Recovery Of Europium Research Articles

Selective recovery of europium from real acid mine drainage using modified Cr-MIL and SBA15 adsorbents

The successful adoption and widespread implementation of innovative acid mine drainage treatment and resource recovery methods hinge on their capacity to demonstrate enhanced performance, economic viability, and environmental sustainability compared to conventional approaches. Here, an evaluation of the efficacy of chromium-based metal–organic frameworks and amine-grafted SBA15 materials in adsorbing europium (Eu) from actual mining wastewater was conducted. The adsorbents underwent comprehensive characterization and examination for their affinity for Eu. Cr-MIL-PMIDA and SBA15-NH-PMIDA had a highest Langmuir adsorption capacity of 69 mg/g and 86 mg/g, respectively, for an optimum level of pH 4.8. Preferential adsorption tests followed using real AMD collected at a disused mine in the north of Norway. A comparative study utilizing pH-adjusted real AMD revealed that Cr-MIL-PMIDA (88%) exhibited slightly higher selectivity towards Eu compared to SBA15-NH-PMIDA (81%) in real mining wastewater. While Cr-MIL-PMIDA displays excellent properties for the selective recovery of REEs, practical challenges related to production costs and potential susceptibility to chromium leaching make it less appealing for widespread applications. A cost–benefit analysis was then undertaken to quantify the advantages of employing SBA15-NH-PMIDA material. The study disclosed that 193.2 g of EuCl3 with 99% purity can be recovered by treating 1000 m3 of AMD.

Investigation of europium(III) uptake from highly sulphate solution via cloud point extraction by mono-Schiff base combined with Triton X-100

ABSTRACT Owing to its unique physico-chemical properties, europium is one of the most precious and sought-after rare earth elements in the field of high technology. The major economic and commercial importance of such an element, combined with the pollution risks associated with its intensive use, require the development of efficient and eco-compatible recovery and recycling processes. This study focuses on the recovery of europium from highly saline sulphate media (0.5 mol/L) using an environmentally friendly two-phase aqueous extraction technique (known as cloud point extraction (CPE)), using 2((phenylimino)methyl)phenol mono-Schiff base (HPIMP) as the extractant and Triton X-100 as the non-ionic surfactant. The influence of key experimental parameters such as pH, extractant concentration, surfactant concentration and separation temperature on the europium extraction process was systematically studied and optimized. Under optimum experimental conditions, a quasi-quantitative extraction with a minimal volume fraction of surfactant-rich phase (φs = 0.025), and concentration factor of (CF = 38) was achieved at pH 9.8, in one stage. The analysis of the extraction data revealed that the CPE of europium(III) takes place by a cation exchange-solvation mechanism. The stoichiometry of the complex extracted into the surfactant-rich phase was ascertained to have a composition of 1:2 [Eu:HPIMP] with the slope analysis method. A higher extraction constant was obtained for CPE compared with conventional solvent extraction, confirming the feasibility and usefulness of CPE for Eu(III) recovery. On the other hand, this new HPIMP/Triton X-100 chelating system showed superior extractability for Eu(III) in the CPE process relative to other systems reported previously.

Removal and Recovery of Europium with a New Functionalized Mesoporous Silica-Based Adsorbent

The discharge of acid mine drainage (AMD), characterized by a high concentration of rare earth elements (REEs), poses a significant threat to the health of ecosystems surrounding water sources. The global market demand for REEs has experienced a notable surge in the past decade. Consequently, recovering REEs from waste streams like AMD not only benefits the environment but also offers financial advantages. Europium (Eu), the rarest among REEs, constitutes only 0.1% w/w in monazite and bastnaesite ores. Eu is extensively used in the production of phosphors, alloys, and additives, and is a critical raw material for developing smart devices, ranging from high-resolution color screens to circuitry. Traditional adsorbents typically exhibit limited selectivity towards REE recovery. Mesoporous silica materials, such as SBA15 (Santa Barbara Amorphous-15), provide excellent tunability and modification capabilities, making them an attractive and cost-effective alternative. This research focused on two key aspects: (i) evaluating the dynamic adsorption column performance of granulated SBA15–NH–PMIDA to preferentially recover Eu, and (ii) employing mathematical modeling to optimize the dynamic adsorption column’s operating conditions for real-world applications with a minimal number of experimental runs. Granulated SBA15–NH–PMIDA was chosen as the adsorbent due to its high adsorptive capacity and selectivity in capturing Eu. The study revealed that granulated SBA15–NH–PMIDA exhibited 57.47 mg/g adsorption capacity and an 81% selectivity towards Eu. Furthermore, SBA15–NH–PMIDA demonstrated preferential adsorption toward Eu in complex multi-component solutions, such as AMD. The linear driven force approximation model (LDFAM) provided an acceptable simulation (R2 > 0.91) under varying operational conditions. This validates the use of the model as a tool to effectively simulate and optimize column experiments that used granulated SBA15–NH–PMIDA to recover Eu.

