جستجوی مقالات مرتبط با کلیدواژه « Heavy metal ions » در نشریات گروه « شیمی »

A new electrochemical sensor was constructed with the nanometer coaxial cable, which was prepared based on Multi-Walled Carbon NanoTubes (MWCNTs) and pyridine. the analysis of trace Pb(II) with Differential Pulse Anodic Stripping Voltammetry (DPASV) was studied. The MWCNTs–TPI–2–Ph was characterized by SEM, TEM, and electrochemical methods. Various parameters such as deposition time, pH values, deposition potential, interference experiment, stability, and reproducibility were investigated. DPASV was used for evaluating the detection of trace Pb(II) based on the accumulation process. Under the optimal conditions, the MWCNTs–TPI–2–Ph/GCE showed excellent stripping response of Pb(II) in the ranges of 1 to 100 μmol/L, the peak currents linearly increased with the concentration of Pb(II). The detection limit was calculated to be 0.03 μM (S/N=3). Detection mechanism for Pb(II) based on MWCNTs–TPI–2–Ph/GCE was proposed. Therefore, it was essential to design an electrochemical sensor based on a new metal ions capture reagent.

In this study, an amide-functionalized metal-organic framework, namely TMU-24 was selected to adsorb Co(II) from wastewater with an adsorption capacity of 500 mg. g-1 in less than 20 minutes in neutral pH (pH=7). The effect of diverse parameters such as adsorbent dosage, competitive ions, and contact time on the adsorption process was investigated to find the optimal amounts of them. Also, the modeling calculations demonstrated that this compound obeys Pseudo-Second-order and Langmuir models with correlation coefficients of R² = 0.9996 and R² = 0.9761, respectively. So, the adsorption mechanism could be monolayer chemical interaction according to these models. Moreover, PXRD patterns of the framework before the adsorption procedure and after that revealed that the MOF could keep its structure, suggesting the stability of the framework. So, we can claim that our proposal adsorbent is a promising candidate for cobalt(II) removal from pollutant water.

In the presented study, CuO-CoO-MnO/SiO2 nanocomposite was synthesis by Cu(II), Co(II), Mn(II), with 1:1:1 mole ratio and Tetraethyl orthosilicate. azo–azomethine 1-(3-imino-4-hydroxophenylazo-4-nitrobenzene)-4-methyl phenol (L) was synthesized and used as a ligand for capturing the metal ions. Also, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide was applied as the ionic liquid in order to increase the conductivity of the electrode. The nanomaterials were investigated using Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM); SEM image shows a homogeneous CuO-CoO-MnO/SiO2 nanocomposite, with an average particle size distribution of 40 nm. Also, the electrochemical characterization of L/CuO-CoO-MnO/SiO2/IL/CPE was checked by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques. The modification of carbon paste electrode applied to determination of some heavy metal ions include Hg(II), Cd(II), Pb(II) and Zn(II) by square wave anodic stripping voltammetry (SWASV), for the first time. The linear range for determination of analytes in optimized condition was obtained as Hg: 0.0007-0.21 and 0.21-27 μM, Cd: 0.0007-0.21 and 0.21-27 μM, Pb: 0.0009-0.23 and 0.23-27 μM, Zn: 0.001-0.25 and 0.25-27 μM. Also, the detection limits for Hg(II), Cd(II), Pb(II) and Zn(II) were calculated to be 3.019×10-4, 3.445×10-4, 2.407×10-4 and 5.134×10-4 μM, respectively. Finally, the sensor was successfully used for the measurement of the analytes in Tap water and River water samples with recoveries ranging between 98.1% and 102.7%. Also, the obtained results accorded very well with those obtained by atomic absorption spectroscopy (AAS) that corroborated the accuracy and validity of the proposed method.

Heavy  metal  pollution  is  propagating  throughout  the  world  with  the  enlargement  of  industrial activities.  The  elimination  of  heavy  metal  ions  from  industrial  wastewaters  has  drawn  much attention  because  of  the  hazardous  effects  of  the  heavy  metal  ions  on  different  organisms. According to these facts, poly (2, 2, 3, 3- tetracyanocyclopropyl) phenyl acrylate (PTCP) with multi cyanocyclopropane functionalities in the pendant group were prepared by reacting benzoyl peroxide with p-(2,2,3,  3-tetracyanocyclopropyl)  phenylacrylate  (TCP) monomer.  (TCP)  monomer was synthesized by reacting cyanogen bromide and malononitrile with p-acryloyloxybenzaldehyde at 0 °C  in  a  short  time. The  synthesized  PTCP momopolymer were  examined  in heavy  metal  ions adsorption  such  as  Ni  (II),  Cu  (II),  Cr  (III)  and  Zn  (II)  under  competitive  and  non-competitive conditions in aqueous solutions at different pH. The high adsorption rate (<65 min) was seen. The synthesized polymer and its metal chelates were investigated by thermogravimetric analysis (TGA),Fourier-transform  infrared  spectroscopy  (FT-IR),  atomic  absorption  techniques  (AAS),  UV-vis spectroscopy and scanning electron microscopy (SEM).

