Search Results (58)

A novel centrifuge-less cloud point extraction (CL-CPE) method was developed for the spectrophotometric determination of copper(II) using 4-nitrocatechol (4NC) as the chelating agent. The extraction system utilizes a mixed micellar phase composed of the nonionic surfactant Triton X-114 and the ionic liquid (IL) Aliquat^® 336 (A336). The extracted ternary ion-association complex, identified as (A336⁺)₂[Cu(4NC)₂], exhibits a maximum absorbance at 451 nm, with a molar absorption coefficient of 8.9 × 10⁴ M⁻¹ cm⁻¹ and a Sandell’s sensitivity of 0.71 ng cm⁻². The method demonstrates a linear response in the copper(II) concentration range of 32–763 ng mL⁻¹ and a limit of detection of 9.7 ng mL⁻¹. The logarithmic extraction constant (log K_ex) was determined to be 7.9, indicating efficient extraction. Method performance, evaluated by the Blue Applicability Grade Index (BAGI) and the Click Analytical Chemistry Index (CACI), confirmed its feasibility, practicality, simplicity, convenience, cost-effectiveness, environmental friendliness, and analytical competitiveness. The proposed IL-CL-CPE method was successfully applied to the analysis of a dietary supplement, a solution for infusion, and synthetic mixtures simulating various copper alloys. Full article

Next-generation recycling technologies must be urgently innovated to tackle huge volumes of spent batteries, photovoltaic panels or printed circuit boards (WPCBs). Current e-waste recycling industrial technology is dominated by traditional recycling technologies. Herein, ionic liquids (ILs), deep eutectic solvents (DESs) and promising oxidizing additives that can overcome some traditional recycling methods of metal ions from e-waste, used in our works from last year, are presented. The unique chemical environments of ILs and DESs, with the application of low-temperature extraction procedures, are important environmental aspects known as “Green Methods”. A closed-loop system for recycling zinc and manganese from the “black mass” (BM) of waste, Zn-MnO₂ batteries, is presented. The leaching process achieves a high efficiency and distribution ratio using the composition of two solvents (Cyanex 272 + diethyl phosphite (DPh)) for Zn(II) extraction. High extraction efficiency with 100% zinc and manganese recovery is also achieved using DESs (cholinum chloride/lactic acid, 1:2, DES 1, and cholinum chloride/malonic acid, 1:1, DES 2). New, greener recycling approaches to metal extraction from the BM of spent Li-ion batteries are presented with ILs ([N_8,8,8,1][Cl], (Aliquat 336), [P_6,6,6,14][Cl], [P_6,6,6,14][SCN] and [Benzet][TCM]) eight DESs, Cyanex 272 and D2EHPA. A high extraction efficiency of Li(I) (41–92 wt%) and Ni(II) (37–52 wt%) using (Cyanex 272 + DPh) is obtained. The recovery of Ni(II) and Cd(II) from the BM of spent Ni-Cd batteries is also demonstrated. The extraction efficiency of DES 1 and DES 2, contrary to ILs ([P_6,6,6,14][Cl] and [P_6,6,6,14][SCN]), is at the level of 30 wt% for Ni(II) and 100 wt% for Cd(II). In this mini-review, the option to use ILs, DESs and Cyanex 272 for the recovery of valuable metals from end-of-life WPCBs is presented. Next-generation recycling technologies, in contrast to the extraction of metals from acidic leachate preceded by thermal pre-treatment or from solid material only after thermal pre-treatment, have been developed with ILs and DESs using the ABS method, as well as Cyanex 272 (only after the thermal pre-treatment of WPCBs), with a process efficiency of 60–100 wt%. In this process, four new ILs are used: didecyldimethylammonium propionate, [N_10,10,1,1][C₂H₅COO], didecylmethylammonium hydrogen sulphate, [N_10,10,1,H][HSO₄], didecyldimethylammonium dihydrogen phosphate, [N_10,10,1,1][H₂PO₄], and tetrabutylphosphonium dihydrogen phosphate, [P_4,4,4,4][H₂PO₄]. The extraction of Cu(II), Ag(I) and other metals such as Al(III), Fe(II) and Zn(II) from solid WPCBs is demonstrated. Various additives are used during the extraction processes. The Analyst 800 atomic absorption spectrometer (FAAS) is used for the determination of metal content in the solid BM. The ICP-OES method is used for metal analysis. The obtained results describe the possible application of ILs and DESs as environmental media for upcycling spent electronic wastes. Full article

