Selective Transport of Ag(I) through a Polymer Inclusion Membrane Containing a Calix[4]pyrrole Derivative from Nitrate Aqueous Solutions

Removal of Methylene Blue Dye from Aqueous Solutions Using Polymer Inclusion Membrane Containing Calix[4]pyrrole

The effective purification of aqueous solutions of methylene blue dye was tested using polymer inclusion membranes (PIMs) that contained cellulose triacetate (CTA) as a polymer base, o-nitrophenyl octyl ether (o-NPOE) as a plasticizer, and meso-tetra methyl tetrakis-[methyl-2-(4-acetlphenoxy)] calix[4]pyrrole (KP) as a carrier. Scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy were used to define the microstructure and surface of PIMs. Experimental results showed that, with an increased concentration of methylene blue in an aqueous solution, the removal percentage also increased. Further observation showed that the flux increased with the rise in the source phase pH values from 3 to 10. The carrier and plasticizer content in the membrane significantly influenced the membrane's transport properties. The optimal composition of the membrane in percent by weight for KP was 74% plasticizer; 18% support, and 8% carrier. The maximum MB removal (93.10%) was achieved at 0.10 M HCl solution as the receiving phase. It was shown that the membrane with optimal composition showed good reusability and enabled the easy and spontaneous separation of methylene blue from aqueous solutions.

The Use of Polymer Inclusion Membranes for the Removal of Metal Ions from Aqueous Solutions-The Latest Achievements and Potential Industrial Applications: A Review

The growing demand for environmentally friendly and economical methods of removing toxic metal ions from polluted waters and for the recovery of valuable noble metal ions from various types of waste, which are often treated as their secondary source, has resulted in increased interest in techniques based on the utilization of polymer inclusion membranes (PIMs). PIMs are characterized by many advantages (e.g., the possibility of simultaneous extraction and back extraction, excellent stability and high reusability), and can be adapted to the properties of the removed target analyte by appropriate selection of carriers, polymers and plasticizers used for their formulation. However, the selectivity and efficiency of the membrane process depends on many factors (e.g., membrane composition, nature of removed metal ions, composition of aqueous feed solution, etc.), and new membranes are systematically designed to improve these parameters. Numerous studies aimed at improving PIM technology may contribute to the wider use of these methods in the future on an industrial scale, e.g., in wastewater treatment. This review describes the latest achievements related to the removal of various metal ions by PIMs over the past 3 years, with particular emphasis on solutions with potential industrial application.

Separation of Mercury(II) from Industrial Wastewater through Polymer Inclusion Membranes with Calix[4]pyrrole Derivative

Polymer membranes with immobilized ligands are encouraging alternatives for the removal of toxic metal ions from aquatic waste streams, including industrial wastewater, in view of their high selectivity, stability, removal efficacy and low energy demands. In this study, polymer inclusion membranes (PIMs) based on cellulose triacetate, with a calix[4]pyrrole derivative as an ion carrier, were tested for their capability to dispose mercury (Hg(II)) ions from industrial wastewater. The impacts were assessed relative to carrier content, the quantity of plasticizer in the membrane, the hydrocholoric acid concentration in the source phase, and the character of the receiving phase on the performance of Hg(II) elimination. Optimally designed PIMs could be an interesting option for the industrial wastewater treatment due to the high removal efficiency of Hg(II) and great repeatability.

Recent developments in calix[4]pyrrole (C4P)-based supramolecular functional systems

Recent advances with calix[4]pyrrole-based supramolecular functional entities in the fields of molecular recognition (receptors, sensors, and metal ion caged systems), self-assembly (polymers), photo/pH-responsive molecular switches and catalysis are reviewed.

The Physical Chemistry and Chemical Physics (PCCP) Section of the International Journal of Molecular Sciences in Its Publications: The First 300 Thematic Articles in the First 3 Years

The Physical Chemistry and Chemical Physics Section (PCCP Section) is one of the youngest among the sections of the International Journal of Molecular Sciences (IJMS)-the year 2021 will only mark three years since its inception [...].

Efficient Recovery of Noble Metal Ions (Pd2+, Ag+, Pt2+, and Au3+) from Aqueous Solutions Using N,N'-Bis(salicylidene)ethylenediamine (Salen) as an Extractant (Classic Solvent Extraction) and Carrier (Polymer Membranes)

