The adsorption of coumarin at solid metal electrodes

The effect of coumarin on the “deposition potential” of a number of metals at solid metal surfaces has been compared with that at a dropping mercury electrode. These results have been used to interpret the adsorption of coumarin on different metal surfaces and to suggest that Tl⁺ and Pb²⁺ ions are specifically adsorbed on mercury and that Tl⁺, Co²⁺, Fe²⁺, Ni²⁺ and Zn²⁺ are specifically adsorbed on their parent metals.     

The influence of lead upd on the oxidation of glucose at platinum electrodes an electrochemical quartz crystal microbalance study

The oxidation of glucose at Pt electrodes with upd deposits of Pb in acid media has been investigated using the electrochemical quartz crystal microbalance (EQCM). Glucose alone has a small effect on the mass response but changes in upd Pb coverage have a large effect. This allows changes in upd Pb coverage to be followed easily despite the fact that the associated current is largely obscured in the cyclic voltammogram. Cyclic voltammetry at low glucose concentrations shows a multiple peak structure in the double layer region of potential at low upd coverages that is charged to the more familiar single peak as upd coverage increases. Mass responses also reveal some blockage of Pb upd by glucose or species derived from it during cyclic voltammetry. Data from mass transients show that the deliberate formation of poisons prior to addition of Pb²⁺ ions to the electrolyte results in a substantial suppression of upd coverage especially between −0.1 and 0.1 V (sce). Finally, mass transients accompanying injections of Pb²⁺ in the presence of glucose in the electrolyte reveal the suppression of adsorption of Pb²⁺ cations on an oxidised Pt surface by species derived from glucose.     

Electrochemical formation of Au2Na alloy and the characteristics of (Au2Na+Au) reference electrode in a LiF–NaF–KF eutectic melt

A cyclic voltammogram at a Au electrode in a LiF–NaF–KF eutectic melt at 773 K showed a cathodic peak at 0.45 V (vs. K⁺/K). XRD analysis of the electrode confirmed that the cathodic peak corresponded to the formation of Au₂Na alloy phase. The equilibrium potential of the reaction: 2Au+Na⁺+e⁻Au₂Na was determined to be 0.535 V at 773 K by open-circuit potentiometry at the Au–Na alloy electrode. The thermodynamic properties including the standard Gibbs free energy of formation were estimated for Au₂Na alloy at 773–860 K. The (Au₂Na+Au) electrode was proved to have excellent characteristics as a reference electrode in terms of reproducibility, stability and reversibility.     

聚丙烯酸钠包覆Fe3O4磁性交联聚合物的制备及其对Pb(Ⅱ)和Cd(Ⅱ)的吸附性能

采用溶液分散聚合和Ca²⁺表面交联制备了聚丙烯酸钠包覆Fe₃O₄的磁性交联聚合物（CPAANa@Fe₃O₄）,对其进行了XRD、FT-IR、SEM和TGA等表征。以CPAANa@Fe₃O₄为吸附剂研究了CPAANa@Fe₃O₄对水溶液中Pb²⁺、Cd²⁺的静态吸附,考察了溶液pH、吸附剂投加量、金属离子初始浓度对吸附的影响。结果表明：CPAANa@Fe₃O₄在pH 2～6范围内均具有较好的吸附性能,当吸附剂投加量分别为1.0 g·L^-1和1.6 g·L^-1时对初始浓度分别为200 mg·L^-1的Pb²⁺和100 mg·L^-1的Cd²⁺的去除率达到最大,可使Pb²⁺实现达标排放（GB 8978-1996）;CPAANa@Fe₃O₄对Pb²⁺和Cd²⁺的吸附动力学符合准二级模型,吸附等温线符合Langmuir模型,对Pb²⁺和Cd²⁺的最大吸附量分别为454.55 mg·g^-1和275.48 mg·g^-1。将CPAANa@Fe₃O₄用于处理实际电解矿浆废水,发现能有效吸附其中的Pb²⁺和Cd²⁺,具有潜在实用价值。     