The widespread, worldwide utilisation of alkaline batteries requires development of proper recycling methods for used batteries, which are considered both as a secondary source of valuable metals and as a threat to the environment (may contain toxic substances). As many separation methods of metal ions from battery leachates are based on the use of substances that require complex synthesis or are not eco-safe, new materials suitable for this purpose are systematically sought. Therefore, in this study, the results of the separation of Ni(II), Zn(II) and Mn(II) ions from alkaline battery leachates using polymer materials (PMs) impregnated with easily synthesised, “green” deep eutectic solvents (DESs) or with ionic liquids (ILs) were presented. Additionally, PMs surface wettability were determined and their chemical compositions were analysed using the Fourier transform infrared spectroscopy–attenuated total reflectance (FTIR–ATR) method. Among all PMs synthesised, materials containing DESs (composed of Aliquat 336 or Cyphos IL 101 and diacetamide) performed best in the separation of Ni(II) ions (removal of 93.42% and 80.86%). The application of DES-based PMs for the separation of metal ions from battery leachates is in line with green chemistry principles, and such materials can potentially be used in the processing of e-waste. Full article

A novel method for the spectrophotometric determination of trace amounts of molybdenum has been developed. This method utilizes a centrifuge-less cloud point extraction (CL-CPE) in a mixed micellar (MM) system containing a nonionic surfactant (Triton X-114) and an ionic liquid (Aliquat^® 336, A336). The chromophore chelating reagent employed was 4-nitrocatechol (4NC, H₂L). This work marks its first application as a CPE reagent. Under the optimal conditions, Mo(VI) forms a yellow ternary complex with 4NC and A336, which can be represented by the formula (A336⁺)₂[MoO₂L₂]. The method possesses the following characteristics: limit of detection (LOD) of 3.2 ng mL⁻¹, linear range of 10.8–580 ng/mL, absorption maximum of 435 nm, molar absorptivity coefficient of 3.34 × 10⁵ L mol⁻¹ cm⁻¹, and Sandell’s sensitivity of 0.29 ng cm⁻². The method has been successfully employed for the determination of molybdenum in reference standard steel samples, bottled mineral water, and a molybdenum-containing dietary supplement. Full article

