Preparation of quaternized dimethylaminoethylmethacrylate grafted nonwoven fabric for the removal of phosphate

Dimethylaminoethylmethacrylate (DMAEMA) grafted polyethylene/polypropylene (PE/PP) nonwoven fabric was prepared by radiation-induced graft polymerization. Grafting conditions were optimized and about 150% DMAEMA grafted samples were used for further experiments. DMAEMA graft chains were later quaternized with dimethyl sulphate for the removal of phosphate ions. Adsorption experiments were conducted with quaternized DMAEMA grafted fabric for phosphate removal at low (0.5–25 ppm) and high phosphate concentrations (50–1000 ppm). Adsorbed phosphate amounts at pH 7 were found to be 63 mg phosphate/g polymer and 512 mg phosphate/g polymer for low (25 ppm) and high phosphate concentrations (1000 ppm) respectively showing the efficiency of the adsorbent material in removing phosphate. The pH effect on phosphate adsorption showed that the quaternized DMAEMA grafted nonwoven fabric can adsorb phosphate over a wide pH range (5.00–9.00) indicating that adsorbent material can effectively remove different forms of phosphate ions, namely H₂PO₄^?, HPO₄^2? and PO₄^3? in aqueous solution at this pH range where the species exist. Competitive adsorption experiments were also carried out with two concentration levels at pH 7 to investigate the effect of competing ions. Phosphate adsorption on quaternized DMAEMA grafted nonwoven fabric was found to be higher than the other competing ions at two concentration levels. At high concentration level, the adsorption order was phosphate>nitrite>bromide>sulphate>nitrate whereas at low concentration level, the order was phosphate?sulphate>bromide>nitrite>nitrate.     

A mild method of amine-type adsorbents syntheses with emulsion graft polymerization of glycidyl methacrylate on polyethylene non-woven fabric by pre-irradiation

A mild pre-irradiation method was used to graft glycidyl methacrylate (GMA) onto polyethylene (PE) non-woven fabric (NF). The polymer was irradiated by electron beam in air atmosphere at room temperature. The degree of grafting (D_g) was determined as a function of reaction time, absorbed dose, monomer concentration and temperature. After 30 kGy irradiation, with 5% GMA, surfactant Tween 20 (Tw-20) of 0.5% at 55 °C for 15 min, the trunk polymer was made grafted with a D_g of 150%. Selected PE-g-PGMA of different D_g was modified with aminated compounds such as ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA) and tetraethylenepentamine (TEPA). The obtained amine-type adsorbents were prepared to remove copper and uranium ions from solution. It was shown that at least 90% of copper and 60% of uranium with the initial concentration from 3 to 1000 ppb can be removed from water.     

On the electrodialysis of aqueous H2SO4–CuSO4 electrolytes with metallic impurities

This work aims to contribute to the characterization of the electrodialysis (ED) of aqueous sulfuric acid–copper sulfate solutions. The presence of impurities such as As and Sb, typical of copper electrorefining electrolytes, is also studied. Results from kinetic studies carried out in ED cells with and without re-circulation are presented. The concentrations were: 3–9 g l⁻¹ copper, 50 g l⁻¹ sulfuric acid, 3 g l⁻¹ arsenic and 0.025 g l⁻¹ antimony; the temperatures, 22 and 44 °C; the transport rates, depending on experimental conditions, 0.2–0.6 mol h⁻¹ m⁻²of membrane for copper, 0.65–2.8 for sulfate, and 0.016–0.03 for arsenic. A speciation model has been developed and applied in order to interpret the experimental results and the performance of the studied cells has been evaluated. The main conclusion is that ED can be applied to the separation and concentration of chemical species in these systems.     

