紫外差分吸收光谱法定量分析SF6分解物SO2和H2S技术

分解物SO_2和H_2S表征SF_6电气设备内部缺陷,是SF_6电气设备试验必检项,对两种气体的准确定量分析直接关系到SF_6电气设备内部缺陷种类和定位的正确判断。现有的现场检测技术不足以解决气体组分之间的干扰问题,因此,本文开展了相关选型和设计工作,获得基于紫外差分吸收光谱法的SO_2和H_2S混合气体检测装置。采用差分法提取SO_2和H_2S紫外吸收光谱的快变部分,通过吸光度的扣减和浓度反演,去除在紫外吸收光谱区域H_2S和SO_2的交叉干扰问题。对其测试的原始谱图进行数字滤波处理,去噪后获得平滑波形,进一步进行FFT变换和线性拟合,拟合优度达到0.999 9,提高了SF_6背景气体中SO_2和H_2S混合气体检测的灵敏度。所研制装置在系统信噪比为1时,混合气体中SO_2在190～230 nm和280～320 nm波段的检测极限分别为0.108μL/L和0.444μL/L,H_2S在190～230 nm波段检测极限为0.490μL/L,为现场检测应用奠定了基础。     

砷作业的安全防护

红外光纤是一种新型光导材料 ,制作过程属于尖端科技领域。普通玻璃纤维的制作过程可分为两个阶段 :第一阶段为玻璃熔化阶段 ,玻璃（固态）在特定的容器内 ,以一定的温度熔化（变为液态）;第二阶段随着不断地被拉伸 ,熔融的玻璃慢慢冷却 ,变成固态 ,形成了极细的玻璃纤维。红外纤维同普通的玻璃纤维制作过程一致 ,不同的是 ,红外光导纤维的制作过程中砷发生源产生的砷化物 ,因红外光导纤维的原料不是普通玻璃 ,而是硫系红外玻璃如Ａｓ２Ｓ３、Ａｓ２Ｓｅ３ 等。在红外玻璃的熔化和拉丝过程中 ,Ａｓ２Ｓ３、Ａｓ２Ｓｅ３ 除了以蒸气和粉尘等…     

石墨炉原子吸收光谱法测定水环境中的铍含量分析

本文阐述了使用石墨炉原子吸收光谱法测定江水中铍含量的方法与步骤。选用原子吸收分光光度计和铍元素空心阴极灯进行样品测定,试验结果显示,该方法的检出限为0.00223μg/L,回收率为95%~98%之间,线性范围分别为0~2μg/L,是一种简单、快速、准确测定水质中铍含量的较好的检测方法。     

鄱阳湖湿地土壤中胡敏酸对NH_4~+-N的吸附性能研究

采用国际腐殖协会提出的Na OH提取法,从鄱阳湖湿地土壤5个剖面层提取出胡敏酸,应用红外光谱分析仪对胡敏酸进行表征,并研究其对氨氮的吸附特性。结果表明:Freundlich方程能够更好地描述胡敏酸对NH4+-N的吸附,意味着胡敏酸对NH4+-N的吸附主要表现为线性分配过程;通过吸附前后的红外光谱分析,该胡敏酸主要含有芳香环、脂肪类、羧酸类或是酚类等基团,且在NH4+-N的吸附反应过程中其主要作用可能是羧酸类物质或脂肪族类物质,且主要是通过氢键、质子转移或范德华力等弱作用吸附在胡敏酸上;在氨氮的吸附动力学实验中,得出20~30 cm剖面层的胡敏酸对NH4+-N的吸附速率相对其他4个样要快,这可能是由于该剖面层胡敏酸所含基团活性较强的原因;p H对胡敏酸吸附NH4+-N的影响为,在酸性条件下,随着p H的降低,吸附量越小,而在碱性条件下,吸附量随着p H的升高呈减小;胡敏酸浓度的增加会使氨氮的去除率上升。     

Synthesis of novel CeO2-BiVO4/FAC composites with enhanced visible-light photocatalytic properties

To utilize visible light more effectively in photocatalytic reactions, a fly ash cenosphere （FAC）-supported CeO2-BiV04 （CeO2-BiVO4/FAC） composite photocatalyst was prepared by modified metalorganic decomposition and impregnation methods. The physical and photophysical properties of the composite have been characterized by X-ray diffraction （XRD）, scanning electron microscope （SEM） and energy dispersive X-ray spectroscopy （EDX）, X-ray photoelectron spectroscopy （XPS）, and UV-Visible diffuse reflectance spectra. The XRD patterns exhibited characteristic diffraction peaks of both BiVO4 and Ce02 crystalline phases. The XPS results showed that Ce was present as both Ce4＋ and Ce3＋ oxidation states in Ce02 and dispersed on the surface of BiV04 to constitute a p-n heterojunction composite. The absorption threshold of the CeO2-BiVO4/FAC composite shifted to a longer wavelength in the UV-Vis absorption spectrum compared to the pure Ce02 and pure BiV04. The composites exhibited enhanced photocatalytic activity for Methylene Blue （MB） degradation under visible light irradiation. It was found that the 7.5 wt.% CeO2-BiVO4/FAC composite showed the highest photocatalytic activity for MB dye wastewater treatment.     