The increasing demand for critical metals has intensified efforts to recover valuable metals from various sources, including secondary waste. Zn-Pb tailings contain both major and trace metals with economic and environmental significance. This study examined the extraction of transition metals from Zn-Pb tailings using inductively coupled plasma mass spectrometry (ICP-MS) at a constant time of 30 min. Metal extraction efficiencies were evaluated using N-Methyl-N,N,N-trioctylammonium chloride (Aliquat 336), methyl salicylate (MS), di(2-ethylhexyl) phosphoric acid (D2EHPA), tributyl phosphate (TBP),2,4,6-tris(allyloxy)-1,3,5-triazine (TAOT), and triethyl phosphate (TEP). Increasing mixing rates improved mass transfer, enhancing recoveries, with Hf⁴⁺, Ti⁴⁺, and Fe³⁺ reaching 88, 56, and 50%, respectively, at 1000 rpm (mixing rate; rotation per minute) using D2EHPA. At a mixing rate of 1000 rpm, 10% TEP recovered 25% of Cu²⁺ and 34% of Mn²⁺, while 150 g/L extracted 48% of Hf⁴⁺ and 46% of V⁴⁺. Additionally, 10% TBP extracted 33% of Mn²⁺ and 35% of V⁴⁺, 10% MS recovered 41% of Mn²⁺ and 39% of V⁴⁺, while TAOT extracted 35% of V⁴⁺. At room temperature (22.5 °C) and 1400 rpm, 10% of D2EHPA recovered 80% of Hf⁴⁺, 73% of Ti⁴⁺, and 61% of Fe²⁺. However, 10% TAOT selectively recovered 50% of V⁴⁺, while 10% MS, under the same conditions, recovered 50% of V⁴⁺ with co-extraction of Mn²⁺ and Cu²⁺ (<10%). A total of 150 g/L Aliquat 336 effectively extracted Hf⁴⁺ (66%), Zn²⁺ (19%), and V⁴⁺ (56%). A total of 10% TBP recovered 53% and 47% of Mn²⁺ and V⁴⁺, respectively. A total of 10% TEP recovered Cu²⁺ (45%), Mn²⁺ (55%), Zn²⁺ (29%), V (40%), and 26% of Ni²⁺. At room temperature (22.5 °C) and 1400 rpm, pH changes significantly affected extraction, with D2EHPA (10%) demonstrating 89% efficiency for Hf⁴⁺ at pH 1.3, while other metals showed lower recoveries. TEP (10%) increased Cu²⁺ and Hf⁴⁺ recovery to 52% and 80%, respectively, at pH 1.3, while 150 g/L Aliquat 336 favored Cu²⁺ (58%), with co-extraction of 16% of Zn²⁺ at pH 1.3. TBP (10%) extracted 60% and 61% of Cu²⁺ and Fe, respectively, at pH 1.3, while 10% of MS recovered 55% and 50% of V, respectively. A concentration of 10% D2EHPA favored the recovery of 90% of Hf⁴⁺ at pH 1.3, with less than 35% co-extraction of Cu²⁺, Mn²⁺, Zn²⁺, and Fe²⁺. At 1400 rpm, temperature also influenced extraction, with D2EHPA recovering 84% of Hf⁴⁺ at 35 °C, 77% of Ti (55 °C), and 79% of Fe (55 °C) and TBP extracting 73% of Cu²⁺, 67% of Mn²⁺, 68% of Zn, 60% of V⁴⁺, and 47% of Ni²⁺ at 55 °C. A concentration of 10% MS extracted 61% of V⁴⁺and 54% of Fe²⁺, while 150 g/L recovered 61% of V⁴⁺ at 55 °C. TAOT extracted 46% of Mn and 41% of V⁴⁺, while 10% TEP recovered 60% of Mn and 32% of V⁴⁺ at 55 °C. These outcomes contribute to an improved understanding of the solvent extraction mechanisms of different ligands. Full article

Conjugated donor–acceptor (D-A) copolymers are widely used in optoelectronic devices due to their influence on the resulting properties. This study focuses on the synthesis and characterization of the conjugated D-A copolymer constructed with fluorene and di-2-thienyl-2,1,3-benzothiadiazole units, resulting in Poly[2,7-(9,9-dioctyl-fluorene)-alt-5,5-(4,7-di(2-thienyl)-2,1,3-benzothiadiazole)] (PFDTBT). The synthesis associated with reaction times of 48 and 24 h, the latter incorporating the phase-transfer catalyst Aliquat 336, was investigated. The modified conditions produced copolymers with higher molar masses (Mw > 20,000 g/mol), improved thermal stability and red emission at 649 nm. Furthermore, the resulting D-A copolymers exhibited uniform morphology with low surface roughness (P2—Ra: 0.77 nm). These improved properties highlight the potential of D-A copolymers based on PFDTBT for various optoelectronic applications, including photovoltaics, light-emitting devices, transistors and biological markers in the form of quantum dots. Full article

