Waste Fluorescent Lamps Research Articles

Fast and Greener Ultrasound-Assisted Acid Extraction for the Determination of Potentially Toxic Elements in Fluorescent Lamp Waste Using ICP OES.

Understanding the chemical composition of fluorescent lamp residue, particularly potentially toxic elements is crucial for reducing environmental impacts and human health risks after disposal. However, the challenge lies in effectively analyzing these heterogeneous solid samples. Techniques involving quantitative dissolution become imperative, playing a fundamental role in quantifying trace elements. The aim of this work is to develop and present a new, faster, and more efficient and environmentally friendly method using ultrasound-assisted acid extraction to quantify potentially toxic elements (Cu, Mn, Ni, Sr, and Zn) present in fluorescent lamp waste using the inductively coupled plasma optical emission spectrometry technique. An ultrasound-assisted acid extraction method for the quantification of potentially toxic elements in fluorescent lamp waste was developed and applied as a greener alternative to conventional digestion methods. For variables optimization a full factorial design with two levels and two variables (time and temperature) was used to found which factors significantly affect the observed response. The results obtained for the developed extraction method were compared with a reference method employing a heating acid digestion (mixture of HCl, HClO4 and HF) using statistical tools. The best results were obtained using extraction time of 10 min and temperature of 25 °C. Inductively coupled plasma optical emission spectrometry was applied for element quantification. The proposed extraction method showed good results for Cu, Mn, Ni, Sr and Zn. Furthermore, the proposed method based on ultrasound radiation presents additional criteria that align with the concepts of the green analytical chemistry. A greener alternative method for determination of Cu, Mn, Ni, Sr and Zn in fluorescent lamp waste was developed. Optimal conditions for ultrasound extraction of potentially toxic elements were achieved in 10 min at temperature of 25 °C. Environmentally friendly aspects of ultrasound align with the requirements of green analytical chemistry.

Intelligent leaching rare earth elements from waste fluorescent lamps.

Rare earth elements (REEs), one of the global key strategic resources, are widely applied in electronic information and national defense, etc. The sharply increasing demand for REEs leads to their overexploitation and environmental pollution. Recycling REEs from their second resources such as waste fluorescent lamps (WFLs) is a win-win strategy for REEs resource utilization and environmental production. Pyrometallurgy pretreatment combined with acid leaching is proven as an efficient approach to recycling REEs from WFLs. Unfortunately, due to the uncontrollable components of wastes, many trials were required to obtain the optimal parameters, leading to a high cost of recovery and new environmental risks. This study applied machine learning (ML) to build models for assisting the leaching of six REEs (Tb, Y, Eu, La, and Gd) from WFLs, only needing the measurement of particle size and composition of the waste feed. The feature importance analysis of 40 input features demonstrated that the particle size, Mg, Al, Fe, Sr, Ca, Ba, and Sb content in the waste feed, the pyrometallurgical and leaching parameters have important effects on REEs leaching. Furthermore, their influence rules on different REEs leaching were revealed. Finally, some verification experiments were also conducted to demonstrate the reliability and practicality of the model. This study can quickly get the optimal parameters and leaching efficiency for REEs without extensive optimization experiments, which significantly reduces the recovery cost and environmental risks. Our work carves a path for the intelligent recycling of strategic REEs from waste.

Solid-liquid extraction for yttrium recovery using porous polymeric resin (XAD-7) functionalized with D2EHPA

