Copper Ions In Aqueous Solution Research Articles

Colorimetric chemosensor for Cu(II) from electrospun nanofibrous mat mixed with 5‐methoxy‐salicylaldehyde azine

AbstractThe condensation product of 5‐methoxy‐salicylaldehyde with hydrazine hydrate (referred to below as compound 1) was used as a ligand in a cellulose acetate electrospun nanofibrous mat to determine copper ions in aqueous solutions. The electrospun nanofibrous mats, based on cellulose acetate mixed with compound 1, were constructed using an electrospinning method and had a diameter of 260 nm. The sensing nanofibrous mat exhibited a sensitive and selective response for Cu(II) ions over a linear concentration range of 1‐30 µM in a 0.1 M HEPES buffer (pH 7.4) using a colorimeter. The detection limit of the method was 1.04 µM lower than the maximum level of Cu(II) in drinking water (16 µM, as determined by the US Environmental Protection Agency). Additionally, it exhibited high selectivity for Cu(II) ions over 13 other cations. The sensing nanofibrous mat was fully reversible for ethylenediamine tetraacetic acid treatment cycles. Preliminary results indicated the sensitivity and selectivity of the nanofibrous mat for detecting Cu(II) ions by naked‐eye detection from yellow to orange. The reaction product of compound 1 and the Cu(II) ion was studied using X‐ray absorption spectroscopy. The Cu‐coordination number was approximately 5.023 ± 1.42, and the Cu–N distance (R) was 1.986 Å. The nanofibrous mat demonstrated a convenient and straightforward Cu(II) ion‐detection technique in both wastewater and water environments.

Biosorption of copper ions from aqueous solution using Kappaphycus striatum

Biosorption is an eco-friendly alternative technology for the removal of heavy metals from industrial waste and effluents using low-cost and effective biosorbent. Abundant of natural materials like agricultural biomass, industrial waste, and microbial biomass can be used as a promising biosorbent. In the present study, red algae Kappaphycus striatum biomass will be used for the adsorption of copper ions in aqueous solution. The free (non-immobilized) and immobilized form of red algae Kappaphycus striatum biomass and biosorption rate were investigated for the adsorption process. The maximum biosorption of copper ions was achieved when immobilized form of algae biomass were used at the condition pH of 5, biomass dosage, 0.25 g/L, contact time of 90 minutes, and at the temperature of 50 °C with a 65.8% of removal. The experiment data for biosorption rate with time also was used to evaluated two kinetic models (pseudo-first-order and pseudo-second-order) and two isotherm models (Langmuir and Freundlich). The results reveal that metallic ions biosorption on the immobilized Kappaphycus striatum followed the pseudo-second-order kinetic model with a R 2=0.9996 and Langmuir isotherm model with a R 2=0.9999. The present work shows that the red algae of Kappaphycus striatum as a potential biosorbent for the removal of heavy metal ions from aqueous solution.

Facile room temperature synthesis of ultra-small sized porous organic cages for fluorescent sensing of copper ion in aqueous solution

Facile synthesis of nano porous organic cages with small size and good fluorescence property is highly desirable, but still challenging and scarce for their sensing applications. Here we report a rapid room-temperature recrystallization method for the preparation of nano porous organic cages with ultra-small size as a fluorescent probe for copper ion. The prepared nano porous organic cages gave the diameter of 2.49 ± 0.04 nm, and exhibited stable emission at 535 nm with absolute quantum yield of 0.68%. On the basis of the coordination interaction and charge transfer between the nano porous organic cages and copper ion, a simple fluorescent probe for copper ion in aqueous solution was developed. The developed method gave a calibration function of QE = 0.4815lg[Cu2+] + 0.5847 (where QE is the quenching efficiency; [Cu2+] in μM) (R2 = 0.9987) in a concentration range of 0.1–2 μM, the limit of detection (3s) of 8 nM, and the relative standard deviation of 0.36% for 10 replicate determinations of 0.5 μM copper ion. The recoveries of spiked copper ion in tap water samples ranged from 96.8% to 103.0%. The proposed method possesses good sensitivity, selectivity and accuracy.