This paper presents the results of the first application of N,N'-bis(salicylidene)ethylenediamine (salen) as an extractant in classical liquid-liquid extraction and as a carrier in membrane processes designed for the recovery of noble metal ions (Pd2+, Ag+, Pt2+, and Au3+) from aqueous solutions. In the case of the utilization of membranes, both sorption and desorption were investigated. Salen has not been used so far in the sorption processes of precious metal ions. Recovery experiments were performed on single-component solutions (containing only one type of metal ions) and polymetallic solutions (containing ions of all four metals). The stability constants of the obtained complexes were determined spectrophotometrically. In contrast, electrospray ionization high-resolution mass spectrometry (ESI-HRMS) was applied to examine the elemental composition and charge of the generated complexes of chosen noble metal ions and salen molecules. The results show the great potential of N,N'-bis(salicylidene)ethylenediamine as both an extractant and a carrier. In the case of single-component solutions, the extraction percentage was over 99% for all noble metal ions (molar ratio M:L of 1:1), and in the case of a polymetallic solution, it was the lowest, but over 94% for platinum ions and the highest value (over 99%) for gold ions. The percentages of sorption (%Rs) of metal ions from single-component solutions using polymer membranes containing N,N'-bis(salicylidene)ethylenediamine as a carrier were highest after 24 h of the process (93.23% for silver(I) ions, 74.99% for gold(III) ions, 69.11% and 66.13% for palladium(II) and platinum(II) ions, respectively), similar to the values obtained for the membrane process conducted in multi-metal solutions (92.96%, 84.26%, 80.94%, and 48.36% for Pd(II), Au(III), Ag(I), and Pt(II) ions, respectively). The percentage of desorption (%Rdes) was very high for single-component solutions (the highest, i.e., 99%, for palladium solution and the lowest, i.e., 88%, for silver solution), while for polymetallic solutions, these values were slightly lower (for Pt(II), it was the lowest at 63.25%).

Characterization and Kinetic Studies of Poly(vinylidene fluoride-co-hexafluoropropylene) Polymer Inclusion Membrane for the Malachite Green Extraction

Textile industry effluent contains a high amount of toxic colorants. These dyes are carcinogenic and threats to the environment and living beings. In this study, poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP) was used as the based polymer for PIMs with bis-(2-ethylhexyl) phosphate (B2EHP) and dioctyl phthalate (DOP) as the carrier and plasticizer. The fabricated PIMs were employed to extract the cation dye (Malachite Green; MG) from the feeding phase. PIMs were also characterized by scanning electron microscopy (SEM), atomic force microscope (AFM), contact angle, water uptake, Fourier-transform infrared spectroscopy (FTIR) and ions exchange capacity. The performance of the PIMs was investigated under various conditions such as percentage of carrier and initial dye concentration. With permeability and flux values of 0.1188 cm/min and 1.1913 mg cm/min, PIM produced with 18% w/w PVDF-co-HFP, 21% w/w B2EHP, 1% w/w DOP and 40% w/w THF and was able to achieve more than 97% of MG extraction. The experimental data were then fitted with a pseudo-second-order (PSO) model, and the calculated R2 value was ~0.99. This shows that the data has a good fit with the PSO model. PIM is a potential alternative technology in textile industry effluent treatment; however, the right formulation is crucial for developing a highly efficient membrane.

The Application of 2,6-Bis(4-Methoxybenzoyl)-Diaminopyridine in Solvent Extraction and Polymer Membrane Separation for the Recovery of Au(III), Ag(I), Pd(II) and Pt(II) Ions from Aqueous Solutions

The work describes the results of the first application of 2,6-bis(4-methoxybenzoyl)-diaminopyridine (L) for the recovery of noble metal ions (Au(III), Ag(I), Pd(II), Pt(II)) from aqueous solutions using two different separation processes: dynamic (classic solvent extraction) and static (polymer membranes). The stability constants of the complexes formed by the L with noble metal ions were determined using the spectrophotometry method. The results of the performed experiments clearly show that 2,6-bis(4-methoxybenzoyl)-diaminopyridine is an excellent extractant, as the recovery was over 99% for all studied noble metal ions. The efficiency of 2,6-bis(4-methoxybenzoyl)-diaminopyridine as a carrier in polymer membranes after 24 h of sorption was lower; the percentage of metal ions removal from the solutions (%Rs) decreased in following order: Ag(I) (94.89%) > Au(III) (63.46%) > Pt(II) (38.99%) > Pd(II) (23.82%). The results of the desorption processes carried out showed that the highest percentage of recovery was observed for gold and silver ions (over 96%) after 48 h. The results presented in this study indicate the potential practical applicability of 2,6-bis(4-methoxybenzoyl)-diaminopyridine in the solvent extraction and polymer membrane separation of noble metal ions from aqueous solutions (e.g., obtained as a result of WEEE leaching or industrial wastewater).

Simultaneous Recovery of Precious and Heavy Metal Ions from Waste Electrical and Electronic Equipment (WEEE) Using Polymer Films Containing Cyphos IL 101

In this article, the application of a polymer film containing the ionic liquid Cyphos IL 101 for the simultaneous recovery of precious and heavy metal ions ((Ni(II), Zn(II), Co(II), Cu(II), Sn(II), Pb(II), Ag(I), Pd(II), and Au(III)) from waste electrical and electronic equipment (WEEE) is described. The experiments were performed for solutions containing metal ions released from computer e-waste due to leaching carried out with concentrated nitric(V) acid and aqua regia. It was found that the applied polymer film allows for the efficient recovery of precious metals (98.9% of gold, 79.3% of silver, and 63.6% of palladium). The recovery of non-ferrous metals (Co, Ni, Cu, Zn, Sn, and Pb) was less efficient (25-40%). Moreover, the results of the performed sorption/desorption processes show that the polymer film with Cyphos IL 101 can be successfully used after regeneration to recover metals ions several times.