海胆状Fe3O4@TiO2磁性纳米介质对Pb2+的选择吸附特性

耦合溶胶-凝胶技术与水热法,制备具有核壳结构的海胆状Fe₃O₄@TiO₂磁性纳米介质（sea urchin magnetic nanoparticles,SUMNPs）。采用TEM、SEM等方法对SUMNPs的形貌等性质进行表征,证实该材料呈现出以Fe₃O₄为核,以TiO₂为壳的海胆状结构,壳层直径约400 nm,比表面积高达236.082 m²·g^-1,表面孔径约6.274 nm。SUMNPs对重金属离子选择吸附的结果表明,基于Pb²⁺离子半径大、电子层数多等物化特点,在Pb²⁺、Cu²⁺、Ni²⁺、Zn²⁺、Cd²⁺ 5种金属离子混合体系中,SUMNPs可以高容量、高选择性快速吸附Pb²⁺,而对其他4种重金属离子几乎无吸附活性。单一Pb²⁺吸附可在5 min内快速平衡,平衡吸附容量为283 mg·g^-1。吸附过程符合Langmuir等温吸附模型,SUMNPs对Pb²⁺的最大饱和吸附容量为458.72 mg·g^-1。经EDTA二钠解吸,NaOH再生后的SUNMPs可以重复使用8次以上。SUMNPs对Pb²⁺具备优异的选择性吸附性能,在处理水体铅污染、恢复水体生态领域具有良好的应用前景。     

生物除磷颗粒污泥去除Pb2+的效能机制

以好氧颗粒污泥的吸附作用和磷酸盐对重金属的螯合作用为基础,采用富含磷酸盐的生物除磷颗粒污泥作为吸附剂来处理含铅废水,考察了不同吸附条件（pH、Pb²⁺的初始浓度、吸附反应时间）下,颗粒污泥对Pb²⁺的去除效果。结果表明,除磷颗粒污泥在pH为4,初始Pb²⁺浓度为150 mg·L^-1时,对铅的去除率最高（为99.9%）;在吸附反应20 min时即可达到吸附平衡。生物除磷颗粒污泥对Pb²⁺的吸附可以用Langmuir模型拟合（R²=0.993）,最大吸附量为49.5 mg·g^-1。其中离子交换和磷酸盐与Pb²⁺的螯合作用对除磷颗粒污泥去除Pb²⁺起到重要作用;傅里叶变换红外光谱（FTIR）测定表明-COOH、-OH、磷酰基等多种官能团也参与了除磷颗粒污泥除Pb²⁺过程。     

水泥浆粉去除废水中铅离子效果及行为研究

水泥浆粉含有可吸附重金属离子的成分,可作为吸附剂来处理重金属离子废水。本文利用硅酸盐水泥制备了不同水化龄期的水泥浆粉来处理含Pb²⁺废水,通过X射线衍射仪、同步热分析仪、电感耦合等离子体发射光谱仪等测试方法,研究了水泥浆粉龄期、浆粉用量、Pb²⁺浓度、pH值、温度、时间对Pb²⁺去除效果及吸附行为的影响。结果表明,水泥浆粉对废水中的Pb²⁺去除率普遍大于80%。在35 ℃、pH=2、吸附时间200 min时,0.04 g水灰比为0.50、水化龄期为60 d的水泥浆粉对初始浓度为700 mg/L的Pb²⁺溶液的Pb²⁺去除率为96.06%,吸附容量为336.22 mg/g。水泥浆粉对Pb²⁺的吸附热力学符合Freundlich吸附等温模型,吸附动力学符合拟一级动力学模型。     

Faujasite zeolite decorated with cobalt ferrite nanoparticles for improving removal and reuse in Pb2+ ions adsorption

Water pollution caused by heavy metals ions has been gaining attention in recent years, increasing the interest in the development of methodologies for their efficient removal focusing on the adsorption process for these purposes. The current challenge faced by adsorption processes is the adequate adsorbent immobilization for removal and reuse. Thus, the present work aimed at producing a faujasite zeolite nanocomposite decorated with cobalt ferrite nanoparticles for Pb~(2+) ions adsorption in an aqueous medium improving magnetic removal and reuse.As a result, a high surface area(434.4 m~2·g~(-1)) for the nanocomposite and an 18.93 emu·g~(-1) saturation magnetization value were obtained, indicating magnetic removal in a promising material for adsorption process. The nanocomposite regeneration capacity evaluated by magnetic recovery after 24 h suspension presented a high Pb~(2+) ion adsorptive capacity(98.4%) in the first cycle. Around 98% of the Pb~(2+) ions were adsorbed in the second cycle. In this way, the synthesized faujasite:cobalt ferrite nanocomposite reveals itself as a promising alternative in adsorption processes, aiming at a synergic effect of FAU zeolite high adsorptive activity and the cobalt ferrite nanoparticles magnetic activity, allowing for adsorbent recovery from the aqueous medium via magnetic force and successive adsorptive cycles.     

