RESUMO
The safe disposal of waste cathode ray tubes (CRTs) has always been a serious problem due to the stable microstructure of toxic lead (Pb) located in glass. Thousands of researches have been trying to explore environmental and efficient ways to dispose of waste CRTs. To recycle lead from waste CRT funnel glass effectively, a mechanochemical reduction method has been developed in this research. Aluminum was used as a reductant, and the hydrochloric acid solution was used in the leaching process to separate lead from the solution. After mechanochemical ball milling with aluminum, lead ion in CRT funnel glass was transferred into nano-sized element lead. Lead recovery from CRT funnel glass increased significantly as compared to non-activated leaded glass. Approximately 40 % of lead was leached after mechanical activation without aluminum, while over 96 % of lead in the CRT funnel glass could be recovered after mechanochemical reduction with aluminum. Lead chloride (PbCl2) can be recycled from the leaching solution after cooling crystallization. Nano-sized Pb formation and the structural changes of leaded CRT funnel glass by mechanochemical reduction process contributed to obvious improvement in lead recovery. This research provided a high-efficiency and feasible approach for recovering lead in form of PbCl2 crystal from leaded glass.
Assuntos
Tubo de Raio Catódico , Resíduo Eletrônico , Pós , Alumínio , Chumbo , Resíduo Eletrônico/análise , Vidro/químicaRESUMO
The present study focuses on the charged-uncharged particles shielding performance of the addition of a mixed type of cathode ray tube (CRT) in a glass system that is irradiated by the 252Cf neutron source via the MCNPX simulation and analytical calculations, as well as Phy-X: PSD and SRIM software. The CRT waste glass is inserted into the glass system with (70-x) CRT-30K2O-xBaO general formula for x = 0, 10, 20 mol% that produces CG1, CG2, and CG3 glass shielding materials. Using Watt Fission Distribution (WFD) and Doppler Effect (DE) the neutron-gamma photon spectra were extracted for shielded (in the presence of the glass materials) and unshielded (in air) cases. Some calculated attenuation parameters related to the neutron deduced that CG1 is the best neutron attenuator among the selected glass samples. Moreover, by increasing the density of the glass from CG1 to CG3, the ascending trend is observed for the linear attenuation coefficient (LAC, cm-1) of the studied glass, and the best shielding competence is monitored for CG3. Furthermore, two sharp peaks are found in Zeff graphs which may be due to K-edge absorption of Ba and Pb elements and by decreasing the Pb element from CG1 to CG3 the second peak gradually becomes smooth. In addition, Mass Stopping Power/ Projected Ranges of the proton (H1) and alpha particles (He+2) are also estimated by SRIM code and findings show that CG1 can better stop proton and alpha particles in comparison with the other chosen glass structures.
Assuntos
Tubo de Raio Catódico , Vidro , Nêutrons , Chumbo , Prótons , Software , Efeito DopplerRESUMO
Proton therapy is becoming increasingly popular worldwide, and its shielding must be considered. The cathode ray tube (CRT) material is a glass containing heavy metal elements, these materials have become a good choice for the production of radiation-proof concrete. In this study, the ability of concrete containing CRT fragments as shielding materials for proton therapy rooms is evaluated in terms of neutron shielding ability, neutron reflection ability, ambient dose equivalent rate, and induced radioactivity. In addition, this concrete is compared with commonly used ordinary concrete, boron-containing concrete, and barite concrete. The results show that with the increase of CRT content (10%-90%), the transmitted neutron fluence decreases continuously (5.06 × 10-10 - 1.77 × 10-10 cm-2/particle), and the reflection of neutrons gradually increases (2.64 × 10-9 - 3.20 × 10-9 cm-2/particle), resulting in an increased potential to patients. When 50% CRT concrete is used, the ambient dose equivalent rate is below 3.80 µSv/h/nA, and 90% CRT concrete is below 3.11 µSv/h/nA. The trend of radionuclide activity of induced radioactivity from 0 to 60 min after irradiation for concrete with different CRT contents is 2.74-5.38 × 10-3 Bq/cm3, and the maximum photon fluence is 8.13 × 102 cm-2. In conclusion, the optimization model of the three-layer shielding structure of ordinary concrete, high CRT content concrete, and boron-containing concrete is proposed with ambient dose equivalent rate less than 1.88 µSv/h/nA, minimizing the reflected neutrons to which the patient is exposed. This study shows the protection performance of CRT concrete is better than ordinary concrete and barite concrete.