Developing an efficient recycling route for spent single-use medical devices is essential for recovering precious metals. The proposed complete hydrometallurgical route goes through the initial pyrolysis and acid digestion steps, expanding upon our previous relevant work in the field, followed by solvent extraction, stripping, and precipitation procedures. In this study, a complete hydrometallurgical process was developed for the recovery of gold, platinum, iridium, and tantalum, separating them from other metals, i.e., from iron, chromium, and nickel, also present in the examined medical devices, i.e., (i) diagnostic electrophysiology catheters, containing gold, (ii) diagnostic guide wires, containing platinum and iridium alloys, and (iii) self-expanding stents, containing tantalum. This study reports the experimental results of selecting an efficient extractant, stripping, and precipitation agent, along with the effects of key factors that influence each consecutive step of the process, i.e., agent concentration, aqueous to organic phase ratio, contact time, and pH, using simulated metal solutions and also applying the obtained optimal conditions to the treatment of real sample solutions. For the selective separation of gold, Aliquat 336 was used to extract it in the organic phase; it was then stripped using a thiourea solution and precipitated by utilizing an iron sulfate (II) solution and proper pH adjustment. The selective separation of platinum was achieved by using Aliquat 336 for the organic phase extraction and a perchlorate acid solution for stripping it back into the aqueous solution and adding a sodium bromate solution to precipitate it. Due to the similar chemical behavior, the selective recovery of iridium followed the same processes as that of platinum, and the separation between them was achieved through selective precipitation, as heating the solution and adjusting the pH value resulted in the selective precipitation of iridium. Lastly, the selective recovery of tantalum consists of extraction by using Alamine 336, then stripping it back to the aqueous phase by using sodium chloride, and precipitation by using potassium salt solution and proper pH adjustment. A total recovery of 88% for Au, 86% for Pt, 84% for Ir, and 80% for Ta was obtained, thus achieving a high uptake of precious metals from the examined real spent/waste samples. Full article

Solvent extraction of metals from Ti ore was investigated with a view of enhancing extraction yields by changing the concentration of the ligands, the rate of mixing, the pH, and the temperature of the solution. Norwegian Ti ore was leached with 5M HNO₃ alongside 10% ascorbic acid to obtain a pregnant solution containing transition metals and some rare earth elements (REEs). Part Two of the study will address the recovery of the REEs in the ore. The elemental analysis of solid and aqueous samples was done by two models of total reflection X-ray fluorescence spectrometers (S2 PICOFOX, Bruker Corporation, Berlin, Germany; and T-STAR, Bruker Corporation, Berlin, Germany). The same analysis was repeated using an inductively coupled plasma-mass spectrometer (Perkin Elmer Sciex ELAN DRC II, Perkin Elmer, Waltham, MA, USA). The extraction process and parameters were examined by ICP-MS. The extraction efficiencies were studied under different conditions through the use of various concentrations of ligands at different pHs, temperatures, and mixing rates of the solution. At pH 1.0, 22.5 °C, and a mixing rate of 1400 rpm, the selectivity of 150 g/L trioctyl methyl ammonium chloride (Aliquat 336) was 99% Ti⁴⁺, 94% V⁴⁺, and 82% Hf⁴⁺, while 99% of Co²⁺ was recovered at pH 0.8. The extraction efficiency of triethyl phosphate (10% TEP) was 58% Cu²⁺, 68% Mn²⁺, and 63% V⁴⁺ at 55 °C, 1400 rpm, and without a pH change. Tributyl phosphate (10% TBP) was able to retrieve 87% Cu²⁺ and 78% Zn²⁺ at pH 1.3, 1400 rpm, and 22.5 °C, and 80% Ti⁴⁺ at pH 1.2. A 10% solution of 2,4,6-tris (allyloxy)-1,3,5-triazine (TAOT) demonstrated 61% Mn²⁺ and 56% Hf⁴⁺ extraction at pH 1.3, 22.5 °C, and 1400 rpm. Under the same conditions, 10% methyl salicylate (MS) was able to recover 56% Hf⁴⁺ at pH 1.3. Using 1400 rpm, di (2-ethylhexyl) phosphoric acid (10% D2EHPA) was found to selectively extract 87% Hf⁴⁺ at 22.5 °C without a pH change, and around 99% Co²⁺, Ti⁴⁺, and Fe²⁺ at pH 1.3. This study provides valuable insights into optimizing solvent extraction conditions for transition metals’ recovery and serves as a precursor to future research on the extraction of REEs from Ti ores. This process is relevant from the environmental and economic perspectives since it provides the best approach to recycling metals to reduce the rate of raw ore mining. Full article