木屑生物炭的制备及其对Pb2+的吸附特性研究

以松木（SM）和楠木（NM）木屑为原料,分别在300、450、600℃下制备了6种木屑生物炭,通过扫描电镜、孔径与比表面积分析仪、傅里叶红外光谱仪和热重分析仪对生物炭的理化性质进行了表征,并探讨了金属离子（Na⁺、K⁺、Ca²⁺）和pH值对生物炭吸附Pb²⁺的影响,同时研究了其吸附动力学。研究结果表明：在相同制备条件下,随着热解温度升高,生物炭的比表面积和孔容积增大,其最可几孔径呈下降趋势,楠木生物炭的比表面积（23.2~311.4 m²/g）均大于松木生物炭（17.6~210.6 m²/g）;FT-IR分析表明,热解温度的升高使生物炭芳香化程度增强,有助于生物炭与Pb²⁺形成稳定的结构。楠木生物炭对Pb²⁺吸附量（46.92~77.12 mg/g）高于松木生物炭（34.90~62.79 mg/g）;溶液中的Na⁺和K⁺不利于生物炭对Pb²⁺的吸附,Ca²⁺有利于Pb²⁺的去除。生物炭对Pb²⁺的吸附均符合准二级动力学方程,颗粒内扩散模型分析表明吸附受多种因素共同影响。     

牛血清白蛋白纳米球接枝杨梅单宁的制备以及吸附去除水体中Pb2+的性能

采用去溶剂法和杨梅单宁-戊二醛固化接枝制备得到杨梅单宁（BT）接枝牛血清白蛋白（BSA）纳米球（BSA-BT-NSs）吸附材料，并系统探讨了其在不同吸附条件下对水体中Pb²⁺的吸附去除性能。研究结果表明：50%用量杨梅单宁（基于BSA-NSs量）接枝固化得到的BSA-BT-NSs具有较好的球形结构和良好的分散性。在吸附实验中，Pb²⁺初始浓度为250mg/L、pH 5.0、温度为298K 条件下吸附20min，BSA-BT-NSs（0.4g/L）对Pb²⁺的吸附效果最佳，最大吸附容量为76mg/g，优于多数同类型吸附材料。BSA-BT-NSs对Pb²⁺吸附过程符合Langmuir方程和准二级吸附动力学模型，且吸附后的BSA-BT-NSs经0.1mol/L 硝酸进行解吸取得了92.04％的良好解吸效果，并可再次重复使用。进一步分析其Pb²⁺吸附机理，表明BSA-BT-NSs中的氨基氮原子、羟基和羧基氧原子作为电子供体参与了与Pb²⁺的空轨道发生配位作用。     

TOCNF与磁性羧甲基壳聚糖纳米粒子复合物的制备及吸附Pb2+的特性

水体中铅污染对环境及人的健康安全造成了极大的危害。本文将四甲基呱啶（TEMPO）氧化的纤维素纳米纤维（TEMPO-oxidized cellulose nanofibers,TOCNF）与磁性羧甲基壳聚糖纳米粒子（magnetic carboxymethyl chitosan nanoparticles,MCCN）交联复合制备一种经济高效且对环境无毒害的Pb²⁺吸附剂,对复合前后的材料进行结构表征。通过单因素实验研究pH、Pb²⁺初始浓度、吸附时间及温度对Pb²⁺吸附效率的影响,确定最优吸附条件后比较TOCNF/MCCN及TOCNF对Pb²⁺的吸附效果,研究复合材料对Pb²⁺的吸附特性。研究结果表明,Fe₃O₄成功被羧甲基壳聚糖纳米粒子包裹并与TOCNF交联复合,在最优吸附条件（pH=5,Pb²⁺初始浓度为100mg/L,吸附时间为240min,常温下进行实验）下,TOCNF/MCCN吸附Pb²⁺的饱和容量为193.5mg/g,比TOCNF高了近一倍。复合吸附剂吸附Pb²⁺的过程更符合准二级动力学方程,说明决定吸附速率的主要是化学吸附。等温吸附方程的相关系数R²表明,Langmuir方程能更好地拟合吸附过程,说明复合吸附剂对Pb²⁺的吸附主要是表面基团的单分子层吸附。通过线性方程的斜率计算得到的理论饱和吸附量为201.1mg/g,与实际值差3.8%,经过5次解吸再吸附的过程,吸附剂的吸附效率仅下降了13%,表明该吸附剂有良好的可再生性,具有很好的应用前景。     