Assuntos
Tubo de Raio Catódico , Terapia com Prótons , Proteção Radiológica , Sulfato de Bário , Boro , Salas de Parto , Feminino , Humanos , Recém-Nascido , Nêutrons , Gravidez , Terapia com Prótons/métodos , Doses de Radiação , Proteção Radiológica/métodosRESUMO
Cathode-ray tubes (CRTs) from computer monitors and television sets are considered as one of the main sources of waste materials worldwide. Therefore, a new application for such out of use materials is required to solve the relatively huge amount of this waste. In this paper, the popular melt-quench technique was used to synthesis glass samples with the structure: xBi2O3-(100-x) waste CRTs (where x = 0, 10 & 20 wt%) and designated as CRT-Bi0, CRT-Bi10, and CRT-Bi20 accordingly. The physical, structural, optical and radiation absorption competence of the glasses were investigated. The XRD analysis of the glasses reveals an amorphous structure while the mass density increased linearly with the Bi2O3 content of the glasses from 2.86 to 3.08 g/cm3. The optical absorbance of the glasses initially increased and later declined in the visible region as the weight fraction of Bi2O3 increased. The direct optical bandgap Eg values were found to be 3.26, 2.72, and 2.64 eV whereas the indirect Eg values were equal to 3.15, 2.30, and 2.26 eV for CRT-Bi0, CRT-Bi10, and CRT-Bi20, respectively. The gamma-ray interaction parameters of the glasses obtained through FLUKA simulations and XCOM computation showed that mass attenuation falls within the range 0.6991-0.0256, 1.1426-0.0276, 1.5860-0.0301 cm2/g for photon energy range 0.1-10 MeV. Generally, the computed gamma ray interaction quantities show that the gamma ray shielding ability of the CRT-Bi glasses follows the order: CRT-Bi0 < CRT-Bi10 < CRT-Bi20. This order is conserved in the computed interaction cross sections for thermal (25 meV) neutrons. On the other hand the fast neutron removal cross section follows a reverse order with values of 0.0891 cm-1, 0.0867 cm-1, and 0.0850 cm-1 for weight fraction of Bi2O3 from 0 to 20 wt%. The comparison of the gamma-ray attenuation capacity of the CRT-Bi20 with common shielding materials reveals good potential for shielding application. Out of use CRT glasses may thus be recycled for use as radiation shielding glasses as described in this study for gamma radiation protection applications.
Assuntos
Tubo de Raio Catódico , Reciclagem , Vidro/química , Reciclagem/métodos , TelevisãoRESUMO
Solidification of cathode ray tube (CRT) panel glass was carried out using a hydrothermal processing method. In this way, the glass powder was first compacted in a mold at 20 MPa, and then hydrothermally cured in an autoclave under saturated steam pressure at 200 â for 6 h. The CRT panel glass was then hydrothermally solidified by the formation of tobermorite (Ca5Si6O16(OH)2·4H2O), which was encouraged by the addition of slaked lime (Ca(OH)2). The strength of solidified specimen heavily depended on the amount of tobermorite formed, with higher concentrations of tobermorite producing commensurately greater mechanical strength. With the addition of Ca(OH)2 at 20-30% by mass, the specimen achieved a bending strength of approximately 16 MPa, which was sufficiently great for using as a construction material. As such, there is cause to believe that the hydrothermal processing method used here may have great potential for resource utilization of CRT panel glass, and the performance of the product is suitable for use as building materials.