Fabrication of imprinted photonic films via predesigned multiple UV‐polymerizations and their ability to detect solvents and metal ions in aqueous solution

AbstractTo synthesize photonic films without a chiral dopant, a predesigned multiple photopolymerization process was carried out. The photonic films were prepared by the photopolymerization of a mixture of chiral nematic liquid crystals. After polymerization, the chiral dopant, CB15, was removed and recycled. The imprinted photonic polymer films showed Bragg reflection without the presence of the chiral dopant. Upon the sensing of solvents in aqueous solution, significant color changes and peak shifts were observed by the naked eye and ultraviolet–visible spectroscopy, respectively. A linear calibration curve between the central wavelength of the reflection band of the fabricated imprinting film and the volume ratio of 1,4‐dioxane in water was observed. Furthermore, the sensing of chloroform content in methanol, ethanol, and acetone via the imprinted film were also investigated. The results suggest that the synthesized imprinted photonic films can detect different kinds of mixed solvents. The sensing properties of the photonic films were further improved by copolymerization with a rhodamine‐derived monomer. The synthesized modified photonic films can detect heavy metal ions in aqueous solution. This study reports a novel, recyclable, and easy approach to detect organic solvents and copper ions in aqueous solution.

One-Step Synthesis of the Nitrogen and Sulfur Codoped Carbon Dots for Detection of Lead and Copper Ions in Aqueous Solution

Herein, by using the green and cheap L-cysteine as the precursor, nitrogen and sulfur codoped carbon dots (NS-CDs) were synthesized via a facile one-step hydrothermal method. The obtained NS-CDs showed the relatively narrow size distributions (2.1~3.9 nm) with the lattice spacing of 0.29 nm, as well as the excitation-dependent photoluminescence (PL) emission activity with the quantum yield (QY) of 18%. More interestingly, the PL intensity of NS-CDs was quenched by the addition of copper or lead ions (Cu2+ or Pb2+), which was shown in the tradition detection method by PL spectra. The NS-CDs exhibited ultrasensitive colorimetric sensing capability for both Cu2+ and Pb2+ by the color variance using naked eyes without any further treating. Two different coupling ways for detecting Pb2+ and Cu2+ were induced by the analysis of the Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). And the as-prepared NS-CDs showed their potential application in the heavy metal ions detection for the wastewater determination.

Highly fluorescent hematoporphyrin modified graphene oxide for selective detection of copper ions in aqueous solutions

Here, a highly sensitive and selective copper ion (Cu2+) fluorescence sensor is reported. The Hematoporphyrin functionalized Graphene Oxide (HP-GO) fluorescence sensor were synthesized via esterification reaction between Graphene Oxide and Hematoporphyrin (HP). The HP-GO sensor was fully characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), Scanning Electrom Microscopy (SEM), UV–Vis spectroscopy, Transmission Electron Microscopy (TEM), Fluor meter spectroscopy, X-Ray photoelectron spectroscopy(XPS), and Raman spectroscopy measurements. The HP-GO sensor advertised two linear regions over the range of 0–1.18 × 103 nM and 3.93 × 103 to 47.27 nM of copper (II) with detection limit of 54 nM in the aqueous solution. The selectivity of HP-GO for Cu2+ is much higher than that of other metal ions due to the presence of aza macrocyclic ring on the surface of HP-GO which has a high binding affinity with Cu2+. Additionally, the HP-GO shows wide pH viable range (pH 6–10). The effect of other metal ions on the fluorescence intensity of the HP-GO was also studied and other metal ions show a low interference response in the detection of Cu2+. HP-GO sensor manifests advantages of high reproducibility (The quenched fluorescence of HP/GO-Cu can be recovered by EDTA), attractive long term fluorescence stability (>21 days) in water, also remarkable selectivity regarding number of metal ions (Na+, K+, Ca2+, Fe3+, Fe2+, Al3+, Pb2+, Mn2+, Mg2+, Co2+, Ni2+, Cr6+, Cd2+, Hg2+, and Zn2+), low toxicity and can detect Cu2+ in real water samples which acquire well for its promising in environmental applications.

