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Using the crushed waste Cathode Ray Tube (CRT) glass as fine aggregate to produce concrete can be an efficient method to resolve the recycling issue. However, the mediocre mechanical properties of CRT concrete obstructed its wide application. This study aims to resolve this issue based on the study on concrete/mortar specimen incorporating with an innovated surface treatment method. Specifically, a two-step surface treatment method was proposed to improve the performance of CRT concrete by modifying the surface layer of CRT glass sands with NaOH solution and Al(NO 3) 3 solution. About 30% of the portland cement was replaced with class-F fly ash to mitigate possible ASR damage by the reactive CRT aggregate. The mechanical performance (Compressive/flexural strength, dynamic modulus of elasticity, and flexural fracture energy) and the durability performance (Drying shrinkage and ASR expansion) was examined and compared among different specimens. In addition, the leaching levels of lead in different concrete specimens was evaluated by toxicity characteristic leaching procedure (TCLP). The results showed that the surface treatment method of CRT glass sands could obviously improve both the mechanical properties and durability performance. Particularly, the leaching of lead (Pb) level in all concrete specimens was much lower than the TCLP heavy metals limit of 5 mg/L. This experimental study will facilitate the production of CRT glass concrete for secondary structural applications. • The newly developed surface treatment method was applied on crushed CRT glass sands. • Treated CRT glass concrete showed better mechanical properties and durability performance. • The ASR expansion of specimens with 25% CRT glass sands was lower than 0.1% limit. • The leaching of lead for CRT glass concrete was lower than the standard limit (0.5 mg/L). [ABSTRACT FROM AUTHOR]

Abstract In this work, we developed a clean and efficient process for recycling rare earth elements from waste CRT phosphors. A mixture of sulfuric acid and hydrogen peroxide was used for the oxidative leaching of the rare earth elements, and the leaching efficiencies of both Y and Eu reached 99% under the optimal leaching conditions: 3 M H 2 SO 4 , 4 vol.% H 2 O 2 , 55 °C, and 1 h. The S2− was oxidized to S0, which efficiently avoided the sulfur pollution produced by existing technologies. The green solvent ionic liquid [OMIm][PF 6 ] and the extractant Cyanex272 were employed for the separation of the rare earths. The optimal extraction parameters were determined to be 0.2 mol/L H 2 SO 4 , 0.4 vol.% of Cyanex272 in the organic phase, a 10:1 A/O ratio, and an extraction time of 20 min at room temperature, under which, the individual extraction efficiencies of Y, Eu, Zn, and Al were 99%, 87, 8%, and 0%, respectively, and the separation factor of rare earth to Zn reached 593. Additionally, the extraction system could be recycled and reused by stripping. The mechanisms of the leaching and extraction process were also analyzed. Based on a kinetics study, the leaching process was found to follow the model of diffusion-control via the product layer, and the apparent activation energies for Y and Eu were calculated to be 75.86 kJ/mol and 77.06 kJ/mol, respectively. Meanwhile, a simulated leaching model based on diffusion through the solid S0 layer was established. The synergistic extraction mechanism was also discussed, and a cation exchange reaction was speculated to occur between the rare earth elements and Cyanex272. The findings in this study are expected to provide an effective and practical method for the recovery and reutilization of waste CRT phosphors. Graphical abstract An efficient recovery process was designed for waste CRT phosphors. Image 1 Highlights • REs were recycled efficiently by oxidative leaching and IL based extraction. • The leaching kinetics was investigated systematically. • The reaction mechanisms of the leaching and extraction process were analyzed. [ABSTRACT FROM AUTHOR]