Recovery of europium from E-waste using redox active tetrathiotungstate ligands

Rare-earth elements (REEs) are critical to our modern economy, yet their mining from natural ores bears a profound environmental impact. Traditional separation techniques are chemical and energy-intensive because their chemical similarities make REEs very challenging to purify, requiring multiple extraction steps to achieve high purity products. This emphasizes the need for sustainable and straightforward separation methods. Here we introduce a strategy for the direct separation of europium (Eu) from complex mixtures under ambient conditions, leveraging on the redox non innocence of purely inorganic tungsten tetrathiolate (WS42−) ligands. The recovery of Eu is achieved upon reduction of Eu(III) to a Eu(II) coordination polymer, driven by an induced internal electron transfer from the tetrathiotungstate ligand. Applying this strategy to unconventional feedstock such as spent energy-saving lamps allows selective europium recovery with separation factors over 1000 and recovery efficiency as high as 99% without pre-treatment of the waste.

Recovery and concentration of Eu(III) from phosphogypsum leachate using ouricuri endocarp

Ouricuri endocarp was utilized as a biosorbent for the recovery of europium (Eu(III)) from aqueous solutions and rare earth elements (REEs) from authentic leachate derived from phosphogypsum, which encompasses various REEs. Various characterization techniques were applied to analyze the physicochemical and adsorptive properties of the biosorbent. The results indicate that the adsorption kinetic data conform well to the pseudo-first-order model, while the Liu model describes the equilibrium data well. Ouricuri endocarp and Eu interactions are favorable and spontaneous. The maximum adsorption capacity for Eu(III) is determined to be 22.9 mg/g according to the Liu model. Based on experimental results and adsorbent characteristics, the proposed adsorption mechanisms between ouricuri endocarp and Eu include ion exchange and electrostatic interactions as the primary mechanisms. The Eu(III) recovery is also feasible as a continuous flow process demonstrating inclined breakthrough curves and lower values of the length of the mass transfer zone. Ouricuri endocarp demonstrates its selectivity for recovering various REEs from authentic phosphogypsum leachate. It achieves a 98% recovery rate for Eu and approximately 60% for Ce, La, and Nd, affirming its efficacy under real-world conditions. Finally, concentration of REE was done by ashing loaded ouricuri endocarp, and a solid with around 34% (in weight) of REE is obtained.

Selective recovery of europium from real acid mine drainage by using novel amine based modified SBA15 adsorbent and membrane distillation system

Recovery of rare earth elements (REE) from secondary waste streams promises numerous advantages. Europium (Eu) is an essential component in various high-tech applications, including clean energy technologies. Ensuring a stable supply of europium through recycling reduces the vulnerability to supply disruptions and price fluctuations in the global market. To achieve this, there is a need for development of highly selective and commercially viable adsorbents for Eu recovery. This research presents a novel material, SBA15-NH-PMIDA, synthesized through a two-step surface modification process for selective retrieval of Eu from real acid mine drainage (AMD). Initially, comprehensive physical and chemical characterizations of the material were conducted to confirm its successful synthesis. Subsequent single-solute Eu adsorption experiments demonstrated that SBA15-NH-PMIDA achieved equilibrium within 2 h and exhibited a maximum Langmuir adsorption capacity of 86.21 mg/g at optimal pH of 4.8. It exhibited remarkable selectivity in recovering over 80 % of Eu from pH-adjusted real AMD, with an optimal dosage of 0.8 g/L. Next, a hybrid system amalgamating Direct Contact Membrane Distillation (DCMD) and adsorption was devised. This hybrid system involved the suspension of granulated SBA15-NH-PMIDA within the feed tank to treat pH-adjusted AMD. The DCMD system achieved an 80 % recovery of purified water while concentrating Eu ions by more than threefold, facilitating efficient and selective Eu recovery surpassing 90 %. Importantly, the uptake of other competing metals remained below 10 %. This is attributed to the formation of Eu complexes with phosphonic and carboxyl acid functional groups. SBA15-NH-PMIDA demonstrated its sustainability and viability by consistently retaining over 90 % of its adsorption capacity throughout ten regeneration cycles.