Polyvinyltetrazole (PVT) is produced from acrylonitrile (AN) monomer by using free-radicalpolymerization and Click Chemistry methods. The resulting polymer with a broad range of tetrazolegroup contents was conveniently synthesized through [3+ 2] azide-nitrile cycloaddition reaction ofnitrile-containing polymer with sodium azide in DMF. The prepared PVT was characterized by13CNMR,FT-IR and UV-Vis spectroscopies. Elemental analysis indicated that approximately 92% ofthe cyano groups on the polymer surface were converted to tetrazolyl groups. The PVT exhibitedexcellent adsorption form et al ions and the maximum adsorption capacity for Pb (II) was2.39mmol/g which are much higher than corresponding literature results. The adsorption processwas described as an ion exchange and chelation interaction mechanisms. The high adsorption rate(<40 min) was seen. The resulting polymer and its metal chelate were characterized by FT-IR,elemental analysis, gravimetry, scanning electronic microscopy (SEM), thermogravimetry analysis(TGA), UV-Vis spectroscopy, and atomic absorption techniques (AAS). All these analyses methodsconfirmed the presence of metal in the polymer-metal complex.

In the present study, copper ion has been separated from Phosphate Buffer Solution by 2-Amino-N-(2-Pyridyl Methyl)-Benzamide as an organic ligand through a flat type Supported Liquid Membrane (SLM). To this end, the organic ligand was dissolved in various solvents, and then the Polytetrafluoroethylene (PTFE) membrane was immersed in the resulting solutions for 24 h. Before extraction step, solvents with best performances including Ethanol and benzyl acetate were selected as solvent and as plasticizer, respectively. The optimized complexing reagent concentration on the membrane was 0.05 M. The adjusted pH was 4.5 and concentration of Cu solution was 1×10-3 M for feed solution, respectively. Copper ion was then determined using Fast Fourier Transformation Continuous Stripping Cyclic Voltammetry (FFTCCV) technique by a Carbon Paste Electrode (CPE). PTFE with 0.1 μm pore size have more permeability than 0.2 μm. Based on the obtained results, effective parameters imposing sensitivity of copper ion measurement were finally investigated at pH 3.2, at scan rate of 10 mV.s-1, stripping time of 0.1s and potential of -600 mV. Limit of detection of 0.19 μM for copper ion in optimized condition was attained. Under the optimized conditions the recovery of Copper ions from real samples were studied and recovery percentage were 45.71%, 34.28% and 22.58% for tap water, river water and sea water respectively.

In this paper, Taguchi method was applied to determine the optimum conditions for Zn (II) removal from aqueous solution by halloysite nanotubes (HNTs). An orthogonal array experimental design (L16 (45) which is of five control factors including pH, t (contact time), m (adsorbent mass), T (temperature) and C0 (initial concentration of Zn (II)) having four levels was employed. Adsorption capacity (mg/g) and removal percent (%) were investigated as the quality characteristics to be optimized. In order to determine the optimum levels of the control factors precisely, range analysis and analysis of variance were performed. For removal percent, the optimum condition was found to be pH=6, T=35°C, w=0.4 g, and C0=50 mg/L. Under these optimum conditions, adsorption capacity and removal percent can reach to 132.16 mg/g and 99.76%, respectively

Carbon nanotubes (CNTs) are a novel material that exhibits good adsorption behavior toward various toxic pollutants in aqueous solution. These adsorbents have a fast adsorption rate and high adsorption efficiency, efficient to remove various pollutants and they are easy to recover and reuse. These features highlight the suitability of CNTs for the treatment of water polluted with heavy metal ions and dyes. This review outlines the preparation of CNTs as well as different methods of surface modification of these materials by non-covalent and covalent functionalization strategies. Additionally, an overview of recent developments and applications of CNTs for heavy metal ions and dyes pollutant removal is discussed in detail. Based on current research and existing materials, some new and futuristic approaches in this fascinating area are also discussed. The main objective of this review is to provide up-to-date information about the most important features of CNTs and to show their advantages as adsorbents in the treatment of polluted aqueous solutions.

Water pollution by heavy metal ions such as Pb occur globally. The conventional methods for the heavy metal ions removal from the water include electrochemical and chemical precipitations, ion exchange, reverse osmosis and sorption. Among the above mentioned different methods, sorption of heavy metal ions on the surface of solid nanomaterials is one of the most recommended and interest methods. Sorption is attractive due to its merits of efficiency, cheap and simple operation. In this study, hematite/magnetite/iron nanocomposite (MHINC) is synthesized by the low voltage electrical arc method in the presence of 1.2 Tesla external magnetic fields. Scanning electron microscopy and transmission electron microscopy show that the synthesized MHINC includes uniform nanoparticles with 7 nm average diameters. The prepared MHINC is used as a new sorbent to remove heavy metal ions from polluted waters. Experimental data shows that the sorption of lead ions on the surface of MHINC is acceptably fitted to the Langmuir isotherm. Based on the experimental data, a maximum sorption capacity of 86 mg g-1 is achieved for the sorption of lead ions on the surface of MHINC. The experimental optimum conditions for the lead ion removal includes pH=5, 25 ml sample volume, 25 mg sorbet and 25 min mixing time in the room temperature. Desorption studies showed the adsorbed lead ions on MHINC surface can be done by using 1ml acidic solution containing 3 M HCl and 2 M HNO3.