Chitosan-PEO nanofiber mats for copper removal in aqueous solution using a new versatile electrospinning collector

Electrospun chitosan–polyethylene oxide nanofiber mats were fabricated using a new collector design. Besides being reusable, it allows to assess the desired morphology of the mat in a quicker way. To test its efficiency, nonwoven mats designed for water treatment applications were prepared using conditions never been reported before. Under these conditions, continuous and flawless nanofibers of 151 ± 36 nm in diameter were achieved. Adsorption capacity of the mats for copper ions in aqueous solutions were investigated. Results showed that sorption equilibrium was achieved within 150 min with a homogenous distribution of copper ions within the nanofibrous mats. The pseudo-second order kinetic model best fitted the experimental data. The Langmuir isotherm best described the sorption process with a maximum adsorption capacity of 124 mg/g for trial temperatures ranging from 25 to 60 °C. Thermodynamic parameters (ΔG°, ΔH° and ΔS°) demonstrate that the adsorption was feasible, endothermic and spontaneous. The desorption potential and mat’s reusability were also studied. Results reveal that the electrospun chitosan mats can be desorbed and reused up to 5 cycles without significant loss in adsorption performance.

A selective and sensitive sequential ratio/“turn-off” dual mode fluorescent chemosensor for detection of copper ions in aqueous solution and serum

A selective and sensitive sequential ratio/“turn-off” dual mode fluorescent chemosensor BTP-LU for multi-fluorescence signals recognition of Cu2+ based on benzothiazole skeleton has been constructed. The structure of the probe BTP-LU and compound 1 have been confirmed by NMR and HRMS. At low concentration of Cu2+, the ratio fluorescence signals are attributed to the recovery of ESIPT process BTP by Cu2+ induced hydrolysis of the 2-picolinic formate in BTP-LU. When at high concentration of Cu2+, the fluorescence emission intensity gradually decreased, which might be attributed to the chelation of the produced compound BTP with Cu2+ to enhance the fluorescence quenching effect. Moreover, the probe BTP-LU has been successfully used to detect Cu2+ in calf serum and bovine serum albumin solution. This may provides a new analytical tool for detecting Cu2+ in solution and serums.

Influence of Organic Dye Ligands on the Photocatalytic Reduction of Copper Ions in Aqueous Solution Using UV-Nano TIO2 System

This study investigates the influence of some organic dyes on the photocatalytic reduction of Cu (II) ions in aqueous solution. The dyes of interest were Eosin red, Eriochrome black T, Bromothymol blue and Malachite green. Slurry photoreactor design, with nano-sized titanium dioxide photocatalysts, and illuminated by a 15 W UV light, was utilized. Results showed that the percentage reduction of Cu (II) ions altered from 44.7% (without dye) to 25.7% (with ER), 60.7% (with EBT), 15.2% (with BTB) and 17.8% (with MG) after 60 minutes reaction time at pH 5. This implies that EBT enhanced Cu (II) ions reduction while the other three dyes inhibited the photoreduction process. The kinetic study indicated that the photo-reduction of Cu (II) ions followed the pseudo-first-order kinetics, with the exception of Cu-MG reduction which gave the best correlation values in zeroth-order plot. Statistical analysis was carried out with the ANOVA, Dunnetts post-hoc and Tukeys post-hoc multiple comparison tests. Tukeys post-hoc multiple comparison test was effected to determine the pair of Cu (II) ions with significant difference in mean values while Dunnetts post-hoc was effected to compare the measured values with the initial values. Photoreduction of Cu (II) ions were considered significant at P< 0.05 and 95% confidence interval.