The recovery of yttrium is proposed by applying a solid–liquid extraction process using di-2-ethyl hexylphosphoric acid (D2EHPA) as extracting agent. The extracting agents were supported on a macro porous polymeric resin XAD-7 (solid phase). Yttrium ions extraction and discharge tests were performed, firstly from a synthetic aqueous solution of 100 mg/L Y (liquid phase) at 25 °C with stirring. The effects of pH of aqueous solutions bearing yttrium, volume fraction of extracting agents and the solid/liquid (S/L) ratio on the yttrium recovery were studied. The most favorable conditions for yttrium ions extraction are: 20 vol% D2EHPA functionalized resin, pH = 1.5 and an S/L ratio of 10 mg/mL. The discharge of yttrium ions was done under the same conditions of extraction stage, using a 2 mol/L [H2SO4] as stripping solution. Up to 80% yttrium is extracted, while 75% yttrium is recovered in the striping solution. In all experiments, the reaction equilibrium is reached after 20 min, and the kinetics for the extraction stage was determined as a second-order model. Also, experiments were carried out to discharge the yttrium-loaded resins, and it has been determined that the best pH value to strip the Y ions is 1.5. Cyclic tests of extraction and discharge for yttrium ions show that the functionalized resin can work at least five cycles without decreasing its efficiency. Finally, the proposed process was tested in a real solution with Y ions from a waste fluorescent lamp powder leached in H2SO4, demonstrating the ability to effectively recover yttrium, separating it from various metals from the studied residue.

Research on recycle of waste fluorescent lamp glasses and use as mineral filler in asphalt mixture

Research on recycle of waste fluorescent lamp glasses and use as mineral filler in asphalt mixture

Valorization of spent fluorescent lamp waste glass powder as an activator for eco-efficient binder materials

• Use of spent fluorescent lamp waste glass was investigated. • Alternative activators were successfully synthesized using this waste glass. • These activators had similar effects to the commercial activator in producing AAM. • A recycling route for hazardous e-waste was preliminary demonstrated. Spent fluorescent lamp waste glass is considered hazardous and requires an appropriate management and recycling route. Due to its highly alkali-siliceous nature, the feasibility of using the powdered form of the fluorescent lamp waste glass (FGP) to synthesize an activator for activating the GGBS/FA blend was studied. Additionally, the solubility and reactivity of FGP were compared with waste beverage bottle glass powder (BGP). Results showed that FGP had a higher solubility and reactivity than BGP due to the presence of the higher network modifiers. A significant enhancement in solubility (about 19 %), total heat release (57 – 62 %), and compressive strength (85 – 89 %) was observed in FGP-based mixtures, implying its suitability for activator design. The mechanical and microstructural properties of the alkali-activated pastes (AAP) prepared with the FGP activators were similar to those prepared with the commercially sourced reference activator. Before activator preparation, washing FGP with water or acid enhanced the availability of soluble silicates. The activators prepared with those washed FGP accelerated the alkali-activation process and helped achieve better strengths for the corresponding AAP. Their 28-day compressive strength values were in the range of 36 – 40 MPa and comparable to the control (FGP-C). In addition, the microstructural analysis showed that the reaction products in these mixtures were of C-(N)-A S H gels type with high Si/Al and low Ca/Si ratios. Thus, a recycling route for spent fluorescent lamp waste glass was preliminary demonstrated in this study.

Potential of the macroalga Ulva sp. for the recovery of yttrium obtained from fluorescent lamp waste

Secondary sourcing of Rare-Earth elements (REEs) from electronic waste can compensate for supply bottlenecks as well as environmental and health issues associated with ore mining. In this study, recovery of yttrium (Y) from real fluorescent lamp waste (FLW) through biosorption onto the macroalga Ulva sp. is proposed. The initial waste was composed mainly of yttrium oxides (49%) and calcium hydroxides/phosphates (23%). Response surfaces revealed that lower salinity (10) and higher sorbent mass (9 g L−1) improved sorption efficiency (maximum removal of 52% and 32% for initial concentrations of 20 and 120 mg L−1, respectively). Higher concentrations of Y accelerated the sorption kinetics, achieving equilibrium after 3 h. The amount of Y accumulated on the algal tissue (maximum of 22 mg g−1) was not affected by algae dosage. Results show that algal-based sorbents are efficient when applied to real wastes under optimal conditions. While leachate purity still requires optimization, fast kinetics and high concentrations in the biomass indicate that Ulva sp. may constitute a viable material for the biosorption of Y obtained from FLW. Incorporating Ulva sp. biosorption into an Y recovery process will thus contribute to a green and circular economy, compensating the negative effects associated with primary ore mining.