生物炭吸附溶液中Pb2+的定性及定量研究

由木质纤维素类生物质经过热解制得的生物炭能够高效地吸附污水中的重金属离子,将其作为Pb²⁺吸附剂,具有广阔的应用前景。本文以松木与大豆秸秆为原料,分别在400、600、800℃下制备了生物炭,考察了其理化特性与吸附性能之间的关系,并对各吸附机制的相对贡献进行了定性及定量分析。研究结果表明：大豆秸秆生物炭的吸附性能(最大吸附容量分别为209.35、180.62和226.64 mg·g^-1)远优于松木生物炭的(4.62、12.02和23.47 mg·g^-1)。6种生物炭对Pb²⁺的吸附过程都符合Langmuir模型和拟二级动力学模型,以化学吸附为主,受物理微观结构的影响较小。阳离子交换在生物炭吸附Pb²⁺过程中占据重要作用,其中Ca²⁺的交换能力最强。Pb²⁺在生物炭表面的矿物沉淀主要为水白铅矿和碳酸铅。矿物质沉淀(贡献占比21.9%～76.8%)和阳离子交换(18.1%～72.5%)是大豆秸秆炭和松木炭对Pb²⁺的...     

黄腐酸基Cd2+离子印迹聚合物的吸附性能测试

以改性黄腐酸为功能单体,反相悬浮聚合法制备了Cd²⁺离子印迹聚合物,并研究其吸附性能。动力学模型表明,黄腐酸基Cd²⁺离子印迹聚合物对Cd²⁺的吸附符合准二级动力学吸附模型,相关系数达到0.9977;热力学研究发现,黄腐酸基Cd²⁺离子印迹聚合物吸附重金属离子的形式为单分子层表面吸附,与Langmuir等温吸附模型相符;竞争吸附实验显示,竞争离子Pb²⁺、Cr³⁺存在时,Cd²⁺/Pb²⁺、Cd²⁺/Cr³⁺的相对选择性系数分别为4.32、13.47,说明MFA-IIP对模板离子拥有较强的选择识别性能,竞争离子化合价不同,选择识别性更加显著。     

Structure stabilization and dielectric properties of pzn ferroelectric ceramics

Structure stabilization and dielectric properties of Pb (Zn_1/3 Nb_2/3)O₃ -PbTiO₃ -BaTio₃ (PZN-PT-BT) ferroelectric ceramics have been carefully studied. Around morphotropic phase boundary (MPB) of PZN-PT system, heterovalant substitution of K⁺ for Pb²⁺ stabilizes the pesrovskite Structure, while substitution of La³⁺ for Pb²⁺ goes toward the other end. Nonstoichiometry addition of excess ZnO or BaO can also suppress the formation of pyrochlore phase.     

Effect on cathodic reduction of β-PbO2 in sulfuric acid solution of surface concentration of Pb ions formed on β-PbO2

The discharge reaction of positive electrode of lead-acid battery was investigated with the rotating ring-disc electrode. The large supersaturation of Pb²⁺ ion on the electrode surface was obtained during discharge of initial period and the PbSO₄ nuclei was formed. The precipitation of PbSO₄ proceeded smoothly in the presence of PbSO₄ nuclei. In the steady state, the colloidal PbSO₄ film on the electrode surface of which stability depended on the concentrations of sulfuric acids was formed from the dissolving Pb²⁺ ions. Especially its stability in 1.0 M H₂SO₄ was so low that the concentration of Pb²⁺ ions during discharge was the largest of those in any other sulfuric acids, so that the effect of the film on the overpotential during galvanostatic discharge is the smallest, as discussed in a following paper[1].

The particle sizes of PbSO₄ precipitated during discharge were related to the concentration of Pb²⁺ ions on the electrode. These sizes increased with increasing concentration of Pb²⁺ ions. If the discharge capacity is limited by the passivation with PbSO₄ crystal, the use of 1.0 M H₂SO₄ as the electrolyte of lead-acid battery may be favoured.     

Hydrothermal synthesis of zeolitic material from circulating fluidized bed combustion fly ash for the highly efficient removal of lead from aqueous solution

The utilization of coal fly ash derived from circulating fluidized bed combustion(CFBFA) still faces great challenges because of its unique characteristics. In this study, a zeolitic material with Na-P1 zeolite as the main phase was successfully synthesized via a hydrothermal method by using CFBFA as the raw material.The effects of hydrothermal temperature, time, and added CTAB amount on the characterizations of synthesized materials were investigated by XRD, SEM, and XPS. The properties of the ...     

