Level Of Cu2 Research Articles

A Novel Quinoline Derivative for Selective and Sensitive Visual Detection of PPB Level Cu2+ in an Aqueous Solution

Aim: Selective and sensitive visual detection of Cu2+in aqueous solution at PPB level using easily synthesized compound. Background: The search for a chemosensor that can detect Cu2+ is very long owing to the fact that an optimum level of Cu2+ is required for human health and the recommended amount of Cu2+ in drinking water is set to be 1-2 mgL-1 . Thus, it is very important to detect Cu2+ even at a very low concentration to assess the associated health risks. Objective: We are still seeking for the easiest, cheapest, fastest and greenest sensor that can selectively, sensitively and accurately detect Cu2+ with lowest detection limit. Our objective of this work is to find one such Cu2+ sensor. Methods: We have synthesized a quinoline derivative following very easy synthetic procedures and characterize the compound by standard methods. For sensing study, we used steady state absorption and emission spectroscopy. Results: Our sensor can detect Cu2+ selectively and sensitively in aqueous solution instantaneously even in the presence of excess amount of other salts. The pale-yellow color of the sensor turns red on the addition of Cu2+ . There is no interference from other cations and anions. A 2:1 binding mechanism of the ligand with Cu2+ is proposed using Jobs plot with binding constant in the order of 109 M-2 . We calculated the LOD to be 18 ppb, which is quite low than what is permissible in drinking water. Conclusion: We developed a new quinoline based chemo-sensor following straightforward synthetic procedure from very cheap starting materials that can detect Cu2+ visually and instantaneously in aqueous solution with ppb level sensitivity and zero interference from other ions.

Synthesis of orange-emissive silicon nanoparticles as “off-on” fluorescence probe for sensitive and selective detection of l-methionine and copper

Fluorescent silicon nanoparticles (Si NPs) are of great interest as they are free of heavy ions. However, most of Si NPs exhibit blue or green emission, while orange or red-emitting Si NPs are required for an extensive range of applications. Copper ion (Cu2+) and l-methionine (L-Met) detection is critically valuable point since their abnormal level is an indicator of various diseases. In this work, we illustrate an “off-on” method for sensitively and selectively determination of Cu2+ and L-Met using Si NPs as fluorescent probe. The Si NPs emitting orange fluorescence with the quantum yield of 2.23% were prepared via one and easy step of hydrothermal treatment of 3(2-aminoethylamino) propyl (dimethoxymethylsilane) (AEAPDMMS) and 2–aminophenol as precursors. The fluorescence of Si NPs was quenched in the presence of Cu2+ due to the strong metal-ligand coordination and electrostatic interactions between the large amount of amino and hydroxyl groups on the surface of Si NPs and Cu2+. Surprisingly, the resulted non-fluorescent Si NPs-Cu2+ complex displayed a fluorescence “turn-on” toward L-Met, due to the competitive coordination of Cu2+ between L-Met and Si NPs which leads to the unique “off-on” response to L-Met after the release of free Si NPs. The as-proposed approach is fast, simple, low cost and environmental-friendly. More importantly, it has been applied in the determination of Cu2+ and L-Met in water and urine samples, respectively with satisfactory recoveries. Furthermore, the approach could detect Cu2+ and L-Met with detection limit of 0.012 μM and 0.07 μM, which are lower than the level of Cu2+ in drinking water and of L-Met in human urine sample (maximum ~20 μM and ~5.9 μM, respectively).

A pilot-scale sulfur-based sulfidogenic system for the treatment of Cu-laden electroplating wastewater using real domestic sewage as electron donor