Assuntos
Tubo de Raio Catódico , Materiais de Construção , VidroRESUMO
Waste CRT funnel glass (FG) is a typical hazardous waste produced by the electronics industry that contains toxic lead oxide, red mud (RM) is the first waste produced during alumina production. Both of these are extremely difficult to reuse. Here, we report a method to control FG waste, in which RM was used to enhance the removal of Pb from FG via a vacuum thermal process. The removed residual glass was utilized to create glass-ceramics. The results showed that RM can enhance the lead removal from waste CRT funnel glass by the vacuum thermal process. When 30% RM was added, the removal rate reached 98.54%. A significant mechanism of enhancing delead is investigated by a Fourier transform infrared (FTIR) spectrometer and X-ray photoelectron spectroscopy (XPS). The results showed that the -Pb-O-Si-O- network structure was broken by the free calcium ions of RM. Afterward, valuable glass-ceramics with tetragonal-KAlSi2O6 and triclinic-CaSiO3 crystals were synthesized using the residual glass. The Pb, Ba, Cr, and Cu leaching concentrations of the glass-ceramics were well below the regulatory limit (5 mg/L) of the CA-EPA, as measured by the toxicity characteristic leaching procedure (TCLP) test. Overall, the results indicated that RM enhanced the removal of lead during the vacuum thermal process. The synthesis of value-added glass-ceramics reutilized silicate resources from waste cathode ray tube (CRT) funnel glass and RM.
Assuntos
Tubo de Raio Catódico , Cerâmica , Vidro , Resíduos Perigosos , Chumbo , SilicatosRESUMO
Paving block is a widely used pavement material due to its long service life, fast and easy production and easily replaced for maintenance purpose. The huge production volume of paving blocks consumes large amount of natural aggregates such as sand and granite. Therefore, there is a necessity to review the utilization of alternative materials as the aggregate replacement to cut down both the consumption of natural resources and disposal of various waste. This paper thus analyses published works and provides a summary of knowledge on the effect of utilizing selected waste materials such as soda-lime glass, cathode ray tube (CRT) glass, recycled concrete waste, marble waste, crumb rubber (CR) waste and waste foundry sand (WFS) as aggregate replacement in concrete paving blocks fabrication. The influence of each waste material on the properties of paving block is discussed and highlighted in this paper. The adherence of the waste material paving block to the standard requirements is also presented to provide a clear direction on the utilization of these materials for practical application. Soda-lime glass, CRT glass, pre-treated RCA and calcined WFS have the potential to be utilized in high quantities (30-100%), normal RCA and marble waste can be incorporated in moderate amount (30%) while CR waste and WFS is limited to low amount (6-10%). In overall, the usage of waste materials as aggregate replacement has good potential for producing eco-friendly concrete paving block towards the sustainable development of construction material.
Assuntos
Tubo de Raio Catódico , Resíduos Industriais , Materiais de Construção , Vidro , Resíduos Industriais/análise , ReciclagemRESUMO
PURPOSE: Owing to several factors, peak latencies of pattern-reversal visual evoked potentials (p-VEP) are delayed when viewing liquid crystal display (LCD) monitors compared to those evoked when viewing cathode ray tube (CRT) monitors. However, few studies have examined whether biological factors affect latency in LCD. This study aimed to investigate whether biological factors caused latency changes in LCD among young subjects. METHODS: Twenty-eight subjects (56 eyes) aged 21-29 years (mean ± SD, 22.7 ± 1.7) participated in this study. We recorded output from each eye twice for both CRT and LCD monitors under the same conditions for monocular p-VEP. The peak latencies of three components (N75, P100, and N145) were compared between these two monitors. RESULTS: All peak latencies recorded with LCD were delayed compared to those recorded with CRT: N75, 9.7 ± 2.5 ms; P100, 10.1 ± 3.0 ms; and N145, 8.4 ± 6.2 ms (all p < 0.001). The degree of latency delay varied depending on the components. Moreover, all peak latencies of CRT appeared earlier than standard values of N75, P100, and N145. CONCLUSIONS: These findings suggest that the following aspects should be considered when assessing biological factors that may affect latency: components might influence latency changes; a young age could be related to an early appearance of peak latencies; inter-individual differences might cause latency change. These biological factors should be considered as possible causes for the varying latencies in an LCD monitor. Further studies should include healthy adults with a wider age range to assess the effects of age on latency.
