Cu In Presence Research Articles

Dissolution of brominated epoxy resin for environment friendly recovery of copper as cupric oxide nanoparticles from waste printed circuit boards using ammonium chloride roasting

This work focuses on development of an environment benign approach for separation of brominated epoxy resin (BER) and recovery of copper (Cu) as copper oxide (CuO) from end-of-life waste printed circuit boards (PCBs). The typical Cu concentration in PCBs varies in the range of 60 kg/t – 270 kg/t of Cu, which is much higher than its respective mineral ores. In the present work, dimethylformamide (DMF) was used for dissolution of BER followed by roasting with ammonium chloride (NH4Cl) for recovery of Cu. Separation of BER provides better metallic surface exposer and mitigates the possibility of formation of toxic polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) during the roasting process. More than 97% of BER was separated from the PCBs using DMF as solvent at 140 °C. The investigation revealed that at reaction conditions, dry HCl vapour formed due to decomposition of NH4Cl, reacts with Cu in presence of air to form CuCl2. The solid residue obtained after roasting was subsequently treated with water for extraction of CuCl2. More than 93% Cu was extracted when the delaminate PCBs (DPCBs) was roasted at optimum conditions of temperature: 275 °C, NH4Cl dose: 300%, and time: 180 min. From the leached solution, Cu was precipitated using ammonia solution as precipitating agent, which subsequently calcined at 500 °C to obtain 98% pure CuO nanoparticles (NPs).

Potential of <i>Mimulas glabratus</i> in removal of Fe and Cu from the aqueous solutions containing Nitrate and Phosphate and its growth responses

The metal bioabsorption potential and survival efficiency of aquatic macrophyte M. glabratus was examined for the removal of Fe and Cu in presence of nitrate and Phosphates. M.glabratus removes Fe 10% more than Cu in case of bio-chemical and physical responses the increment in fresh weight found 0.74% more in Fe treated plants than Cu treated plants and in photosynthetic pigments there was 10% more increment was noted in the plants treated with Fe. Bioabsorption of Fe was noted 18.9% more than Cu by M. glabratus . The results demonstrate that M.glabratus can be utilized in the remediation operations of aquatic systems Keywords : Bioabsorption, M. glabratus, Photosynthetic pigments, Biomass

Point-of-Care Sensor with Interdigitated Array Electrodes for Lead Determination

In this work, we report on our continued development of a point-of-care electrochemical sensor for determination of trace levels of lead (Pb) in environmental and biological applications. Here we refine our Cu-based sensor concept [1] by integrating interdigitated array (IDA) electrodes on a flexible polyethylene terephthalate (PET) substrate. The sensor offers simple fabrication with competitive performance, making it well-suited for disposable, point-of-care applications. Similar to the geometry of our first generation Cu-based sensor [1], the sensor in this work consists of a three-electrode system fabricated in Cu. Two shorted IDA fabricated in Cu form the working electrode (WE), with finger width/spacing of 10 µm/5 µm. An auxiliary electrode (AE) was formed in Cu, while the reference electrode (RE) was formed as Cu/CuCl2. A batch-fabricated array of electrodes on flexible PET film are shown in Fig. 1a. The fabrication process includes a single photolithography step, followed by wet etching to define electrode patterns. The RE is formed by oxidizing Cu in presence of chloride. The USB style four connection pads of the sensor are designed for simplify in connecting to a potentiostat. The potential window of the sensor for anodic stripping was confirmed by cyclic voltammetry (CV). As shown in Fig. 1b, the potential window spans from approximately -0.85 V to 0 V (vs. Cu/CuCl2RE) in 0.2 M, pH 5.5 acetate buffer (blue curve). As expected, this is similar to our previous design [2]. This potential window is sufficient for determination of Pb. The voltammogram of 100 ppm (483 µM) Pb (red curve) exhibits two oxidation peaks of Pb at ~-0.47 V and -0.3 V, which are believed to be due to high metal concentration. High metal content in sample can result in a large portion of Pb to be stripped-off on top of a Pb surface (appearing as a more negative peak), while the remaining thin layer of Pb strips-off the solid Cu WE as (which generates signal peak at the expected, more positive potential). The sensor offers great performance in acetate buffer (0.2 M, pH 5.5). Fig. 2a illustrates anodic stripping voltammograms in the 20-200 ppb (96 nM-960 nM) of Pb range in 100 µL samples. The small peak in the background cure (dark grey) is considered with interference of oxygen during preconcentration, which can be removed by sacrificing the simplicity of the system and de-aerating the sample. Calibration curve for determination of Pb after baseline subtraction, which was used to remove interference and to ensure accuracy of measurements, is shown in Fig. 2b. This sensor exhibits a low limit of detection (LOD) of 49.6 nM (10.3 ppb) with a good sensitivity of 4.1 µA/µM and good linearity (R2=0.99) below 1 µM. These performance metrics are comparable to that of our first generation Cu-based sensor [2]. The addition of IDA structure however increased signal strength, by improving signal-to-noise and reducing surface charging effects on the WE. As we showed previously, ASV of Pb can provide stable response in environmental samples with no need of complex pretreatment and demonstrate there is no Pb contamination in river water sample. In conclusion, we developed an improved electrochemical sensor for determination of trace Pb. With the integration of PET substrate, the sensor is disposable and could be widely applied in point-of-care applications. Fig1. (a) Image of an array of Cu sensors with IDA WE on a flexible PET substrate, with the AE, WE and RE indicated. (b) CV scans of background in acetate buffer, 0.2 M, pH 5.5 (blue) demonstrating the potential window, and in 100 ppm Pb (red) demonstrating Pd reduction and oxidation peaks. Fig2. SWASV determination of Pb from 20-200 ppb in acetate buffer, 0.2 M, pH 5.5: (a) Stripping voltammograms of Pb; (b) calibration curve plotted after baseline subtraction. Reference [1] Pei, X.; Kang, W.; Yue, W.; Bange, A.; Heineman, W. R.; Papautsky. Anal. Chem. 2014, 86, 4893-4900. [2] X. Pei, W. Kang, W. Yue, A. Bange, W. R. Heineman, and I. Papautsky, Transducers Conference, 2013, 247-249 Acknowledgement This work was supported in part by funds provided by the NIEHS award R01ES022933. Figure 1

