A novel sandwich supported liquid membrane system for simultaneous separation of copper, nickel and cobalt in ammoniacal solution

Hydrodynamic features of pulsed solvent extractor for separation of two metals by using the antagonistic effect of solvents

Separating copper and cobalt ions is crucial due to the industry's strategic reliance on both these elements. When the extraction process is able to significantly increase the separation factor, it becomes favorable to separate two ions. However, the presence of Cu(II) ions together with Co(II) hinders the achievement of optimum efficiency when using commonly available extractants. This study conducted the separation of the two elements using both batch and continuous methods in a pilot plant pulsed column equipped with a disc and doughnut structure. The initial step involved optimizing the key variables to maximize the separation factor using the central composite design procedure. The optimization of Cyanex272, Cyphos IL 101 concentrations, and the pH value of the aqueous phase were all adjusted to 0.024 M, 0.046 M, and 7.3, correspondingly. In the following step, the hydrodynamic characteristics and extraction performance were examined in the pulsed column of the pilot plant. The findings indicated that the presence of Cyphos IL 101 resulted in an increased separation factor and efficiency within the column. As a result, the ionic liquid enhances performance without encountering any operational issues. This additive is considered an environmentally friendly solvent and does not cause any negative impacts. Consequently, it is suggested for utilization in continuous industrial processes.

Separation of Chromium (VI), Copper and Zinc: Chemistry of Transport of Metal Ions across Supported Liquid Membrane

Prior to applying supported liquid membranes (SLM) with strip dispersion for separation of chromium (VI), copper and zinc, suitable chemical settings were determined through solvent extraction and stripping studies. More than 90% of copper and zinc could be simultaneously extracted with at least 3% (v/v) di-(2-ethylhexyl)phosphoric acid (D2EHPA) at a feed equilibrium pH in the range of 3.5–5.0. For stripping, theoretical model equations derived and experimental results revealed that suitable concentrations of lower acid strength reagents can strip metals that have weaker metal-extractant bond without significantly stripping metals that have a stronger metal-extractant bond. Therefore, in a setup comprising three compartments separated by two SLM, we propose to fill the three compartments in the following order: feed—strip dispersion containing low acid strength reagent—strong acid. An organic phase with 4% (v/v) D2EHPA was used. From stripping experiments, 0.2 mol/L pH 3 citrate buffer, which resulted in the highest copper recovery (88.8%) and solution purity (99.0%), was employed as the low acid strength reagent while the strong acid consisted of 1 mol/L sulfuric acid. In 26 h, 99.1% copper was recovered by citrate buffer with 99.8% purity and 95.1% zinc was recovered by sulfuric acid with 98.4% purity. Chromium (VI), copper and zinc could be separated effectively using this separation strategy.

Utilization of green organic solvents in solvent extraction and liquid membrane for sustainable wastewater treatment and resource recovery-a review

Water pollution and depletion of natural resources have motivated the utilization of green organic solvents in solvent extraction (SX) and liquid membrane (LM) for sustainable wastewater treatment and resource recovery. SX is an old and established separation method, while LM, which combines both the solute removal and recovery processes of SX in a single unit, is a revolutionary separation technology. The organic solvents used for solute removal in SX and LM can be categorized into sole conventional, mixed conventional-green, and sole green organic solvents, whereas the stripping agents used for solute recovery include acids, bases, metal salts, and water. This review revealed that the performance of greener organic solvents (mixed conventional-green and sole green organic solvents) was on par with the sole conventional organic solvents. However, some green organic solvents may threaten food security, while others could be pricey. The distinctive extraction theories of various sole green organic solvents (free fatty acid-rich oils, triglyceride-rich oils, and deep eutectic solvents) affect their application suitability for a specific type of wastewater. Organic liquid wastes are among the optimal green organic solvents for SX and LM in consideration of their triple environmental, economic, and performance benefits.

Evolution of Environmentally Friendly Strategies for Metal Extraction

The demand for the recovery of valuable metals and the need to understand the impact of heavy metals in the environment on human and aquatic life has led to the development of new methods for the extraction, recovery, and analysis of metal ions. With special emphasis on environmentally friendly approaches, efforts have been made to consider strategies that minimize the use of organic solvents, apply micromethodology, limit waste, reduce costs, are safe, and utilize benign or reusable materials. This review discusses recent developments in liquid- and solid-phase extraction techniques. Liquid-based methods include advances in the application of aqueous two- and three-phase systems, liquid membranes, and cloud point extraction. Recent progress in exploiting new sorbent materials for solid-phase extraction (SPE), solid-phase microextraction (SPME), and bulk extractions will also be discussed.