Europium recovery process by means of polymeric nanoparticles functionalized with acrylic acid, curcumin and fumaramide

Polymeric nanoparticles of poly(methyl methacrylate) were obtained by emulsion polymerization techniques in a process of two stages. The particles were functionalized with acrylic acid, curcumin, and fumaramide and three series of polymeric particles were obtained. The incorporation of functional groups was confirmed by Fourier transform-infrared spectrosocopy (FT-IR) and ultraviolet–visible (UV–Vis) methods. The spherical morphology of particles with an average diameter of 100 nm was observed by scanning electron microscopy (SEM). The polymeric materials were used for recovery of [Eu] from synthetic solutions. The nanoparticles show excellent chelation capacity to trap rare-earth ions, because they recover more than 85% of [Eu] at pH of 2. The images of SEM after extraction process show arrays between particles with larger average particle sizes to 1.5 μm. In addition, the particles have a good stripping capacity, exceeding 50% of it, maintaining their homogeneity in morphology and good stability in dispersion for the recovery and stripping processes. A pseudo-second model order is obtained for the extraction and stripping processes while the best results of stripping process are obtained at pH of 6.

Enhancing the adsorptive recovery of europium from real-world solid samples through the synergistic impact of lysozyme fibril and melamine phytate

Rare earth elements and precious metals have key multiple applications in varying fields inclusive of electronics, renewable energy and healthcare. Europium is often recovered in the recycling process as an essential metal having utility in several electronic items. Here, we report the preparation of a bio-sorbent, a self-assembly technique of lysozyme fibrils on phytate melamine (named LF-MP) for the recovery of Eu(III) from compact fluorescent lamps (CFL) waste. Spectroscopy-related techniques and electron microscopy not only confirms their interaction between the LF-MP and Eu(III) but also provided new insight into the morphology behavior, structure and chemical composition. The maximum Eu(III) adsorption was shown at a pH = 6.0, with an adsorption (Langmuir) capacity of 540 mg g−1. We further elucidated the mechanism of interaction between Eu(III) and LF-MP, mainly through electrostatic attraction followed by the formation of coordination bonding. It has been demonstrated that the LF-MP can recover Eu(III) from a wide range of europium-containing waste materials.

Green and robust adsorption and recovery of Europium(III) with a mechanism using hybrid donor conjugate materials

The hybrid donor chemical ligand of 5-tert-butyl-2-hydroxybenzaldehyde thiosemicarbazone (THTB) was prepared and then embedded onto inorganic porous silica as hybrid conjugate materials (HCM). The Europium (Eu(III)) ion was selected from the lanthanides (Ln(III)) series for green and robust adsorption and recovery based on the adsorption, complexation, and selectivity tendency from the standpoint of the pH-dependent factor. The chemical compound of THTB consisted of O-, N-, and S-donor atoms and was able to make stable complexation with Ln(III) ions in optimum conditions due to the open functionality of the HCM. A surface complexation with a good complexation fitting to the experimentally collected data was used to describe the adsorption mechanism. The Eu(III) ion adsorption performance was measured with batch equilibrium methods. The affecting experimental protocols including solution pH, contact time, initial Eu(III) ion concentration, foreign ions effect, and recovery were carried out and evaluated consistently. The Eu(III) ion adsorption by the HCM was at pH 5.0 and this pH was selected to avoid the precipitation problem to ensure the adsorption mechanism. The co-existing several metal ions were not interfered with Eu(III) ion adsorption by the HCM due to the high affinity between Eu(III) ion and the functional groups of HCM. The bonding mechanism suggested that O-, N-, and S-donor atoms of THTB were strongly coordinated to Eu(III) with 2:1 ratio complexation. The Langmuir adsorption isotherm model was plotted due to the HCM morphology and applied to validate the adsorption isotherms according to the homogeneous ordered frameworks. The Eu(III) ion adsorption capacity by the HCM was 176.31 mg/g as expected because of the high surface area of the HCM. The adsorbed Eu(III) ion was completely eluted from HCM with the eluent of 0.20 M HNO3 and simultaneously regenerated into its initial form without significant deterioration. This study could be of great applicative utility for Eu(III) ions from waste aqueous solutions as green technology.

