水杨酸修饰聚苯乙烯对Pb2+和Cu2+的吸附

水杨酸;聚苯乙烯;吸附;Pb2+;Cu2+     

PAMAM Dendrimers在水/1,2-二氯乙烷界面上的简单离子转移

PAMAM dendrimer是一类三维高度有序的高分子化合物.其具有良好的生物相容性,易于设计,结构上与蛋白质相似,因此在催化、纳米工程、药物设计与运输等方面有广泛的应用~([1]).本研究探讨了Dendrimer在液/液界面电化学上的一些性质.     

DNA/银纳米簇荧光探针在检测Pb2+中的应用

基于DNA/银纳米簇的荧光特性报道了一种简单、灵敏、高选择性的荧光方法检测Pb²⁺.以茎部为富G结构,环状部分为聚C结构的发夹型DNA为模板合成具有稳定荧光的银纳米簇.当加入Pb²⁺后,发夹型DNA在Pb²⁺诱导下形成G-四链体结构,破坏了发夹型DNA的构型,极大地影响了合成银纳米簇的模板结构,导致银纳米簇的荧光强度降低.Pb²⁺存在和不存在时所产生荧光强度的差异与发夹型DNA的碱基序列和茎部配对碱基数有关.依据这一现象,在优化DNA碱基序列和茎部配对碱基数的基础上,可实现100 μmol/L至100 nmol/L范围内对Pb²⁺的定量检测,检出限为10 nmol/L.该方法对Pb²⁺的检测具有较好的选择性,并可应用于实际水样中Pb²⁺的检测.检测结果与原子吸收光谱进行比对,显示出较好的一致性.     

壳聚糖-叶酸复合凝胶的制备及Pb2+吸附性能研究

叶酸(FA)通过离子交联壳聚糖构筑了壳聚糖-叶酸水凝胶(CS-FA-HG),利用红外光谱、紫外-可见光谱、电子扫描显微镜等对其结构进行表征,并考察了CS-FA-HG对Pb²⁺的吸附性能。实验结果表明,FA、壳聚糖醋酸盐(CS-Ac)浓度均为35 mg/mL,Na₂CO₃溶液的质量分数为5.0%时,FA钠盐通过静电作用离子交联CS-Ac,形成CS-FA-HG,微观呈枝状纤维结构;在pH 5.0,吸附温度30℃的条件下,80 mg干CS-FA-HG在50 mL初始浓度15 mg/L的Pb²⁺溶液中,对Pb²⁺的吸附量为8.14 mg/g;吸附符合二级动力学方程和Langmuir吸附等温式。CS-FA-HG制备方法简单,绿色环保,无二次污染,在重金属离子吸附方面有潜在应用。     

巯基乙酸-纳米银比色传感快速检测水样中的Pb2+

利用巯基乙酸含S配位原子,能与纳米银形成Ag-S配位键吸附在纳米银表面,防止纳米银团聚,Pb²⁺的引入导致纳米银溶胶发生团聚现象,溶液的颜色由亮黄色变灰红色,由此建立了测定痕量Pb²⁺的比色方法。在优化的实验条件下,Pb²⁺的线性范围为0.1~5.0×10^-6mol/L (R²=0.9956),裸眼检出限为0.5μmol/L。此方法用于环境中Pb²⁺的检测,其回收率在90%~110%之间,RSD <2.5%。     

巯基功能化膨润土吸附Pb2+的动力学和热力学研究

研究了自制巯基功能化膨润土(TFB)对Pb2+的吸附行为,考察了溶液的pH值、离子强度、吸附时间和温度对吸附平衡的影响,并对吸附过程进行了动力学与热力学研究.结果表明,常温下,吸附时间为60min、0.1mol/L的KNO3、pH=6.0、5.0g/L TFB对200mg/L的Pb2+的吸附率达到85.4％以上,TFB对Pb2+的吸附动力学符合准二级动力学方程;TFB对Pb2+的吸附热力学符合Langmuir等温线方程和Dubinin-Radushkevich (D-R)等温线方程,表明吸附主要发生在TFB表面的活性区域,属于单分子层吸附,其吸附平均活化能E在8-16kJ/mol范围内,表明该吸附过程为化学吸附,不同温度下的吸附热力学的吉布斯自由能以及熵变和焓变表明该吸附过程为自发放热反应.     

