Monovalent Copper Ions Inhibit Enzymatic Systems

The effect of monovalent copper ions on enzymatic systems has hardly been studied to date; this is due to the low stability of monovalent copper ions in aqueous solutions, which led to the assumption that their concentration is negligible in biological systems. However, in an anaerobic atmosphere, and in the presence of a ligand that stabilizes the monovalent copper ions over the divalent copper ions, high and stable concentrations of monovalent copper ions can be reached. Moreover, the cell cytoplasm has a substantial concentration of potential stabilizers that can explain significant concentrations of monovalent copper ions in the cytoplasm. This study demonstrates the effect of monovalent and divalent copper ions on DNA polymerase, ligaseT4 DNA, the restriction enzymes EcoP15I and EcoR I, acid phosphatase, and α and βamylase enzymes. These systems were chosen because they can be monitored under conditions necessary for maintaining a stable concentration of monovalent copper ions, and since they exhibit a wide range of dependency on ATP. Previous studies indicated that ATP interacts with monovalent and divalent copper ions and stabilizing monovalent copper ions over divalent copper ions. The results showed that monovalent copper ions dramatically inhibit DNA polymerase and acid phosphatase, inhibit ligaseT4 DNA and the restriction enzyme EcoP15I, moderately inhibit α and β amylase, and have no effect on the restriction enzyme EcoR I. From the results presented in this work, it can be concluded that the mechanism is not one of oxidative stress, even though monovalent copper ions generate reactive oxygen species (ROS). Molecular oxygen in the medium, which is supposed to increase the oxidative stress, impairs the inhibitory effect of monovalent and divalent copper ions, and the kinetics of the inhibition is not suitable for the ROS mechanism.ATP forms a complex with copper ions (di and monovalent ions, where the latter is more stable) in which the metal ion is bound both to the nitrogen base and to the oxygen charged on the phosphate groups, forming an unusually distorted complex. The results of this study indicate that these complexes have the ability to inhibit enzymatic systems that are dependent on ATP.This finding can provide an explanation for the strong antimicrobial activity of monovalent copper ions, suggesting that rapid and lethal metabolic damage is the main mechanism of monovalent copper ions’ antimicrobial effect.

Kinetics, Isotherms and Thermodynamic Studies on Removal of Divalent Copper using Mallet Flower Leaf Powder as Bio-Adsorbent

The effectiveness and efficacy of Mallet Flower Leaf Powder (MFLP) as a bio-sorbent for the removal of heavy metal copper ions from the aqueous solutions have been studied. Experiments were conducted varying the pH, agitation time, temperature, biosorbent size and dosage as parameters. Speed of the mixing is kept at 200 rpm. The analysis of copper was done by using Atomic Absorption Spectrophotometer (AAS). The adsorption of copper was found to be dependent on pH and a maximum removal of 98.78 % was obtained at an optimum pH of 6.0. The optimum biosorbent dosage was 1 g for an agitation time of 40 min. The biosorption data obtained were validated for the best isotherm. The data collected were verified with the available adsorption isotherms. Experimental data obtained was well represented by Langmuir (RL = 0.161, qm = 5.96 mg/g, R2 = 0.9142), Freundlich (n = 0.64, Kf = 0.79L/g, R2 = 0.9995) and Tempkin (R2 = 0.9083, bT = 267.63) isotherms, indicating favorable biosorption. The experimental data obtained were tested for the best fit and the Freundlich Model has yielded the best correlation with the highest regression coefficient, R2 = 0.9844. Kinetic data has also been presented using thermodynamic analysis and the pseudo second order model was found to be the best fit with a correlation coefficient of 0.999. For the removal of copper from the solution, bioadsorbent showed a maximum adsorption capacity of 5.96 mg/g. HIGHLIGHTS Removal of divalent copper from the aqueous solution using Mallet Flower Leaf powder Atomic Absorption Spectroscopy, Scanning Electron Microscopy and Fourier transform infrared analysis were used to characterize the Mallet Flower Leaf Powder Kinetic data has been presented using thermodynamic analysis and the pseudo second order model was found to be the best fit with a correlation coefficient of 0.999 The maximum adsorption capacity of MFLP for copper was found to be 5.96 mg/gm GRAPHICAL ABSTRACT