Efficient recovery of europium by biosorption and desorption using beads developed from sericin residues from silk yarns processing, sodium alginate and poly(ethylene glycol) diglycidyl ether

The removal and recovery of critical rare-earth elements (REEs) are important from an environmental and economic perspective. The recovery of critical metals from secondary sources has received considerable attention. This work aims to evaluate the beads produced from sericin, alginate, and poly(ethylene glycol) diglycidyl ether (SA@PEGDGE) to recover Eu3+. The pH effect showed that pH 5.0 had the highest uptake of Eu3+ (0.289 ± 0.006 mmol/g) with stoichiometric cationic exchange with Ca2+ (0.425 ± 0.023 mmol/g) by SA@PEGDGE. The kinetic (pseudo-first order, pseudo-second order, and external diffusion) and equilibrium (Langmuir) models adequately represented the adsorption results. The particles had an increase in adsorptive capacity from 0.555 mmol/g at 25 °C to 0.633 mmol/g at 55 °C. Hydrochloric acid (0.1 mol/L) showed the highest recovery rate of Eu3+ (96.50 ± 0.84%) from SA@PEGDGE. Eu3+ recovery was highly successful for five cycles. The recovery was greater than 95% and the reuse of the eluent in the adsorption cycles enriched the Eu3+ concentration 10-fold, from 1.07 mmol/L to 9.96 mmol/L. The SA@PEGDGE also showed better performance for biosorption of Eu3+ with other competing ions. The characterization analyzes showed that the SA@PEGDGE beads produced by the ionotropic gelation technique have a spherical shape, surface with low roughness, and amorphous character. The mechanisms of Eu3+ biosorption involved interactions with the functional groups present on the SA@PEGDGE surface, cation exchange, and electrostatic interactions. Thus, the crosslinked sericin/alginate particles can be a sustainable alternative for the recovery of critical REEs from wastewater, resulting in social and economic benefits from a circular economy.

Biosorption and Bioaccumulation Capacity of Arthospiraplatensis toward Europium Ions

Europium recovery from wastewater is determined by its high significance for industry and toxicity for living organisms. The capacity of cyanobacteria Arthospira platensis (Spirulina) to remove Eu(III) through biosorption and bioaccumulation was evaluated. In biosorption experiments, the effects of four variables pH, metal concentration, time, and temperature on metal removal were studied. In bioaccumulation experiments, the effect of Eu(III) concentrations on biomass bioaccumulation capacity and biochemical composition was assessed. The efficiency of Eu(III) uptake in both experiments was determined using ICP-AES techniques. Maximum biosorption of Eu(III) was achieved at pH 3.0. Equilibrium data fitted well with the Langmuir and Freundlich models, with maximum adsorption capacity of 89.5 mg/g. The pseudo-first-, pseudo-second-order, and Elovich models were found to correlate well with the experimental data. According to thermodynamic studies the sorption was feasible, spontaneous, and endothermic in nature. At addition of Eu(III) ions in the cultivation medium in concentrations of 10–30 mg/L, its accumulation in biomass was 9.8–29.8 mg/g (removal efficiency constituting 98–99%). Eu(III) did not affect productivity and content of carbohydrates and pigments in biomass but led to the decrease of the content of protein and an increase in the amount of MDA. The high Eu(III) biosorption and bioaccumulation efficiency of Arthrospira platensis may constitute an effective and eco-friendly strategy to recover it from contaminated environment.

