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1.
J Hazard Mater ; 415: 125599, 2021 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-33765563

RESUMO

With a huge amount of waste liquid crystal displays (LCDs) generated annually, their proper recycling raises continuous concern to realize pollution control (heavy metal and liquid crystal) and resource recovery (indium). However, due to their multi-metal feature, traditional hydrometallurgy lacks of sufficient selectivity, which makes the recycling route lengthy, costly, and generate more waste. Electrodeposition acts as a promising technique for selective metal extraction from multi-metal system due to its high selectivity and electron as clean reagent. To fully develop its application in metal recovery, stepwise Cu/MoO2 and In electrodeposition from In-Cu-Mo-Fe waste LCD leachate is explored in depth. Electrochemical behavior analysis shows Cu and MoO2 can be first electrodeposited for their higher electroreduction potential. Cl- plays a key role in accelerating indium electroreduction kinetics, which largely shortens the extraction time without the sacrifice of current efficiency. This accelerating effect is attributed to the increased concentration of electroactive species or collision frequency. Under optimized condition, 99.41% of indium (> 99% purity) can be electrodeposited within 13 h with high current efficiency. This study provides a cleaner approach for waste LCDs recycling and gives implications for the potential application of electrochemical technique in e-waste recycling.

2.
Environ Sci Technol ; 55(6): 4027-4036, 2021 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-33663209

RESUMO

Every year, billions of tons of lignite are burnt to generate electricity, meanwhile generating large amounts of coal fly ash (CFA) that is regarded as an industrial waste. During lignite combustion, arsenic and scarce metals are simultaneously volatilized in the form of oxide into CFA. This study proposed an effective vacuum distillation method to remove As and recover Ge and W from CFA. The feasibility of separating As and recycling Ge and W from CFA was verified by the theoretical analysis. The experimental result indicated that the removal ratio of As was 96 ± 1% and the contents of Ge and W reached 0.75 ± 0.023 and 0.24 ± 0.016 wt % in the residue, which were enriched 17.2 and 1.2 times, respectively, at a temperature of 550 °C, with 50 wt % sulfurizing agent added under pressure of 1 Pa and 240 min of heating. For the condensed product, chemical species As2S3 and As4S4 were detected by X-ray photoelectron spectroscopy analysis. For Ge and W in the residue, GeOx (x < 2), GeS, WOx (x < 3), and WS2 were the main chemical species. The potential mechanism involved in the release of arsenic from CFA, vacuum sulfurization, evaporation, and condensation was proposed. The kinetic analysis indicated that the apparent activation energy (Eα) was 31.24 kJ mol-1. Those results encourage further exploration of vacuum separation technology to environmentally friendly recycle CFA.

3.
Waste Manag ; 124: 94-101, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33611158

RESUMO

How to realize the high value-added utilization of scrap copper from e-waste is a meaningful topic. In the study, an Ohno Continuous Casting (OCC) process is an existing method you applied to purify the copper. Based onthe model of diffusion-controlled grain growth kinetics, the redistribution of impurity of tin in the scrap copper were studied under the different continuous casting speed and mold temperature. On the centerline, macrosegregation in the axial direction of the tin was more obvious with the decrease of continuous casting speed. The small continuous casting rate was beneficial to the segregation and enrichment of tin. The axial segregation gradually decreased with the increase of the mold temperature. The flattening of the liquid-solid interface resulted in a weakening of the solute enrichment at the root of the interface with the increase of temperature. Morphology, electron backscattered diffraction (EBSD) analysis showed the structure of single crystal copper. The range of resistance of single crystal copper was from 5 × 10-6 to 3 × 10-5 Ω m. Obviously, the resistance of the single crystal copper was significantly smaller than that of ordinary copper wire (9.0 × 10-3 Ω m). This study provided a key theoretical and practical basis for the high value-added reuse of copper in e-waste.