Assuntos
Tubo de Raio Catódico , Cristais Líquidos , Adulto , Fatores Biológicos , Eletrorretinografia , Potenciais Evocados Visuais , HumanosRESUMO
Liquid crystal display (LCD) monitors are nowadays standard in computerized visual presentation. However, when millisecond precise presentation is concerned, they have often yielded imprecise and unreliable presentation times, with substantial variation across specific models, making it difficult to know whether they can be used for precise vision experiments or not. The present paper intends to act as hands-on guide to set up an experiment requiring millisecond precise visual presentation with LCD monitors. It summarizes important characteristics relating to precise visual stimulus presentation, enabling researchers to transfer parameters reported for cathode ray tube (CRT) monitors to LCD monitors. More importantly, we provide empirical evidence from a preregistered study showing the suitability of LCD monitors for millisecond precise timing research. Using sequential testing, we conducted a masked number priming experiment using CRT and LCD monitors. Both monitor types yielded comparable results as indicated by Bayes factor favoring the null hypothesis of no difference between display types. More specifically, we found masked number priming under conditions of zero awareness with both types of monitor. Thus, the present study highlights the importance of hardware settings for empirical psychological research; inadequate settings might lead to more "noise" in results thereby concealing potentially existing effects.
Assuntos
Percepção/fisiologia , Teorema de Bayes , Tubo de Raio Catódico , Humanos , Cristais Líquidos , Estimulação LuminosaRESUMO
Cathode ray tube televisions (TVs) contributes significantly to the rapidly increasing waste stream of cathode ray tubes in the e-waste. This study mainly focused on the material flow of waste cathode ray tube TVs in China. Currently, waste cathode ray tubes constitute a major part of the total generation of e-waste in China. The study aimed to emphasise the flow of materials in the generated waste cathode ray tube TVs by using stock-based material flow analysis model. The modelling was conducted to investigate the disposable number of obsolete devices, in-use stock, and end-of-life of cathode ray tube TVs. SubSTance flow ANalysis (STAN) software was used to perform the material flow analysis modelling and graphical model of the waste cathode ray tube TVs. The results show that in a period of 10 years, overall about 3241.37 kt of cathode ray tube TVs were net produced in China, containing 183.6 kt of glass, 1718.2 kt of plastic, 243 kt of steel/iron, 153.5 kt of lead, 76.6 kt of copper, 7.8 kt of aluminium, and 1.6 kt of antimony. The results revealed that almost 125 kt of end-of-life cathode ray tube TVs containing about 68 kt of glass, 40 kt of plastic, 9 kt of steel/iron, 6 kt of lead, 3 kt of copper, 0.3 kt of aluminium, and 0.07 kt of antimony were dumped in the period of 10 years. Therefore, the management of waste cathode ray tube TVs required better infrastructure for recycling and better regulation to achieve better results in the high recovery of valuable resources.
Assuntos
Tubo de Raio Catódico , Resíduo Eletrônico , China , Vidro , Reciclagem , TelevisãoRESUMO
Cathode ray tube (CRT) glass contains significant amounts of alkali and alkaline earth oxides, making it a useful by-product for use in the ceramics industry. Among the various alkali oxides present, those of strontium (SrO), calcium (CaO), and magnesium (MgO) are well known flux materials used widely in the ceramics industry. The most effective flux, SrO, is also a limited resource. In this study, we aimed to develop an environmentally friendly, low-cost method for recycling CRT waste by using it to produce transparent ceramic frits on an industrial scale. Four different samples were fabricated containing between 13 and 25 wt.% CRT panel glass. The color values, sintering behaviors, phases, and microstructural properties of the corresponding samples were analyzed and compared. The results indicate that a composition containing 25 wt.% CRT panel glass could pass the ISO 10545 test. Thus, the results confirm that CRT glass can be used to inexpensively produce transparent ceramic frits at an industrial scale. Implications: The recycling of electronic waste (e-waste), including CRT waste, has increased by high rates of computer and TV consumption. This increase in consumption is likely to increase the rate at which CRTs are discarded. However, CRTs cannot be recycled in the desired amount. Owing to the high silicate, barium and strontium content of CRTs, it has great potential for glass ceramics such as frits. CRT panel glass to produce commercial transparent frit at low cost through an industrial production route for use in single-fire sintered products. Thus, CRT wastes can be recycled cost-effective, sustainable and environmentally friendly.