Potential application of graphene oxide and Aspergillus niger spores with high adsorption capacity for recovery of europium from red phosphor, compact fluorescent lamp and simulated radioactive waste

The recovery of rare earth elements (REEs) is a global challenge and the mining of rare earths has serious environmental implications due to the toxic waste released post mining. Hence, the rising demand for rare earths and their far reaching electronic applications necessitates an effective strategy to recover the REEs from more viable sources. In this work, the graphene oxide–Aspergillus niger spores (GO–A. niger spores) blend was utilized for adsorptive recovery of a precious rare earth Eu(III) and the adsorption variables like pH of the medium, adsorbent dosage, sorption kinetics, thermodynamics, and isotherm were optimized for the developed biosorbent. The adsorption process suits the Langmuir isotherm model with a maximum adsorption capacity of 147.3 mg/g. The pseudo–second–order kinetics is a perfect fit to describe the adsorption process. The results obtained through the Van't Hoff plot show negative free energy change (ΔG0) which implies the spontaneity of the adsorption process. The negative standard enthalpy change (ΔH0) values show that the nature of the adsorption process is exothermic. The analytical characterizations including Fourier transform infrared spectroscopy (FTIR), Raman, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET), thermal gravimetric analysis (TGA), and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) were employed to study the biosorbent. The features of GO–A. niger spores biosorbent were applied to recover Eu(III) from real samples such as fluorescent lamp phosphor, red phosphor powder, and a simulated radioactive waste solution.

Combinative influence of graphitic carbon nitride and Halomonas BVR1 bacteria augment the adsorptive recovery of precious ‘Euro’pium

In this communication, we present the synergistic influence of graphitic carbon nitride (g-C3N4) and a prokaryotic non-pathogenic bacteria-Halomonas BVR1 for the adsorptive recovery of europium. The surface characterizations reveal the interaction of cationic europium hydroxides with triazine units of g-C3N4 and the functional groups on the surface of bacteria. The prospective application is illustrated in recovering europium from a spent fluorescent lamp phosphor. Endowed with a worthy potential to recover europium, this directed application-oriented lucid method opens its doors to explore carbonaceous materials in conjunction with microorganisms as a sustainable alternative for the recovery of other precious rare earths.

Ion-imprinted nanofibers of PVDF/1-butyl-3-methylimidazolium tetrafluoroborate for dynamic recovery of europium (III) ions from mimicked effluent

Discharge of liquid effluents from industries in an open environment causes severe pollution to natural water sources and carcinogenicity to aquatic animals. Present study reports the utilization of ion-imprinted polyvinylidene/1-butyl-3-methylimidazolium tetrafluoroborate (PVDF/RTIL) nanofibers fabricated via facile electrospinning technique, for effective recovery of europium III [Eu3+] ions for supplementing its supply for technological applications. RTIL used in this study provided active sites for recovery of Eu3+ ions through its functional groups. Maximum recovery of Eu3+ ions on PVDF/RTIL nanofibers was found to be 22.37 mg/g, with 90% of recovery achieved within 3 h (at pH ∼ 7.0, and T = 298 K). FE-SEM, FTIR and BET characterizations confirmed the recovery of Eu3+ ions on PVDF/RTIL nanofibers. Experimental parameters like adsorption isotherm, influence of pH of solution, and initial metal ion concentration were also investigated. Results demonstrated that recovery of Eu3+ ions onto ion-imprinted PVDF/RTIL nanofibers corresponds to Freundlich isotherm model (R2 = 0.98297). For investigation of economic viability sequential adsorption–desorption experiments were carried out which confirmed that PVDF/RTIL nanofibers can be readily regenerated and reused for five successive cycles without significant drop in effectiveness. Results demonstrate that PVDF/RTIL nanofibers can be effectively used for recovery of Eu3+ ions from mimicked liquid effluents.