Deep eutectic solvents (DESs) have emerged as a greener alternative to other more polluting traditional solvents and have attracted a lot of interest in the last two decades. The DESs are less toxic dissolvents and have a lower environmental footprint. This paper presents an alternative synthesis method to the classical heating–stirring method. The ultrasound method is one of the most promising synthesis methods for DESs in terms of yield and energy efficiency. Therefore, the ultrasound synthesis method was studied to obtain hydrophobic (Aliquat 336:L-Menthol (3:7); Lidocaine:Decanoic acid (1:2)) and hydrophilic DESs based on choline chloride, urea, ethylene glycol and oxalic acid. The physical characterization of DESs via comparison of Fourier transform infrared (FTIR) spectra showed no difference between the DESs obtained by heating–stirring and ultrasound synthesis methods. The study and comparison of all the prepared DESs were carried out via nuclear magnetic resonance spectroscopy (NMR). The density and viscosity properties of DESs were evaluated. The density values were similar for both synthesis methods. However, differences in viscosity values were detected due to the presence of some water in hygroscopic DESs. Full article

This manuscript analyses changes in the optical parameters of a commercial alumina nanoporous structure (Anodisc^TM or AND support) due to surface coverage by the ionic liquid (IL) AliquatCl (AlqCl). XPS measurements were performed for chemical characterization of the composite AND/AlqCl and the AND support, but XPS resolved angle analysis (from 15° to 75°) was carried out for the homogeneity estimation of the top surface of the ANDAlqCl sample. Optical characterization of both the composite AND/AlqCl and the AND support was performed by three non-destructive and non-invasive techniques: ellipsometry spectroscopy (SE), light transmittance/reflection, and photoluminescence. SE measurements (wavelength ranging from 250 nm to 1250 nm) allow for the determination of the refraction index of the AND/AlqCl sample, which hardly differs from that corresponding to the IL, confirming the XPS results. The presence of the IL significantly increases the light transmission of the alumina support in the visible region and reduces reflection, affecting also the maximum position of this latter curve, as well as the photoluminescence spectra. Due to these results, illuminated I–V curves for both the composite AND/AlqCl film and the AND support were also measured to estimate its possible application as a solar cell. The optical behaviour exhibited by the AND/AlqCl thin film in the visible region could be of interest for different applications. Full article

A study of the liquid–liquid extraction of ReO₄⁻ anions from hydrochloric acid solutions using the ionic liquid Aliquat 336 (QCl: trialkyl(C₈–C₁₀)methylammonium chloride) via the well-known method of slope analysis along with the determination of the process parameters is presented. This study employs CCl₄, CHCl₃ and C₆H₁₂ as diluents. This study was carried out at room temperature (22 ± 2) °C and an aqueous/organic volumetric ratio of unity. The ligand effect on the complexation properties of ReO₄⁻ is quantitatively assessed in different organic media. The organic extract in chloroform media is examined through ¹H, ¹³C and ¹⁵N NMR analysis as well as the HRMS technique and UV-Vis spectroscopy in order to view the anion exchange and ligand coordination in the organic phase solution. Final conclusions are given highlighting the role of the molecular diluent in complexation processes and selectivity involving ionic liquid ligands and various metal s-, p-, d- and f-cations. ReO₄⁻ ions have shown one of the best solvent extraction behaviors compared to other ions. For instance, the Aliquat 336 derivative bearing Cl⁻ functions shows strongly enhanced extraction as well as pronounced separation abilities towards ReO₄⁻. Full article

Nowadays, there is a need for new sources of noble metals due to their dwindling natural resources. This paper presents studies on the sorption of noble metals such as Au(III), Pt(IV), Pd(II) and Rh(III) from model chloride solutions on a newly prepared Amberlite XAD-16–Aliquat 336 sorbent. A “warm impregnation” method without the use of toxic organic solvents was applied to impregnate the polymer matrix. The influence of such factors as hydrochloric acid concentration, sorbent mass and phase contact time was investigated. Kinetic as well as adsorption isotherm studies were carried out. The sorption capacity of the synthesized sorbent was Au(III)—94.34 mg/g, Pt(IV)—45.35 mg/g and Pd(II)—46.03 mg/g. Based on thermodynamic considerations, their sorption proved to be endothermic, as the values of ΔH° > 0. Sorption was spontaneous and favourable (ΔG° < 0). After leaching the RAM module, there was obtained a real solution, in which the metal contents were determined: 38.10 mg/g of gold and 1.76 mg/g of palladium. Totals of 99.9% of gold and 45.4% of palladium were removed from the real leaching solution, with other elements in the solution. Full article