活性炭的改性及对Pb2+的动力学吸附研究

论文以活性炭为主体吸附剂,进行氯化铁改性,制备出氯化铁改性活性炭吸附剂,并通过FT-IR、SEM、比表面积和孔体积进行表征。实验进一步探究改性活性炭对Pb²⁺的吸附能力,结果表明,当吸附时间为300 min,吸附剂投加量为0.4 g, pH为6时,吸附效果最佳。在此吸附条件下,改性活性炭对Pb²⁺的去除率达到91.2%。对改性活性炭吸附Pb²⁺进行动力学吸附研究,结果表明二级速率方程能够更好地描述其动力学吸附过程,吸附的机理可归结为氯化铁改性导致活性炭孔道结构中酸性官能团增加,使得金属阳离子与官能团上的H之间产生离子交换作用,有利于吸附的进行,这一实验结果为后期循环吸附研究提供了新依据。     

活性炭电极的改性及对Co2+,Mn2+和Ni2+的电吸附性能

以商用活性炭(AC)为原料,分别采用磷酸和氢氧化钠改性的方法制备了两种不同的改性活性炭电极材料.采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、 Brunauer-Emmett-Teller(BET)测试、傅里叶变换红外光谱(FTIR)和X射线光电子能谱(XPS)等手段以及电化学分析方法,对改性前后活性炭材料的表面性质和电化学性能进行了探究.结果表明, H3PO4改性使活性炭的孔隙分布更加密集, NaOH改性使活性炭表面的孔隙结构更加清晰均匀; H₃PO₄和NaOH改性均使活性炭的比表面积增加.循环伏安测试结果表明,改性前后活性炭电极在低扫描速率下均具备良好的双电层特性,并且两种改性处理均能提高活性炭电极的比电容;当扫描速率为5 mV/s时,未改性、 H₃PO₄以及NaOH改性活性炭电极的比电容分别为36.51, 77.25和85.19 F/g.电吸附实验结果证明,两种改性活性炭电极对Co²⁺, Mn²⁺和Ni²⁺均有较好的去...     

Square‐Wave Voltammetric Transfer of Silver Ions Across the Water|1,2‐Dichloroethane Interface

Recently reported studies on the transfer of silver ions across the aqueous|1,2‐dichloroethane interface using cyclic voltammetry (CV), facilitated by organic phase electrolyte anions, have been augmented by square‐wave voltammetry (SWV) and square‐wave stripping voltammetry (SWSV) studies and by consideration of the possible transfers of additional metal cations. Using SWV and SWSV, detection limits have been improved, from the 0.02 mM obtained by CV, to 1.4 μM (SWV) and 2 nM (SWSV). Additional studies show that mercury(I and II) ions, platinum(II) ions and gold(III) ions are also transferable across this interface, to differing extents. Of these three ions studied, highest sensitivity is achieved for the gold species.     

Facilitated Proton Transfer by a Novel 2-Aminothiazole Derivative Across the Water/1,2-Dichloroethane Interface

The behavior of proton transfer facilitated by a novel thiazole derivative, N-methyl-4-(4-phenoxyphenyl)thiazol-2-amine (MPPT), across the water/1,2-dichloroethane (1,2-DCE) interface was investigated electrochemically. The ionic partition diagram for MPPT was obtained from interpretation of the cyclic voltammograms. The apparent partition coefficient of MPPT was evaluated by the shaking-flask method under experimental conditions, while that for the protonated form of MPPT was calculated from its transfer potential obtained from the ionic partition diagram. It was suggested that the mechanism for transfer of MPPT across the water/1,2-DCE) interface depends on the pH of the aqueous phase. The parameters of the facilitated proton transfer across the water/1,2-DCE interface were evaluated as a quantitative measure of its lipophilicity.     

Electrochemical Investigation of Heavy Metal Ion Transfer Across the Water/1,2‐Dichloroethane Interface Assisted by 9‐Ethyl‐3‐Carbazolecarboxaldehyde‐Thiosemicarbazone

The transfer of heavy metal ions across the polarized water/1,2‐dichloroethane (1,2‐DCE) interface assisted by 9‐ethyl‐3‐carbazolecarboxaldehyde‐thiosemicarbazone (ECCAT) in the 1,2‐DCE phase has been studied by cyclic voltammetry. Voltammetric waves of Pb(II) and Cd(II) ions were reversible and quasi‐reversible, respectively, whereas that of Hg(II) and Zn(II) ion were irreversible. The voltammogram of Cu(II) ion showed a two‐step wave, however the nature of the transfer could not be satisfactorily evaluated by analyzing the cyclic voltammetric data. When Ni(II) and Co(II) was used no peak was visible under the experimental conditions used in this study. The dependence of the half‐wave potentials of Pb(II) and Cd(II) ions on the ligand concentration reveals that their ion‐transfer is assisted by the formation of 1:3 metal‐ECCAT complex in 1,2‐DCE. The over‐all association constants of [Pb(ECCAT)₃]²⁺ and [Cd(ECCAT)₃]²⁺ complexes in DCE‐phase have been determined to be log β =14.03 and log β =15.44, respectively.     