Assuntos
Tubo de Raio Catódico , Cerâmica , Vidro , Reciclagem , Gerenciamento de Resíduos/métodos , Resíduo Eletrônico , Resíduos IndustriaisRESUMO
Cathode ray tubes (CRTs) have an appreciable amount of rare earth elements (REEs). In this document, the leaching and recovery of the REEs from CRTs, with different organic and inorganic ligands is presented. Among the complexing agents tested, the pyrophosphate ion was found to be the most advantageous for the extraction of REEs from CRTs, as an alternative to the traditional methods that use highly acidic solutions (pHâ¯<â¯1) and elevated temperatures. Thermodynamic analyses predict the formation of soluble REE-pyrophosphate complexes in a pH range of 2-8. Leaching solutions of 0.1â¯M Na4P2O7 at pH 6 and room temperature were employed. REE dissolution from the untreated CRT powder under these conditions was extremely low, due to the encapsulation by other components in the powders, such as ZnS (26%), and the high content of phosphates (6%), that severely limited the solubility of the REEs. To increase extraction, pretreatments were employed to alter and remove the passivating species: roasting at 800⯰C or contact with concentrated solutions of sodium hydroxide at 95⯰C. The combination of these pretreatments completely eliminated the Zn and 79% of the phosphate ion, as well as other base metals, resulting in an improved exposure of REEs for subsequent leaching. Extractions for Y, Eu, Sm, and Ce of 58, 90, 90 and 87%, respectively, were achieved with the pyrophosphate solution at ambient temperature. The REEs were later recovered as oxides by adjusting the solution pH to 11. Subsequently, once the pyrophosphate solution pH is reestablished, it may be reused for leaching.
Assuntos
Tubo de Raio Catódico , Metais Terras Raras , Ligantes , Fosfatos , PósRESUMO
BACKGROUND: Recent patents reveal that vegetable ingredients have several applications in novel food formulations. Many so-called antinutritional components (e.g. tannins, saponins, lectins and protease inhibitors) have nutraceutical as well as pharmaceutical significance. Seeds of two wild legumes of the genus Canavalia inhabitants of the coastal sand dunes of Southwest India are known for a variety of bioactive principles (e.g. phenolics, tannins, canavanine, concanavalin and phytohemagglutinins). OBJECTIVE: This study evaluates the impact of Electron Beam (EB) irradiation on the bioactive components of seeds of two coastal sand dune wild legumes Canavalia cathartica and C. maritima. METHODS: The dry seeds of C. cathartica and C. maritima were EB irradiated with different doses (2.5, 5, 10 and 15 kGy) to follow changes in six bioactive principles (total phenolics, orthodihydric phenols, tannins, canavanine, trypsin inhibitors and phytohemagglutinins) in comparison to control seeds. One-way ANOVA was employed to follow the variation in bioactive components of seeds in control and different doses of irradiation. RESULTS: Seeds of both legumes were devoid of orthodihydric phenols and trypsin inhibitors. In C. cathartica, the total phenolics showed significant dose-dependent increase up to 5 kGy and decreased thereafter. Tannin content was not altered up to 10 kGy followed by significant decrease at 15 kGy. There was no significant change in canavanine content and the phytohemagglutinin activity against human erythrocytes was not altered. Seeds of C. maritima did not show significant changes in total phenolics as well as tannin contents. The content of canavanine showed significant dose-dependent increase up to 5 kGy followed by significant decrease. There was no variation in phytohemagglutinin activity against erythrocytes A, B and O, while against AB, the activity decreased at 2.5 kGy and further decrease was constant at higher doses. CONCLUSION: The EB irradiation doses employed have selectively altered the bioactive principles of Canavalia seeds and such treatments may facilitate to maneuver desired medicinal, nutritional, functional and cooking properties. Besides selective changes in bioactive components the seeds have extended shelf life.