Utilization and processing of waste cathode ray tube (CRT) glass causes serious environmental damage due to its presence of lead and huge growing volume. The use of waste CRT glass in cement-based materials is an effective recycling method, whereas the huge amount of waste CRT glass usually results in severe lead leaching and weakened interfacial bonding. This paper presents an effective method for improving the lead immobilization and microstructure of the interfacial transition zone between cement paste and waste CRT glass (30 and 60 wt% of fine aggregates) using graphene oxide (GO) (up to 0.10 wt%). In order to investigate the environmental compatibility of the GO-waste CRT cement mortars, the standard toxicity characteristic leaching procedure (TCLP) was performed for lead leaching evaluation, and their mechanical properties were examined. Moreover, thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) observation with backscattered electron mode were conducted. The results of TCLP indicate that the degrees of lead leaching from the waste CRT cement-based materials with both fine (0.075–0.15 mm) and coarse (8–9.5 mm) size containing 0.1 wt% GO were significantly lower than the regulatory limit specified by the United States Environmental Protection Agency and Chinese standard. The data obtained via mechanical testing revealed that the presence of 60 wt% waste CRT reduced its 28-day compressive and flexural strengths only slightly, whereas 0.1 wt% GO addition significantly increased their values. By analyzing the thermogravimetric and microstructural results, it was found that the increased formation of portlandite (CH) and calcium-silicate-hydrate (C S H) caused by GO addition reduced the number of interconnected cracks and pores and improved the properties of the interface between waste CRT glass and cement paste. This obtained improvement in environmental compatibility of the waste CRT cement mortars not only examines the reduced lead pollution caused by GO addition, but also sustainably promotes the industrial utilization of toxic waste CRT glass. [ABSTRACT FROM AUTHOR]

The growing generation of waste electrical and electronic equipment (WEEE) in developing countries has attracted increasing attention due to its potential health and environmental impacts and high recycling potentials. For example, along with the rapid economic development, China has been experiencing a sharp increase in the production and use of TV sets and a quick transition from old fashion cathode ray tube (CRT) ones to flat panel display (FPT) ones. Understanding such dynamics would be important for predicting future WEEE generation. In this article, we developed a dynamic (from 1992 to 2040), bottom-up (TV sets by module by material), and stock-driven (using future possession as a driver) material flow analysis model to investigate the amount of metals and plastics embodied in obsolete TV sets in the future. We found that the total generation of obsolete TV sets in China will reach 142 million units by 2040, in which FPD TV sets contribute more after they started to dominate the market after 2009. These growing obsolete TV sets would mean potentially large amount of embodied materials that can be recycled. While most of the embodied precious metals (e.g., gold, silver, and palladium), common metals (e.g., iron, aluminum, zinc, and tin), toxic metals (e.g., mercury, barium, and antimony), and plastics will increase in future, copper and nickel show a first decrease then increase trend, and lead will be gradually phased out in obsolete TV sets. Our results could help inform waste management and recycling strategies and relevant decision makers (e.g., governmental agencies, manufactures, and recyclers) in the TV sets sector in China. Such a stock-driven and bottom-up approach can also be used for other e-waste issues and other countries. [ABSTRACT FROM AUTHOR]

Using recycled cathode ray tube (CRT) funnel glass as a substitute for sand contributes to both reducing natural aggregate consumption and the disposal of CRT funnel glass. Currently, most studies have focused on the mechanical and durability properties of mortar or concrete containing CRT glass as fine aggregate. However, the study of the dynamic loadings (e.g., earthquake load, wind load and impact load) of major concrete structures containing CRT glass is still limited. In this paper, a dynamic thermo-mechanical analysis test with various frequencies (0.1 Hz–2.0 Hz) and temperatures (−30 °C−30 °C) is undertaken on mortars with different CRT replacement ratios (0, 20%, 40%, 60%, 80%, and 100%). The test results show that the storage modulus (stiffness) of mortar with incorporated CRT glass is lower than that of control mortar in most cases, but the decreasing trend is not proportional to the CRT replacement ratio. However, the presence of CRT glass in the mix has a negligible impact on the frequency dependence of the storage modulus of mortar. The storage modulus of each replacement ratio is nearly constant for all excitation frequencies. The frequency dependence of loss tangent (damping behavior) is significantly improved with CRT glass under 0 °C. This indicates that a frequency dependent damping model is needed when dynamic analysis is conducted on concrete structures with incorporated CRT glass in cold weather. [ABSTRACT FROM AUTHOR]

