Heterogeneous uptake of NO2 on soils under variable temperature and relative humidity conditions

Heterogeneous reactions of nitrogen dioxide (NO₂) on soils collected from Dalian (S1) and Changsha (S2) were investigated over the relative humidity (RH) range of 5%-80% and temperature range of 278-328 K using a horizontal coated-wall flow tube. The initial uptake coefficients of NO₂ on S2 exhibited a decreasing trend from (10 ± 1.3) × 10^-8 to (3.1 ± 0.5) × 10^-8 with the relative humidity increasing from 5% to 80%. In the temperature effect studies, the initial uptake coefficients of S1 and S2 decreased from (10 ± 1.2) × 10^-8 to (3.8 ± 0.5) × 10^-8 and from (16 ± 2.2) × 10^-8 to (3.8 ± 0.4) × 10^-8 when temperature increased from 278 to 288 K for S1 and from 278 to 308 K for S2, respectively. As the temperature continued to increase, the initial uptake coefficients of S1 and S2 returned to (7.9 ± 1.1) × 10^-8 and (20 ± 3.1) × 10^-8 at 313 and 328 K, respectively. This study shows that relative humidity could influence the uptake kinetics of NO₂ on soil and temperature would impact the heterogeneous chemistry of NO₂.     

Size, composition, and mixing state of individual aerosol particles in a South China coastal city

Aerosol samples were collected in summer in Macao,a coastal city of the Pearl River Delta Region in China.Morphology,size,elemental composition,and mixing state of individual aerosol particles were determined by scanning electron microscopy coupled energy dispersive X-ray(SEM/EDX) and transmission electron microscopy(TEM).Based on the morphologies of 5711 aerosol particles,they consist of soot(32%),mineral(17%),secondary(22%),and unknown fine particles(29%).The sizes of these particles were mostly distributed between 0.1 and 0.4 μm.Compositions of 202 mineral particles were obtained by SEM/EDX.Mineral particles were mainly classified into three types:Si-rich,Ca-rich,and Na-rich.The compositions of typical mineral particles can indicate their sources in sampling location.For example,mineral particles,collected along the main street,were associated with trace amounts of heavy metals,such as Zn,Ti,Mn,Ba,Pb,and As.TEM observations indicate that most Na-rich particles were aged sea salt particles(e.g.,Na2SO4 and NaNO3) which formed through heterogeneous chemical reactions between sea salt and acidic gases.Additionally,aging time of soot was short in Macao due to high humidity,high temperature,and high levels of sunlight in Macao.Most of soot and fine mineral dust particles were internally mixed with secondary particles.     

铁炭微电解-光催化氧化-生化处理有机磷废水

对高有机磷废水采用铁炭微电解-光催化氧化-生化工艺进行处理,经过8个月调试,污水处理系统运行稳定,处理效果好。进水平均ρ(COD)=12 890 mg/L、ρ(BOD5)=3 472 mg/L、ρ(NH3-N)=118 mg/L、ρ(TP)=664 mg/L,出水平均ρ(COD)=96 mg/L、ρ(BOD5)=19 mg/L、ρ(NH3-N)=13 mg/L、ρ(TP)=0.45 mg/L,达到了GB 8978—1996《污水综合排放标准》一级标准。     

多相催化-臭氧氧化法处理模拟有机磷农药废水

实验通过臭氧氧化法来降解模拟废水中的有机磷农药,将其转化为无害物质,并试验研究了在废水中加入2种自制的催化剂对降解结果的影响。采用气相色谱法测定水中有机磷农药的量。结果表明,只用臭氧处理的情况下1周后有机磷的去除率为78.03%;在催化剂A存在下,去除率可达93.85%;在催化剂B存在下,去除率可达为88.35%。结果表明,臭氧氧化法对此类污水具有较好的降解作用,尤其在有催化剂存在的情况下处理效果更好,在室温和中性介质中均属于一级反应。     

炭法烟气脱硫技术现状与趋势

介绍了炭法烟气脱硫在脱硫剂、脱硫工艺和设备等方面的应用现状和研究进展 ,分析了制约炭法烟气脱硫技术发展的原因 ,并提出 :开发新材料、新工艺 ,变传统的炭吸附法脱硫技术为炭催化法脱硫技术是炭法脱硫技术的发展方向     