Assuntos
Canavalia/efeitos da radiação , Tubo de Raio Catódico , Tecnologia de Alimentos/métodos , Sementes/efeitos da radiaçãoRESUMO
A novel and effective system was developed for recycling cathode ray tube (CRT) funnel glass wastes. Initially, the combination of nanoscale Fe0 with ball milling promoted lead transfer that was strongly encapsulated in the glass inner structure to the surface of funnel glass and/or adhere to iron substance due to the collapse of SiO bonds. This condition enhanced the dissolution of lead in the acid solution. A high lead extraction rate of 97.8% from funnel glass was achieved through nitric acid leaching by optimizing the operational parameters (Fe0/funnel glass mass ratio, 0.5:1; ball milling time; 72â¯h). Subsequently, lead sulfate, iron hydroxides, and sodium nitrate were gradually recovered from the acid leachate by using three simple operations, namely, sulfation, alkali neutralization, and salt evaporation. Meanwhile, the leaching results of short-term toxicity characteristic leaching (TCLP) and long-term multiple extraction procedures (MEP) clearly demonstrated that the residual high silica products (after acid leaching) had no impact on the environment and could be used to synthesize high value-added zeolites as raw materials. With the addition of Al sources, the complete conversion of high silica residues into high crystalline zeolites with high cation exchange capacity value was realized by applying an alkaline fusion method during the hydrothermal treatment. Furthermore, lead, NO-3, and SO2-4 concentrations of the resulting drainage were considerably lower than the relevant standard for surface water quality. Therefore, the proposed recycling system provided an eco-friendly and feasible technique for complete reutilization of obsolete CRT funnel glass.
Assuntos
Tubo de Raio Catódico , Nanoestruturas , Reciclagem , Vidro , Ácido Nítrico , Dióxido de SilícioRESUMO
This study quantitatively determined the extraction of lead from CRT funnel glass and examined the mechanisms of thermally reducing lead in the products of sintering Pb-glass with carbon in the pre-heated furnace. The experimentally derived results indicate that a 90.3â¯wt% lead extraction efficiency can be achieved with 20â¯wt% of C addition at 950⯰C for 3â¯min under air. The formation of viscous semi-liquid glass blocked the oxygen supply between the interaction of C and Pb-glass, and was highly effective for the extraction of metallic Pb. A maximum of 87.3% lead recover was obtained with a C to Na2CO3 ratio of 1/3 at 1200⯰C. The decrease of C/Na2CO3 ratio enhanced the metallic lead recovery by increasing the glass viscosity for effective sedimentation of metallic lead in the bottom. However, with the further increase of temperature and treatment time, re-vitrification of lead back to silicate-glass matrix was detected in both Pb-glass/C and Pb-glass/C/Na2CO3 systems. The findings indicated that with proper controls, using C as an inexpensive reagent can effectively reduce treatment time and energy, which is crucial to a waste-to-resource technology for economically recovering lead from the waste CRT glass.
Assuntos
Tubo de Raio Catódico , Resíduo Eletrônico , Chumbo/química , Carbono , VidroRESUMO
Because they were used for decades to present visual stimuli in psychophysical and psychophysiological studies, cathode ray tubes (CRTs) used to be the gold standard for stimulus presentation in vision research. Recently, as CRTs have become increasingly rare in the market, researchers have started using various types of liquid-crystal display (LCD) monitors as a replacement for CRTs. However, LCDs are typically not cost-effective when used in vision research and often cannot reach the full capacity of a high refresh rate. In this study we measured the temporal and spatial characteristics of a consumer-grade LCD, and the results suggested that a consumer-grade LCD can successfully meet all the technical demands in vision research. The tested LCD, working in a flash style like that of CRTs, demonstrated perfect consistency for initial latencies across locations, yet showed poor spatial uniformity and sluggishness in reaching the requested luminance within the first frame. After these drawbacks were addressed through software corrections, the candidate monitor showed performance comparable or superior to that of CRTs in terms of both spatial and temporal homogeneity. The proposed solution can be used as a replacement for CRTs in vision research.