Atomistic insights into aqueous corrosion of copper

Corrosion is a fundamental problem in electrochemistry and represents a mode of failure of technologically important materials. Understanding the basic mechanism of aqueous corrosion of metals such as Cu in presence of halide ions is hence essential. Using molecular dynamics simulations incorporating reactive force-field (ReaxFF), the interaction of copper substrates and chlorine under aqueous conditions has been investigated. These simulations incorporate effects of proton transfer in the aqueous media and are suitable for modeling the bond formation and bond breakage phenomenon that is associated with complex aqueous corrosion phenomena. Systematic investigation of the corrosion process has been carried out by simulating different chlorine concentration and solution states. The structural and morphological differences associated with metal dissolution in the presence of chloride ions are evaluated using dynamical correlation functions. The simulated atomic trajectories are used to analyze the charged states, molecular structure and ion density distribution which are utilized to understand the atomic scale mechanism of corrosion of copper substrates under aqueous conditions. Increased concentration of chlorine and higher ambient temperature were found to expedite the corrosion of copper. In order to study the effect of solution states on the corrosion resistance of Cu, partial fractions of proton or hydroxide in water were configured, and higher corrosion rate at partial fraction hydroxide environment was observed. When the Cl(-) concentration is low, oxygen or hydroxide ion adsorption onto Cu surface has been confirmed in partial fraction hydroxide environment. Our study provides new atomic scale insights into the early stages of aqueous corrosion of metals such as copper.

COPPER EFFECTS ON PRUNUS PERSICA IN TWO DIFFERENT GRAFTING COMBINATIONS (P. PERSICA × P. AMYGDALUS AND P. CERASIFERA)

Growth, chlorophyll content, biomass dry weight (DW), nutrient uptake and copper (Cu) accumulation were evaluated in BigTop® peach (Prunus persica L. Batsch) grafted onto two different rootstocks [GF677 (P. persica × P. amygdalus) and Mr.S2/5 (P. cerasifera)] when grown in the presence of 0.1, 10 or 100 μM copper sulfate (CuSO4). Although scion shoot length varied significantly in response to Cu concentration only with Mr.S2/5 rootstock (40%reduction at 100 μM Cu compared with control), Cu concentration in the scion grafted on GF677 was higher (18.2 mg kg−1) compared to that grafted on Mr.S2/5 (10.5 mg kg−1). In both graft combinations, the Cu concentrations in leaves were not statistically different although values ranged between 4.7 and 8.1 mg kg−1. The DW of leaves and stems was not statistically different from control plants in both graft combinations. On the contrary, root DW of Mr.S2/5 increased, about 13% at 10 μM Cu and 43% at 100 μM Cu. In contrast, DW of GF677 roots at higher Cu treatment was significant lower than control. Chlorophyll reduction Cu induced was not found, suggesting that the degradation of these pigments is maintained at low levels. The uptake of sodium (Na), zinc (Zn), and iron (Fe) changed during Cu stress. The different behavior observed between GF677 and Mr.S2/5 regarding Cu accumulation proves that these two rootstocks have a different ability in translocation and accumulation of Cu in presence of this heavy metal. The use of GF677 rootstocks, in substrates particularly rich of Cu, insures a better development of scion growth when compared to Mr.S2/5, but determines a higher Cu concentration in the stem, while Mr.S2/5 seems to be able to stabilize the Cu concentrations in the scion.

Impacts of quicklime (CaO) on the toxicity of copper (CuSO 4, 5H 2O) to fish and fish food organisms

Static bioassays of 96 h duration were conducted in the laboratory using fry of common carp ( Cyprinus carpio), adult tubificid worm ( Branchiura sowerbyi) and adult copepod plankton ( Cyclops viridis) to determine LC 50 values of Cu and CaO to these organisms and effects of interaction between Cu and CaO. Ninety-six hour LC 50 values of Cu to fry of common carp, worm and copepod were found to be 1.40 mg l −1, 0.08 mg l −1 and 0.03 mg l −1 respectively. CaO up to 500 mg l −1 did not produce any mortality of the fry of common carp up to 96 h. But 96 h LC 50 values of CaO to worm and copepod were 83.00 mg l −1 and 27.80 mg l −1 respectively. When common carp fry, worm and the copepod were exposed to respective LC 50 dose of Cu in presence of varying concentration of CaO, mortality of the organisms significantly reduced and was found inversely correlated with the doses of CaO [ y = 48.36 − 0.807 x, r = −0.99 ( n = 7) for fish; y = 44.46 − 0.146 x, r = −0.97 ( n = 7) for worm; y = 49.46 − 0.66 x, r = −0.99 ( n = 7) for the copepod]. The present results indicate that CaO is non-toxic to fish and is capable of reducing the toxicity of Cu to fish while CaO and Cu are antagonistic to each other for the worm and the copepod. Potential of using CaO as antitoxic agent for Cu in water is discussed.