Leaching of yttrium and europium from fluorescent lamp phosphor powder using nitric acid: kinetics and optimization

ABSTRACT Rare earth elements (REEs) are recognized as one of the most critical elements and considered essential for the development of sustainable energy technologies, lasers, electronics, alloys, catalysts, and other applications. In order to meet the increasing demand to ensure those essential usages, the supply of REEs is however limited from the primary sources. Recovery of REEs from secondary resources, such as discarded electrical and electronic equipment, referred to as electronic waste (e-waste) is consequently crucial. Fluorescent lamps among such wastes are of special concern due to the high quantity of REEs present in them. This article discusses a potential hydrometallurgical method for recovering REEs (yttrium and europium) from fluorescent lamp waste via nitric acid leaching. The effects of leaching factors including acid concentration and temperature were examined. To assist the leaching yields of those metals, the effect of alkaline fusion was specifically examined. The kinetics of both processes, direct- and alkaline fusion-assisted leaching were investigated based on the shrinking core model. In the case of direct leaching, the metal dissolution was controlled by surface chemical reaction with apparent activation energies of 43.9 and 48.1 kJ/mol for yttrium and europium, respectively, in the temperature range 303–333 K. Pretreatment, viz., the alkaline fusion changed the subsequent leaching mechanism to diffusion control with apparent activation energies of 7.4 and 9.5 kJ/mol for the respective metal in the same temperature range. Optimization of the alkaline fusion-assisted acid leaching process was undertaken by applying response surface methodology (RSM) based on the central composite design (CCD). Under the alkaline fusion conditions such as soda/fluorescent powder mass ratio of 0.65 g/g, temperature of 1223 K and reaction time of 7200 s followed by acid leaching (nitric acid concentration – 3.5 M, temperature-323 K, pulp density – 30 g/L and leaching duration – 1200 s), the leaching efficiencies of 92.6% and 99.5% for yttrium and europium, respectively, could be achieved.

Vegetable Oils Based Ionic Liquids for Rare Earth Elements Recovery: A Techno-Economic Analysis

This study aims to evaluate the feasibility of the yttrium recovery from compact fluorescent lamp waste using methyltrioctylammonium peanut oil ([N1,8,8,8][PO]) compared to methyltrioctylammonium naphthenic acid ([N1,8,8,8][NA]) and tetraoctylphosphonium oleate ([P8,8,8,8][Oleate]) on a large scale. Based on the techno-economic analysis, the process was feasible on a large scale commercially due to changes in economic parameters such as gross profit margin (GPM), payback period (PBP), break-even point (BEP), break even capacity (BEC), cumulative net present value (CNPV), profitability index (PI), internal rate return (IRR), and return on investment (ROI) tend to be positive with the greatest profit when using [P8,8,8,8][Oleate] compared to [N1,8,8,8][NA] and [N1,8,8,8][PO] under ideal conditions and the use of [N1,8,8,8][PO] can still be profitable under non-ideal conditions with certain fluctuation limits.

Intensive Leaching of Red Phosphor Rare Earth Metals from Waste Fluorescent Lamp: Parametric Optimization and Kinetic Studies

Intensive Leaching of Red Phosphor Rare Earth Metals from Waste Fluorescent Lamp: Parametric Optimization and Kinetic Studies

Urban mining of terbium, europium, and yttrium from real fluorescent lamp waste using supercritical fluid extraction: Process development and mechanistic investigation