Assuntos
Cobre , Resíduo Eletrônico , Resíduo Eletrônico/análise , Reciclagem , Soluções , Temperatura
4.
J Hazard Mater ; 408: 124772, 2021 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-33388630

RESUMO

Electronic waste, as hazardous waste, contains a large amount of metals, which is of great recovery value. However, they are difficult to separate due to wide variety and complex distribution. Most of current recycling methods are environmentally-unfriendly or complicated. In this study, a simple, efficient and green approach for metals separation from Ni-Cu-Ag-Pd-Bi-Sn multi-metal system of e-waste was proposed combining mild leaching and stepwise potential-controlled electrodeposition. The leaching efficiencies of Ni, Ag, Pd, Cu and Bi were 99.16%, 99.09%, 94.91%, 99.61% and 23.76% with 1 mol/L HNO3 at 80 °C. The leaching process was analyzed. It showed that the existence of Ag-Pd continuous solid solution in the alloy lowered the oxidation potential of Pd, which facilitated its leaching. Sn precipitated as SnO2. Then Ag-Pd alloy and Cu-Bi alloy were separately extracted from the leaching solution by stepwise electrodeposition. 97.72% of Ag and 98.05% of Pd were recycled after 5 h with potential of 0.35 V. The recovery efficiencies of Cu and Bi were 97.87% and 97.33% after 7 h with potential of 0.05 V. The EDS results showed high purity property of Ag-Pd and Cu-Bi alloy. This process can achieve cleaner and efficient extraction of metals from multi-metal system in e-waste.

5.
Environ Sci Technol ; 55(2): 1279-1289, 2021 01 19.
Artigo em Inglês | MEDLINE | ID: mdl-33390010

RESUMO

The increasingly large stream of e-waste is seriously threatening the environment; meanwhile, global energy shortage is on the rise. Based on the principles of energy regeneration and waste utilization, we introduced a win-win approach to utilize waste capacitors for construction of magnetic and core-shell Z-scheme Nb-Pb-codoped BaTiO3/Ni-Pd@graphite-like carbon nitride (g-C3N4) photocatalysts for H2 evolution. Using simple ball-milling, waste capacitors were transformed to Nb-Pb-codoped BaTiO3/Ni-Pd-Ag-Sn nanoparticles and g-C3N4 was coated on the nanoparticles, forming a core-shell structure. The Ni-Pd acted as the electron mediator in the Z-scheme, and Ag-Sn also facilitated the electron transfer. Moreover, Ni made the Z-scheme magnetically separable. The Z-scheme showed a remarkably enhanced photocatalytic H2 evolution rate, which was 22.2 times higher than that of g-C3N4. Such an enhanced photocatalytic performance was attributed to the special Z-scheme and core-shell structure, improving the light adsorption, increasing the Brunauer-Emmett-Teller (BET) surface area, facilitating the efficient separation of electron-hole pairs, and maintaining the strong redox ability of charge carriers. Furthermore, the photoluminescence analysis combined with density functional theory (DFT) calculations provided the basis for the Z-scheme mechanism. This study adequately utilized the composition of e-waste to construct a highly efficient and magnetically separable Z-scheme for H2 generation, which realizes energy regeneration, waste recycling, and environmental protection.


Assuntos
Resíduo Eletrônico , Catálise , Luz , Fenômenos Físicos
6.
Environ Pollut ; 271: 116312, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-33360583

RESUMO

Antibiotics are commonly used in livestock and poultry breeding along with organic arsenic. Through long-term accumulation, they can enter into the surrounding soil through various pathways and contaminate the soil. In this paper, tetracycline antibiotics (TCs) and roxarsone (ROX) contaminated soil were used as the representatives of the two kinds of veterinary drugs contaminated soil, respectively, to study the thermal desorption behavior and arsenic stabilization process. Different parameters like heating temperatures, heat duration, stabilizer type and dosage were optimized for effective removal of TCs and ROX. Furthermore, TCs and ROX removal path and ROX stabilization mechanism were explored. Results of the study showed that over 98% of tetracycline antibiotics and roxarsone were effectively removed at 300 °C for 60 min. The heat treatment process of TCs contaminated soil was controlled by the first-order kinetics. Based on the detection of degradation products and thermogravimetric analysis, the possible thermal degradation path of TCs and ROX was proposed. Addition of FeSO4.7H2O (10% by weight) as stabilizer during the heat treatment process yielded 96.7% stabilization rate. Through the analysis of arsenic fractions, valence and the characterization of soil samples collected after the heat treatment, mechanism of arsenic stabilization in ROX was explored. The results show that thermal treatment combined with chemical stabilization technology can not only degrade TCs and ROX efficiently and completely, but also convert organic arsenic into inorganic state, which is conducive to better stabilization, and finally achieve effective and safe remediation of this kind of contaminated soil.


