铅污染土壤电动修复增强技术的研究

利用电动修复技术对铅污染土壤的修复进行了实验室研究,研究了修复时间和络合剂EDTA对电动修复效果的影响,分析了土壤重金属的迁移和变化特征。结果表明,在电场力作用下随着修复时间的增长污染物的去除率相应提高,去除率由修复时间5 d时的13%增加到15 d时的20%。以EDTA作为阴极控制液,EDTA可与硝酸铅反应形成溶解态的络合物,提高铅离子的移动性,从而提高修复效果。随着EDTA浓度由0.1 mol/L到0.2 mol/L,Pb的去除率由44.4%提高到61.5%,说明添加络合剂可以提高修复效果。另外,电动修复效果与铅的形态分布有密切关系,交换态和碳酸盐结合态有利于重金属铅的去除。     

EDTA滴定法测定水质总硬度的改进实验

根据EDTA滴定法测定水质总硬度的实践经验,对EDTA滴定法进行改进,该改进方法和标准方法通过地表水、地下水以及总硬度标准样品的比对测定,实验证明改进方法测定结果准确、可靠,操作更加简便、快捷。     

重金属絮凝剂DTMPAM去除水中Cu2+和EDTA-Cu的性能

以聚丙烯酰胺、甲醛、二硫化碳、氢氧化钠为原料,制备出新型重金属絮凝剂二硫代羧基化羟甲基聚丙烯酰胺(DTMPAM).分别以含Cu~(2+)单一水样及含Cu~(2+)、EDTA的混合水样为考察对象,研究DTMPAM在单一和混合体系中对Cu~(2+)的去除性能.结果表明,单一体系中DTMPAM对Cu~(2+)有着良好的去除效果,当水样pH值为2.0～6.0时,Cu~(2+)的最高去除率在93.85%～97.49%之间.EDTA对DTMPAM除Cu~(2+)呈抑制作用,随着体系pH值的降低,这种抑制作用减弱;高pH值体系中,随着EDTA浓度的增大,抑制作用增强;在混合体系中,EDTA与DTMPAM存在配位竞争作用,高pH值体系中EDTA的配位竞争作用占主要优势.在单一体系和混合体系中螯合絮体DTMPAM-Cu的分形维数与Cu~(2+)的去除率均有显著的正相关性,即絮体分形维数越大,相对应的Cu~(2+)去除率越高.     

EDTA对剩余污泥磷释放及MAP法磷回收影响

探究乙二胺四乙酸（EDTA）的添加对剩余污泥厌氧过程中磷释放及后续鸟粪石（MAP）法磷回收的影响.根据EDTA添加量对污泥上清液中总磷（TP）、蛋白质、多糖、DNA和SCOD的影响确定了最优释磷条件,采用响应曲面法（RSM）构建MAP磷回收的二次多项式模型并验证了模型的有效性.结果表明：EDTA添加量为5mmol/L,厌氧5d时预处理效果最佳.污泥SCOD破解度（DD）和TP、DNA、蛋白质及多糖均有显著相关,其中TP相关性最强,皮尔逊相关系数为0.866.MAP磷回收的最佳工艺参数是：pH=9.5,n（Mg）：n（P）=1.6,搅拌时间22min,此时磷回收率可达95.68%,形成晶体的主要成分为磷酸铵镁（MgNH₄PO₄·6H₂O）,纯度为79.19%.     

Determination of paraquat in water samples using a sensitive fluorescent probe titration method

Paraquat (PQ), a nonselective herbicide, is non-fluorescent in aqueous solutions. Thus, its determination through direct fluorescent methods is not feasible. The supramolecular inclusion interaction of PQ with cucurbit[7]uril was studied by a fluorescent probe titration method. Significant quenching of the fluorescence intensity of the cucurbit[7]uril-coptisine fluorescent probe was observed with the addition of PQ. A new fluorescent probe titration method with high selectivity and sensitivity at the ng/mL level was developed to determine PQ in aqueous solutions with good precision and accuracy based on the significant quenching of the supramolecular complex fluorescence intensity. The proposed method was successfully used in the determination of PQ in lake water, tap water, well water, and ditch water in an agricultural area, with recoveries of 96.73% to 105.77%. The fluorescence quenching values (ΔF) showed a good linear relationship with PQ concentrations from 1.0×10^-8 to 1.2× 10^-5 mol/L with a detection limit of 3.35×10^-9 mol/L. In addition, the interaction models of the supramolecular complexes formed between the host and the guest were established using theoretical calculations. The interaction mechanism between the cucurbit[7]uril and PQ was confirmed by ¹H NMR spectroscopy.     