A benzothiazolinic spiropyran for highly selective, sensitive and visible light controlled detection of copper ions in aqueous solution

A benzothiazolinic-spiropyran based optical receptor was synthesized with suitable donor group ortho to the phenolic oxygen atom. The structure was established through 1H, 13C-NMR, HRMS techniques. Owing to the presence of donor group at a suitable position, it was screened for affinity toward metal ions. The receptor detected the presence of copper ions in aqueous buffered acetonitrile solution by producing a reddish-orange color. The receptor displayed 0.75 μM as the limit of the detection value towards copper ions. The receptor successfully released the copper ions upon irradiation with a light of 532 nm. Test strips coated with spiropyran derivative were developed, which were used for the detection of copper ions in aqueous solution. The DFT calculations indicated that the CTT stereoisomer of the merocyanine form is more stable, while TTT stereoisomer forms the most stable complex with Cu2+ ions. The DFT calculations were further used to calculate the preorganization energies required for the complex formation between the receptor and the copper ions. DFT studies indicated higher than usual stability of the CCC stereoisomer of the merocyanine form, which promoted the reversibility. In addition, the calculations indicated that the copper ion reduced the activation energy barrier for the ring-opening process. TD-DFT calculations were used to investigate the observed absorption band for the receptor and the complex.

Adsorption mechanism of copper ions in aqueous solution by chitosan–carboxymethyl starch composites

ABSTRACTBased on the structural characteristics of chitosan (CTS) and carboxymethyl starch (CMS)， CTS–CMS composites were prepared by crosslinking. The composites had a plurality of reactive functional groups such as NH2, NH3+, COOH, and OH and are applied to the adsorption of Cu2+ in aqueous solution. The adsorption capacity and stability in acidic solution of the composites were preferable to that of raw material. The effects of temperature, contact time, initial concentration, and pH on the adsorption of Cu2+ were investigated. Infrared spectroscopy, scanning electron microscope–energy dispersive spectrometer, X‐ray diffraction, and X‐ray photoelectron spectroscopy were used to explore the adsorption mechanism. The experiment showed that chemisorption and physisorption coexisted in the adsorption process. It is promising to apply this adsorbent to remove the metal ions in wastewater. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48636.

Preparation of high-concentration colloid solutions of metallic copper particles and their use in metal–metal bonding processes

A high-concentration colloid solution of metallic copper nanoparticles was prepared by the reduction of copper ions in aqueous solutions, and the nanoparticles were used to study metal–metal bonding. The colloid solution of metallic copper nanoparticles was prepared by mixing an aqueous solution of CuCl2 and an aqueous solution of hydrazine (reductant) in the presence of citric acid and n-hexadecyltrimethylammonium bromide (stabilizers) at a final copper concentration as high as 0.1 M. The copper-particle size was ca. submicrometer. Many tiny particles with sizes of ca. 10–20 nm were deposited on the submicron-sized particles at high hydrazine concentrations. The tiny particles were considered to be produced through the growth of particle nuclei generated at the final reaction stage by residual hydrazine derived from the high hydrazine concentration. Metallic-copper discs were successfully bonded by annealing at 400 °C and a pressure of 1.2 MPa for 5 min in hydrogen gas with the help of the metallic-copper particles. The shear strength of the bonded copper discs was then measured. The highest shear strength of 41.7 MPa was recorded for the tiny particles/immobilized particles, which could be explained by the low melting points of the tiny particles and the increase in bulk density provided by the dominant incorporation of the tiny particles into voids between the submicron-sized particles.

Preparation of Carbon Aerogel Electrode for Electrosorption of Copper Ions in Aqueous Solution.

Carbon aerogel (CA) has a rich porous structure, in which micropores and mesopores provide a huge specific surface area to form electric double layers. This property can be applied to the application of capacitive deionization (CDI). The adsorption effect of CA electrode on Cu2+ in an aqueous solution was explored for solving heavy metal water pollution. The CAs were synthesized by a sol-gel process using an atmospheric drying method. The structure of CAs was characterized by scanning in an electron microscope (SEM) and nitrogen adsorption/desorption techniques. The adsorption system was built using Cu2+ solution as the simulation of heavy metal pollution solution. The control variate method was used to investigate the effect of the anion species in copper solution, the molar ratio of resorcinol to catalyst (R/C) of CA, and the applied voltage and concentration of copper ion on the adsorption results.