Electrochemical Study of s‐Triazine Herbicides Transfer Across the Water/1,2‐Dichloroethane Interface

The transfer of three s‐triazine herbicides, atrazine (ATR), propazine (PRO) and prometrine (PROM), across the water/1,2‐dichloroethane interface was investigated using cyclic voltammetry. A facilitated proton transfer mechanism from the aqueous to organic phase is demonstrated by the analysis of positive peak potential and peak current as a function of pH. It is shown that the determination of 2.5×10^?5 M – 5×10^?4 M concentration of herbicides in aqueous phase may be possible under the experimental conditions employed.     

Study of Electron Transfer Reactions Between a Water／1,2-Dichloro-ethane Interface by Scanning Electrochemical Microscopy

Electron transfer (ET) from ascorbic acid (AA) in aqueous to ferrocene (Fc) in 1,2-dichloroethane (DCE) was probed by the scanning electrochemical microscopy (SECM). Therate constants were extracted from the dependence of the steady-state current at ultramicro- electrode (UME, tip) on the distance between the tip and the phase boundary by comparison to theoretical working cures.     

氯喹药物在水／1,2—二氯乙烷界面上的传输机理研究

用滴电解液电极(EDE)极谱法、电流环扫伏安法和计时电位法研究了水相中氯喹离子、有机相中非离子化氯喹及以缔合物形式存在的氯喹在水/1,2-二氯乙烷界面上的传输过程.探讨了水相pH、氯喹浓度、EDE速度和扫描速度对传输行为的影响.提出了相应的传输机理.     

基于琼脂支撑的液/液界面上AgTCNQ的电化学合成

具有高导电性和独特电学性质的金属有机络合物AgTCNQ是一种重要的电荷转移盐.本文采用琼脂作为胶凝剂构成水|1,2-二氯乙烷液液界面;施加电压时银离子由水相穿过水凝胶进入有机相,与TCNQ^-反应生成AgTCNQ纳米棒.结果表明液/液界面电化学方法为合成有机金属功能材料的有效途径.     

应用扫描电化学显微镜研究水/1,2-二氯乙烷界面上离子诱导的电子转移反应

应用扫描电化学显微镜和微电极技术研究了水/1,2二氯乙烷界面上的反向电子转移反应.分别以K₄Fe(CN)₆和7,7,8,8四氰代二甲基苯醌(TCNQ)作为水相和有机相的电活性物质,通过选择合理的共同离子(TPAs⁺与TBA⁺)来控制界面电位差,实现了这一在热力学上通常不可能实现的反向电子转移反应.利用扫描电化学显微镜给出的正负反馈信息,研究了界面电位差驱动的液/液界面上的电子转移反应,并进一步得到了在不同的共同离子浓度比时,此异相界面反应速率常数k_f为1.3×10^-31.8×10^-2cm/s(共同离子为TBA⁺)和2.5×10^-32.8×10^-2cm/s(共同离子为TPAs⁺).验证了此反应速率常数k_f是由界面电位差所决定的.在此实验条件下,此反应速率常数kf与界面电位差的关系遵守Butler-Volmer公式.     

钙调素与重金属Pb2+结合反应的方波极谱与循环伏安法研究

采用方波极谱法研究了重金属Pb2+与钙调素(CaM)的结合反应, 直接检测到Pb2+-CaM配合物的存在, 并进一步利用循环伏安法研究了Pb2+-CaM的电极反应. 在pH=6.5时, 用方波极谱法在Pb2+-CaM体系中检测出2个还原峰, 峰电位分别为-0.44~-0.47 V和-0.73~-0.77 V, 说明在Pb2+-CaM体系中铅有2种存在形式, -0.44~-0.47 V的还原峰对应于游离态Pb2+, 电位更负的还原峰对应于配合物[Pb2+-CaM]. 2个还原峰的峰电流均随着cPb2+/cCaM比值增大而增大; 至cPb2+/cCaM≥10后, 配合物[Pb2+-CaM]的峰电流基本不再变化, 而游离态Pb2+的峰电流则继续增大. 利用极谱滴定曲线的拐点可判断出Pb2+在CaM中有10个结合位点. 进一步的测量结果表明, 循环伏安曲线出现游离态Pb2+的氧化峰和还原峰, 而络合态的[Pb2+-CaM]只有其还原峰, 反向电压扫描时不出现阳极波, 即没有相对应的氧化峰出现.     

Pb2＋在液/液界面迁移的电化学研究及其应用

用循环伏安法研究了双硫腙络合推动Pb^2＋在水/乙酰丙酮界面迁移的伏安过程. 实验证明, 该过程是受扩散控制的不可逆过程, Pb^2＋由水相转移到有机相中, 与双硫腙形成络合物Pb(DzH)₂. Pb^2＋的峰电位在－0.3 V处, 并且在5× 10^－6～0.1 mol•L^－1范围内与峰电流成正比. 这一方法为工业废水中铅的在线、现场测定提供了可靠、灵敏的检测方法.