Elemental sulfur (S0) reduction process has been demonstrated as an attractive and cost-efficient approach for metal-laden wastewater treatment in lab-scale studies. However, the system performance and stability have not been evaluated in pilot- or large-scale wastewater treatment. Especially, the sulfide production rate and microbial community structure may significantly vary from lab-scale system to pilot- or large-scale systems using real domestic sewage as carbon source, which brings questions to this novel technology. In this study, therefore, a pilot-scale sulfur-based sulfidogenic treatment system was newly developed and applied for the treatment of Cu-laden electroplating wastewaters using domestic sewage as carbon source. During the 175-d operation, >99.9% of Cu2+ (i.e., 5580 and 1187 mg Cu/L for two types of electroplating wastewaters) was efficiently removed by the biogenic hydrogen sulfide that produced through S0 reduction. Relatively high level of sulfide production (200 mg S/L) can be achieved by utilizing organics in raw domestic sewage, which was easily affected by the organic content and pH value of the domestic sewage. The long-term feeding of domestic sewage significantly re-shaped the microbial community in sulfur-reducing bioreactors. Compared to the reported lab-scale bioreactors, higher microbial community diversity was found in our pilot-scale bioreactors. The presence of hydrolytic, fermentative and sulfur-reducing bacteria was the critical factor for system stability. Accordingly, a two-step ecological interaction among fermentative and sulfur-reducing bacteria was newly proposed for sulfide production: biodegradable particulate organic carbon (BPOC) was firstly degraded to dissolved organic carbon (DOC) by the hydrolytic and fermentative bacteria. Then, sulfur-reducing bacteria utilized the total DOC (both DOC degraded from BPOC and the original DOC present in domestic sewage) as electron donor and reduced the S0 to sulfide. Afterwards, the sulfide precipitated Cu2+ in the post sedimentation tank. Compared with other reported technologies, the sulfur-based treatment system remarkable reduced the total chemical cost by 87.5‒99.6% for the same level of Cu2+ removal. Therefore, this pilot-scale study demonstrated that S0 reduction process can be a sustainable technology to generate sulfide for the co-treatment of Cu-laden electroplating wastewater and domestic sewage, achieving higher Cu2+removal and higher cost-effectiveness than the conventional technologies.

Activated Bentonite Modified-Carbon Paste Electrode for Determination The Level of Copper Ion (Cu2+) in Tomato

Voltammetry is an electroanalytical method measure current as a function of applied potential. The working electrode in the voltammetry method dramatically affects the result of the electrochemical analysis. Modification of the working electrode can improve measurement performance. In this research, the carbon paste electrode (CPE) was modified with Bentonite (CPEB) to determine copper's level using differential pulse voltammetry technique. CPE and CPEB were used as working electrodes, handmade Ag/AgCl as a reference electrode, and Pt wire as the counter electrode. The measurement parameters were optimized, including the composition of bentonite in carbon paste and scan rates. Furthermore, the measurement conditions were validated, involved linear concentration range, detection limit (LoD), the limit of quantization (LoQ), repeatability, and recovery. The results showed that bentonite's optimum composition was 40% of the total weight of graphite and activated bentonite. The scan rate optimum for Cu2+ measurement was obtained at 20 mV/s with CPE and became faster to be 25 mV/s with CPEB. The linearity of the standard solution measurement of Cu2+ using CPE was in the range of 5 to 100 μg/L and changed to 5 to 500 μg/L using CPEB. LoD and LoQ values of standard solution Cu2+ measurement with CPEB were slower than CPE. The Horwitz ratio calculation was smaller than two for both CPE and CPEB. The recovery of Cu2+ standard measure in sample solution as the matrix was obtained 93,49 ± 6,39%. According to the Decree of the Ministry of Health Number, the level of Cu2+ in the tomato sample was found 6.019 ± 0.69 mg/kg, which is over than threshold value of Cu2+ (5 mg/kg) 03725/B/SK/VII/89.

A fast, highly selective and sensitive colorimetric and fluorescent sensor for Cu2+ and its application in real water and food samples.

A new oligothiophene functionalized Schiff base sensor 3TDC has been successfully designed and synthesized. Sensor 3TDC exhibited "naked-eye" colorimetric and selective "on-off" fluorescence response toward Cu2+ with high selectivity and sensitivity within a wide pH range. The binding ratio of the sensor 3TDC and Cu2+ was determined to be 1:1 through fluorescence titration, Job's plot, 1H NMR titration, FTIR and DFT studies. The detection limit is calculated to be as low as 2.81 × 10-8 M, which is much lower than the allowable level of Cu2+ in drinking water set by U.S. Environmental Protection Agency (~20 μM) and the World Health Organization (~30 μM). The binding constant (Ka) of Cu2+ to sensor 3TDC was found to be 2.52 × 104 M-1. Sensor 3TDC for Cu2+ detection exhibited fast fluorescence response within 30 s and high anti-interference performance. Moreover, sensor 3TDC could be used as an effective fluorescent sensor for detecting Cu2+ ions in various real water and food samples with good accuracy and high precision.

