壳聚糖分离富集分光光度法测定微量镍

研究了壳聚糖对Ni(Ⅱ)的富集、洗脱性能及苯并噻唑重氮氨基偶氮苯BTDAB与Ni(Ⅱ)的显色反应,建立了微量镍的分离富集光度测定新方法。实验表明,壳聚糖对Ni(Ⅱ)吸附性能良好,其吸附的最佳pH为8.0,吸附在4h内已基本达到平衡;在非离子表面活性剂Triton X-100的存在下,BTDAB与Ni(Ⅱ)形成3:1的橙红色配合物,最大吸收波长位于550nm处,表观摩尔吸光系数为1.64×105L·mol-1·cm-1,镍含量在0-10μg/25mL范围内符合比尔定律。方法直接应用于废水中微量镍的测定,结果令人满意。     

Solid-phase extraction for simultaneous separation and preconcentration of Fe(III) and Zn(II) traces using three chelatants and Ramelak bark-derived activated carbon as a new bio-sorbent

This article introduces a comparative study for the simultaneous separation and preconcentration of Fe(III) and Zn(II) traces in various water samples using three well-known ligands as chelating agents and activated carbon (AC) derived from Ramelak bark as a new bio-sorbent prior to the determination by ?ame atomic absorption spectrometry. The chelating agents were 4,4’-[(4-Cyano-phenyl)methylene]bis(3-methyl-1-phenyl-1H-pyrazol-5-ol) (CMBM), diethyldithiocarbamate (DDTC) and ammonium pyrrolidine dithiocarbamate (APDC). CMBM was synthesized by a procedure reported in the literature. The newly prepared AC was characterized by Scanning Electron Microscopy (SEM) and Fourier-Transform Infrared (FTIR) Spectrometry. The analytical parameters affecting the separation efficiency of the analytes including pH, shaking time, chelating agent volume (concentration), sorbent mass, sample ?ow rate and elution conditions were investigated and discussed. Common coexisting ions did not seriously interfere with the separation, showing the good selectivity of the proposed method. The calibration graph was linear in the range of 0.35–70, 0.50–80, 0.9–100, 0.55–75, 0.75–90 and 1.0–120 ng mL^?1 for Fe-CMBM, Fe-DDTC, Fe-APDC, Zn-CMBM, Zn-DDTC and Zn-APDC, respectively. Under optimized conditions, the limits of detection were 0.11, 0.13, 0.27, 0.16, 0.22 and 0.30 ng mL^?1 for Fe-CMBM, Fe-DDTC, Fe-APDC, Zn-CMBM, Zn-DDTC and Zn-APDC, respectively. The proposed method has been applied to the determination of Fe(III) and Zn(II) in different water samples with satisfactory recovery percentages. The developed method, validated with standard reference materials, was used successfully in determining the concentrations of metal ions in water samples.     

Determination of trace amount of silver in water samples by flame atomic absorption after preconcentration by ZnO nano sorbent

A simple and fast method based on solid phase extraction (SPE) applying zinc oxide (ZnO) nanoparticles and atomic absorption spectrometry (AAS) was developed for the trace amount determination of silver (Ag) in aqueous samples. The method linearity was in the range of 14 to 700 ng mL^?1. The extraction efficiency of Ag was greater than 98% and limit of detection (LOD) was 4.2 ng mL^?1. The preconcentration factor was 200 and the relative standard deviation (RSD%) of the method was 3.7% (n = 6).     

Flame atomic absorption spectrometric determination of Cd,Pb, and Cu in food samples after pre-concentration using 4-(2-thiazolylazo) resorcinol-modified activated carbon

This work aimed to develop a solid-phase extraction method using low-cost activated carbon produced from waste and modified with 4-(2-thiazolylazo) resorcinol for Cd(II), Pb(II), and Cu(II). The results showed that quantitative recovery of analytes was obtained at pH 6 with 3 M nitric acid as the eluent and a sample volume up to 1000 mL. The method was validated using certified reference material and addition-recovery tests. The limits of detection (LODs) for Pb(II), Cd(II), and Cu(II) were 2.03 μg L⁻¹, 0.15 μg L⁻¹, and 0.19 μg L⁻¹, respectively. The procedure was applied for determination of analytes in food samples.     