重金属离子吸附用微凝胶研究新进展

微凝胶聚合物网络中易于引入能够与重金属离子螯合或络合的功能基团,且比表面积大,对重金属离子具有较快的吸附速率,因此,微凝胶在重金属离子的去除方面具有广阔的应用前景。本文介绍了重金属离子吸附用微凝胶研究新进展,重点回顾了基于羧基、氨基、磺酸基、羟基及巯基等多官能团化合物与重金属离子通过静电相互作用形成稳定络合物的微凝胶用于重金属离子的吸附,离子印迹型微凝胶用于重金属离子的吸附,以及基于冠醚环（苯并-18-冠-6醚）与Pb²⁺离子通过超分子主-客体识别作用形成稳定络合物的微凝胶用于重金属离子的吸附;描述了这三类微凝胶对重金属离子的吸附性能、优点、用途等;指出了这三类微凝胶适用于不同场合下重金属离子的吸附。     

花生壳生物炭的改性及其吸附Pb2+性能研究

以花生壳为原料热解制备生物炭,并分别采用NaOH和KMnO₄进行改性,经表征发现改性后生物炭微观结构较为疏松、孔径变小、稳定性增强,NaOH改性花生壳生物炭（AB）和KMnO₄改性花生壳活性炭（MnB）的比表面积分别增至花生壳生物炭（B）的3.178倍和5.065倍,以KMnO₄作为改性剂时,锰氧化物成功地固定在生物炭上,B、AB和MnB的零电荷点（pH_PZC）分别为2.193、2.888和2.466。探究改性前后生物炭对Pb²⁺的吸附性能发现：B、AB和MnB吸附Pb²⁺的适宜pH值分别为4.5~6.5、5.5~6.5和5.0~6.5,达到相同Pb²⁺去除率时,生物炭用量MnB 2+的吸附平衡时间较B吸附Pb²⁺的吸附平衡时间（1 080 min）分别缩短了180和480 min。通过吸附动力学模型和等温线模型分析可知,3种生物炭吸附Pb²⁺的过程均受化学吸附控制,吸附速率MnB>AB>B,AB和MnB的最大理论吸附量分别是53.19和80.65 mg/g,分别提高至B的1.38倍和2.10倍。     

生物炭负载纳米羟基磷灰石复合材料的制备及对铅离子的吸附特性

以玉米秸秆为前体,在高温限氧条件下,将纳米羟基磷灰石（nano-HAP）负载于生物炭（BC）表面制备出了生物炭负载纳米羟基磷灰石（nHAP/BC）复合材料,并利用SEM、XRD和FTIR对其进行表征。批量吸附实验考察其对Pb²⁺的吸附特性,研究pH、投加量、吸附时间、初始浓度及吸附温度等因素对吸附的影响。通过吸附动力学、吸附等温线和吸附热力学分析了吸附特性,通过解吸实验考察了解吸再生效应,并对吸附机制进行了探讨。结果表明：与BC相比,nHAP/BC复合材料具备更好的吸附效果,25℃时理论最大吸附量为383.75mg/g。nHAP/BC对Pb²⁺的吸附符合拟二级动力学方程和Langmuir等温吸附模型,表明nHAP/BC对Pb²⁺的吸附为单分子层化学吸附。热力学参数ΔG < 0、ΔH > 0,表明吸附是一个自发的吸热过程。nHAP/BC对Pb²⁺的吸附机制主要包括nano-HAP的溶解-沉淀作用以及生物炭表面-OH和-COOH等含氧官能团的络合作用。nHAP/BC具有良好的循环利用能力,是一种潜在的Pb²⁺高效吸附材料。     

On the nature of the adsorbed species and mechanism of adsorption of In(III) from iodide solutions at the dme

The reduction of In(III) in solutions containing 0.05, 0.1 and 0.25 M of NaI and with an ionic strength of 1.00 maintained with sodium perchlorate, has been studied by means of interfacial admittance measurements at different frequencies and dc potentials of the dropping mercury electrode.

Our results demonstrate that the process takes place with specific adsorption of electroactive species. The adsorption parameters and their dependence with potential have been determined. From the analysis of our results, together with those obtained in a previous study at higher concentrations of I⁻, it can be deduced than InI⁺₂ is the species preferentially adsorbed, this adsorption taking place via a bridge-like mechanism, through I⁻ ions previously adsorbed.