Retraction: Selective Chelating Resin for Copper Removal and Recovery in Aqueous Acidic Solution Generated from Synthetic Copper-Citrate Complexes from Bioleaching of E-waste

This research focused on batch experiment using a new generation of chelating resins via an ion exchange process to describe the metabolic adsorption and desorption capacity onto iminodiacetic acid/Chelex 100, bis-pyridylmethyl amine/Dowex m4195, and aminomethyl phosphonic/Lewatit TP260 functional groups in bioleaching. The results showed that Dowex m4195 had the highest performance of adsorption capacity for copper removal in both H+-form and Na+-form. Results for Lewatit TP260 and Chelex 100 revealed lower adsorption performance than results for Dowex m4195. The investigation of desorption from chelating resins was carried out, and it was found that 2 M ammonium hydroxide concentration provided the best desorption capacity of about 64.86% for the H+-form Dowex m4195 followed by 52.55% with 2 M sulfuric acid. Lewatit with 2 M hydrochloric acid gave the best desorption performance in Na+-form while Chelex 100 using hydrochloric at 1 M and 2 M provided similar results in terms of the H+-form and Na+-form. As aspects of the selective chelating resins for copper (II) ions in aqueous acidic solution generated from synthetic copper-citrate complexes from bioleaching of e-waste were considered, H+-form Dowex m4195 was a good performer in adsorption using ammonium hydroxide for the desorption. However, chelating resins used were subsequently reused for more than five cycles with an acidic and basic solution. It can be concluded from these results that selective chelating resins could be used as an alternative for the treatment of copper (II) ions contained in e-waste or application to other divalent metals in wastewater for sustainable water and adsorbent reuse as circular economy.

A comparative study was conducted on the adsorptions of cobalt(II) and nickel(II) from aqueous ammonium nitrate solutions on a Levextrel resin containing acidic organophosphinate extractant, Cyanex 272, as an active component and on chelating resins containing phosphorus-based acidic functional groups. It was found that the Levextrel resin has much higher selectivity for cobalt(II) over nickel(II) then the chelating resins. The origins of the low selectivity of the chelating resins are qualitatively discussed.

Biochar (BC) is considered to be a great potential adsorbent to remove various contaminants, but the sorption capacity for chromium (Cr) is predominantly limited for the net negative charge. In this study, BC from rice husk was impregnated with Mn(NO3)2 solution to synthesize MnOx-modified BC (MnOBCs) for enhancing Cr(VI) removal in an aqueous solution. MnOBCs were characterized, and MnOx (manganese ore) was found to be the dominant crystal in MnOBCs. Batch sorption and kinetic experiments combined with spectral analysis were carried out to elucidate the sorption capacity and mechanisms of Cr(VI) sorption onto BC and MnOBCs. Results showed that the sorption kinetic process fitted to the Elovich model, and the modification enhanced the sorption capacity of Cr(VI) on BC. Compared to ion strength, pH is the main control factor for Cr(VI) fixed on BC and MnOBCs, and the sorption amount decreased with the pH value increasing. Moreover, X-ray photoelectron spectroscopy results showed that the proportion of Mn(II) decreased from 33.59% to 8.33%, and that of Mn(VI) increased from 30.58% to 52.72% after Cr(VI) sorption on MnOBCs. Meanwhile, the reduction reaction of Cr(VI) occurred during the sorption process on the BC and MnOBCs surface, and the reduction reaction was more obvious on the MnOBCs surface. MnOx loaded in BC can enhance the electrostatic attraction and redox capacity, which can improve the removal of Cr(VI) in an aqueous solution. This study provides information on the sorption and redox of Cr(VI) on BC, and allows us to better understand the mechanism of Cr(VI) removal in solutions by MnOBCs.

Heap leaching method is known as cheap method for copper extraction. Presence of clay and acid consumer waste minerals are the most critical issues because they may bring out the process from economic mode. For reduce acid consumption and increasing copper extraction in heap leaching method, about 3 tons sample was taken randomly from different low grade zones. After homogenization and spelling into small parts, bottle roll tests were carried out to achieve maximum copper recovery and acid consumption in a short time at pH= 1, 1.1 and 1.2. Maximum copper recovery were 60.8, 60.2 and 60.1%, respectively. Also acid consumption were 107.30, 99.90 and 93.23 kg/t of ore, respectively. After diagnostic tests, nine columns with dimension 2m height and 15cm diameter were filled by 0.5, 1 and 1.5 inches ore. Columns were irrigated with 7, 9 and 11 g/l as acid solution concentration at flow rates of 7, 11 and 15 l/m2*h for 63 days. Results showed that there are high correlation between copper and iron recoveries. Copper recovery changed from 25.5% to 58.9% while iron recovery changed from 4.7% to 15.2%. Acid consumption were achieved between 18 to 54 kg per ton of ore. Acid solution concentration and irrigation flow rate are the most important parameters on the copper and iron recoveries. By increasing of leaching period Copper extraction will increase, but acid will be waste more. Copper and iron recoveries were increased with increasing the acid solution concentration and irrigation flow rate but Increasing in amount of acid consumption does not increase copper extraction inevitably. Irrigation flow rate of acid solution has significant effect on acid consumption. With decreasing the ore particle size, both of copper recovery and acid consumption were increased.