柴胡疏肝散复方前后微量元素溶出量变化分析

采用硝酸∶高氯酸为4∶1的混酸消解,用火焰原子吸收法柴胡疏肝散复方前后提取液中的三种人体必需的微量元素Cu、Mn、Fe的溶出量。结果表明,单煎液中铜、铁的含量高于合煎液中铜、铁的含量,而单煎液中锰的含量低于合煎液中锰的含量。     

Influence of the surface chemistry of modified activated carbon on its electrochemical behaviour in the presence of lead(II) ions

Cyclic voltammetric studies of the influence of surface chemistry on the electrochemical behaviour of granulated and powdered activated carbon samples in the presence of lead(II) ions both in bulk solution and pre-adsorbed on carbon were carried out. Variety in surface chemical character was achieved through modification of carbon samples by heat treatment in vacuum, ammonia and ammonia-oxygen atmospheres, as well as by oxidation in moist air and with concentrated nitric acid. For the samples obtained, the surface area (BET), acid–base neutralization capacities and sorption capacity towards Pb²⁺ ions were estimated. The states of the deposited Pb species were assessed by means of FTIR and XPS spectra as well as cyclic voltammetry. The importance of the surface chemistry of the carbon electrode materials are discussed in terms of their electrochemical properties and the mechanism of adsorption processes. The Cπ-metal and heteroatom-metal interaction are dominant in amphoteric and basic carbons, but in oxidized samples adsorption take place mainly by ion-exchange. Other forms of adsorption, such as the formation metal hydroxide species, are also covered buy this paper. Various forms of adsorbed lead species exhibit different electrochemical activities.     

The effects of acid leaching on porosity and surface functional groups of cocoa (Theobroma cacao)-shell based activated carbon

Cocoa shell pellets were converted into activated carbon (CSAC) by carbonization at 800 °C followed by activation at 850 °C in CO₂ flow until reaching burn off at approximately 48%. The CSAC was treated with hydrochloric acid (HCl) using response surface methodology (RSM), where the effect of soaking times (1, 2 and 4 h), temperatures (30, 50, 70 °C) and concentration of HCl (0.1, 1 and 2 M) were studied. CSAC treated with 1 M HCl at higher temperatures (>60 °C) yielded CSAC with low ash content (<10%). Acid-treatment process parameters, particularly the reaction temperature, determined the composition and types of functional groups existing in the CSAC. High concentrations of oxygen functional groups were detected in both untreated CSAC and CSAC treated at low acid concentration (1 M). High concentrations of nitrogen functional groups were detected only in CSAC treated at acid concentration (2 M).     

Cycling stability of a hybrid activated carbon//poly(3-methylthiophene) supercapacitor with N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide ionic liquid as electrolyte

A long cycle-life, high-voltage supercapacitor featuring an activated carbon//poly(3-methylthiophene) hybrid configuration with N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide ionic liquid, a solvent-free green electrolyte, was developed. The cyclability of a laboratory scale cell with electrode mass loading sized for practical uses was tested at 60 °C over 16,000 galvanostatic charge-discharge cycles at 10 mA cm⁻² in the 1.5 and 3.6 V voltage range. The reported average and maximum specific energy and power, specific capacitance and capacity, equivalent series resistance and coulombic efficiency over cycling demonstrate the long-term viability of this ionic liquid as green electrolyte for high-voltage hybrid supercapacitors.     

Multiwalled carbon nanotube impregnated with bis(5-bromosalicylidene)-1,3-propandiamine for enrichment of Pb2+ ion

Multiwalled carbon nanotube impregnated by bis(5-bromosalicylidene)-1,3-propandiamine (BBSPN) was synthesized and applied as adsorbent for the enrichment of trace amount of Pb²⁺ ion subsequent their determination by flame atomic absorption spectroscopy (FAAS). The influences of the analytical parameters including pH, amount of ligand and adsorbent, type and condition of eluent and sample volume on the Pb²⁺ ion recoveries were investigated. The optimum pH value for the separation of Pb²⁺ ion on the new sorbent was 6 and the adsorbed Pb²⁺ ion could be completely eluted by using 5.0 mL of 2.0 mol L⁻¹ HNO₃ solutions with 0.015 g of ligand and 0.100 g of adsorbent. Common coexisting ions did not interfere with the separation and determination of target metal ions. The method has high sorption–preconcentration efficiency with relative standard deviation less than 4.0%, especially for lead determination in radish, vegetable, potato, tomato and cheeps.     

