Investigation of metal ions binding of humic substances using fluorescence emission and synchronous‐scan spectroscopy

Abstract

The binding site interactions of IHSS humic substances, Suwannee River Humic Acid, Suwannee River Fulvic Acid, Nordic Fulvic Acid, and Aldrich Humic Acid with various metals ions and a herbicide, methyl viologen were investigated using fluorescence emission and synchronous‐scan spectroscopy. The metal ions used were, Fe(III), Cr(III), Cr(VI), Pb(II), Cu(II) and Ni(II). Stern‐Volmer constants, K_SV for these quenchers were determined at pH 4 and 8 using an ionic strength of 0.1M. For all four humic substances, and at both pH studied, Fe(III) was found to be the most efficient quencher. Quenching efficiency was found to be 3–10 times higher at pH 8. The bimolecular quenching rate constants were found to exceed the maximum considered for diffusion controlled interactions, and indicate that the fluorophore and quencher are in close physical association. Synchronous‐scan spectra were found to change with pH and provided useful information on binding site interactions between humic substances and these quenchers.     

纳米零价铁/玉米淀粉的制备及其对Pb2+的吸附

以玉米淀粉为载体,采用液相还原法制备纳米零价铁/玉米淀粉,并用于溶液中Pb2+的去除。采用SEM技术对吸附材料进行了表征。考察了溶液pH、纳米零价铁/玉米淀粉加入量、初始Pb2+质量浓度、反应时间等因素对Pb2+吸附效果的影响。表征结果显示,纳米零价铁/玉米淀粉球体间主要呈链状连接,不仅保持了纳米零价铁的特性,且颗粒的团聚现象明显减少。实验结果表明,在溶液pH 7.0、纳米零价铁/玉米淀粉加入量0.8 g/L、初始Pb2+质量浓度50 mg/L、反应时间60 min的条件下,纳米零价铁/玉米淀粉对Pb2+具有较好的吸附效果,Pb2+去除率为93.17%、吸附量为47.27 mg/g。     

一种新型复合除砷材料的制备及其性能

将锆的水合氧化物固载于大孔螯合树脂D401上制备出一种新型除砷材料,并研究了不同实验条件下复合吸附剂D401-Zr对水溶液中As(V)的吸附性能。研究结果表明,在pH<5.2时D401-Zr对As(V)都具有较强的吸附性能;其吸附等温线与Langmuir吸附模型具有较高的吻合度;吸附动力学研究表明,D401-Zr对砷的吸附均遵循二级动力学方程;竞争吸附实验表明,与SO24-、Cl-共存时,D401-Zr对砷的去除率大于90%,而与PO34-、F-竞争离子共存时,其去除率明显下降。     

APEC会议期间天津市PM_(2.5)中水溶性无机离子的污染特征

2014年11月6—11日,亚太经济合作组织(APEC)会议在北京市召开,京津冀区域采取了最高级别的空气质量保障措施。于2014年11月3—20日同步手动采集天津市PM2.5样品,对APEC会议期间(2014年11月3—11日,在此期间实施了空气质量保障措施)及会议后(2014年11月12—20日)天津市PM2.5中水溶性无机离子组分浓度、二次转化特征等进行了分析。结果表明,APEC会议期间,天津市PM2.5平均质量浓度为78μg/m3,而会议后达到87μg/m3;会议期间PM2.5中水溶性无机离子的浓度为NO-3SO2-4NH+4Cl-K+Na+Ca2+Mg2+,会议后,除Mg2+外,各项离子浓度均有不同程度的上升;会议期间,PM2.5中NO-3浓度最高,在水溶性无机离子中所占比例为38.9%,其次为SO2-4(为22.0%)、NH+4(为20.8%),3者所占比例合计为81.7%,会议后3者所占比例降至75.0%;会议期间的大气污染以流动源为主;会议后,硫氧化率和氮氧化率均不同程度减弱,说明会议期间的二次离子转化更为明显;会议期间的停工停产措施对PM2.5中一次离子来源有明显改变,城市扬尘得到明显抑制。     

土壤中Pb、Cd的稳定化修复技术研究进展

在众多重金属修复技术当中,稳定化技术具有花费少、环境损失小等诸多优势。综述了国内外土壤中Pb、Cd稳定化修复的研究进展;分析了稳定剂的作用机制、土壤中Pb、Cd的赋存形态;探讨了土壤中Pb、Cd稳定化修复的主要影响因素。最后,还提出了稳定化修复技术在土壤中Pb、Cd污染治理应用中尚存在的问题。     