Preparation of activated carbon from kenaf by activation with H3PO4. Kinetic study of the adsorption/electroadsorption using a system of supports designed in 3D, for environmental applications

•Activated carbons were prepared from kenaf by chemical activation with phosphoric acid in different concentrations. Its electrical conductivity was also determined. From the series of prepared activated carbons, those with better textural properties, chemistry and high electrical conductivity were selected for their use in adsorption and electroadsorption processes.•The removal of Cu (II) ions from aqueous media is of great interest due to their harmful effects on health and environment. The aim of this work was to study the kinetics in the process of retention of copper ions in aqueous solution by adsorption and electroadsorption using activated carbon. Thus, when comparing both processes it was observed that the adsorption equilibrium times were generally greater than those corresponding to electroadsorption. Different kinetic models were applied. The kinetic models applied to the adsorption/electroadsorption processes indicated that the pseudo-second order model described both processes in a better way than the pseudo-first order model. The values of R2 in electroadsorption kinetics were closer to 1 than those obtained in adsorption kinetics. Therefore, it can be affirmed that the pseudo-second order model for the samples, object of study, is better adjusted to the electroadsorption process.

Complexes of Polyethyleneimine with Cu2+ Ions in Aqueous Solutions as Precursors for Obtaining Copper Nanoparticles

The regularities of the formation of a polyethyleneimine complex with copper ions in aqueous solutions have been studied. It has been shown that the complex of polyethylenimine with copper ions is formed according to the principle of uniform distribution of ions over a macromolecule, and the composition of the complex may vary depending on the molar ratio of reagents and pH of the medium. The synthesis of copper nanoparticles has been carried out under conditions where copper ions are complexed with polyethyleneimine macromolecules. According TEM, it has been found that the copper polyethylenimine complex used as a precursor makes it possible to obtain copper particles with a diameter of 1.4 nm and a narrow size distribution.

DTT–Au NCs Interact with DNA to Form Raspberry‐Like Particles

AbstractNoble metal nanoclusters (NCs) have emerged as intriguing nanomaterials with widespread interest. Previously, it was shown that dithiothreitol (DTT)‐conjugated gold nanoclusters (Au NCs) respond to copper ions in aqueous solution. Here, it is shown that these DTT–Au NCs can interact with DNA by forming raspberry‐like particles. The raspberry‐like structures protect the capped DNA from enzymatic attack and show excellent biocompatibility. Moreover, these supramolecular complexes cross the plasma membrane of yeast cells and express green fluorescent protein encoded by the DNA, suggesting that DTT–Au NCs can serve as an efficient carrier for gene delivery.

Synthesis of a novel hexaazatriphenylene derivative for the selective detection of copper ions in aqueous solution.

A hexaazatriphenylene (HAT) derivative, naphtho[2,3-h]naphtho[2′,3':7,8]quinoxalino[2,3-a]naphtho[2′,3′:7,8]quinoxalino[2,3-c]phenazine-5,10,15,20,25,30-hexaone (NQH) was synthesized, characterized, and found to have novel properties in being selective toward the detection of copper (Cu2+) ions. The capability of NQH to be employed as a colorimetric, chemo-fluorescence and electrochemical sensor for the detection of Cu2+ was demonstrated by performing UV-Vis absorbance, fluorescence intensity, and cyclic voltammetry (CV) measurements. The interaction between NQH and Cu2+ was initially observed with an obvious color change from yellow to brown upon the addition of Cu2+ ions to NQH. The interaction was also confirmed by UV-Vis absorbance, fluorescence intensity, and mass spectroscopy (MS/MS) measurements. UV absorbance, fluorescence and CV of NQH toward Cu2+ showed good linearity with a detection limit of 3.32 μM, 2.20 μM and 0.78 μM, respectively, which are lower than the toxicity levels of copper in drinking water (20–30 μM) set by the U.S. Environmental Protection Agency (EPA) and World Health Organization (WHO). A 1 : 2 stoichiometry complexation between NQH and Cu2+ was confirmed by Job's plot and MS/MS. In addition, the selectivity and sensitivity of the NQH compound towards Cu2+ ions were further confirmed by performing CV on a screen printed flexible and planar electrochemical sensor.