A highly selective colorimetric chemosensor for copper(II) based on N-phenyl-N’-(pyridin-2-yl)thiourea(HPyPT)

An efficient synthesis and applications of a N-Phenyl-N’-(pyridin-2-yl)thiourea(HPyPT) as a chemosensor for the selective detection of Cu2+ over other common metal ion is described. The HPyPT chemosensor could detect Cu2+ by forming 1:1 complex in acidic media. The complex exhibits maximum absorption at 393nm with molar absorptivity 5.795×103lmol−1cm−1 and Sandell’s sensitivity was found to be 0.01096μgcm−2 of Cu2+; Beer’s law is obeyed in the range of 1μgcm−3–14μgcm−3. The standard deviation for ten replicate samples at 10μgcm−3 level of Cu2+ is found to be 0.08. The detection limit was found to be 0.065μgcm.−3 The yellowish green coloured complex of Cu2+ with HPyPT is stable up to 12h. Under optimized conditions, the HPyPT shows excellent sensitivity and selectivity for Cu2+ over a series of metal ions such as Fe2+, Fe3+, Al3+, Zn2+, Sn2+, Ni2+, Mn2+ Co2+, Cr+2, Cd+2, Hg2+, Au+3and Mg2+. The present chemosensor shows stable and consistent yellowish green coloration in acetic acid and there is no need to use buffer solutions for complexation. Moreover, the application of the present chemosensor was extended for the detection of Cu2+ from water, copper alloys such as brass and Monel metal.

Sensitive and selective ratiometric nanosensors for visual detection of Cu2+ based on ions promoted oxidation reaction

Copper is a highly toxic environmental pollutant in the environmental, biological and chemical fields. Therefore, sensitive, selective and visual detection of Cu2+ is very important for human health and practical applications. Herein, a novel hybrid ratiometric fluorescent nanosensor was developed for rapid and on-site visualization of Cu2+ on the basis of integrating benzothiazole fluorophore (MDBT) and red-emissive quantum dots (QDs) embedded in silica nanospheres. Such hybrid ratiometric fluorescent nanosensor exhibits dual emissions at 420 and 640nm under a single excitation wavelength. Due to the ions promoted oxidation reaction of Cu2+ towards MDBT, the fluorescence of MDBT can be selectively enhanced. Although the embedded QDs are insensitive to the analyte, variations of the dual emission intensity ratios display continuous colour changes from red to blue. The ratiometric fluorescent approach shows high sensitivity and selectivity towards Cu2+ against other interfering metal ions. The detection limit of Cu2+ for the hybrid ratiometric fluorescent nanosensor is determined to be 41.71nM, which is much lower than the allowable level of Cu2+ (∼20μM) in drinking water set by U.S. Environmental Protection Agency. Furthermore, this kind of novel nanosensor can also be applied for Cu2+ detection in actual water samples and exhibits excellent detection ability. This hybrid ratiometric fluorescent nanosensor is simple, fully self-contained and thus potentially attractive for visual identification without the need of elaborate equipments.

Dihydroquinazolinone based “turn-off” fluorescence sensor for detection of Cu2+ ions

A strategy for the synthesis of a dihydroquinazolinone derivative, 2-(pyridine-2-yl)-2,3-dihydroquinazolin-4(1H)-one and its application in selective recognition of Cu2+ ions has been developed. The sensor shows “turn-off” type paramagnetic fluorescence quenching towards Cu2+ ions. The binding constant (Ka) of Cu2+ ions with the sensor was found to be 8.02 × 104 M−1 and binding stoichiometry was determined to be 1:1 based on the Job's plot analysis. The sensor can detect up to nanomolar (0.1 nM) level of Cu2+ ions from tap water. The single crystal of the QZP·Cu2+Cl·H2O complex was characterized using X-ray diffraction and the paramagnetic nature of Cu2+ was manifested by electron spin resonance (ESR) spectroscopy.