区域生态质量评价指标选择基础框架及其实现

论述了区域生态质量评价的理论基础、基本单元、指标选择原则及方法、基本评价指标及其实现 ,旨在为区域生态质量评价指标框架的建立打下基础     

纳米Cu0@Fe3O4活化PMS降解对-硝基苯酚的协同反应机制

为解决纳米Cu⁰活化过硫酸盐体系主要依赖浸出铜离子参与均相反应且适应pH范围窄(<7)的缺陷,本研究采用共沉淀法制备了纳米Cu⁰@Fe₃O₄催化剂,以对-硝基苯酚(PNP)为目标污染物,较系统地考察了Cu⁰@Fe₃O₄活化PMS的性能和降解PNP的反应机制.结果表明:(1) pH=5.65、 200 mg·L^-1 Cu⁰@Fe₃O₄和0.5 mmol·L^-1 PMS在60 min内对5 mg·L^-1 PNP的降解率可达到96%;(2)在Cu⁰@Fe₃O₄/PMS体系中,总铜离子(TCu)和总亚铜离子(TCu⁺)以及铁离子浸出几乎可以忽略,可认为是非均相反应体系;(3)通过包覆Fe₃O     

氧化法处理水中酚的研究方法综述

目前氧化法处理含酚废水的方法有化学氧化法即臭氧氧化法、Fenton试剂氧化法等，酶催化氧化法以及光化学氧化法即光敏化氧化、光催化氧化法等；分析了它们的优势及存在的问题；并提出了今后的研究方向，即臭氧-生物活性炭、臭氧辐射、臭氧-H2O2技术，水溶性酶制剂连接到固体载体上制成固化酶，H2O2－BAC、O3－H2O2－BAC联用技术等。     

单原子环境催化研究进展

单原子催化剂不仅实现了对金属原子最大化利用,而且具有较高催化活性和选择性,还是理想的催化理论研究位点,近年来引起了广泛关注。环境催化在环境保护和污染修复中扮演着重要的角色。单原子催化剂在环境催化领域越来越受关注并有望应用于解决环境问题。单原子催化剂研究的重点和难点集中在单原子催化剂可控合成和催化位点分析表征。为推进单原子催化剂在环境催化领域中的应用,本文综述了单原子的主要制备方法和常规表征手段以及单原子催化剂在环境催化中应用的典型案例,并对单原子催化剂在环境催化中的应用将面临的挑战进行了展望。     

Use of catalytic wet air oxidation (CWAO) for pretreatment of high-salinity high-organic wastewater

Catalytic wet air oxidation (CWAO) coupled desalination technology provides a possibility for the effective and economic degradation of high salinity and high organic wastewater. Chloride widely occurs in natural and wastewaters, and its high content jeopardizes the efficacy of Advanced oxidation process (AOPs). Thus, a novel chlorine ion resistant catalyst B-site Ru doped LaFe_1-xRu_xO_3-δ in CWAO treatment of chlorine ion wastewater was examined. Especially, LaFe_0.85Ru_0.15O_3-δ was 45.5% better than that of the 6%RuO₂@TiO₂ (commercial carrier) on total organic carbon (TOC) removal. Also, doped catalysts LaFe_1-xRu_xO_3-δ showed better activity than supported catalysts RuO₂@LaFeO₃ and RuO₂@TiO₂ with the same Ru content. Moreover, LaFe_0.85Ru_0.15O_3-δ has novel chlorine ion resistance no matter the concentration of Cl⁻ and no Ru dissolves after the reaction. X-ray diffraction (XRD) refinement, X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM), and X-ray absorption fine structure (XAFS) measurements verified the structure of LaFe_0.85Ru_0.15O_3-δ. Kinetic data and density functional theory (DFT) proved that Fe is the site of acetic acid oxidation and adsorption of chloride ions. The existence of Fe in LaFe_0.85Ru_0.15O_3-δ could adsorb chlorine ion (catalytic activity inhibitor), which can protect the Ru site and other active oxygen species to exert catalytic activity. This work is essential for the development of chloride-resistant catalyst in CWAO.

1. Download : Download high-res image (171KB)
2. Download : Download full-size image