Assuntos
Tubo de Raio Catódico , Apresentação de Dados/normas , Desenho de Equipamento , Cristais Líquidos , Estimulação Luminosa , Humanos , Estimulação Luminosa/instrumentação , Estimulação Luminosa/métodos , Psicofísica , Psicofisiologia , Software , Análise Espaço-Temporal , Visão Ocular/fisiologiaRESUMO
In this study, a novel process was developed for extracting lead from the hazardous waste cathode ray tube (CRT) funnel glass and simultaneously producing glass-ceramics. CRT funnel glass was mixed with coal fly ash and subjected to carbon thermal reduction with the addition of CaO. The homogeneous glass melt and reduced metallic lead were quenched in water. Glass-ceramics were produced from the parent glass through an appropriate heat treatment. The optimum carbon loading amount (calculated as the molar ratio of C/PbO), CaO/SiO2 ratio, smelting temperature and holding time for lead recovery were 1.0, 0.3-0.6, 1450⯰C and 2â¯h, respectively. Under these conditions, more than 95% of lead can be extracted from the funnel glass and a low lead content of the resultant parent glass below 0.6â¯wt% was successfully achieved. CaO behaved as a network modifier to reduce the viscosity of the glass and also acted as a substitution to release lead oxide from the silicate network structure, resulting in a high lead separation efficiency. X-ray diffraction (XRD) analysis revealed that the main crystalline phase was gehlenite when 50-70â¯wt% funnel glass was added. Scanning electron microscopy (SEM) observation showed that well-crystallized crystals occurred in the specimens with 50-70â¯wt% funnel glass additions, whereas the specimens with 40â¯wt% and 80â¯wt% glass additions exhibited a relative low crystallization degree. Furthermore, property measurements, chemical resistance tests and leaching characteristics of heavy metals confirmed the possibility of engineering and construction applications of the superior glass-ceramic products. Overall results indicate that the process proposed in this paper is an effective and promising approach for reutilization of obsolete CRT funnel glass.
Assuntos
Tubo de Raio Catódico , Cerâmica , Cinza de Carvão , Chumbo/química , Carvão Mineral , Vidro , Microscopia Eletrônica de Varredura , Dióxido de SilícioRESUMO
BACKGROUND: Vegetable proteins have widespread application in the food industry as functional ingredients in food formulations according to the recent patents. Requirement to develop less expensive protein-rich supplementary foods has resulted in shift of emphasis towards lesser known wild than popular legumes. OBJECTIVE: The aim of this study is to expose seeds of two coastal sand dune wild legumes of the Southwest India (Canavalia cathartica and C. maritima) to different doses of electron-beam (EB) irradiation to assess changes in functional attributes. METHOD: Intact dried seeds were exposed to EB irradiation (2.5, 5, 10, 15 kGy). Protein solubility, gelation concentration, water-absorption capacity, oil-absorption capacity, emulsion properties and foam properties of control and irradiated seeds were assessed by standard methods. RESULTS: Protein solubility of both seed flours attained the highest at 2.5 kGy, followed by gradual dosedependent decrease. The gelation concentration increased in C. cathartica only at 5 kGy, while it decreased in C. maritima at 2.5 kGy without further change at higher doses. The water-absorption capacity of C. maritima was significantly higher than C. cathartica in control sample, while at 15 kGy C. cathartica showed significantly higher absorption capacity than C. maritima. The oil-absorption capacity was significantly higher in C. maritima than C. cathartica in control as well as all doses of irradiation. Emulsion activity of C. maritima was slightly higher than C. cathartica in control and irradiated samples, while both seeds showed similar emulsion stability in control with significant increase in C. cathartica at 10 kGy and 15 kGy. The foam capacity in both seeds was similar up to 2.5 kGy followed by significant increase in C. maritima at 5 kGy and 10 kGy. The foam stability was significantly higher C. cathartica than C. maritima in control as well as in irradiated samples. The foam capacity was higher in C. maritima than C. cathartica in control and irradiated samples, which showed gradual time-dependent decrease in stability with higher stability at 8 hr in C. cathartica than C. maritima. CONCLUSION: Improved functional properties (protein solubility, emulsion stability and foam capacity) and decreased gelation concentration in seeds of C. maritima irradiated at 5 kGy is advantageous in the production of functional foods. Even though both species of Canavalia grew on the coastal sand dunes and their seeds were exposed to same doses of radiation, they differed in functional attributes confirm that it is species-specific. Canavalia seeds being rich in proteins, carbohydrates, essential amino acids, essential fatty acids and bioactive components, further studies on the impact of EB irradiation helps in optimization of nutraceutical potential as well as functional attributes for future applications.