Metallic copper removal optimization from real wastewater using pulsed electrodeposition

Preparation of a Porous Geopolymer (SPG) to be Used as an Adsorbent for Cu2+ Removal

A porous geopolymer was synthesized using steel slag (accounting for 71.6 wt %) with the aim of effectively removing Cu2+ ions. The chemical composition and microstructure of this material were investigated using X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscope analysis, and BET method. The effects of H2O2 doping, H2O doping, and the curing temperature on the properties of this porous geopolymer were systematically investigated. Subsequently, the adsorption behavior of the porous geopolymer toward Cu2+ was explored through static adsorption experiments. The findings reveal that there are a higher specific surface area and pore capacity for the porous geopolymer compared to the original steel slag, with a total porosity of 90.3%, compressive strength of 0.29 MPa, and volume water absorption rate of 69.4%. The adsorption capacity of this material toward Cu2+ is found to be 36.8 mg·g-1, which is slightly superior to that of commercial spherical 4A molecular sieves. The adsorption process follows the quasi-first-order kinetic model, while the isothermal adsorption conforms to the Freundlich model.

Electrocoagulation/flotation process for removing copper from an aqueous environment

The presence of copper in aqueous environments such as drinking water has led to several environmental effects, such as flavor and odor. The increase in Cu levels in ground and surface water has been mainly attributed to anthropogenic and natural sources. Consequently, this applied-analytical study aimed to investigate copper removal from urban drinking water through batch reactor electrocoagulation/flotation (ECF) with aluminum electrodes. The copper removal efficiency was evaluated under various operating conditions of current density (0.8-2.4 mA/cm2), initial concentration (1-100 mg/L), pH (3.5-10.5), and time (10-30 min). Cu was determined using the method outlined in the standard procedures (3500-Cu B at 4571 nm). The results indicated that increasing the current density from 0.8 to 2.4 mA/cm2 and the reaction time from 10 to 30 min improved Cu+2 removal efficiency (from 95 to 100%). In addition, the results demonstrated that Cu+2 reduction is 100% with an initial concentration of 100 mg/L, a pH of 7.5, a reaction time of 30 min, and an anode current density of 2.4 mA/cm2. The Taguchi method results for copper removal efficiency show that reaction time is the most significant variable. Furthermore, Cu removal kinetics models in an ECF reactor are second-order (R2 > 0.92). The Cu removal in the ECF reactor is due to redox and adsorption. Moreover, the operational costs of Cu treatment with Al electrode pairs are estimated to range from 8857 and 9636 Rial/kg of Cu removed. Thus, it can be concluded that the ECF process is very efficient in removing Cu from aqueous environments under optimum conditions.

Removal of Copper Ions from Wastewater: A Review

Copper pollution of the world's water resources is becoming increasingly serious and poses a serious threat to human health and aquatic ecosystems. With reported copper concentrations in wastewater ranging from approximately 2.5 mg/L to 10,000 mg/L, a summary of remediation techniques for different contamination scenarios is essential. Therefore, it is important to develop low-cost, feasible, and sustainable wastewater removal technologies. Various methods for the removal of heavy metals from wastewater have been extensively studied in recent years. This paper reviews the current methods used to treat Cu(II)-containing wastewater and evaluates these technologies and their health effects. These technologies include membrane separation, ion exchange, chemical precipitation, electrochemistry, adsorption, and biotechnology. Thus, in this paper, we review the efforts and technological advances made so far in the pursuit of more efficient removal and recovery of Cu(II) from industrial wastewater and compare the advantages and disadvantages of each technology in terms of research prospects, technical bottlenecks, and application scenarios. Meanwhile, this study points out that achieving low health risk effluent through technology coupling is the focus of future research.

Novel high capacity model for copper binary ion exchange on e-waste derived adsorbent resin

Heavy metal water pollution is a global concern in recent years. Copper is a toxic metal at higher concentrations (> 20 μg /g) and needs to be removed using ion exchanger systems. This study investigates the removal efficiencies of copper by the non-metallic fraction (NMF) waste printed circuit boards (PCBs). The high maximum adsorption capacity of copper by the PCB-derived material after activation with KOH was 2.65 mmol/g, and the experimental isotherm was best correlated by the Temkin model. Finally, this study presents a novel dual site adsorption/ion exchange mechanism, wherein the potassium (from the activation) and calcium (present in the structure) served as ion exchange sites for the copper in the solution. Therefore, this recycling study, focusing on cyclic environmental management, converts a major waste material to an activated ion exchange resin (high capacity) for the removal of copper from wastewater solutions and successfully regenerates the resin for re-use while producing an acidic copper solution for recovery by electrolysius or chemical salt precipitation.

Removal behavior and mechanisms of cadmium and lead by coupled ethylenediaminetetraacetic acid washing and electrochemical reduction: influence of current conditions

Ethylenediaminetetraacetic acid (EDTA) washing has been used extensively to remediate heavy metal-contaminated soils. Electrochemical reduction treatment of spent washing solution is an effective method of EDTA regeneration. However, at present, these two technologies are usually regarded as two independent treatment processes. This research raised a new heavy metal-contaminated soil treatment strategy-a combination technique of coupled EDTA washing and electrochemical reduction. We speculated that the combination of EDTA washing and electroreduction treatment could improve the efficiency of Cd and Pb removal from contaminated soil. In this study, the removal performance and mechanisms of Cd and Pb under different current conditions were investigated based on a coupling of EDTA washing and electrochemical reduction. The combination technique can increase Cd and Pb removal efficiencies by 13.37-15.24% and 14.91-27.05%, respectively, compared with EDTA washing alone. Sequential extraction analysis showed that the reducible fraction improved metal removal efficiency. The percentage of metal removed increased with an increased current value and EDTA concentration. In addition, pulse current mode removed more Cd and Pb than continuous current, although the difference was not significant (p > 0.05). However, pulse current could effectively eliminate the cathodic hydrogen evolution reaction, resulting in a further heavy metal deposition at the cathode. The combination technique exhibited enhanced removal efficiency due to EDTA regeneration in the suspension and the cathodic reduction reaction. The most cost-effective treatment in 48 h was a pulse current mode of 32 min on/16 min off-32 mA-EDTA-10 mM, where 47.56% of Cd and 77.00% of Pb were removed from the soil with an electric energy consumption of 8.24 Wh.

