沈阳市黑臭水体表层水DOM紫外光谱特征分析

为识别黑臭水体中DOM组成、结构及腐殖化水平,运用UV-vis(紫外-可见吸收光谱)与多元统计相结合的方式,对沈阳市5条黑臭水体的27个表层水样中DOM的UV-vis特征及9个紫外光谱指数进行研究。研究表明:27个表层水样中DOM的UV-vis吸收系数的变异系数在30%～80%之间,轻度黑臭水体相对于重度黑臭水体的紫外吸收峰在356、487、657 nm处分别发生了1、2、2 nm的蓝移;轻度黑臭水体紫外光谱指数SUVA_(254)、S_(275～295)、S_(350～400)、A_2/A_1、A_3/A_1、A_3/A_2均高于重度黑臭水体,而E_2/E_3、E_4/E_6、E_2/E_4低于重度黑臭水体,轻度黑臭水体的腐殖化水平与腐殖化趋势高于重度黑臭水体。进一步分析得出:苯酚基(木质素和奎宁基团)决定了黑臭水体中DOM腐殖化进程,不同黑臭水体DOM的组分存在明显差异;轻度黑臭水体中DOM的腐殖化水平、芳香化程度、木质素与其他物质在腐殖化开始的比例、分子质量等均高于重度黑臭水体。多元统计与UV-vis技术对黑臭水体中DOM的组成及结构进行了定性,为黑臭水体的溯源和整治工作提供理论基础。     

阴阳极成对耦合紫外光辅助电催化降解毒死蜱

以空气扩散阴极、纯铂阳极和紫外灯构建了阴阳极成对耦合紫外光辅助电催化的体系,并系统地研究了电流密度、阳极SO42-浓度以及毒死蜱初始浓度对毒死蜱降解效果的影响.结果表明,当阴极/阳极的电流密度为45/450 mA·cm^-2,阳极SO42-浓度为1.0 mol·L^-1,毒死蜱初始浓度为25 mg·L^-1时,反应60 min后毒死蜱降解率可达99%.对阴极产物的红外分析结果表明,毒死蜱降解后结构中的吡啶环和PS被破坏,产生亚硝氮和正磷酸盐,毒性得到减弱.通过对比阴阳极成对耦合紫外光复合体系与阴极耦合紫外光复合体系、阳极耦合紫外光复合体系的电流效率,发现阴阳极成对耦合紫外光复合体系的电流效率是阴极耦合紫外光复合体系的2倍,是阳极耦合紫外光复合体系的4倍.     

天水市紫外吸收性气溶胶时空动态的遥感监测

采用OMI传感器的气溶胶产品,分析了2006—2015年中国西部城市天水市对流层紫外吸收性气溶胶的时空分布特征。结果表明:空间上,十年间天水市的吸收性气溶胶表现出从中部向周围依次减弱的南北向带状分布规律;季节变化呈现出秋冬季高于春夏季的规律;时间上,吸收性气溶胶指数(AI)从2006年的0.075增至2015年的0.506,年均值为0.28,年均增长率为57.5%;十年间出现2次阶段性增长和2次阶段性减小;AI年际变化与天水市地方总产值相关性为0.902,第一产业对其影响最大,第三产业影响最小。     

城郊关键带土壤中溶解性有机质的光谱特性及其时空变异

溶解性有机质(DOM)作为地球关键带中物质与能量循环的重要活性组分,其与关键带中诸多重要环境过程有着密切关系.本研究以宁波樟溪流域作为城郊关键带的典型代表区域,采集土壤样品,结合紫外可见光谱(UV-Vis)、三维荧光光谱(3D-EEM)进行特征表征,分析不同类型土壤中DOM的分布特征、影响因素和季节性变化规律.主要结果如下:林地DOC平均含量均大于耕地,其中林地秋季(15.4 mg·L~(-1))林地春季(12.5 mg·L~(-1));耕地秋季(11.9 mg·L~(-1))耕地春季(11.4 mg·L~(-1));DOM结构在紫外可见光谱下表现为耕地DOM芳香化程度(SUVA_(254))、疏水性组分(SUVA_(260))和分子量(S_R)较林地大,其中耕地秋季最为突出;三维荧光光谱结合平行因子分析(PARAFAC)把土壤DOM分为5种组分,主要以富里酸类物质为主(C_1、C_3、C_5),也含有色氨酸、酪氨酸类蛋白质(C_4)和腐殖酸(C_2)等物质,其中耕地春季的腐殖化程度最大,耕地秋季比春季含有较多类蛋白质,林地较耕地含有更多的类蛋白质,林地春秋两季中DOM结构变化不大.     