Cu nanoclusters-based ratiometric fluorescence probe for ratiometric and visualization detection of copper ions

Copper is a highly toxic environmental pollutant with bioaccumulative properties. Therefore, sensitive detection of Cu2+ is very important to prevent over-ingestion, and visual detection is preferred for practical applications. In this work, we developed a simple and environmental friendly approach to synthesize hyperbranched polyethyleneimine-protected copper nanoclusters (hPEI-Cu NCs) with great stability against extreme pH, high ionic strength, thiols etching and light illumination, which were then conjugated to the surface of silica coated CdSe quantum dots (QDs) to design a ratiometric fluorescence probe. In the presence of different amounts of Cu2+ ions, the fluorescence of Cu NCs can be drastically quenched, while the emission from QDs stayed constant to serve as a reference signal and the color of the probe changed from yellow-green to red, resulting in ratiometric and visualization detection of Cu2+ ion with high accuracy. The detection limit for Cu2+ was estimated to be 8.9 nM, much lower than the allowable level of Cu2+ in drinking water (∼20 μM) set by U.S. Environmental Protection Agency. Additionally, this probe can be also applied for the determination of Cu2+ ion in complex real water samples.

Luminescence Enhancement of ZnS:Cu Nanocrystals by Zinc Sulfide Coating with Core/Shell Structure

Via wet chemical method with organic assistant, ZnS:Cu/ZnS core/shell structure was prepared. X-ray diffraction measurements showed that ZnS:Cu was formed with zinc blende structure, and ZnS shell growth on the surface was indicated through a red-shift in the UV-Vis absorption spectra with increasing particle size. The emission peak at about 510 nm was observed, which should be assigned to recombination of an electron from the shallow delocalized donor levels at the t2 level of Cu2+ centers. As passivation layer, effect of ZnS shell on luminescence intensity and lifetime of ZnS:Cu were investigated. Comparing with uncoated ZnS:Cu, ZnS shell really enhanced the luminescence intensity and lifetime significantly, which resulted from the reduction of nonradiative recombination sites.

重金属胁迫对毛竹种子萌发及其富集效应的影响

Along with the increase of economics,heavy metal pollution in soil directly threatens food production security,and the toxicity affects humans because of their longevity and accumulation in organs. Phytoremediation is a new technology that usually employ hyperaccumulator plants to remove pollutants from environment or to render them harmless. The biomass of hyper-accumulators discovered before are less,and as a result in actual applications the hyper-accumulators are restricted significantly. Moso bamboo( Phyllostachy pubescens) is not hyperacculator specie,but it has several advantages compared with hyperaccumulators. Moso bambo grows quickly,reaching maximum size within two months with an average height of15 m. In present paper the seeds of Moso bamboo are taken as test materials,the toxicity effects of four heavy metals involving Pb2+,Zn2+,Cu2+and Cd2+on seed germination and its accumulation of heavy metals were studied. The results indicated that:( 1) The addition of Pb2+and Cd2+inhibited the germination rate,germination energy,germination index and vigor index of Moso bamboo seed significantly. For the low treatment level of Cu2+and Zn2+,the germination rate,germination energy,germination index and vigor index increase significantly,while the results were on the contrary for the high treatment level. When the treatment dosage reached to 1600 μmol / L,the Cd2+addition has strong inhibition on seed germination than other three heavy metals.( 2) The addition of low levle of Pb2 +and Zn2+would promote the root growth significantly,while with the stress of Cu2+and Cd2+the root morphology are inhibited.( 3) The concentration of Pb2+,Zn2+,Cu2+and Cd2+in shoots of Moso bamboo reached 6810.51,1387.77,951.77 and 429.33 mg / kg respectively after treating for10 d. The translocation factor dimension is Zn2+Cd2+ Pb2+ Cu2+,and the tolerance order of bamboo seedlings to heavy metal is: Zn2+Pb2+ Cu2+Cd2+. In summary,the results of above all would provide useful reference for soil test in future,and it also opens a new perspective for the study of phytoremediation species selection.

Synthesis, surface characterization and optical properties of 3-thiopropionic acid capped ZnS:Cu nanocrystals

3-Thiopropionic acid (TPA) capped ZnS:Cu nanocrystals have been successfully synthesized by simple aqueous method. Powder X-ray diffraction (XRD) studies revealed the particle size to be 4·2 nm. Surface characterization of the nanocrystals by FTIR spectroscopy has been done and the structure for surface bound TPA based on spectral analysis was proposed. The optical studies were done using UV-VIS spectroscopy and particle size and diameter polydispersity index (DPI) were calculated. Photoluminescence (PL) spectrum reveals emission related to the transition from conduction band of ZnS to t 2 level of Cu2 + . Electron microscopy was also done by scanning electron microscopy (SEM).