A comprehensive study on removal and recovery of copper(II) from aqueous solutions by NaOH-pretreated Marrubium globosum ssp. globosum leaves powder: Potential for utilizing the copper(II) condensed desorption solutions in agricultural applications

Recovery of copper and chelating agents from sludge extracting solutions

Part Ⅰ. Polymerization of acriflavine performed in acidic aqueous solution produced thin one redox couple electrochemically active film. The electrochemical quartz crystal microbalance and cyclic voltammetry were used to study the in situ growth of the poly(acriflavine) film. The polymer films were more stable in acidic solutions as their formal potentials being pH dependent with a slope close to –60 mV/pH.The film was produced on glassy carbon, gold, and transparent semiconductor tin(IV) oxide electrodes. The modified film was electrocatalytically oxidation active for NADH in acidic and neutral aqueous solutions, as the electrocatalytic oxidation current developed from the anodic peak of the redox couple. The electrocatalytic oxidation of SO32- and electrocatalytic reduction of NO2-, SO52- and S2O82- by the poly(acriflavine) film in acidic aqueous solutions also showed the electrocatalytic reaction activity. The electrocatalytic oxidation of SO52- was investigated using the UV–visible absorption spectroscopy and the stopped-flow kinetic method. While the electrocatalytic oxidation of NADH was investigated using the cyclic voltammetry and the Chronoamperometric method. Part Ⅱ. The electrochemically active films of Nordihydroguaiaretic acid (NDGA,1,4-Bis(3,4-dihydroxyphenyl)2.3-dimethylbutane) film modified electrodes can produce by direct deposition on nafion modified electrodes from the Nordihydroguaiaretic acid. The deposition of NDGA/nafion films are stable and show obvious electrochemical activity in various pH aqueous solutions. An electrochemical quartz crystal microbalance and cyclic voltammetry were used to study the in situ growth of NDGA/nafion films. When NDGA/nafion films are prepared and transferred to aqueous solutions at various pH, the formal potential was found to be pH dependent. NDGA/nafion films were electrocatalytically oxidation active for dopamine, epinephrine, and norepinephrine in aqueous solutions, with the electrocatalytic oxidation current developing through the oxidized form of NDGA/nafion film. NDGA/nafion films also shows reversible electrocatalytic properties. Such films electrocatalytically reduce those oxidation products of dopamine, epinephrine, and norepinephrine that are produced from the electrocatalytic oxidation of these compounds by a NDGA/nafion film. NDGA/nafion modified films are also electrocatalytically oxidation active for the mixture of dopamine and ascorbic acid and their electrochemical properties show the reaction of dopamine quinone with ascorbic acid, This reaction was investigated using the rotating ring-disk electrode method. Part Ⅲ. Preparation of nordihydroguaiaretic acid performed in neutral aqueous solution produced thin one redox couple electrochemically active film. The electrochemical quartz crystal microbalance and cyclic voltammetry were used to study the in situ growth of the nordihydroguaiaretic acid film. The modified film was electrocatalytically oxidation of NADH to NAD+ and the electrocatalytic oxidation of ascorbic acid, dopamine, and N2H4 by the nordihydroguaiaretic acid film in neutral aqueous solutions showed the electrocatalytic reaction activity. Well-separated voltammetric peaks were observed for dopamine with uric acid and ascorbic acid with uric acid using the NDGA/GC modified electrodes. Hybrid films composed of nordihydroguaiaretic acid- flavin adenine dinucleotide (FAD) adsorbed film modified electrodes have been prepared in neutral aqueous solutions. The hybrid NDGA/ FAD film showed two redox couples. When transferred to various aqueous acidic solutions, the two redox couples and the formal potentials of the hybrid films were observed to be pH-dependent. The electrocatalytic oxidation and reduction of NADH and NAD+ by a NDGA/ FAD hybrid film in neutral aqueous solutions was carried out. The electrocatalytic oxidation of NADH and the reversible electrocatalytic reactions of NADH / NAD+ using a NDGA/ FAD hybrid film were found active.