This study aimed to explore the feasibility of using cement blended with ISSA as cementitious materials in the production of cement mortars using recycled CRT glasses as fine aggregates. For comparison purposes, fly ash (FA) and ground granulated blast furnace slag (GGBS) were also used. Fresh and hardened properties of the cement mortars, as well as potential lead (Pb) leaching were investigated. The experimental results showed that the incorporation of ISSA to replace cement reduced the workability, hardened density and compressive strength but increased the water adsorption, drying shrinkage and flexural strength of the mortars. The influence of the different mineral admixtures on the properties of cement mortars was closely related to their pozzolanic activities and water adsorption abilities. ISSA was superior to FA and GGBS in enhancing the flexural strength and reducing Pb leaching of the mortar samples. It is noteworthy that Pb leaching from the mortar samples prepared with both ISSA and CRT glass was greatly reduced and it complied with the local regulatory limits, and increasing the replacement ratio of cement by ISSA led to a corresponding reduction in the Pb leachate concentrations mainly due to the adsorption and precipitation of Pb by ISSA. [ABSTRACT FROM AUTHOR]

An efficient mechano-thermal method was developed for lead removal from the CRTs funnel glass. The method comprises the activation of funnel glass with carbon by the planetary ball-milling apparatus. The mixture has been sintered for different lengths of time. The separation phenomenon was accelerated by the thermal treatment in the presence of carbon, the lead oxide (PbO) in a funnel glass quickly reduced into Pb and assembled on the surface of the glass matrix. With acid leaching, lead was efficiently removed from the treated glass residues. The optimum temperature, carbon powder adding amount, and holding time were 900 °C, 10%, and 30 min, respectively. During the process, more than 99 wt% of lead can be volatilized from the funnel glass and 93.60 wt% of lead was removed by the leaching process. The findings in this study provides an efficient and practical application for CRTs funnel glass detoxification and reutilization. [ABSTRACT FROM AUTHOR]

Phosphor powder from waste cathode ray tubes (CRT) was leached by acid leaching technology, and also, “H 2 SO 4 + H 2 O 2 ” system was utilized to reduce the release of poisonous gas H 2 S into atmosphere, single-factor method was used to determine the optimal operation conditions (H 2 SO 4 concentration, the volume of H 2 O 2 and H 2 SO 4 , temperature, time and the ratio of liquid and solid). Moreover, a quantitative analysis on recovery benefits was conducted to evaluate the effect of this method. Our results demonstrated that the recovery of Y and Eu has highly positive profits, as their price reached 1018.69 CNY/kg and 380.64 CNY/kg, separately. However, the recovery of Zn and Al has negative profits was due to its lower enrichment factors (EFs) and market price in comparison with Y and Eu. In general, this technology has a great potential to recover four major metals from waste phosphor powder, about 757.04 CNY per kilogram powder economic value can be produced using this process. Therefore, using “H 2 SO 4 + H 2 O 2 ” system for recycling Zn, Al, Y and Eu is a green and sustainable technology from waste cathode-ray tube fluorescent powder. [ABSTRACT FROM AUTHOR]

Electrical and electronic waste (e-waste), is an emerging and fast growing waste stream in the world. Among all the e-waste, cathode ray tubes (CRTs) are significantly recyclable in principle, but in practice, recycling is often inefficient because of limits imposed by hazardous behavior, recycling technologies, and the composition of glass. These topics were studied in this paper based on their characteristics and concluded the recycling challenges and most recent developed recycling technologies that could improve recycling rates. As a global society, we are currently far away from a closed-loop material system because the demand for CRT glass closed-loop recycling is extremely limited. However, much improvement is possible through recent developed recycling technologies but the challenge for the future is to transfer these environmentally friendly and energy-saving technologies into practice. [ABSTRACT FROM AUTHOR]