Synthesis and photoluminescence of ZnS:Cu nanoparticles

The room-temperature photoluminescence (PL) of copper doped zinc sulfide (ZnS:Cu) nanoparticles were investigated. These ZnS:Cu nanoparticles were synthesized by a facile wet chemical method, with the copper concentration varying from 0 to 2 mol%. By Gaussian fitting, the PL spectrum of the undoped ZnS nanoparticles was deconvoluted into two blue luminescence peaks (centered at 411 nm and 455 nm, respectively), which both can be attributed to the recombination of the defect sates of ZnS. But for the doped samples, a third peak at about 500 nm was also identified. This green luminescence originates from the recombination between the shallow donor level (sulfur vacancy) and the t(2) level of Cu2+. With the increase of the CU2+ concentration, the green emission peak is systematically shifted to longer wavelength. In addition, it was found that the overall photoluminescence intensity is decreased at the Cu2+ concentration of 2%. The concentration quenching of the luminescence may be caused by the formation of CuS compound. (c) 2005 Elsevier B.V. All rights reserved.

PH-Dependent Association of Factor VIII Chains: Enhancement of Affinity at Physiological pH by Cu2+.

Factor VIII circulates as a heterodimer composed of a heavy chain (HC) and light chain (LC). The structural integrity of the heterodimer is crucial for factor VIII function. In this study we found that the reconstitution of factor VIII from isolated HC and LC was pH-dependent. In the presence of Ca2+, up to 80% of native factor VIII activity was recovered over a wide range of pH values. The affinity of HC and LC was maximal at pH 6.5-6.75 (Kd ~ 4 nM), whereas a Kd of ~20 nM was observed at physiological pH (7.25) (Figure). The effect of Cu2+ (0.5 μM total Cu2+) on maximal activity regenerated was negligible at pH 6.25–8.0. However, this level of Cu2+ increased the inter-chain affinity by ~5 fold at pH 7.25 (Figure). This effect resulted from an ~1.5-fold increased association rate constant (kon) and an ~3-fold reduced dissociation rate constant (koff). Addition of Cu2+ to a mixture of HC and LC at equilibrium resulted in an increase in cofactor activity that followed a single exponential, suggesting that association was defined by a simple reaction model. High affinity (Kd = 5.3 fM) of the factor VIII chains for Cu2+, as estimated by increases in cofactor activity, suggested a rapid association rate for the metal ion. Together, these results suggest that the protonation state of specific residues, His in particular, modulate inter-chain affinity. Furthermore, copper ion contributes to the maintenance of the heterodimer at physiologic pH by a mechanism consistent with bridging the two chains. [Display omitted]

Photoluminescence of doped ZnS nanoparticles under hydrostatic pressure

AbstractThe pressure dependence of the photoluminescence from ZnS:Mn2+, ZnS:Cu2+, and ZnS:Eu2+ nanoparticles were investigated under hydrostatic pressure up to 6 GPa at room temperature. Both the orange emission from the 4T1 – 6A1 transition of Mn2+ ions and the blue emission from the DA pair transition in the ZnS host were observed in the Mn‐doped samples. The measured pressure coefficients are –34.3(8) meV/GPa for the Mn‐related emission and –3(3) meV/GPa for the DA band, respectively. The emission corresponding to the 4f65d1 – 4f7 transition of Eu2+ ions and the emission related to the transition from the conduction band of ZnS to the t2 level of Cu2+ ions were observed in the Eu‐ and Cu‐doped samples, respectively. The pressure coefficient of the Eu‐related emission was found to be 24.1(5) meV/GPa, while that of the Cu‐related emission is 63.2(9) meV/GPa. The size dependence of the pressure coefficients for the Mn‐related emission was also investigated. The Mn emission shifts to lower energies with increasing pressure and the shift rate (the absolute value of the pressure coefficient) is larger in the ZnS:Mn2+ nanoparticles than in bulk. Moreover, the absolute pressure coefficient increases with the decrease of the particle size. The pressure coefficients calculated based on the crystal field theory are in agreement with the experimental results. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)