珊瑚碎屑颗粒内孔隙特性微观试验研究∗

珊瑚碎屑是一种特殊的岩土材料,其显著特征是存在大量的内孔隙。为了深入揭示珊瑚碎屑内孔隙特性,通过电镜扫描(SEM)和压汞试验(MIP),分别定性和定量化地分析了珊瑚碎屑颗粒表面及内部孔隙形态特征和分布规律。结果表明:珊瑚碎屑存在由珊瑚虫生长和微生物共生形成的两类大小、形态及分布不同的内孔隙;珊瑚碎屑的整体孔隙度为9%～25%,由珊瑚虫生长而形成的孔隙等效直径为10～200μm;由微生物形成的孔隙面孔隙度低,孔隙直径多为4μm以下,且等轴或不等轴孔隙占绝大部分。     

K_2Cr_2O_7法和紫外分光光度法测定污水COD的对比研究

分别利用重铬酸钾法、重铬酸钾紫外分光光度法和紫外分光光度法测定污水的COD极差分别为2.43mg/L、1.19 mg/L和4.72 mg/L,RE%分别为0.84%、0.53%和1.36%,重铬酸钾紫外分光光度法和紫外分光光度法的线性范围分别在0~280 mg/L和0~400 mg/L.结果表明:重铬酸钾紫外分光光度法测定的准确度和精密度最高,简化了用标准溶液进行标定的步骤,缩短了实验时间;紫外分光光度法测定的结果准确度和精密度相对差一些,但是快速、操作简单、节省试剂,为广大环境工作者提供借鉴参考的实例。     

Photocatalytic activity of Fe-doped CaTiO3 under UV-visible light

The photocatalytic degradation of methylene blue（MB） over Fe-doped CaTiO3 under UV-visible light was investigated. The as-prepared samples were characterized using X-ray diffraction（XRD）, scanning electron microscope（SEM） equipped with an energy dispersive spectrometer（EDS） system, Fourier transform infrared spectra（FT-IR）, and UV-visible diffuse reflectance spectroscopy（DRS）. The results show that the doping with Fe significantly promoted the light absorption ability of CaTiO3 in the visible light region. The Fe-doped CaTiO3 exhibited higher photocatalytic activity than CaTiO3 for the degradation of MB.However, the photocatalytic activity of the Fe-doped CaTiO3 was greatly influenced by the calcination temperature during the preparation process. The Fe-doped CaTiO3 prepared at500°C exhibited the best photocatalytic activity, with degradation of almost 100% MB（10 ppm）under UV-visible light for 180 min.     

Dyes adsorption using a synthetic carboxymethyl cellulose-acrylic acid adsorbent

Removal of noxious dyes is gaining public and technological attention. Herein grafting polymerization was employed to produce a novel adsorbent using acrylic acid and carboxymethyl cellulose for dye removal. Scanning electron microscopy and Fourier-transform infrared spectroscopy verified the adsorbent formed under optimized reaction conditions. The removal ratio of adsorbent to Methyl Orange, Disperse Blue 2BLN and malachite green chloride reached to 84.2%, 79.6% and 99.9%, respectively. The greater agreement between the calculated and experimental results suggested that pseudo second-order kinetic model better represents the kinetic adsorption data. Equilibrium adsorptions of dyes were better explained by the Temkin isotherm. The results implied that this new cellulose-based absorbent had the universaiity for removal of dyes through the chemical adsorption mechanism.     

Comparison of quartz sand, anthracite, shale and biological ceramsite for adsorptive removal of phosphorus from aqueous solution

The choice of substrates with high phosphorus adsorption capacity is vital for sustainable phosphorus removal from waste water in constructed wetlands. In this study, four substrates were used： quartz sand, anthracite, shale and biological ceramsite. These substrate samples were characterized by X- ray diffractometry and scanning electron microscopy studies for their mineral components （chemical components） and surface characteristics. The dynamic experimental results revealed the following ranking order for total phosphorus （TP） removal efficiency： anthracite 〉 biological ceramsite 〉 shale 〉 quartz sand. The adsorptive removal capacities for TP using anthracite, biological ceramsite, shale and quartz sand were 85.87, 81.44, 59.65, and 55.98 mg/kg, respectively. Phosphorus desorption was also studied to analyze the substrates＇ adsorption efficiency in wastewater treatment as well as the substrates＇ ability to be reused for treatment. It was noted that the removal performance for the different forms of phosphorus was dependent on the nature of the substrate and the adsorption mechanism. A comparative analysis showed that the removal of particulate phosphorus was much easier using shale. Whereas anthracite had the highest soluble reactive phosphorus （SRP） adsorptive capacity, biological ceramsite had the highest dissolved organic phosphorus （DOP） removal capacity. Phosphorus removal by shale and biological ceramsite was mainly through chemical adsorption, precipitation or biological adsorption. On the other hand, phosphorus removal through physical adsorption （electrostatic attraction or ion exchange） was dominant in anthracite and quartz sand.     

Ultrasonic preparation of nano-nickel/activated carbon composite using spent electroless nickel plating bath and application in degradation of 2,6-dichlorophenol

Ni was effectively recovered from spent electroless nickel （EN） plating baths by forming a nano-nickel coated activated carbon composite. With the aid of ultrasonication, melamine- formaldehyde-tetraoxalyl-ethylenediamine chelating resins were grafted on activated carbon （MFT/AG）. PdC12 sol was adsorbed on MFT/AC, which was then immersed in spent electroless nickel plating bath; then nano-nickel could be reduced by ascorbic acid to form a nano-nickel coating on the activated carbon composite （Ni/AC） in situ. The materials present were carefully examined by Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, X-ray photoelectron spectroscopy and electro- chemistry techniques. The resins were well distributed on the inside and outside surfaces of activated carbon with a size of 120 ± 30 nm in MFT/AC, and a great deal of nano-nickel particles were evenly deposited with a size of 3.8 ± 1.1 nm in Ni/MFT. Moreover, Ni/AC was successfully used as a catalyst for ultrasonic degradation of 2.6-dichloronhenol.