Abstract: This paper investigates the feasibility of using recycled glass derived from discarded cathode ray tube (CRT) glass as an alternate fine aggregate for the production of dry-mixed concrete paving blocks. The recycled CRT funnel glass used had been acid treated and regarded as a non hazardous material based on the regulatory thresholds of the Toxicity Characteristic Leaching Procedure (TCLP). Two series of concrete paving blocks were prepared, one with and one without the use of coarse aggregate. Additionally, TiO2, a photo-catalyst was added to the surface layer of the blocks during the fabrication process to effect photo-catalytic reaction for the removal of an air pollutant, nitrogen oxide (NO). For each series, the CRT glass was used to replace the fine aggregate by volume at different ratios. Their physical, mechanical and durability properties, lead leachability, and photocatalytic air purifier performance were studied. The results show that the use of up to 100% CRT funnel glass as fine aggregate in concrete paving blocks not only have satisfactory levels in compressive strength (>45 MPa) and ASR expansion (<0.1%), but improved the resistance to water absorption, drying shrinkage and photocatalytic performance for reducing air pollutants. However, the TCLP results reveal that the casting method of producing dry-mixed concrete blocks had a significant influence on lead leaching, and the replacement ratio of the CRT glass should be limited to about 25%. [Copyright &y& Elsevier]

Abstract: The rapid advance in the electronics industry has led to the disposal problem related to the cathode ray tube (CRT) glass waste. In this study, the Ordinary Portland cement (OPC) of 15% was replaced by fly ash to mitigate the potential of alkali–silica reaction (ASR) expansion, the crushed nitric acid-treated CRT funnel glass sand (TCF) was used to replace river sand fine aggregate of 0%, 25%, 50%, 75% in the high-density concrete. The fresh, mechanical properties of the high-density concrete containing TCF glass sand were studied, the alkali–silica reaction (ASR) of the mortar and drying shrinkage of the concrete were also evaluated. The test results showed that the use of TCF glass sand improved the fresh properties of the concrete, but reduced the mechanical properties of the concrete. Furthermore, at the drying period of 56 days, all concrete mixtures had an acceptable drying shrinkage value below 0.075%. ASR expansion values of the mortar with TCF glass sand were found to be below the limit of 0.1% at tested age of 14 days. Preliminary results obtained from this study had demonstrated that the CRT funnel glass (an original hazardous material) can be treated, processed and reutilized for the production of the high-density concrete. [Copyright &y& Elsevier]

Abstract: The challenge of managing discarded cathode ray tube (CRT) waste has become a major environmental concern in Hong Kong and other cities. Recycled CRT funnel glass with a relatively high density (∼3000 kg m−3) can be used as a potential material for the production of heavyweight concrete. This paper presents the results of an investigation on the feasibility of using recycled CRT funnel glass, both treated (lead has been removed from the glass surface) and untreated (without removal of lead) as partial and full replacements of fine aggregates in heavyweight barite concrete. The inclusion of barite aggregate and recycled funnel glass increased the hardened density but reduced the compressive and splitting tensile strengths. The replacement of natural fine aggregate with recycled CRT glass had no significant effect on the elastic modulus but considerably improved the drying shrinkage of the concrete. In conclusion, the overall properties of heavyweight barite concrete made with the treated and untreated recycled CRT funnel glass are comparable, except for lead leaching results. The results show that it is feasible to use the treated CRT glass as 100% substitution of fine aggregate in making heavyweight concrete. However, the substitution of untreated glass should be limited to below 25% due to its potential lead leaching. [Copyright &y& Elsevier]