电镀废水中硫氰酸根离子含量的自动电位滴定

研究了用自动电位滴定测定硫氰酸根离子的条件和方法。实验结果表明,选用银电极为指示电极,217型双液接电极为参比电极,在硝酸介质中滴定硫氰酸根离子,方法具有高选择性; 应用于电镀废水分析,方法简便快捷,在4min内能打印出分析结果。     

Mobility of radionuclides in soil/groundwater system: Comparing the influence of EDTA and four of its degradation products

The adsorption behavior of ²⁴¹Am, ⁶⁰Co, ¹³⁷Cs and ⁸⁵Sr in the presence and absence of chelating ligands (ethylenediaminetetraacetic acid, ethylenediaminediacetic acid, hydroxyethyliminodiacetic acid, iminodiaceiticacid and methyliminodiacetic acid) was investigated. Sorption affinity in the absence of chelating ligands followed: Am(III) > Co(II) > Cs(I) > Sr(II). The presence of chelating ligands generally had little effect on sorption of ⁸⁵Sr and ¹³⁷Cs with K_d values 110 and 690 mL g⁻¹, respectively. But at 0.02 M of ethylenediaminetetraacetic or hydroxyethyliminodiacetic, the K_d decreased to 5 or 63 mL g⁻¹, respectively, where thermochemical modeling indicated almost all ⁸⁵Sr is complexed with these ligands. The K_d values for ²⁴¹Am and ⁶⁰Co generally decreased with increasing chelating agent concentrations. In notable cases, the K_d values for Am increased at specific concentrations of 10⁻³ M for IDA, MIDA and 10⁻⁴ M for EDDA. This is proposed to be due to formation of a ternary surface complex.     

High capacity adsorption of antimony in biomass-based composite and its consequential utilization as battery anode

Antimony is more than an emerging pollutant in water but a scare resource. In this study, we report an adsorbent with the record capacity so far from the balanced view of Sb(III) and Sb(V). The composite adsorbent was fabricated by encapsulating hollow Fe₃O₄ nanosphere with the EDTA grafted chitosan, and it has superhigh adsorption capacity of for 657.1 mg/g for Sb(III) and 467.3 mg/g for Sb(V), respectively. The mechanism study reveals that the adsorption of Sb initializes from the Fe₃O₄, propagates along the chitosan with hydrogen bond, and terminates at the inner sphere complex with the EDTA moiety in the adsorbent. In view of the ultra-high adsorption capacity of the adsorbent, the recovered adsorbent that contains abundant (>36.4%) highly dispersed antimony nanoparticles (600-FCSE-Sb) is applied to Li-ion battery anode after reduction. This article provides a new idea for connecting water treatment and electric energy storage.     

EDTA对Pd/Fe体系还原脱氯2,4-D的影响

针对Pd/Fe体系对含氯有机物催化还原脱氯过程中,零价铁易腐蚀并在颗粒表面形成钝化层,阻碍目标污染物的进一步脱氯去除,本研究利用乙二胺四乙酸(EDTA)与Fe2+和Fe3+的络合作用,消除Pd/Fe颗粒表面的钝化层,使还原脱氯过程得到持续进行.实验考察了EDTA的投加方式和投加量、p H、钯负载率、温度等因素对2,4-二氯苯氧乙酸(2,4-D)还原脱氯的影响.结果表明:1EDTA浓度为25.0 mmol·L-1、投加速率为20 m L·h-1时,苯氧乙酸(PA)生成率在20 min达到了90.7%.而未加EDTA的反应体系,反应210 min后,PA的生成率仅为74.5%;2EDTA可以络合Pd/Fe体系在催化脱氯过程中生成的Fe2+和Fe3+,防止或减缓了Pd/Fe颗粒表面钝化层的形成,提高了反应活性;3适宜的2,4-D催化脱氯条件为:浓度25.0mmol·L-1的EDTA溶液,投加速率20 m L·h-1、初始p H为4.2、钯负载率0.050%、温度30.0℃、搅拌速率200 r·min-1,反应210 min,20.0 mg·L-1的2,4-D几乎可完全转化为PA;42,4-D催化脱氯的中间产物主要是2-氯苯氧乙酸及微量的4-氯苯氧乙酸,最终产物为苯氧乙酸.     

三维电极反应器用负载型活性炭粒子电极的研究

为提高粒子电极的电催化活性与稳定性,以活性炭为载体,采用浸渍法制备了以Fe、Mn、Zn、Ni、Sn-Sb和Sn-Sb-Ce氧化物为催化活性组分的负载型粒子电极.以EDTA废水为目标污染物,考察改性粒子电极的电催化活性与稳定性,并借助SEM、XRD对其表面形貌和物相进行了表征,从结构上分析了不同负载型粒子电极的性能差异.结果表明,所制备的粒子电极中,Sn-Sb-Ce/GAC(活性炭颗粒)粒子电极表现出了较高的电催化活性和稳定性;消除吸附效应的干扰后,在pH值为4.8、电流为200 mA的条件下,120 rin后总有机碳(TOC)去除率为71.1％,EDTA转化率为88.7％.