Carbon footprint assessment of recycling technologies for rare earth elements: A case study of recycling yttrium and europium from phosphor

Rare earth elements are key raw materials in high-technology industries. Mining activities and manufacturing processes of such industries have caused considerable environmental impacts, such as soil erosion, vegetation destruction, and various forms of pollution. Sustaining the long-term supply of rare earth elements is difficult because of the global shortage of rare earth resources. The diminishing supply of rare earth elements has attracted considerable concern because many industrialized countries regarded such elements as important strategic resources for economic growth. This study aims to explore the carbon footprints of yttrium and europium recovery techniques from phosphor. Two extraction recovery methods, namely, acid extraction and solvent extraction, were selected for the analysis and comparison of carbon footprints. The two following functional units were used: (1) the same phosphor amounts for specific Y and Eu recovery concentrations, and (2) the same phosphor amounts for extraction. For acid extraction method, two acidic solutions (H2SO4 and HCl) were used at two different temperatures (60 and 90°C). For solvent extraction method, acid leaching was performed followed by ionic liquid extraction. Carbon footprints from acid and solvent extraction methods were estimated to be 10.1 and 10.6kgCO2eq, respectively. Comparison of the carbon emissions of the two extraction methods shows that the solvent extraction method has significantly higher extraction efficiency, even though acid extraction method has a lower carbon footprint. These results may be used to develop strategies for life cycle management of rare earth resources to realize sustainable usage.

Selective separation of yttrium and europium using Cyanex 572 for applications in fluorescent lamp waste processing

The quest for a circular economy has directed attention towards processing of end-of-life products and industrial streams to recover the valuable fractions these contain. Fluorescent lamp waste is acknowledged to be an important source of yttrium and europium, two of the rare earth elements presently regarded as having critical supply risk. In this study, a commercial extractant for solvent extraction separations of REEs, Cyanex 572, was successfully applied to separate yttrium and europium from solutions obtained during processing of fluorescent lamp waste streams. Yttrium was selectively separated from europium at pHeq=0, followed by further recovery of europium at pHeq=1. Better extraction efficiencies of REEs were achieved using aliphatic diluents e.g. kerosene in comparison to aromatic diluents or long chain alcohols. Increases in temperature in the range 25–65°C led to decreases in the separation factors between yttrium and europium. Stripping with hydrochloric acid solutions at concentrations higher than 3M led to complete recovery of extracted yttrium and europium. Precipitation of these elements from their respective stripping products with oxalic acid, followed by calcination of the precipitate, led to yttrium and europium oxides of 99.82% and 91.60% purity, respectively. A flowsheet that encompass the main steps for fluorescent lamp waste processing is also presented.

Integrated process development for the recovery of Europium and Yttrium from waste fluorescent powder

Fluorescent powder plays an important role in the modern electronic lighting products. During the production of electronic lighting products, a large amount of waste fluorescent powder is generated. The major rare earth composition of this waste fluorescent powder is Europium (Eu) and Yttrium (Y), both being valuable resources worthy of the recycling process. To recover (Eu) and (Y) from the fluorescent powder, an integrated leaching method is adopted in this study. Leaching tests are performed and optimized with the use of various leaching reagents. Reagents such as HCl, HNO3, H2SO4, and NaOH are used along with the method of varying the leaching time and solid/liquid ratios at 27 and 70 °C. The result of leaching tests shows that the Eu and Y present in the waste fluorescent powder can be 100 % leached using 1 N sulfuric acid under the conditions of 1 h leaching time, 3 g/50 mL solid/liquid ratio, and 70 °C temperature. The optimal leaching solution is subjected to crystallization and replacement process to recover Eu and Y and achieved maximum recovery of 79 and 47 % Eu and Y, respectively. Further, the recovery efficiency of Eu and Y are compared with various precipitating reagents such as sodium carbonate, sodium bicarbonate, sodium sulfate, potassium sulfate, ammonium bicarbonate and ammonium sulfate, and achieved 100 % with sodium bicarbonate and ammonium bicarbonate. The recovery efficiency of Eu and Y is also achieved to be 100 % with pH adjustment method.

Photochemical recovery of europium from non-aqueous solutions.