Studies were conducted to investigate the removal and recovery of copper (II) ions from aqueous solutions by Micrococcus sp., which was isolated from a local activated sludge process. The equilibrium of copper biosorption followed the Langmuir isotherm model very well with a maximum biosorption capacity (q max ) of 36.5 mg of Cu2+/g of dry cell at pH 5.0 and 52.1 mg of Cu2+/g of dry cell at pH 6.0. Cells harvested at exponential growth phase and stationary phase showed similar biosorption characteristics for copper. Copper uptake by cells was negligible at pH 2.0 and then increased rapidly with increasing pH until 6.0. In multimetal systems, Micrococcus sp. exhibited a preferential biosorption order: Cu ~ Pb > Ni ~ Zn. There is virtually no interference with copper uptake by Micrococcus sp. from solutions bearing high concentrations of Cl-, SO4 2-, and NO3 - (0–500 mg/L). Sulfuric acid (0.05 M) was the most efficient desorption medium, recovering >90% of the initial copper sorbed. The copper capacity of Micrococcus sp. remained unchanged after five successive sorption and desorption cycles. Immobilization of Micrococcus sp. in 2% calcium alginate and 10% Polyacrylamide gel beads increased copper uptake by 61%. Biomass of Micrococcus sp. may be applicable to the development of potentially cost-effective biosorbent for removing and recovering copper from effluents.

Studies were conducted to investigate the removal and recovery of copper (II) ions from aqueous solutions by Micrococcus sp., which was isolated from a local activated sludge process. The equilibrium of copper biosorption followed the Langmuir isotherm model very well with a maximum biosorption capacity (q(max)) of 36.5 mg of Cu2+/g of dry cell at pH 5.0 and 52.1 mg of Cu2+/g of dry cell at pH 6.0. Cells harvested at exponential growth phase and stationary phase showed similar biosorption characteristics for copper. Copper uptake by cells was negligible at pH 2.0 and then increased rapidly with increasing pH until 6.0. In multimetal systems, Micrococcus sp. exhibited a preferential biosorption order: Cu approximate to Pb > Ni approximate to Zn. There is virtually no interference with copper uptake by Micrococcus sp. from solutions bearing high concentrations of Cl-, SO4(2-), and NO3- (0-500 mg/L). Sulfuric acid (0.05 M) was the most efficient desorption medium, recovering >90% of the initial copper sorbed. The copper capacity of Micrococcus sp. remained unchanged after five successive sorption and desorption cycles. Immobilization of Micrococcus sp. in 2% calcium alginate and 10% polyacrylamide gel beads increased copper uptake by 61%. Biomass of Micrococcus sp. may be applicable to the development of potentially cost-effective biosorbent for removing and recovering copper from effluents.

PurposeThe purpose of this paper is to focus on the removal of copper(II) ions from aqueous model salt solution by using chitosan-coated magnetite nanoparticles.Design/methodology/approachThe chitosan-coated magnetite nanoparticles were characterized using X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy and thermogravimetric differential thermal analysis. The adsorption of Cu(II) by using magnetite nanoparticles as an adsorbent was investigated under different adsorption conditions. The parameters studied were contact time, adsorbent dose and initial concentrations.FindingsThe sorption capacities of prepared samples were studied for the removal of Cu2+ ions from aqueous model solutions with varying experimental conditions of the initial metal concentration, contact time and dosage. It is found that the removal percent of Cu2+ ions increases with an increase in initial metal concentration, contact time and amount of dosage.Originality/valueBased on the obtained results, this study recommends that chitosan-coated magnetite nanoparticles can also be applied for removal of some heavy metal ions and/or organic compounds in aqueous solution. It is recommended that this study be shared with the polymer-based nanomaterial researchers, especially material science.

A galvanic system for the removal of copper from aqueous solutions using a divided flow-through cell is proposed. The present study looks into the feasibility of removing copper from dilute electroplating rinse water and recovering it in metallic form by a galvanic cementation process. This process does not require an external supply of energy due to the spontaneous chemical reaction between the copper/iron couple. Therefore, this operation is attractive in reducing operating costs, especially when dealing with low ion concentrations and serves as an alternative to current wastewater treatments available. The performance of the proposed system was evaluated as a function of cathode potential, catholyte flow rates, initial copper(II) concentration and types of electrode materials used. Results have shown that the galvanic flow system can remove copper effectively below the maximum permissible level from simulated copper(II) solutions. For a sample of copper bearing rinse water with relatively low conductivity containing 74.2 mg L−1 copper, 81.2% removal of the copper was achieved using a reticulated vitreous carbon as cathode.