Abstract: The rapid development of the electronic industry has led to a growing hazardous waste management and disposal problem related to the management of cathode ray tube (CRT) waste. This study aimed to compare the feasibility of using CRT recycled glass: non-treated funnel glass (n-TFG, crushed without treatment) and treated funnel glass (TFG, crushed and treated with acid nitric to remove lead on the glass surface) as fine aggregates in cement mortar. Fresh and hardened properties of the cement mortars, including their x-ray radiation shielding and potential lead leaching were investigated. The mortar prepared with crushed beverage glass (CBG, lead-free) was also evaluated for comparison purposes. The experimental results show that the use of glass cullets, irrespective of glass type, improved the fluidity and drying shrinkage but reduced the strength. About 60% enhancement in x-ray radiation shielding property was achieved with the use of 100% CRT glass in the cement mortar owing to the increase of mortar density due to the presence of lead in the CRT glass. Furthermore, lead leaching (based on TCLP test) from the mortar samples prepared with the TFG complied with the regulatory limits. The results have demonstrated that the CRT glass (an original hazardous material) can be treated, processed, and re-utilized for making cement mortars. The mechanical performance of the cement mortar is comparable to that made with beverage glass. [Copyright &y& Elsevier]

Abstract: Liquid Crystal Display (LCD) technology has evolved and developed over the past decades to replace Cathode Ray Tube (CRT) display technology as the market leader. This is evident, with global market figures for liquid crystal displays surpassing $75 Billion in 2008. Current End-of-Life (EoL) disposal for LCD screens is typically landfill or incineration, this form of disposal restricts the ability to recover potentially reusable materials from waste LCD screens e.g. steel, aluminium, copper etc. Thus to conserve raw materials and to protect the environment it is essential to replace the traditional flow of products from manufacturer to landfill with a recycle and recover approach. While the recycling methods for CRTs are well established, however those of LCDs are as yet in their infancy. However to reduce consumption of natural resources and reduce quantities of waste going to landfill, recycling process must be encouraged and developed. This paper aims to address the challenges facing EoL treatment of LCD units by analysing LCD build types, structures and component material to establish traits which may make EoL treatment less of a challenge. Analysing this data will lay the foundation to developing a balanced recovery system meeting the needs of economic viability and environmental conservation in future work. [Copyright &y& Elsevier]

The study assessed the possibility of using waste glass cullet from the screen part of CRTs (cathode ray tube) in the vitrification of asbestos-cement materials (ACM). The composition consisting of 50% by mass ACM and 50% by mass cullet was subjected to vitrification. The research material before and after vitrification was subjected to comparative analysis. As a result of vitrification, a transparent amorphous material was produced with a hardness about 7% higher than that of CRT glass and lower ion leachability in an aqueous environment compared to ACM. X-ray and spectroscopic examinations did not reveal the presence of chrysotile, i.e. a type of asbestos found in ACM. This fact proves that during vitrification the asbestos decomposed and formed a lattice of glass composed of the products of this decomposition. Moreover, the presence of heavy metals in the vitrified product was found, including Ba and Sr, the source of which was the CRT cullet. The obtained research results prove that ACM vitrification with CRT cullet leads to the effective utilization of both types of waste during one technological process. Therefore, the vitrification of ACM can be successfully carried out using waste CRT glass, and the harmless product obtained in the vitrification process can be used in practice. The use of CRT cullet in the vitrification of asbestos-cement materials will also have a positive impact on the environment as it will reduce the amount of electronic waste deposited in landfills. [Display omitted] • The vitrification of ACM can be successfully carried out using CRT glass cullet. • It is possible to simultaneously dispose of ACM and CRT cullet in one process. • The vitrification process transforms the hazardous wastes into a harmless product. • Vitrification is an effective method of neutralizing asbestos-cement materials. • The vitrification process leads to the complete decomposition of chrysotile. [ABSTRACT FROM AUTHOR]