There is a significant global push towards recycling of waste electrical and electronic equipment (WEEE) to enable the circular economy. In this study an environmentally sustainable process using supercritical carbon dioxide as the solvent, along with a small volume of tributyl-phosphate-nitric acid (TBP-HNO3) adduct as the chelating agent, is developed to extract rare earth elements (REEs) from fluorescent lamp waste. It is found that mechanical activation using oscillation milling improves extraction efficiency. To elucidate the process mechanism, an in-depth characterization of solids before and after the process using transmission electron microscopy(TEM) and X-ray photoelectron spectroscopy (XPS)is performed. Furthermore, UV visible spectroscopy is performed to determine the coordination chemistry of the rare earths of interest, i.e., yttrium, europium, and terbium during the complexation with TBP-HNO3 adduct. It is found that Al3+ and Ca2+ cations from the aluminium oxide (Al2O3) and hydroxyapatite (Ca5(PO4)3OH) present in the fluorescent lamp waste compete with REEs in reacting with TBP-HNO3 adduct; hence, REE extractions from real fluorescent lamp waste is less than previously reported extractions from synthetic feeds. Not only can management of fluorescent lamp waste help conserve natural resources and protect ecosystems, but it can also facilitate efficient utilization of materials and promote the circular economy.

Feasibility study of fluorescent lamp waste recycling by thermal desorption

The proposed Minamata Convention ban on the use of fluorescent lamps at the end of 2020, with a consequent reduction in mercury (Hg) light products, is expected to produce large amounts of discarded fluorescent bulbs. In this context, the most effective recycling options are a thermal mercury recovery system and/or aqueous solution leaching (lixiviation) to recover rare earth elements (REEs). Due to the heterogeneous nature of these wastes, a complete characterization of Hg compounds in addition to a determination of their desorption temperatures is required for their recycling. The objective of this study is to assess the feasibility of a fast cost-effective thermal characterization to ameliorate recycling treatments. A pyrolysis heating system with a heat ramping capability combined with atomic absorption spectrometry makes it possible to obtain residue data with regard to the temperature ranges needed to achieve total Hg desorption. The major drawback of these heat treatments has been the amount of Hg absorbed from the residue by the glass matrices, ranging from 23.4 to 39.1% in the samples studied. Meanwhile, it has been estimated that 70% of Hg is recovered at a temperature of 437 °C.

Case study on the application of low-temperature plasma integration technology for the treatment mercury-containing waste gas from the crushing process of waste fluorescent lamps

Because mercury has the characteristics of volatility, toxicity and global migration, mercury pollution has become a hot, difficult and focus issue of global concern. Based on China’s environmental technology verification method, the case study for low-temperature plasma integrated technology for the treatment mercury-containing exhaust gas in the treatment process of waste fluorescent lamps was carried out. The total gaseous mercury in the exhaust gas after treatment was less than 0.01mg/m3, which met the emission limit requirements in the Emission Standard (GB16297-1996). The pulse voltage of the plasma power supply is 10-35kV, the pulse current is 8-160A, and the pulse frequency is100-1000Hz. Case study showed that low temperature plasma integrated treatment technology is the available technology for advanced treatment of mercury-containing waste gas.

Recycling of rare earths from fluorescent lamp waste by the integration of solid-state chlorination, leaching and solvent extraction processes

Rare earths (RE) are currently considered some of the most critical elements, being crucial in future sustainable applications. Their high demand, price fluctuations, supply risk and geopolitical factors increase the interest in recovering RE from secondary sources such as pre-consumer scrap, industrial residues and end-of-life products. RE recovery from fluorescent lamp wastes and their subsequent selective separation was successful along a three-step process: (i) solid-state chlorination (SSC), (ii) leaching at pH 3 and (iii) solvent extraction. SSC is the key-step to separate RE from residual material. Optimal SSC parameters were set by using an experimental statistical design which allows for evaluating the cross effects between temperature, residence time and NH4Cl:waste ratio. The digestion step was optimized as well reaching a liquid:solid ratio (L:S) of 40 which accounted for a reduction of 20% in the use of water. Yttrium and Europium have been recovered separately from the pregnant solution by a four-stage cross-flow solvent extraction process combining Cyanex 923 and Cyanex 572 reaching initial purities ≥ 94%. This approach is an integrated process for RE recycling from fluorescent lamp wastes, which contributes to reducing chemicals consumption at better process economy.