Isobaric vapor–liquid equilibria for 1-propanol + water + copper(II) chloride at 100 kPa

Isobaric vapor–liquid equilibria for the ternary system 1-propanol + water + copper(II) chloride has been measured at 100 kPa using a recirculating still. The addition of copper(II) chloride to the solvent mixture produced a salting-out effect of the alcohol, but the azeotrope did not tend to be eliminated when the salt content increased. The experimental data sets were fitted with the electrolyte NRTL model and the parameters of Mock's model were estimated. This model has proved to be suitable to represent experimental data in the entire range of compositions. The effect of copper(II) chloride on the vapor–liquid equilibrium of the 1-propanol + water system has been compared with that produced by other salts.     

Mass transfer effect on corrosion inhibition process of copper–nickel alloy in hydrochloric acid by Benzotriazole

The corrosion inhibition of copper–nickel alloy by Benzotriazole (BTA) in 1.5 M HCl has been investigated by weight loss and polarization techniques at different temperatures. Maximum value of inhibitor efficiency was 99.8% for BTA at 35 °C and 0.1 M inhibitor concentration, while the lower value was 86.8% at 55 °C and 0.02 M inhibitor concentration. The non-linear region of the polarization curve near the corrosion potential can be discussed depending on data of over potential as a function of current densities. These data can be analyzed by suggestion of a mathematical model to take into account the effect of mass transfer on activation process.     

Effect of heating on speciation of copper in Si/Al/Ca-based environmental matrices

X-ray absorption spectroscopy is used to investigate the speciation of sorbed copper in heated fly ash. CuO and Cu(OH)₂ are determined to be the principal copper species in the Cu-sorbing fly ash heated at 500 °C for 2 h. Heating the Cu-sorbing fly ash to 900 °C or 1100 °C can result in the formation of CuSO₄, representing 41% and 32% of the total copper, respectively. Ash sintering and/or co-melting at 900 and 1100 °C occur, thereby triggering chemical reaction between CuO/Cu(OH)₂ and sulfur compounds.     

Kinetics of copper UPD on stepped platinum single crystals in the presence of acetonitrile

The kinetics of copper underpotential deposition on stepped Pt(h k l) electrodes with controlled width of (1 1 1) terraces in acidic solutions of copper sulfate with 0–200 mM of acetonitrile (AcN) has been studied by means of cyclic voltammetry. In the presence of AcN Cu UPD process is hindered both at (1 0 0) steps and (1 1 1) terraces of Pt(17 15 15) and Pt(7 5 5) faces due to blocking of the electrode surface with organic molecules, strongly adsorbed at the steps and nearby ones. The decoration of (1 1 0) steps with copper adatoms is slightly accelerated for Pt(7 7 5) electrode in the solution with 0.04 mM AcN. Increase in AcN concentration leads to inhibition of the UPD process. The difference in behavior of the stepped platinum electrodes is controlled by competitive adsorption of AcN, (bi)sulfate and Cu atoms at the step sites. AcN adsorption at (1 0 0) steps is stronger as compared with (1 1 0) ones.     

The effect of copper content on the reactivity of Cu/Co6Al2 solids in the catalytic steam reforming of methane reaction

The steam reforming of methane over Cu/Co₆Al₂ mixed oxides with different copper contents was studied. The Co₆Al₂ support was prepared via the hydrotalcite route. It was thermally stabilized at 500 °C, impregnated with 5 wt.%, 15 wt.% or 25 wt.% copper using copper (II) nitrate Cu(NO₃)₂·3H₂O precursor and then calcined again at 500 °C under an air flow. The impregnation of copper enhanced significantly the reactivity of the solids in the considered reaction. The 5Cu/Co₆Al₂ solid was the most reactive one, with a methane conversion of 96% at 650 °C. The selectivities of H₂ and CO₂ were also better for the catalyst containing 5 wt.% copper compared to higher copper loadings. The decrease in the catalytic reactivity with increasing the copper content was attributed to the formation of agglomerated and less reactive CuO species, which were detected by XRD and TPR analyses.     