Catalytic oxidation of Fe(II) by activated carbon in the presence of oxygen.: Effect of the surface oxidation degree on the catalytic activity

The catalytic oxidation of Fe(II) species in aqueous solution by activated carbons with different degrees of surface oxidation is described. The parent activated carbon was oxidized with aqueous solutions of nitric acid or hydrogen peroxide, and submitted to thermal treatment at 373, 523 and 773 K. The activated carbons prepared were characterized by N₂ adsorption and temperature-programmed desorption, and their catalytic behavior was determined by measuring the oxidation rate of Fe(II) to Fe(III) and the generation of hydrogen peroxide. Catalytic activity is a function of the nature of oxygen surface groups generated by oxidation.     

Removal of Cd（II） by Nanometer AIO（OH） Loaded on Fiberglass with Activated Carbon Fiber Felt as Carrier

A new nanometer material, nanometer AlO（OH） loaded on the fiberglass with activated carbon fibers felt（ACF） as the carrier, was prepared by hydrolytic reaction for the removal of Cd（II） from aqueous solution using column adsorption experiment. As was confirmed by XRD determination, the hydrolysis production loaded on fiberglass was similar to the orthorhombic phase AlO（OH）. SEM images showed that AlO（OH） particles were in the form of small aggregated clusters. The Thomas model was applied for estimating the kinetic parameters and the saturated adsorption ability of Cd（II） adsorption on the new adsorbent. The results showed that the maximum adsorption capacity of Cd（II） was 128.50 mg·g^-1 and 117.86 mg·g^-1 for the adsorbent mass of 0.3289 g and the adsorbent mass of 0.2867 g, respectively. The elution experiment result indicated that the adsorbed Cd ions was easily desorbed from the material with 0.1 mol·L^-1 HCl solution. Adsorption-desorption cycles showed the feasibility of repealed uses of the composited material. The adsorption capacities were influenced by pH and the initial Cd（II） concentration. The amount adsorbed was greatest at pH 6.5 and the initial Cd（II） concentration of 0.07 mg·L^-1, respectively. Nanometer AlO（OH） played a major role in the adsorption process, whereas the fiberglass and ACF were assistants in the process of removing Cd（II）. In addition, the adsorption capacities for Cd（II） were obviously reduced from 128.50 mg·L^-1 to 64.28 mg·L^-1 when Pb ions were present because Pb ions took up more adsorption sites.     

Effect of the oxidation of activated carbon by hydrogen peroxide on its catalytic activity in the regeneration of Co(II)TETA

Cobalt(II) triethylenetetramine (Co(II)TETA) formed by soluble cobalt(II) salt combining with triethylenetetramine will be used as a wet denitration technique since it can interact with nitric oxide to accomplish quick absorption of NO from gas phase. However, the oxygen in the flue gas will oxidize Co(II)TETA to Co(III) TETA, resulting in the reduction of denitrification efficiency. Activated carbon has been used to promote the regeneration of Co(II)TETA due to its unique surface characteristics. Hydrogen peroxide solution is utilized as a modifier in the carbon modification to improve the catalytic performance of activated carbon. The experiments demonstrate that the best regeneration efficiency of Co(II)TETA is gained by the modified carbon impregnated in 0.05 mol L⁻¹ H₂O₂ solution at 70°C for 12 h with a solid/liquid ratio of 1/50 (g/mL) followed being activated at 400°C for 2 h in N₂. After being treated with hydrogen oxide solution, the surface area and acidity of the carbon is increased. Continuous experiments reveal that the NO removal efficiency gained by modified activated carbon is about 8.36% higher than that gained by the original carbon.     

A Pongamia pinnata pods based activated carbon as an efficient scavenger for adsorption of toxic Co(II): kinetic and thermodynamic study

ABSTRACT

A porous and high surface area-activated carbon based on Pongamia pinnata pods (PPP) was synthesized using a chemical method. The synthesized material was characterized using FTIR, XRD, BET, SEM, EDX, XPS and TGA. Plausible adsorption mechanism of Co(II) on PPPAC was evaluated systematically. The effect of various contributing parameters were investigated through batch adsorption experiments. Results reveal that the equilibrium was attained within 360 min having 0.35 g PPPAC amount at pH 6 and the maximum equilibrium capacity was observed 190.30 mg/g. Kinetically adsorption of Co(II) was best described by pseudo-second-order-model. The equilibrium data well suited with the Langmuir isotherm model and thermodynamic parameters indicate that the process was spontaneous and endothermic in nature.     

