosion of Fe probably sustained a higher level of SRB activity in the FeOC column. These results suggest that zero-valent iron can be used to provide an electron donor in sulfate reducing PRBs. A sharp increase in the δ¹³C value of the dissolved inorganic carbon and a decrease in the concentration of HCO₃⁻ indicate that hydrogenotrophic methanogenesis is occurring in the first 15 cm of the FeOC column.     

Degradation of Carbofuran in Water by Solar Photocatalysis in Presence of Photosensitizers

The effect of the presence of photosensitizers, methylene blue (MB) and rose Bengal (RB), on the degradation of carbofuran (2,3-dihydro-2,2-dimethylbenzofuran-7-yl methylcarbamate) in water in a solar photocatalytic system was investigated. It was found that as compared to MB, RB generally showed a stronger effect on the decomposition of carbofuran under comparable conditions. Among the conditions studied, adding 2 × 10^?6 M of RB, that corresponding to 2% of the initial concentration of carbofuran solution in the system, rendered the most effective degradation of carbofuran. As a result, a carbofuran removal percentage of 69.9%, a mineralization efficiency of 28.0%, and a microtoxicity reduction of 65.0% could be achieved. The degradation and mineralization of carbofuran was found to follow the pseudo-first order reaction kinetics. The decomposition mechanism of carbofuran was further investigated through identification of the intermediates to elaborate the influence of dye photosensitizer on the solar photocatalysis of carbofuran in water. On the basis of the intermediates identified, including carbofuran phenol, 3-hydroxy carbofuran phenol, and substituted alcohols (3-phenoxy 1-propanol, 2-ethyl 1-hexanol, 2-butoxyl ethanol), it appears that hydrolysis and hydroxylation were the two key mechanisms for decomposing carbofuran during the process of solar photocatalysis with the aid of dye photosensitizer.     

沿面放电氧活性物质注入协同SCR脱除烟气中NO_x

为了提高选择性催化还原(SCR)在低温区(200℃)的脱硝性能,提出利用插在烟道中的沿面放电反应器生成氧活性物质,部分氧化NO以实现低温快速SCR脱硝过程.同时,研究了氧活性物质注入实现快速SCR的脱硝性能,考察了氧活性物质注入降低二氧化硫和水蒸汽对SCR反应的影响.实验结果表明:在模拟烟气温度为150℃时,采用氧活性物质注入,部分氧化烟气中的NO以实现快速SCR反应条件下(NO/NO2浓度比为1),脱硝效率为51.9%,比标准SCR提升23%;当模拟烟气中存在SO2或H2O时,氧活性物质注入可有效降低SO2、H2O对SCR脱硝效率的影响.     

Effects of UV-A LED light irradiation on growth of cultured RAW 264.7 cells

The aim of this study was to examine the effects of ultraviolet A (UV-A) irradiation-induced damage on cultured macrophage RAW 264.7 cells and determine which components produced these manifestations. RAW 264.7 cells were irradiated with 365 nm UV-A using a light-emitting diode (LED). Cell viability and damage were determined using a calcein-AM and propidium iodide dual-staining assay and lactate dehydrogenase leakage, respectively. Intracellular reactive oxygen species (ROS) were measured by H₂DCF-DA. The components of ROS in each medium were measured using an electron paramagnetic resonance (EPR) spectrometer in the presence of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and 2,2,5,5-tetramethyl-3-pyrroline-3-carboxamide (TPC). While UV-A irradiation for 2 min significantly suppressed cell growth, LDH leakage did not occur. Addition of N-acetyl cysteine restored inhibition of cell proliferation, and reduced intracellular ROS levels. The EPR signal in the presence of TPC increased with time but was decreased by sodium azide. In addition, a typical EPR spectrum was obtained in the presence of DMPO, indicating the presence of a hydroxyradical. The spectrum was diminished by L-histidine. Data suggest that ROS generated in cells or culture medium by UV-A irradiation is predominantly singlet oxygen, and this singlet oxygen suppressed cell proliferation.     

碳纳米管负载纳米四氧化三铁多相类芬顿降解亚甲基蓝

在课题组前期研究的基础上,以碳纳米管(MWCNTs)为载体制备了Fe3O4/MWCNTs复合物并作为催化剂,以染料亚甲基蓝(MB)为降解对象,研究了该催化剂催化H2O2对亚甲基蓝溶液的降解特性及其影响因素,并考察了催化剂的重复使用效果,探讨了催化反应的机理.结果表明,在pH值3~8的范围内,催化反应体系都能有效降解MB,最佳pH值为3.5.随着催化剂投量的增加,MB的降解率明显提高,500 mg·L-1催化剂投量条件下,MB的降解率最高.随着H2O2初始浓度的增加,MB的降解率增加,10 mmol·L-1时MB的降解率最高.溶液中共存的阴离子会降低MB的降解率.在最佳条件,即温度25℃、H2O2浓度10 mmol·L-1、催化剂浓度500 mg·L-1的条件下,0.20 mmol·L-1MB在30 min内的降解率达到99.1%.催化剂重复使用后仍然具有较好的催化活性,说明Fe3O4在MWCNTs表面负载比较牢固,催化剂具有反复使用的能力.催化反应机理是催化剂催化H2O2产生羟基自由基,高活性的羟基自由基氧化MB.     

Natural and waste materials as metal sorbents in permeable reactive barriers (PRBs)

A range of waste products and natural materials including chitin, fly ash, clay soil, cocoa shell, calcified seaweed and the natural zeolite clinoptilolite were tested in batch experiments to assess their ability to remove metals from a synthetic groundwater containing 10 mg l^–1 Cu, Pb and Zn and 1 mg l^–1 Cd. All had the ability to remove more than 70% of the metals from solution with fly ash being the most efficient, then chitin, clinoptilolite, calcified seaweed, clay soil and cocoa shell. After consideration of geochemical and morphological properties, calcified seaweed and clinoptilolite were shown to have potential as barrier materials. Given current issues with regard to the longevity of zero-valent iron barriers alternative materials could be the key to the future adoption of this remediation technology.     

“绿水”的多角度评估及其管理研究

传统的水资源评估和管理忽视了在粮食生产和维护生态系统等方面都具有重要作用的"绿水".本文引入绿水概念,并针对现有绿水评估研究中缺乏小尺度评估方法研究等问题,以碧流河上游地区为例,使用SWAT水文模型在小尺度建立了多角度评估绿水(包括绿水流和绿水贮存)的方法.并使用此方法估算得到了绿水量,绿水时空分布规律以及气候变化条件下绿水的响应规律,研究了引入绿水概念后传统水资源管理的重要革新内容.研究结果表明,使用SWAT水文模型评估流域绿水,是引入绿水概念后进行小尺度绿水评估的有效办法,值得在中国推广使用.绿水评估结果对水资源管理有重要的指导作用.绿水概念的引入为水资源的管理与决策提供了新的思路和更加科学的办法.