Dendrocalamus strictus Charcoal: An Efficient Adsorbent for Removal of Cu (II) Ions from Aqueous Solution and its Applicability in the Reduction of Genotoxic Potential of Cu (II) Ions.

The present study pertains to evaluate the efficiency of Dendrocalamus strictus charcoal powder as an adsorbent to adsorb copper ions from aqueous solution under different conditions of pH, initial metal ion concentration, adsorbent dose, contact time, and temperature. Physical characterization of Dendrocalamus strictus charcoal powder was performed using different techniques such as scanning electron microscopy, scanning electron microscopy-energy dispersive X-ray spectroscopy, Brunauer Emmett and Teller surface analysis and X-ray diffraction. Langmuir, Freundlich, and Temkin isotherm models were employed to describe the adsorption behavior of adsorbent in the removal of copper ions from aqueous solution. Thermodynamic parameters indicated that the adsorption of copper ions onto the surface of the adsorbent was feasible, spontaneous, and endothermic in nature. Data analysis using kinetic models revealed the pseudo-second-order as the suitable model to describe the process of adsorption. Studies were further carried out to analyze the genotoxic effects of copper ions in aqueous solution before and after adsorption, using Allium cepa assay. This study revealed that Dendrocalamus strictus charcoal powder could be applied as an alternative for more costly adsorbents in the detoxification of copper ions from aqueous solution.

Rapid capture and visual detection of copper ions in aqueous solutions and biofluids using a novel cellulose-Schiff base

In this work, a novel colorimetric sensor was prepared via a cellulose-polyethylenimine-based Schiff base (cellulose-Schiff base) for capturing and detecting copper ions (Cu2+) in aquatic environments and life systems. The cellulose-Schiff base displayed continuous color changes from inherent pale yellow to deep green due to the formation of a cellulose-Schiff base-Cu2+ charge transfer complex within 30 s, indicating excellent “naked-eye” detection capability for Cu2+ ions in aqueous solution. The limit of detection (LOD) was 1.054 ppm, lower than the U.S. EPA guidelines for drinking water of 1.3 ppm. Moreover, the cellulose-Schiff base colorimetric sensor was successfully used to capture and detect exogenous Cu2+ ions in biofluids (simulated urine and bovine serum). The proposed sensing mechanism of the cellulose-Schiff base for Cu2+ ions is that N atoms (C=N and N–H) in the sensor capture and concentrate Cu2+ ions to form sensor-Cu2+ complexes, then intramolecular charge transfer occurs as a consequence. In addition, test strips based on cellulose-Schiff base were developed, and provide a convenient, cheap, sensitive, and reliable monitoring platform for on-site semi-quantitative analysis of Cu2+ ions in real samples.

Formation of multilayer through layer-by-layer assembly of starch-based polyanion with divalent metal ion

The layer-by-layer (LbL) assembly between metal ion and starch-based anion driven by electrostatic interaction was investigated. Multilayer films were obtained from starch-based derivative containing carboxyl groups (SC) with copper or lead ions. It was found that the concentration of metal ion in aqueous solution decreased with increasing the layers. X-ray photoelectron spectroscopy exhibited the content of Cu(II) was higher when the surface was copper-ion-layer than that composed of SC. The surface of the film was smooth and no obvious fault plane was observed on its cross-section, which also indicated that the LbL assembly between starch-based polyanion and metal ion was carried out. Sodium alginate was adopted as another polyanion to conduct the LbL assembly. Part of metal ion was replaced with rhodamine B to fabricate composite multilayer. During such an assembly, the concentration of copper ion in aqueous solution decreased with increasing the layers as well. These phenomena suggested that the LbL assembly between polysaccharide-based polyanion and metal ion was feasible.