Insights into the surface and redox properties of single-walled carbon nanotube—cobalt(II) tetra-aminophthalocyanine self-assembled on gold electrode

This paper describes for the first time the electrochemical properties of redox-active self-assembled films of single-walled carbon nanotubes (SWCNTs) coordinated to cobalt(II)tetra-aminophthalocyanine (CoTAPc) by sequential self-assembly onto a preformed aminoethanethiol (AET) self-assembled monolayer (SAM) on a gold electrode. Both redox-active SAMs (Au-AET-SWCNT and Au-AET-SWCNT-CoTAPc) exhibited reversible electrochemistry in aqueous (phosphate buffer) solution. X-ray photoelectron spectroscopy (XPS) confirmed the appearance on the gold surface of the various elements found on the SAMs. Atomic force microscopy (AFM) images prove, corroborating the estimated electrochemical surface concentrations, that these SAMs lie normal to the gold surface. Electrochemical impedance spectroscopy (EIS) analyses in the presence of [Fe(CN)₆]^3−/4− as a redox probe revealed that the Au-AET-SWCNT-CoTAPc showed much lower (∼10 times) electron-transfer resistance (R_et) and much higher (∼10 times) apparent electron-transfer rate constant (k_app) compared to the Au-AET-SWCNT SAM. Interestingly, a preliminary electrocatalytic investigation showed that both SAMs exhibit comparable electrocatalytic responses towards the detection of dopamine in pH 7.4 phosphate buffer solutions (PBS). The electrochemical studies (cyclic voltammetry (CV) and EIS) prove that SWCNT greatly improves the electronic communication between CoTAPc and the Au electrode surface.     

In situ solvent formation microextraction based on a new ionic liquid for green preconcentration of trace amount of Cu (II) ions in water samples

A simple, fast, and effective analytical technique known as in situ solvent formation microextraction was used to preconcentrate/separate trace amounts of Cu(II) ions in water samples prior to determination by flame atomic absorption spectroscopy. In the present method, 6,6′-(1Z,1′Z)(butane-1,4-diylbis(azan-1-yl-1-ylidene)bis(methan-1-yl-1-ylidene)bis-3-bromophenol (Schiff base ligand) as the complexing agent and 1-methyl-3-pentylimidazolium bromide (ionic liquid) as an extracting agent were successfully synthesized and characterized by FTIR, C-NMR, and H-NMR spectroscopies. The effects of several analytical parameters on the method were studied and optimized, and the merits of the method, such as LDR (0.2–1000 µg L^?1), LOD (0.12 µg L^?1), RSD (4.1%), and preconcentration factor (70) were evaluated.     

Catalytic oxidation of Fe(II) by activated carbon in the presence of oxygen.: Effect of the surface oxidation degree on the catalytic activity

The catalytic oxidation of Fe(II) species in aqueous solution by activated carbons with different degrees of surface oxidation is described. The parent activated carbon was oxidized with aqueous solutions of nitric acid or hydrogen peroxide, and submitted to thermal treatment at 373, 523 and 773 K. The activated carbons prepared were characterized by N₂ adsorption and temperature-programmed desorption, and their catalytic behavior was determined by measuring the oxidation rate of Fe(II) to Fe(III) and the generation of hydrogen peroxide. Catalytic activity is a function of the nature of oxygen surface groups generated by oxidation.     

Aliphatic hyperbranched polyesters based on 2,2-bis(methylol)propionic acid—Determination of structure, solution and bulk properties

Due to their highly branched structure and the large number of functional groups hyperbranched polymers possess unique properties that make them interesting for uses in a wide variety of applications. Some of the most widely investigated hyperbranched polymers are the polyesters based on 2,2-bis(methylol)propionic acid. In this paper we present the results of characterization studies of hyperbranched polyesters based on 2,2-bis(methylol)propionic acid which show that they are very complex products with a multidimensional distribution of various properties. The influence of the synthesis conditions on the structure and molar-mass characteristics of hyperbranched polyesters as well as the findings that allow a thorough understanding of the structure-property relationships are reviewed in detail.