Platinum nanoparticles supported on nitrobenzene-functionalised graphene nanosheets as electrocatalysts for oxygen reduction reaction in alkaline media

A systematic study on the electrocatalytic properties of Pt nanoparticles supported on nitrobenzene-modified graphene (Pt-NB/G) as catalyst for oxygen reduction reaction (ORR) in alkaline solution was performed. Graphene nanosheets were spontaneously grafted with nitrophenyl groups using 4-nitrobenzenediazonium salt. The electrocatalytic activity towards the ORR and stability of the prepared catalysts in 0.1 M KOH solution have been studied and compared with that of the commercial Pt/C catalyst. The results obtained show that the NB-modified graphene nanosheets can be good Pt catalyst support with high stability and excellent electrocatalytic properties. The specific activity of Pt-NB/G for O₂ reduction was 0.184 mA cm⁻², which is very close to that obtained for commercial 20 wt% Pt/C catalyst (0.214 mA cm⁻²) at 0.9 V vs. RHE. The Pt-NB/G hybrid material promotes a four-electron reduction of oxygen and can be used as a promising cathode catalyst in alkaline fuel cells.     

Solvothermal growth and morphology study of Cu2Se films

Solvothermal growth of cuprous selenide films on copper substrate has been succeeded by treating copper foil in the mixture of selenium powder and amines or hydrazine. The films were characterized by methods of XRD, SEM, TEM and optical spectra (Cu₂Se, JCPDS 47-1448). Films with hexagonal microcrystals can be obtained in hydrazine/water reaction system. When CTAB (CTAB = cetyltrimethylammonium bromide) is added to the system, the film is composed of thin leaf-like microcrystals. When ethylenediamine (en) is used as solvent, the leaf-like microcrystals are crimped.     

Nanorods of transition metal oxalates: A versatile route to the oxide nanoparticles

A versatile route has been explored for the synthesis of nanorods of transition metal (Cu, Ni, Mn, Zn, Co and Fe) oxalates using reverse micelles. Transmission electron microscopy shows that the as-prepared nanorods of nickel and copper oxalates have diameter of 250 nm and 130 nm while the length is of the order of 2.5 μm and 480 nm, respectively. The aspect ratio of the nanorods of copper oxalate could be modified by changing the solvent. The average dimensions of manganese, zinc and cobalt oxalate nanorods were 100 μm, 120 μm and 300 nm, respectively, in diameter and 2.5 μm, 600 nm and 6.5 μm, respectively, in length. The aspect ratio of the cobalt oxalate nanorods could be modified by controlling the temperature.The nanorods of metal (Cu, Ni, Mn, Zn, Co and Fe) oxalates were found to be suitable precursors to obtain a variety of transition metal oxide nanoparticles. Our studies show that the grain size of CuO nanoparticles is highly dependent on the nature of non-polar solvent used to initially synthesize the oxalate rods. All the commonly known manganese oxides could be obtained as pure phases from the single manganese oxalate precursor by decomposing in different atmospheres (air, vacuum or nitrogen). The ZnO nanoparticles obtained from zinc oxalate rods are ～55 nm in diameter. Oxides with different morphology, Fe₃O₄ nanoparticles faceted (cuboidal) and Fe₂O₃ nanoparticles (spherical) could be obtained.     

Comparison of the electrochemical properties of metallic layered nitrides containing cobalt,nickel and copper in the 1 V–0.02 V potential range

We report the first example of an intercalation compound based on the nitrogen framework in which lithium can be intercalated and deintercalated. A comparison of the structural and electrochemical properties of the ternary lithium cobalt, nickel and copper nitrides is performed. Vacancy layered structures of ternary lithium nitridocobaltates Li_3−2xCo_xN and nitridonickelates Li_3−2xNi_xN with 0.10 ⩽ x ⩽ 0.44 and 0.20 ⩽ x ⩽ 0.60, respectively, are proved to reversibly intercalate Li ions in the 1 V–0.02 V potential range. These host lattices can accommodate up to 0.35 Li ion par mole of nitride. Results herein obtained support Li insertion in vacancies located in Li₂N⁻ layers while interlayer divalent cobalt and nickel cations are reduced to monovalent species. No structural strain is induced by the insertion–extraction electrochemical reaction which explains the high stability of the capacity in both cases. For the Li_1.86Ni_0.57N compound, a stable faradaic yield of 0.30 F/mol, i.e. 130 mAh/g, is maintained at least for 100 cycles. Conversely, the ternary copper nitrides corresponding to the chemical composition Li_3−xCu_xN with 0.10 ⩽ x ⩽ 0.40 do not allow the insertion reaction to take place due to the presence of monovalent copper combined with the lack of vacancies to accommodate Li ions. In the latter case, the discharge of the lithium copper nitrides is not reversible.     