Chitosan/Phosphate Rock-Derived Natural Polymeric Composite to Sequester Divalent Copper Ions from Water

Herein, a chitosan (CH) and fluroapatite (TNP) based CH-TNP composite was synthesized by utilizing seafood waste and phosphate rock and was tested for divalent copper (Cu(II)) adsorptive removal from water. The XRD and FT-IR data affirmed the formation of a CH-TNP composite, while BET analysis showed that the surface area of the CH-TNP composite (35.5 m2/g) was twice that of CH (16.7 m2/g). Mechanistically, electrostatic, van der Waals, and co-ordinate interactions were primarily responsible for the binding of Cu(II) with the CH-TNP composite. The maximum Cu(II) uptake of both CH and CH-TNP composite was recorded in the pH range 3–4. Monolayer Cu(II) coverage over both CH and CH-TNP surfaces was confirmed by the fitting of adsorption data to a Langmuir isotherm model. The chemical nature of the adsorption process was confirmed by the fitting of a pseudo-second-order kinetic model to adsorption data. About 82% of Cu(II) from saturated CH-TNP was recovered by 0.5 M NaOH. A significant drop in Cu(II) uptake was observed after four consecutive regeneration cycles. The co-existing ions (in binary and ternary systems) significantly reduced the Cu(II) removal efficacy of CH-TNP.

Electrochemical reduction of indigo by combination of sodium borohydride and copper salt

Purpose The purpose of this study is to improve the performance of sodium borohydride in reducing indigo at room temperature, the divalent copper ion complex was combined with electrochemical technology for the reduction of indigo by sodium borohydride. Design/methodology/approach According to the K/S value of the dyed cloth sample, find a more suitable ligand for the copper ion in the catholyte. Response surface analysis tests were performed to evaluate the effects of sodium borohydride concentration, sodium hydroxide concentration and copper sulfate pentahydrate concentration on the reduction potential of the dye solution and the K/S value of the dyed fabric samples. Findings Sodium gluconate was found to be a more suitable ligand for copper ions in catholyte. The effects of NaOH concentration as well as the interaction of NaBH4 and NaOH on the reduction potential of the catholyte and the K/S value of the dyed fabric samples were extremely significant. The optimal concentrations of NaBH4, NaOH and CuSO4•5H2O were 0.5, 2.5 and 0.65 g/L. In the case of the optimized condition, the absolute value of the reduction potential was 968, and the K/S value was 11.92, which is comparable with that of the conventional reduction process with sodium dithionite. Originality/value The divalent copper ion complex combined with electrochemical technology was applied in the process of reducing indigo with NaBH4 at room temperature.

Utilization of Polypyrrole/ZnO Nanocomposite in the Adsorptive Removal of Cu2+, Pb2+ and Cd2+ Ions from Wastewater

The present study was demonstrated the synthesis, characterization, and utilization of Polypyrrole/ZnO (Polypy/ZnO) nanocomposite in the removal of divalent copper, lead, and cadmium ions from aqueous solutions. Leaves extract of Mangifera indica has been used to synthesize zinc oxide nanoparticles (ZnO NPs) and green synthesized ZnO NPs incorporated in the polypyrrole system for enhancing metal loading capacity. Synthesized Polypy/ZnO was characterized using FT-IR, P-XRD, FE-SEM, and EDX methods. Maximum adsorption of copper, lead, and cadmium ions have been found at contact time 50 minutes, dosage 1 g, and pH 6, respectively. The Langmuir equilibrium constants were 6.75, 7.19, and 7.59 L/g for Cu2+, Pb2+, and Cd2+ ions. The desorption constants for the adsorptive removal of Cu2+, Pb2+, and Cd2+ ions by using Polypy/ZnO were evaluated from the Elovich model as 1.96, 1.68, and 1.17 g/mg, respectively.