For thermal insulation to be sustainable, its performance and production efficiency must be considered. Foamed glass prepared from the mixture of waste cathode ray tube panel glass (CRT), Mn 3 O 4 and carbon could become such a material assuming that its production efficiency could be improved. In light of this, the aim of the study was to engineer the transfer of the foaming process from inert to air atmosphere without drastically disturbing the primary mechanism of expansion. Foaming of carbon-containing mixtures in air atmosphere is normally a challenge due to premature oxidation of carbon by the oxygen from the air. Here, we systematically investigate how the addition of water glass (WG) affects the process by thermogravimetry coupled with mass spectrometry (TG/MS) and heating-stage microscopy analysis. Further, we propose an explanation about how WG protects the carbon and show that the addition of WG allows for the process to be successfully performed in air atmosphere. Two direct sources of expansion were identified (carbon-Mn 3 O 4 reaction and WG) and quantitatively evaluated, allowing determination of an optimal addition of WG, 12 wt %, for the foaming temperature of 800 °C. The obtained foamed glass samples have a relatively low density and degree of open porosity, which reflects in their low thermal conductivity (λ). The lowest λ obtained was 39 mW m−1 K−1 at a density of 145 kg m−3, which is comparable to the samples prepared in inert atmosphere and best commercial products. Image 1 • Water vapours displace the air and form less oxidative atmosphere within the sample. • Main expansion source identified from different combinations of additives. • Water glass content with minimum effect on primary foaming mechanism determined. • Obtained product with similar properties as in a controlled atmosphere. • Effective use of the process in the air atmosphere provides environmental benefits. [ABSTRACT FROM AUTHOR]

This study intends to evaluate the feasibility of the use of recycled cathode ray tube (CRT) glass in water-foamed asphalt mixtures used in low volume roads. In the asphalt mixture samples, 21.5% (wt.) aggregates were replaced by the recycled CRT glass to evaluate the mechanical performance and leaching potential. First, the leaching test was used to characterize the leaching potential of the CRT mixes since there is high lead content in CRT glass, which may be harmful to the groundwater if the hazardous lead leaches from the CRT mixes. Second, the high-temperature rutting and the low-temperature cracking performance of the asphalt mixtures were measured via the Hamburg Wheel Tracking Test (HWTT) and the Disk-Shape Compact Tension (DCT) test, respectively. In addition, the Moisture-Induced Stress Tester (MIST) was used to simulate the pore pressure generated in a wet pavement under moving traffic loading. The experimental results showed that, although the measured lead leaching of the pure CRT glass particles was higher than the regulatory level of 5 mg/L, the coated asphalt could effectively insulate the contact between CRT glass and the external environment, resolving the leaching issues. In summary, from the view of the mechanical performance of the water-foamed asphalt mixtures containing recycled CRT glass, the performance is acceptable in various temperatures when used in low volume roads. Recycling CRT glass in asphalt mixture should be carried out with extreme caution because if not done correctly, the potential leaching may eliminate the benefits of recycling unwanted waste materials. [ABSTRACT FROM AUTHOR]

Cathode ray tube (CRT) funnel glass is classified as a hazardous waste because it contains lead, which can endanger the environment and human health. In this paper, an innovative cementitious material, ultra-high performance concrete (UHPC) was introduced to recycle hazardous waste CRT without lead extraction. Crushed CRT funnel glass without lead extraction was used to replace sand as fine aggregate in various ratios in UHPC. The mechanical properties and toxic heavy metal leachability of UHPC were investigated. Results showed that the addition of CRT glass can increase the flowability and decrease the compressive and flexural strength of UHPC. Analyses by X-ray diffraction and scanning electron microscopy demonstrated that the CRT glass increases the porosity, inhibits cement hydration, and weakens the interfacial transition zone, resulting in the reduced strength of UHPC. Meanwhile, the leached lead concentration of UHPC was still below regulatory limit of U.S. code even when the replacement ratio reaches 100%. The working principle behind the sharp drop in leached lead in UHPC was proposed, that is the dense microstructure and low permeability coefficient of UHPC can effectively restrain the lead leaching from CRT glass. The findings of this study can provide an effective alternative to recycling hazardous waste CRT without limitations on the replacement ratio and safety concern. Image 1 • Recycling of waste CRT funnel glass without lead treatment through UHPC is explored. • The influence of waste CRT funnel glass on the properties of UHPC is investigated. • UHPC with waste CRT funnel glass fulfills safety requirement from US code. • Lead leaching is inhibited in UHPC and its working principle has been revealed. [ABSTRACT FROM AUTHOR]