An efficient copper(II)-catalyzed direct access to primary amides from aldehydes under neat conditions

A simple expeditious one-pot conversion of a wide assortment of aldehydes to corresponding primary amides in good to excellent yields has been accomplished employing hydroxylamine hydrochloride (1 mol equiv), sodium acetate (1.1 mol equiv), and copper sulfate pentahydrate (5 mol %) under neat conditions at 110 °C. The protocol based upon ligand-free copper (II)-catalysis avoids the use of relatively expensive late transition metal-based catalysts, and is performed under operationally simple conditions without any demanding procedure of isolation and purification of products.     

Real time observation of the anodic dissolution of copper in NaCl solution with the digital holography

There are three possible cases of the initial electro-dissolution reactions of bare copper in acid/neutral chloride media. Two of them involve the direct formation of a cuprous chloride species from the metal, while the other, the dissolution of copper as cuprous ion. In the present work, the digital holography has been employed with an attempt to identify the actual mechanism through observing the dynamic changes of the diffusion layer at the electrode/electrolyte interface during the anodic processes of copper in 0.5 mol dm^?3 NaCl solution. On the basis of the phase distribution reconstructed from the holograms, the dynamic changes of concentration field within the diffusion layer of the process can be obtained. The results confirm that, at the initial stage, the cuprous ion is formed first, which then reacts to produce the cuprous chloride and/or cuprous chloride complexes.     

Synthesis of covellite (CuS) from the elements

A one-step, corrosion-assisted reaction was developed to synthesize copper sulfide (CuS) from elemental copper and sulfur in water at 60 °C. The as-prepared polycrystalline CuS consists of polyhedral-shaped 2–3 μm crystallites. CuS forms by the oxidation of copper metal in the presence of sulfur, whereas in the presence of water, a continuous solid-state reaction occurs without passivation by the product.     

Structures and magnetic properties of one-dimensional copper(II) complexes bridged with diazaaromatic rings

Seven kinds of polynuclear complexes of [Cu(hfac)₂] (Hhfac = 1,1,1,5,5,5-hexafluoropentane-2,4-dione) with diazaaromatic rings have been prepared. The crystal structures of [{Cu(hfac)₂(μ-L)}_n] (L = 2,5- and 2,6-dimethylpyrazines, propylpyrazine (prpyz), quinoxaline, phenazine, 4,6-dimethylpyrimidine, and 1,6-naphthyridine) have been determined. These complexes consist of a one-dimensional chain structure, and the geometry around the copper ion is approximately an octahedral structure. The relations between the magnetic properties and coordination structure were discussed from the magnetic measurements. In the μ-prpyz complex, one nitrogen atom is coordinated to a copper ion at an axial position, and at the same time the other coordinated at an equatorial site of a neighboring copper ion. This complex showed antiferromagnetic interaction with J/k_B = −0.086(3) K estimated from the Bonner–Fisher model. Weak magnetic interaction is caused by the somewhat long Cu–N distances due to the steric effect from the bridging ligands.     