Solar distillation meets the real world: a review of solar stills purifying real wastewater and seawater

Solar energy-driven evaporation-based freshwater production is one of the sustainable ways to purify contaminated/salty water. Recent advances in solar absorbers' assemblies, design modifications, and integrations with heating sources improved the rate of freshwater productivity. However, the type of feed water affects the evaporation rate in a solar desalination system (SDS). Many studies used tap water with added contaminants to test the performance of a SDS and studied the water quality improvement. As a typical result, pH, total dissolved solids (TDS), and electrical conductivity (µS/cm) are reduced after solar evaporation. The performance of SDSs for real wastewaters are also important to understand, e.g., the reduction of high organic pollutants after solar evaporation. In this aspect, the main objective of the present work is to review solar distillation of real wastewaters and seawater by using SDSs. Further, the mechanism of a solar distiller with heat transfer principles, parameters affecting evaporation process, real wastewaters and seawaters purified in a solar distillation system, improvement of various parameters before and after solar evaporation, pathways of handling wastewaters, challenges, and future perspectives are discussed. Conclusively, SDSs are found to remove pollutants effectively after solar evaporation. The evaporation rate is relatively slower due to high concentration of pollutants that reduce vapor pressure. The COD removal of various real wastewaters, including sludge, kitchen, textile, palm oil, petroleum, water plant, and municipal wastewaters, was 98.13%, 97.85%, 96.84%, 96.71%, 87.99%, 86.99%, and 85.67%, respectively. The reduction rate of salt concentration in real seawater after evaporation in the solar distiller was 99.99%.

Copper removal kinetic from electroplating industry wastewater using pulsed electrodeposition technique

This study presents a kinetic determination of copper removal from a real jewelry industry wastewater, with removal reaching 82.49% at 37°C, using fast galvanic pulse electrochemical technique in a process lasting 115 min. In the temperature range from 20 to 40°C, the mathematical model of the pseudo-first-order irreversible rate equation, with a correlation coefficient of 0.99, described the process behaviour. In this same temperature range, the Arrhenius' equation described the system, in which the temperature increase favoured the reaction kinetics. The scanning electron microscope (SEM), with energy-dispersive X-ray detector (EDX), X-ray photoelectron spectroscopy (XPS) results, and the mathematical model fitting at the temperatures of 10 and 50°C indicated the formation of copper oxide I.

Preparation of bio-absorbents by modifying licorice residue via chemical methods and removal of copper ions from wastewater

In this paper, a series of bio-adsorbents (LR-NaOH, LR-Na₂CO₃ and LR-CA) were successfully prepared by modifying Licorice Residue (LR) with NaOH, Na₂CO₃ and citric acid, and were used as the adsorbents to remove Cu²⁺ from wastewater. The morphology and structure of bio-adsorbents were characterized by Fourier Transform Infrared, scanning electron microscopy (SEM), thermogravimetry (TG) and X-ray diffraction (XRD). Using static adsorption experiments, the effects of the adsorbent dosage, the solution pH, the adsorption time, and the initial Cu²⁺ concentration on the adsorption performance of the adsorbents were investigated. The results showed that the adsorption process of Cu²⁺ by the bio-adsorbents can be described by pseudo-second-order kinetic model and the Langmuir model. The surface structure of the LR-NaOH, LR-Na₂CO₃ and LR-CA changed obviously, and the surface-active groups increased. The adsorption capacity of raw LR was 21.56 mg/g, while LR-NaOH and LR-Na₂CO₃ significantly enhanced this value up to 43.65 mg/g and 43.55 mg/g, respectively. After four adsorption-desorption processes, the adsorption capacity of LR-NaOH also maintained about 73%. Therefore, LR-NaOH would be a promising adsorbent for removing Cu²⁺ from wastewater, and the simple strategy towards preparation of adsorbent from the waste residue can be a potential approach for use in the water treatment.

An Old Technique with A Promising Future: Recent Advances in the Use of Electrodeposition for Metal Recovery

Although the first published works on electrodeposition dates from more than one century ago (1905), the uses of this technique in the recovery of metals are attracting an increasing interest from the scientific community in the recent years. Moreover, the intense use of metals in electronics and the necessity to assure a second life of these devices in a context of circular economy, have increased the interest of the scientific community on electrodeposition, with almost 3000 works published per year nowadays. In this review, we aim to revise the most relevant and recent publications in the application of electrodeposition for metal recovery. These contributions have been classified into four main groups of approaches: (1) treatment and reuse of wastewater; (2) use of ionic liquids; (3) use of bio-electrochemical processes (microbial fuel cells and microbial electrolysis cells) and (4) integration of electrodeposition with other processes (bioleaching, adsorption, membrane processes, etc.). This would increase the awareness about the importance of the technology and would serve as a starting point for anyone that aims to start working in the field.