Leaching process for terbium recovery from linear tube fluorescent lamps: optimization by response surface methodology.

Until now, rare earth elements (REEs) recycled from the green phosphor of waste fluorescent lamps (FLs), essentially terbium, remain a major challenge. The sulfuric acid effect on leaching efficiency of REEs from phosphor powder (PP) is investigated in this paper. According to a composite central design, experimental leaching study is performed under various parameters (acid concentration, leaching temperature, and time as well as liquid-to-solid ratio (L/S)). A statistical model of experiments and an analysis of variance are studied in order to predict leaching process. The results showed that by decreasing concentration and L/S ratio while increasing leaching time at optimal temperature value permits profitable terbium extraction. Afterwards, the developed statistical model is explored for an optimized response surface methodology. The obtained results were tested experimentally and showed best terbium extraction with 75%. Moreover, 0.01% for the major contaminant, that is calcium, is reached. This low calcium yield may have a further advantage during REE recovery in the downstream. Therefore, resulting solution under optimal conditions is treated with oxalic acid followed by a calcination of the solid precipitate. Finally, 43.57% and 49.38% are produced for terbium and yttrium oxides, respectively.

A Study on Improvement of Recycling Process of Waste Fluorescent Lamps

A Study on Improvement of Recycling Process of Waste Fluorescent Lamps

A Basic Study for Manufacturing High Refractive Beads from the Waste Fluorescent Glass

This study was carried out to get the optimum conditions for manufacturing high refractive glass beads from waste fluorescent lamp glass. Chemical composition, X-ray diffraction pattern, particle size distribution, refractive index of glass beads, and the effect of air mixing ratio and ejection rate were investigated. The obtained results are as follows. The X-ray diffraction pattern and chemical composition of glass beads made of waste fluorescent glass are similar to common glass except ReO2 0.0108 wt%, BaO 0.071 wt%, NiO 0.0039 wt% and CaO 7.8 wt% but 11.7 wt% of common glass. The glass beads made of waste fluorescent lamp glass have the narrower particle size distribution of and the higher refractive index than the glass beads made of common glass. The optimal conditions of kiln operation for manufacturing glass beads from waste fluorescent lamp glass are 20 m/sec of ejection rate, 1.7 of air mixing ratio, and 940°C of temperature.

Recovery of yttrium ions from fluorescent lamp waste through supported ionic liquid membrane: process optimisation via response surface methodology

ABSTRACT In this study, the removal technique with the use of supported ionic liquid membrane was proposed for the selective yttrium extraction from fluorescent lamp waste. The mixture of imidazolium ionic liquid, tributyl phosphate, and D2EHPA was utilised for the preparation of the carrier phase. Additionally, the central composite design was performed to evaluate the impact of pH in the feed phase, yttrium ion concentration, extractant concentrations, and the concentration of stripping phase. The quadratic equation was utilised for analysis of variance, which indicates that extractant concentration is the most critical parameter in recovering yttrium from aqueous solution. Time-dependent extraction can be described by using the first-order kinetic model. The optimum parameters from CCD design were pH of 6, yttrium extraction amount of 412.5 mg/l, 12.5% (v/v) of [C6MIM.NTf2], 25% (v/v) of TBP, 20% (v/v) of D2EHPA, and [HNO3] in stripping phase equal to 1.5 M. The result revealed that the supported ionic liquid membrane could be applied as a cost-consuming and straightforward for the extraction of yttrium ions from leaching solution.