Assuntos
Arsênico , Roxarsona , Poluentes do Solo , Animais , Antibacterianos , Esterco , Solo , Poluentes do Solo/análise , Tetraciclinas
7.
J Hazard Mater ; 402: 123667, 2021 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-33254748

RESUMO

The emission characteristics of respirable particulate matter (PM10), and polybrominated diphenyl ether (PBDE) size distribution, gas-particle partitioning and occupational exposure in two e-waste recycling workshops (manual and thermal dismantling workshop: ManuDW and TherDW) were investigated. The PM10 mass concentration was higher but the number concentration was lower in the ManuDW than in the TherDW. The gaseous phase PBDE concentration (40.5 ng/m3) was higher in the ManuDW than in the TherDW (10.6 ng/m3) while the particulate phase PBDE concentration was just reverse (57.7 vs 156 ng/m3). The size distribution of particle was similar for two workshops but the size distribution of particle-bound PBDE exhibited remarkable differences. BDE-209 was the dominant congener in particle-bound PBDE in the TherDW, while Tri-, Tetra-, and Deca-BDE were the three most abundant homologues in the ManuDW. The size distribution of particle-bound PBDE homologue profile in the ManuDW was also distinct from that in the TherDW. The PBDE exposure doses were 13.9 and 15.3 ng/kg/day in the ManuDW and the TherDW, far lower than reference doses. Gaseous and particle phase have same contribution to the total doses in the ManuDW but the exposure doses in the TherDW mainly come from the particle phase.

8.
J Hazard Mater ; 402: 123684, 2021 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-33254750

RESUMO

In order to ensure the performance and safety of electronic products, a large number of polymeric insulation resins are used as housing materials. When electronic products are discarded as e-waste, these resins containing organobromine compounds and antimony trioxide as flame retardants are difficult to be disposed of by traditional recycling methods, due to their excellent resistance to acid, alkali, high temperature and photooxidation. It not only brings the hazardous risks for environmental protection, but also hinders the recovery of resources in e-waste. In this study, supercritical water oxidation(SCWO) process was applied to decompose waste high-impact polystyrene(HIPS) resin in e-waste combining debromination of decabromodiphenyl ethane and recovery of antimony trioxide. The results showed that HIPS could be quickly and efficiently decomposed during SCWO process. The optimum SCWO parameters were temperature of 500 ℃, holding time of 60 min, pressure of 23 MPa, and excess oxygen of 200 %, respectively. The decomposition products of HIPS were hydrocarbons, carbon dioxide and water. Meanwhile, brominated flame retardants and antimony trioxide added to the HIPS were also debrominated and recovered. Without secondary pollution, the SCWO process developed in this study could effectively achieve decomposition of HIPS resins, debromination of brominated flame retardants and recovery of antimony trioxide in one procedure.

9.
J Hazard Mater ; 403: 123465, 2021 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-32846256

RESUMO

Pyrolysis is a promising technology for recycling organic materials from waste printed circuit boards (WPCBs). Nevertheless, the generated organic bromides are toxic and urgently needed to be removed. The coexisting copper (Cu) of WPCBs has potential performance on debromination. However, the catalytic effect and mechanism of Cu on pyrolysis process and products were still unclear. To clarify the in-situ catalysis of Cu, the analysis on kinetics and pyrolysis products was performed. The results showed that Cu can change the mechanism function of pyrolysis, which reduced the apparent activation energy (Ea). The mechanism function of Cu-coated WPCBs was obtained by Sesták-Berggren model and expressed as: dαdt=1.65×107×1-α-1.30α6.09-ln1-α-6.03exp⁡-202.45KJ/molRT. Product analysis suggested that Cu promoted the conversion of organic bromides to Br2 and HBr. During the process of pyrolysis, bromide atoms interacted with Cu to form coordination compound, which can weaken the strength of C-Br bond and generate bromide free radical (Br*). Besides, Cu can promote the conversion of aromatic-Br to Br2 as the catalyst for Ullmann cross-coupling reaction. Therefore, the presence of Cu was beneficial to pyrolysis. This work provided the theoretical basis for the improvement and application of pyrolysis technology.