In this study, the facile removal of the chromium-complex-based reactive azo dye C. I. Reactive Black 8 (RB8) from model wastewaters by the co-action of alternative sorbents—biochar (BC) and bentonite (BT)—with ionic liquids such as benzalkonium chloride (BAC) or Aliquat 336 (A336) was studied. The experiments using model RB8-containing wastewater proved that the co-action of BAC with BC is the most promising method of RB8 separation from wastewater containing 1 g L⁻¹ of RB8 dye. The application of 2 g L⁻¹ BC in co-action with 1.5 g L⁻¹ BAC or 1 g L⁻¹ BT in co-action with 2 g L⁻¹ BAC enables the removal of more than 98% of contaminant RB8 after 30 min of action. Similar removal efficiency (RE) was achieved using 40 g L⁻¹ of powdered activated carbon (PAC) after 180 min of action. To reach the same RE using real RB8-containing wastewater, a four times higher dose of BC and a four times higher dose of BAC per gram of removed RB8 were required. The proposed mechanism of RB8 removal by the co-action of alternative sorbents with BAC comprises a parallel effect of (i) sorption, (ii) the formation of less polar ion pairs accompanied by their sorption on an alternative sorbent and (iii) the separation of used alternative sorbents covered with ion pairs. The removal efficiency of organic contaminant(s) from both model and real wastewater was evaluated by VIS spectroscopy applying the Lambert–Beer law and by the determination of chemical oxidation demand (COD) and/or adsorbable organically bound halogen (AOX) parameters. Full article

Cobalt, nickel, manganese and zinc vanadates were synthesized by a hydrometallurgical two-phase method. The extraction of vanadium (V) ions from alkaline solution using Aliquat^® 336 was followed by the production of metal vanadates through precipitation stripping. Precipitation stripping was carried out using solutions of the corresponding metal ions (Ni (II), Co (II), Mn (II) and Zn (II), 0.05 mol/L in 4 mol/L NaCl), and the addition time of the strip solution was varied (0, 1 and 2 h). The time-dependent experiments showed a notable influence on the composition, structure, morphology and crystallinity of the two-dimensional vanadate products. Inspired by these findings, we selected two metallic vanadate products and studied their properties as alternative cathode materials for nonaqueous sodium and lithium metal batteries. Full article

A partial least squares (PLS) quantitative chemometric method based on the analysis of the mid-Fourier transform infrared spectroscopy (MID-FTIR) spectrum of polymer inclusion membranes (PIMs) used for the extraction of Cr(VI) from aqueous media is developed. The system previously optimized considering the variables membrane composition, extraction time, and pH, is characterized in terms of its adsorption isotherm, distribution coefficient, extraction percent, and enrichment factor. A Langmuir-type adsorption behavior with K_L = 2199 cm³/mmol, q_max = 0.188 mmol/g, and 0 < R_L < 1 indicates that metal adsorption is favorable. The characterization of the extraction reaction is performed as well, showing a 1:1 Cr(VI):Aliquat 336 ratio, in agreement with solvent extraction data. The principal component analysis (PCA) of the PIMs reveals a complex pattern, which is satisfactorily simplified and related to Cr(VI) concentrations through the use of a variable selection method (iPLS) in which the bands in the ranges 3451–3500 cm⁻¹ and 3751–3800 cm⁻¹ are chosen. The final PLS model, including the 100 wavelengths selected by iPLS and 10 latent variables, shows excellent parameter values with root mean square error of calibration (RMSEC) of 3.73115, root mean square error of cross-validation (RMSECV) of 6.82685, bias of −1.91847 × 10⁻¹³, cross-validation (CV) bias of 0.185947, R² Cal of 0.98145, R² CV of 0.940902, recovery% of 104.02 ± 4.12 (α = 0.05), sensitivity% of 0.001547 ppb, analytical sensitivity (γ) of 3.8 ppb, γ⁻¹: 0.6 ppb⁻¹, selectivity of 0.0155, linear range of 5.8–100 ppb, limit of detection (LD) of 1.9 ppb, and limit of quantitation (LQ) of 5.8 ppb. The developed PIM sensor is easy to implement as it requires few manipulations and a reduced number of chemical compounds in comparison to other similar reported systems. Full article