武汉市秋、冬季大气PM_(2.5)中水溶性离子污染特征及来源分析

采用离子色谱法测定武汉市秋、冬季大气PM2.5中水溶性离子浓度,对其化学组成、质量浓度变化特征及源解析等方面进行了研究。结果表明,NO-3、SO2-4、NH+4为武汉市秋、冬季大气PM2.5中主要的水溶性离子,相关性分析表明,燃烧源是秋、冬季大气PM2.5中水溶性离子的共同来源。成分分析表明,工业区的水溶性离子主要来源于燃烧源,交通区的水溶性离子主要来源于二次污染源,其中包括垃圾焚烧源,植物园的水溶性离子主要来源于二次污染源。     

铈离子光催化降解茜素绿的性能和机理简

主要研究了简单铈离子（Ce³⁺）在紫外光（UV）的作用下对蒽醌染料茜素绿（AG）的光催化降解效果和反应机理。结果表明,UV/Ce³⁺体系能够有效降解AG,初始反应速率随AG浓度的倒数值和Ce³⁺浓度的增加而线性增加,随初始溶液pH的增加先降低后增加,在酸性条件下有很高的TOC去除率。荧光探针实验表明,反应过程中可以产生·OH自由基。UV/Ce³⁺体系对其他类型染料和对硝基苯酚都有较好的降解效果。     

改性松针对水体中铅(II)的吸附

探讨了改性松针(GXLsp)作为吸附剂对水体中铅离子的吸附性能,考察了吸附时间、溶液pH值、吸附剂用量、盐离子浓度、Pb(II)初始浓度及温度对改性松针吸附Pb(II)的影响。利用Langmuir和Freundlich等温线模型对实验数据进行非线性拟合分析,结果表明,Freundlich等温线模型能很好地描述松针对Pb(II)的吸附过程。热力学参数表明吸附是一个自发的吸热过程。改性松针对铅的吸附行为符合拟二级动力学方程,表明吸附过程是以化学吸附为主。在293K时松针对Pb(II)的饱和吸附量为318.3 mg/g,因此,GXLsp可作为一种高效低值生物质吸附剂以去除水体中重金属Pb(II)的污染。     

Pulsed discharge plasma induced Fenton-like reactions for the enhancement of the degradation of 4-chlorophenol in water

To sufficiently utilize chemically active species and enhance the degradation rate and removal efficiency of toxic and biorefractory organic pollutant para-chlorophenol (para-CP), the introductions of iron metal ions (Fe²⁺/Fe³⁺) into either pulsed discharge plasma (PDP) process or the PDP process with TiO₂ photo-catalyst were tentatively performed. The experimental results showed that under the same experimental condition, the degradation rate and removal efficiency of para-CP were greatly enhanced by the introduction of iron ions (Fe²⁺/Fe³⁺) into the PDP process. Moreover, when iron ions and TiO₂ were added together in the PDP process, the degradation rate and removal energy of para-CP further improved. The possible mechanism was discussed that the obvious promoting effects were attributed to ferrous ions via plasma induced Fenton-like reactions by UV light irradiation excited and hydrogen peroxide formed in pulsed electrical discharge, resulting in a larger amount of hydroxyl radicals produced from the residual hydrogen peroxide. In addition, the regeneration of ferric ions to ferrous ions facilitates the progress of plasma induced Fenton-like reactions by photo-catalytic reduction of UV light, photo-catalytic reduction on TiO₂ surface and electron transfer of quinone intermediates, i.e. 1,4-hydroquinone and 1,4-benzoquinone.     

流动注射在线离子交换微柱富集-火焰原子吸收法测定环境样品中的铜、铅和镉

本文用流动注射在线阳离子交换树脂预富集-火焰原子吸收法测定了标准参考物(头发GBW09 101和桃叶GBW08501)及水样中的微量铜、铅和镉.对铜、铅和镉测定灵敏度分别提高27.0 ,37.5和27.5倍;回收率分别为93.7-109.9%,88.9-101.4%,84.7-103.0% ;分析速度为30次·h-1.对0.05μg·ml-1Cu2+,0.2μg·ml-1 Pb2+,0.02μg·ml-1Cd2+溶液,其测定相对标准偏差(n ＝11)分别为2.74%,1.05%和2.97%.