10.
J Hazard Mater ; 407: 124799, 2021 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-33348202

RESUMO

Recycling activity for waste electrical and electronic equipment is always accompanied with leaching solution containing copper. Its selective extraction is of environmental and economic significance, and is beneficial for subsequent resource purification procedure. Compared with techniques such as chemical precipitation and solvent extraction, potentiostatic electrodeposition is outstanding with the advantage of high selectivity, electron as clean reagent, and minimal chemical usage. However, key factors affecting copper electrodeposition behavior as well as its kinetic process remain unclear, which blocks its further application. In this study, selective copper electrochemical extraction from multi-metal leaching solution of waste liquid crystal display panels is explored. Copper electrodeposition is analyzed from electrochemical and mass transport point of view, and the main results are summarized: (i) copper can be first electrodeposited due to its higher reduction potential compared with indium; (ii) applied potential and agitation are the most influential factors towards space-time yield and current efficiency; (iii) a semi-empirical kinetic model could quantitatively describe the influence of agitation and the time-current-concentration relationship. The model-predicted extraction rate agreed well with experimental data throughout electrodeposition; (iv) electrodeposition experiments show over 95% of copper can be selectively extracted as ultrafine copper powder (~150 nm) at 0.05 V (vs. SHE).

11.
J Hazard Mater ; 404(Pt B): 124056, 2021 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-33065501

RESUMO

Polycarbonate/acrylonitrile-butadiene-styrene blends (PC/ABS) has become one of the most common polymer insulation materials as packaging resin in electronics industry, due to its excellent mechanical, flame retardant and insulating properties. Once electronic products are eliminated and discarded, refractory PC/ABS will become a huge obstacle to e-waste recycling. Conventional solid waste treatment methods may lead to the release of toxic organobromine compounds and endocrine interferons, posing a threat to the environment and human health. In this study, supercritical water oxidation (SCWO) process was applied to decompose PC/ABS as e-waste packaging resin. The results showed that waste PC/ABS could be environmentally friendly and efficiently decomposed and debrominated during SCWO process. The decomposition mechanism could be proposed as depolymerization, generation of free radicals, conjugation of free radicals and carbonization. The debrominated products such as carbon materials, small molecular weight hydrocarbons, carbon dioxide and water were obtained and could be recycled as chemical feedstocks. The optimum SCWO parameters were temperature of 500 °C, holding time of 90 min, pressure of 23 MPa, and excess oxygen of 100%, respectively. The maximum weight loss rate and debromination rate of waste PC/ABS were 78.57% and 99.62%. Thus, the process developed in this study provided a green and sustainable approach for disposal of e-waste packaging resin.

12.
J Hazard Mater ; 407: 124704, 2020 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-33338813

RESUMO

Spent lithium-ion batteries (LIBs) recycling has attracted much attention because it is highly favorable to environment protection and sustainable development. Developing a cleaner method for metals extraction can greatly reduce risk of secondary pollution. Chlorinating technology has been proved as an efficient method for metals extraction instead of traditional hydrometallurgy. In this paper, cathode materials from spent LIBs could be rapidly converted into metal chlorides by NH4Cl roasting at 623 K for 20 min. The results indicated nearly 100% metal leaching rates were achieved. Further, in-depth study is performed to obtain the mechanism function of chlorinating conversion based on roasting and TGA experiments. The apparent activation energy as 73.40 kJ/mol was firstly obtained, and then the reaction model of chlorination reaction was determined by model fitting and verifying. Herein, sub-reactions of chlorination reaction were figured out and their contributions were used to determinate reaction controlling mechanisms of chlorination reaction. The results indicated that nucleation reaction played a leading role in the initial stage (0.05 <α < 0.43) while phase boundary reaction took the control in next stage (0.43 <α < 0.95), which gave a good explanation to activation energy change. Finally, our findings provided inspirations for studying the controlling mechanism of gas-solid reaction.