Catalytic effects of copper(II) chloride and aluminum chloride on the pyrolytic behavior of cellulose

The cellulose without and with catalyst (CuCl₂, AlCl₃) was subjected to pyrolysis at temperatures from 350 to 500 °C with different heating rate (10 °C/min, 100 °C/s) to produce bio-oil and selected chemicals with high yield. The pyrolytic oil yield was in the range of 37–84 wt% depending on the temperature, the heating rate and the amount of metal chloride. The non-catalytic fast pyrolysis at 500 °C gives the highest yield of bio-oil. The mixing cellulose with both metal chlorides results with a significant decrease of the liquid product. The non-catalytic pyrolysis of cellulose gives the highest mass yield of levoglucosan (up to 11.69 wt%). The great influence of metal chloride amount on the distribution of bio-oil components was observed. The copper(II) chloride and aluminum chloride addition to cellulose clearly promotes the formation of levoglucosenone (up to 3.61 wt%), 1,4:3,6-dianhydro-α-d-glucopyranose (up to 3.37 wt%) and unidentified dianhydrosugar (MW = 144; up to 1.64 wt%). Additionally, several other compounds have been identified but in minor quantities. Based on the results of the GC–MS, the effect of pyrolysis process conditions on the productivity of selected chemicals was discussed. These results allowed to create a general model of reactions during the catalytic pyrolysis of cellulose in the presence of copper(II) chloride and aluminum chloride.     

Biosorption of copper ions from aqueous solutions by Spirulina platensis biomass

In this study, the economically important micro-alga (cyanobacterium) Spirulina platensis was used as biosorbent for the removal of copper from aqueous solutions. The cyanobacterium was exposed to various concentrations of copper and adsorption of copper by the biomass was evaluated under different conditions that included pH, contact time, temperature, concentration of adsorbate and the concentration of dry biomass. Increased adsorption of copper by the non-living biomass was recorded with gradually increasing pH, and a maximal uptake by the biomass was observed at pH 7. The adsorption of copper was found to increase gradually along with decrease in biomass concentration. Biosorption was found to be at a maximum (90.6%), in a solution containing 100 mg copper/L, at pH 7, with 0.050 g dry biomass and at 37 °C with 90 min of contact time. Analysis of the spectrum obtained with atomic absorption spectrophotometer (AAS), indicated that the adsorbent has a great potential to remove copper from aqueous media contributing to an eco-friendly technology for efficient bioremediation in the natural environment.     

Adsorption of Cr(VI) using cellulose microsphere-based adsorbent prepared by radiation-induced grafting

Cellulose microsphere (CMS) adsorbent was prepared by radiation-induced grafting of dimethylaminoethyl methacrylate (DMAEMA) onto CMS followed by a protonation process. The FTIR spectra analysis proved that PDMAEMA was grafted successfully onto CMS. The adsorption of Cr(VI) onto the resulting adsorbent was very fast, the equilibrium adsorption could be achieved within 15 min. The adsorption capacity strongly depended on the pH of the solution, which was attributed to the change of both the existed forms of Cr(VI) and the tertiary-ammonium group of PDMAEMA grafted CMS with the pH. A maximum Cr(VI) uptake (ca. 78 mg g^?1) was obtained as the pH was in the range of 3.0–6.0. However, even in strong acid media (pH 1.3), the adsorbents still showed a Cr(VI) uptake of 30 mg g^?1. The adsorption behavior of the resultant absorbent could be described with the Langmuir mode. This adsorbent has potential application for removing heavy metal ion pollutants (e.g. Cr(VI)) from wastewater.     

Electrodeposition of copper in the presence of an acoustically excited gas bubble

Copper has been electrodeposited in the presence of an acoustically excited gas bubble (Ar bubbles with radii ∼1.5 mm held below a copper plate). Under the conditions employed, an acoustic pressure amplitude of 69.5 Pa is sufficient to excite multiple surface wave modes on the bubble wall. This is observed using high-speed imaging. This oscillation generates significant micromixing, which brings fresh electrolyte to the electrode surface leading to an enhanced deposition current. Scanning electron microscopy reveals radial streaming patterns in the resulting copper deposit. Experiments carried out using a lower acoustic pressure amplitude of 50.5 Pa (such that only the Faraday wave is excited) exhibit a lesser degree of streaming and mass transfer enhancement. No significant spatially averaged current enhancement is seen if the bubble is only undergoing breathing mode oscillation.