Oilfield "produced" waters usually contain high hardness, and high dissolved solids along with some alkalinity. The problem of disposing of these waters and the need for huge volumes of water for alkaline water flooding and steam generation for steam floods, necessitate the softening and reinjection of softened produced water. Water for alkaline and steam flooding needs to be softened to almost zero hardness to prevent plugging during injection and to prevent scaling on boiler tubes. Softening of high TDS and high hardness waters requires a very selective resin with high operating capacity such as a weak carboxylic acid-type ion exchange resin. Conventional softening with strong acid resins would not work under these conditions. This paper discusses the different processes in softening oilfield produced water. Data obtained in softening varieties of produced waters from different oilfields in California will be presented. Performance characteristics of weak cation exchange resins and their chemical regenerant requirements will also be discussed.

The purpose was to study the patterns of dissolution (solubilization) of phosphorus-containing minerals in aqueous and polysaccharide solutions of organic acids in order to model the mechanism of mineral destruction by soil bacteria synthesizing organic acids and exopolysaccharides. Methods. Model, laboratory-analytical, microbiological, statistical. Results. The destructive effect of organic acids on minerals is manifested both in aqueous and polysaccharide solutions. The introduction of bacterial polysaccharide into an aqueous solution of acids increases the decomposition of phosphorus-containing minerals by 1.34̶ 4.96 times. The influence of the chemical structure of acid molecules on the intensity of mineral decomposition is mainly manifested in the presence of bacterial polysaccharide, while in an aqueous solution the effectiveness of acid action depends on the nature of the mineral being destroyed. To the maximum degree, polysaccharide increases the destruction of minerals in a solution of citric acid: molten magnesium phosphate ̶ 2.55 times, thermophosphate ̶ 2.11 times, phosphate flour ̶ 4.96 times. Decomposition of phosphorus compounds in solutions of ascorbic and oxalic acids enhances bacterial polysaccharide to a lesser extent than in citric acid solution. Modeling the destruction of phosphorus-containing minerals under non-sterile conditions (soil conditions) made it possible to establish that organic acids under non-sterile conditions are subject to consumption by soil microbiota, especially ascorbic and citric acids, and to a lesser extent - succinic. Aqueous solutions of organic acids after 18 hours of incubation in non-sterile conditions lose their leaching activity by 1.06 ̶12.1 times. The introduction of a polysaccharide into aqueous solutions of acids makes it possible to avoid their rapid consumption by microorganisms, because of which the efficiency of mineral leaching under non-sterile conditions decreasшes by only 5–20% compared to sterile ones. Conclusions. The introduction of a bacterial polysaccharide into a solution of organic acids enables the latter to be transferred to a sorbed state, as a result of which their susceptibility to consumption by microorganisms is sharply reduced. Thus, polysaccharide-forming bacteria not only destroy minerals more intensively than microorganisms synthesizing only low-molecular-weight metabolites, but also synthesize a more stable and long-term functioning leaching complex in the soil.

Advanced technologies of electronics industries have led to environmental contamination concerns, especially waste print circuit boards containing a very high concentration of copper (II) ions, which can be discharged in wastewater containing many contaminated metals. A low pH is a necessity for treating industrial wastewater containing heavy metals to meet engineering process design. A novel polymeric bispicolamine chelating resin, Dowex-M4195, was applied as an alternative for investigating the behavior of copper (II) in acidic solution via an ion exchange method in a batch experiment system. Characterization of physical and chemical properties before and after ion exchange were also explored through BET, SEM-EDX, FTIR and XRD. Response surface methodology was also applied for optimization of copper (II) removal capacity using design of experiment for selective chelating resin at a low pH. The results indicate that H+ Dowex-M4195 chelating resin had a high-carbon content and specific surface area of >64% and 26.5060 m2/g, respectively. It was predominantly macropore porous in nature due to the N2 gas adsorption isotherm and exhibited type IV with insignificant desorption hysteresis loop of H1-type. It was spherical and cylindrical. After the ion exchange process of copper (II)-loaded H+ Dowex-M4195, the specific surface area and total pore volume decreased by about 17.82% and 5.39%, respectively, as compared to H+ Dowex-M4195. Hysteresis loop, isotherm and pore size distribution were also similar. Regarding the functional group, the surface morphology and crystalline structures of H+ Dowex-M4195 showed copper (II) compound based on the structure of chelating resin that confirmed effective ion exchange behavior. The design of optimization indicated that copper (II) removal capacity of about 31.33 mg/g was achieved, which could be obtained at 6.96 h, pH of 2 (a desirable low pH), dose of 124.13 mg and concentration of 525.15 mg/L. The study indicated that the H+ Dowex-M4195 (which is commercially available on the market) can successfully be applied as an alternative precursor through the ion exchange method for further reuse and regeneration of the copper (II) in the electronic waste industries and other wastewater applications needed to respond the policy of biocircular green economy in Thailand.

Removal and Recovery of Copper and Zinc by Supported Liquid Membranes with Strip Dispersion