13.
J Hazard Mater ; : 124611, 2020 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-33246811

RESUMO

Ball-milling technology is adopted for the debromination of nonmetallic particles of waste printed circuit boards. During the ball-milling process, too short ball-milling time causes insufficient debromination. Excessive ball-milling leads to the waste of resources and the destruction of the main structure of nonmetallic particles resin, unfavorable for the secondary utilization. However, how to determine debromination time of nonmetallic particles in ball-milling process has not been detailed studied. In this study, the ball-milling energy was coupled with the degradation energy of pentabromodiphenyl ether molecule to compute the time for each chemical bond to break. The ball-milling model was used to accurately compute effective mechanical ball-milling energy (1.234 × 10-3 J) generated by a single collision. The average bond energies of C‒O bond, C‒Br bond and C‒H bond (261.24, 302.05 and 489.50 kJ/mol) were analyzed by density functional theory. Under the conditions of 220 r/min and 1.2 g nonmetallic particles and NZVI (4:1). The C‒O bond, C‒Br bond, and C‒H bond fractured completely in turn at 2.25 h, 7.23 h (optimal debromination time), and 11.72 h. Based on the analysis of debromination pathways, it inferred that H2O, HBr, CH3Br, CH4, FeBr2, and graphite were generated. This paper develops a novel idea of the schedule of debromination time of nonmetallic particles, contributing to the directional removal of organic pollutants by ball-milling.

14.
J Hazard Mater ; : 124409, 2020 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-33168315

RESUMO

From environmental security and resource recovery viewpoint, hydrothermal technology was adopted to recycle Ag, As, and Ga from waste LEDs in present study. Waste LEDs packaging materials (Polyphthalamide (PPA), epoxy resin, and brominated flame retardant (BFR)), which are difficult to degrade under normal conditions, can be effectively decomposed through two steps of hydrothermal treatment. As and Ga were leached and silver was successfully recovered. Under the optimal process parameters (300 â„ƒ, 300r/min, 3% volume ratio of H2O2,400 min), the leaching rates of As and Ga are 98.4% and 80.5%, respectively. Ag and sapphire substrate were left and obtained together. Ag remains in the form of original metal, and almost no Ag ion was detected in the hydrothermal solution. In addition, As species in aqueous systems were simulated and inferred. The simulation results showed that As compounds that exist in the leaching solution is in liquid form and mainly exist as H2AsO4-. Under optimum processing conditions, almost 100% epoxy resin was decomposed. The degradation mechanism may be illuminated through the free radical reaction, and the possible decomposition pathways were speculated. The study proposed a process to recycle Ag, As, and Ga from scrapped LEDs and information could be useful for recycling other e-wastes.

15.
Curr Opin Immunol ; 67: 75-86, 2020 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-33176228

RESUMO

B cell differentiation driven by microbial antigens leads to production of anti-microbial antibodies, such as those neutralizing viruses, bacteria or bacterial toxin, that are class-switched (IgG and IgA) and somatically hypermutated (maturation of the antibody response) as well as secreted in large volume by plasma cells. Similar features characterize pathogenic antibodies to self-antigens in autoimmunity, reflecting the critical role of class switch DNA recombination (CSR), somatic hypermutation (SHM) and plasma cell differentiation in the generation of antibodies to not only foreign antigens but also self-antigens (autoantibodies). Central to CSR/SHM and plasma cell differentiation are AID, a potent DNA cytidine deaminase encoded by Aicda, and Blimp-1, a transcription factor encoded by Prdm1. B cell-intrinsic expression of Aicda and Prdm1 is regulated by epigenetic elements and processes, including DNA methylation, histone post-translational modifications and non-coding RNAs, particularly miRNAs. Here, we will discuss: B cell-intrinsic epigenetic processes that regulate antibody and autoantibody responses; how epigenetic dysregulation alters CSR/SHM and plasma cell differentiation, thereby leading to autoantibody responses, as in systemic lupus; and, how these can be modulated by nutrients, metabolites, and hormones through changes in B cell-intrinsic epigenetic mechanisms, which can provide therapeutic targets in autoimmunity.