Incorporation of Fluorescent Lamp Waste into Red-Clay Bricks: Defect Formation, Physical and Mechanical Properties

Once their life-span is finished, fluorescent lamps are usually processed in vacuum crushers because of their Hg content. This procedure generates glass waste and spent phosphor powders, among other residual materials. Due to their composition, glass waste and phosphor powders could be incorporated as secondary raw materials in the formulation of clay-based construction materials for non-structural applications. In this work, this incorporation was studied, focusing on the analysis of the formation of defects in the final product and its impact on the statistical variability of some physical and mechanical properties of the clay bodies, such as: density, linear shrinkage, water absorption, and compressive strength. It was found that a combination of factors, i.e. the presence of Pb and calcium carbonate in the waste glass, concurred to induce the formation of two kind of defects in the fired ceramics: internal blowholes and external glassy exudations. Despite the presence of these defects, the physical and mechanical properties of the test bricks produced were not statistically different from the standard formulation used as control. The implications of these findings on the possible application of spent fluorescent lamps wastes as an ingredient for clay-based bricks were also briefly addressed.

Liquid–liquid extraction of yttrium from the sulfate leach liquor of waste fluorescent lamp powder: Process parameters and analysis

Global demand for rare earth metals (REMs), including yttrium, has motivated the scientific community to focus on the recovery of such metals from electronic waste materials. Herein, a solvent extraction method was used to isolate and recover yttrium from the original leaching solution from the fluorescent lamp waste powder dissolved by sulfate. The operating parameters were systematically investigated, including pH, equilibrium time, concentration of extractants, and organic/aqueous ratio using Versatic Acid 10, TOPO, D2EHPA, and Alamine 336. The extracting capacities were in the order of D2EHPA > Versatic Acid 10 > TOPO > Alamine 336. The reaction mechanism of yttrium with each extractant demonstrated the formation of complex compounds with concentration ratios of 1:3, 1:1, and 1:2 with Versatic Acid 10, D2EHPA, and TOPO, respectively. On investigating the extraction mode for yttrium and impurities in the range of equilibrium pH (pHeq) values from 0.95 to 2.25 using D2EHPA, pHe 2.02 (initial pH 2.53) was found to be the most suitable for extraction. Fe in the original leaching solution could be utterly eradicated through the acidity control method. Upon calculating the theoretical number of mixer–settler plates, more than 99% of yttrium was extracted in solution with only two plates as the organic phase. Finally, the stripping test showed favorable stripping rates and followed the order HCl (78.12%) > H2SO4 (76.36%) > HNO3 (74.86%) within 10 min. This study is a first step toward developing large-scale operations for extracting REMs from fluorescent lamp waste powder.

Hydrometallurgical process for the recovery of yttrium from spent fluorescent lamp: Leaching and crystallization experiments

Present day rising necessity for rare earth elements (REE) is of great interest for its recovery through processing various waste materials concerning both economic and environmental benefits. The present study investigates the recovery potential of yttrium from fluorescent lamp waste using a hydrometallurgical process. Leaching of metals from the waste was studied by applying acids viz. hydrochloric acid (HCl), nitric acid (HNO3) and sulfuric acid (H2SO4). Influence of various factors (solid:liquid ratio, reaction temperature, reaction time, and acid concentration) were conducted by full factorial design for the recovery of yttrium. Experimental variables such as decomposition, leaching and the oxide preparation were studied and the mechanisms responsible during the progress in each step was systematically investigated. The optimal experimental conditions attained with 40% solid/liquid ratio, at 45 °C in 0.5 h at 150 rpm, with 3N H2SO4 concentration. Whereas, HCl and HNO3 leachants showed poor performance. Leaching process conducted in this study were best suited to ‘ash diffusion control dense constant size-spherical particles model’, which means that the diffusion process through the ash is the rate regulatory step in the leaching process. With increase in the concentration of oxalic acid as precipitating agent, a reduction in the nuclear induction period resulted indicating a higher sedimentation rate and shorter equilibration time. In addition, crystal nucleation rate and crystal growth rate, showed that the reaction velocity of the crystal nucleation ‘p’ is 2.88 and the crystal growth degree and value increases with the increase in the concentration of oxalic acid (n: 0.3437–0.4872). The precipitation rate was improved with the rise in temperature (from 25 °C to 45 °C) while the sedimentation rate was found negligible above 45 °C. This detailed study methodology can be considered as a feasible process thus creating a possibility to treat fluorescent waste lamp powders for various industrial applications.