The photochemical recovery of europium from non-aqueous media, more specifically alcohols, is studied. The recovery was performed by photochemical reduction of europium(iii) to europium(ii) and subsequent removal as the insoluble EuCl2. Two charge transfer bands are present in the UV-C region, one originating from the alcohol (around 230 nm) and the other from the chloride anion (at 271 nm), which are responsible for the photochemical reduction when the solution is illuminated by a medium-pressure mercury lamp. When using different alcohol solvents, a trend is observed with regards to the removal rate and efficiency, following methanol (MeOH) < ethanol (EtOH) < isopropanol (IPA) <50/50 v/v ethanol/isopropanol (EtOH/IPA). This trend can be explained by the solubility of EuCl2 in the different solvents, and by the photon absorption at the wavelengths which provoke the reduction. In a 50/50 v/v EtOH/IPA solution, it is observed that addition of chloride ions (as LiCl) intensifies the chloride-to-europium(iii) CT band, effectively increasing the photon absorption in the 260-340 nm wavelength region. Moreover, addition of extra chloride ions decreases the solubility of EuCl2, which in turn accounts for a better recovery efficiency. However, this beneficial effect disappears when the water content rises above 1.5 wt%. For an EtOH/IPA solution with a high chloride concentration and low water content, it is feasible to recover europium from binary europium/yttrium mixtures with an efficiency of up to 94.7% and a purity of 96.7-99.8%, depending on the Eu/Y molar ratio. For higher yttrium excess, the removal rate of europium is higher, which is explained by the ability of yttrium to coordinate water molecules, decreasing the free water content in the solution. The fact that a large excess of yttrium does not compromise the removal rate of europium from the solution, proves that this technique has potential for europium recovery from red lamp phosphors (Y2O3:Eu3+), which consist entirely of europium and yttrium with a Eu/Y molar ratio of 1/20-1/30.

Process development for the recovery of europium and yttrium from computer monitor screens

This work describes the development of a process for the recovery of Eu and Y from cathode ray tubes (CRTs) of discarded computer monitors with the proposition of a flow sheet for the metals dissolution. Amongst other elements, europium and yttrium are presented in the CRTs in quantities – 0.73 w/w% of Eu and 13.4 w/w% of Y – that make their recovery worthwhile. The process developed is comprised of the sample acid digestion with concentrated sulphuric acid followed by water dynamic leaching at room temperature. In the CRTs, yttrium is present as oxysulphide (Y2O2S) and europium is an associated element – Y2O2S:Eu3+ (red phosphor compound). During the sulphuric acid digestion, oxysulphide is converted into a trivalent Eu and Y sulphate, in solid form, with the liberation of H2S. In the second step, metals are leached from the solid produced in the acid digestion step by dynamic leaching with water. This study indicates that a proportion of 1250 g of acid per kg of the sample is enough to convert Eu and Y oxysulphide into sulphate. After 15 min of acid digestion and 1.0 h of water leaching, a pregnant sulphuric liquor containing 17 g L−1 Y and 0.71 g L−1 Eu was obtained indicating yield recovery of Eu and Y of 96% and 98%, respectively. Both steps (acid digestion and water leaching) may be performed at room temperature.

Recyclables recovery of europium and yttrium metals and some salts from spent fluorescent lamps

Europium and yttrium metals and some valuable salts were recovered from the powder coating the inner surface of the glass tubes of fluorescent lamps. The tubes were broken under 30% aqueous acetone to avoid emission of mercury vapor to the atmosphere, and the powder was collected by brushing. Metals available in the powder were pressure leached using sulfuric/nitric acid mixture. Sulphate salt of europium and yttrium so obtained was converted to thiocyanate. Trimethyl-benzylammonium chloride solvent was used to selectively extract Eu and Y from the thiocyanate solution. The metal loaded in the organic solvent was recovered by N-tributylphosphate in 1M nitric acid to produce nitrate salts of Eu and Y. Europium nitrate was separated from yttrium nitrate by dissolving in ethyl alcohol. The isolated powder contained 1.62% europium oxide, 1.65% yttrium oxide, 34.48% calcium sulphate, 61.52% Ca orthophosphate and 0.65% other impurity metals by weight. Autoclave digestion of the powder in the acid mixture for 4h at approximately 125 degrees C and 5 MPa dissolved 96.4% of the yttrium and 92.8% of the europium. Conversion of the sulphate to thiocyanate is favoured at low temperature. Extraction of Eu and Y from the thiocyanate solution attained its maximum at approximately 80 degrees C. N-tributylphosphate in 1N nitric acid at 125 degrees C achieved a stripping extent of 99%. Thermal reduction using hydrogen gas at 850 degrees C and 1575 degrees C produced europium and yttrium metals, respectively. A metal separation factor of 9.4 was achieved. Economic estimation revealed that the suggested method seemed feasible for industrial applications.