细菌JF901704菌株对铊的吸附特性研究

从某含铊废水中筛选出一株耐铊细菌(菌株序列登陆号:JF901704)菌株,研究了溶液初始浓度、吸附时间、pH值、温度、摇床转速及菌体生物量对铊的吸附效果影响,结果表明,JF901704菌株在铊初始质量浓度20 mg/L,吸附时间60 min,pH值7.0,温度30℃,摇床转速150 r/min,生物量1.0 g/L时,吸附效果最佳,在该条件下,JF901704菌株对铊的吸附率可达89.05%;红外光谱分析结果表明,该菌株细胞壁中的羧基、亚氨基及羟基对铊吸附起主要贡献的官能团。     

石墨炉原子吸收光谱法测定土壤中痕量铋

建立了微波消解土壤、石墨炉原子吸收法测定土壤中痕量铋的方法。采用磷酸二氢铵作为基体改进剂,热解涂层石墨管,塞曼扣背景。此方法对测定土壤中铋的灵敏度、准确度都有很大的提高。方法的最低检出浓度为0.02μg/g,加标回收率为94.5%~103.8%,能够满足环境监测分析的要求。     

红外光谱对土壤类PM2.5颗粒的研究

利用红外光谱和扫描电镜对93#和97#汽油燃烧产物、不同地段的土壤颗粒做了详细的表征。结果表明,97#汽油的燃烧产物含有的有害物质要明显少于93#汽油的燃烧产物;客运站表层土壤颗粒粒径明显小于新鲜土壤;汽油燃烧产物和新鲜土壤混合产物的成分与客运站表层土壤成分接近,说明土壤与汽油的燃烧产物发生了某种相互作用。在离客运站2 km以外测定的浮土成分与客运站表层的土壤成分相同,说明土壤类PM2.5颗粒可以随空气流动。     

Removal of arsenate with hydrous ferric oxide coprecipitation：Effect of humic acid

Insights from the adverse effect of humic acid(HA) on arsenate removal with hydrous ferric oxide(HFO) coprecipitation can further our understanding of the fate of As(V) in water treatment process. The motivation of our study is to explore the competitive adsorption mechanisms of humic acid and As(V) on HFO on the molecular scale. Multiple complementary techniques were used including macroscopic adsorption experiments, surface enhanced Raman scattering(SERS), extended X-ray absorption fine structure(EXAFS) spectroscopy, flow-cell attenuated total reflectance Fourier transform infrared(ATR-FTIR) measurement, and charge distribution multisite complexation(CDMUSIC) modeling. The As(V) removal efficiency was reduced from over 95% to about 10% with the increasing HA concentration to 25 times of As(V) mass concentration. The SERS analysis excluded the HA-As(V) complex formation. The EXAFS results indicate that As(V) formed bidentate binuclear surface complexes in the presence of HA as evidenced by an As-Fe distance of 3.26–3.31 ?. The in situ ATR-FTIR measurements show that As(V) replaces surface hydroxyl groups and forms innersphere complex. High concentrations of HA may physically block the surface sites and inhibit the As(V) access. The adsorption of As(V) and HA decreased the point of zero charge of HFO from 7.8 to 5.8 and 6.3, respectively. The CD-MUSIC model described the zeta potential curves and adsorption edges of As(V) and HA reasonably well.     

Graphene-supported nanoscale zero-valent iron：Removal of phosphorus from aqueous solution and mechanistic study

Excess phosphorus from non-point pollution sources is one of the key factors causing eutrophication in many lakes in China,so finding a cost-effective method to remove phosphorus from non-point pollution sources is very important for the health of the aqueous environment. Graphene was selected to support nanoscale zero-valent iron(nZVI)for phosphorus removal from synthetic rainwater runoff in this article. Compared with nZVI supported on other porous materials,graphene-supported nZVI(G-nZVI) could remove phosphorus more efficiently. The amount of nZVI in G-nZVI was an important factor in the removal of phosphorus by G-nZVI,and G-nZVI with 20 wt.% nZVI(20% G-nZVI)could remove phosphorus most efficiently. The nZVI was very stable and could disperse very well on graphene,as characterized by transmission electron microscopy(TEM) and scanning electron microscopy(SEM). X-ray photoelectron spectroscopy(XPS),Fourier Transform infrared spectroscopy(FT-IR) and Raman spectroscopy were used to elucidate the reaction process,and the results indicated that Fe-O-P was formed after phosphorus was adsorbed by G-nZVI. The results obtained from X-ray diffraction(XRD) indicated that the reaction product between nZVI supported on graphene and phosphorus was Fe3(PO4)2·8H2O(Vivianite). It was confirmed that the specific reaction mechanism for the removal of phosphorus with nZVI or G-nZVI was mainly due to chemical reaction between nZVI and phosphorus.