16.
Cell Signal ; 74: 109709, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32659265

RESUMO

MYCT1 has an inhibitory effect on the migration of laryngeal cancer cells, although the underlying molecular mechanism remains unknown. In this study, we aimed to explore the mechanism of MYCT1 in the epithelial-mesenchymal transition (EMT) and migration of laryngeal cancer cells. We found that MYCT1 significantly decreased the expression of miR-629-3p but increased the expression of ESRP2 in laryngeal cancer cells. The expression of miR-629-3p and ESRP2 in laryngeal cancer tissues showed significantly positive and negative correlations with patient metastasis, respectively. miR-629-3p was confirmed to repress the expression of ESRP2 by targeting its 3'UTR. SP1 was verified to be a direct transcription factor for miR-629-3p and a downstream target of MYCT1. Moreover, MYCT1 inhibited the EMT and migration of laryngeal cancer cells through the SP1/miR-629-3p/ESRP2 pathway. Taken together, our results establish a novel MYCT1 signaling pathway in the EMT and migration of laryngeal cancer cells, thus providing important insights for further studying the pathway in the diagnosis and treatment of laryngeal cancer.

17.
Environ Sci Pollut Res Int ; 27(24): 30342-30351, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32451903

RESUMO

Polybrominated diphenyl ethers (PBDEs) are released from the recycling process of PBDE-containing waste printed circuit board (WPCB), but studies on the mechanism of PBDE emission and migration are limited. In this study, PBDE concentrations in particulate matter (PM), dust, and fumes collected in a pilot-scale workshop for the WPCB de-soldering process were measured, and PBDE emission after gas treatment was estimated. The results showed that the mean concentrations of ∑8PBDEs in TSP and PM2.5 in the workshop were 20.3 ng/m3 (24.7 µg/g) and 16.1 ng/m3 (115 µg/g), respectively. In practice, the fumes containing gaseous and particulate PBDEs were treated by the combination of alkaline solution absorption and activated carbon adsorption. Compared to PBDE concentration in workshop floor dust (2680 ng/g), PBDE concentrations in solution scum (68,000 ng/g) and hood inside dust (20,200 ng/g) were condensed. The concentrations of ∑6PBDEs at the stack outlet (416 pg/m3) after gas treatment were lower than those in the stack pipe (1310 pg/m3) and hood inside (7440 pg/m3). The PBDEs in fumes were removed through physical adsorption of alkaline solution and activated carbon, and solution scum constituted the main mass discharges of PBDEs. The emission factor of PBDEs at the stack outlet was 47.3 ng ∑6PBDEs/kg WPCB. As a result, the WPCB de-soldering process is an important source of PBDE pollution, and gas treatment of solution absorption and activated carbon adsorption can reduce PBDE emission to some extent.


Assuntos
Monitoramento Ambiental , Éteres Difenil Halogenados/análise , China , Poeira/análise , Material Particulado , Reciclagem
18.
Waste Manag ; 108: 172-182, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32360998

RESUMO

The coordinated treatment for two kinds of waste is an effective way to save energy and improve the recovery efficiency of resource. In worldwide, more than half of palladium is used to produce catalysts in automobile. However, with the increasing consumption of palladium, the scarcity of palladium resource is becoming prominent. This paper proposed an integrated process based on capture of copper scrap and electrodeposition process to recycle palladium in spent catalysis from automobile. The technological process mainly consisted of two procedures: capture of copper scrap with the purposes of enriching palladium and electrodeposition process with the purposes of separating and purifying palladium. Several highlights were summarized as follows: (i) a capture mechanism of palladium by copper scrap was studied by the calculation of surface thermodynamics and first principles. (ii) Optimum designs, parameter and product analysis were developed to guide industrial recycling. The appropriate parameters for capture of copper scrap are the melting temperature reached 1400 °C, adding 20% dosage of copper scrap and 2 of mass ratio of SiO2/Al2O3 and for the electrodeposition process, nearly 100% of palladium was deposited on the cathode under 0.1 M concentration of HNO3, -0.042 V of electrodeposition potential and 25 °C reaction temperature with 9 h. (iii) This process overcame the shortages of traditional process and showed its efficiency and environmental performance. This study is significant for high-efficient, low-cost and environment-friendly recycling of valuable resource in spent catalysis from automobile.


Assuntos
Cobre , Paládio , Automóveis , Catálise , Galvanoplastia , Reciclagem , Dióxido de Silício
20.
Front Immunol ; 11: 491, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32265934

RESUMO

Estrogen contributes to females' strong antibody response to microbial vaccines and proneness to autoimmunity, particularly antibody-mediated systemic autoimmunity, in females. We have hypothesized that this is due to estrogen-mediated potentiation of class switch DNA recombination (CSR) and somatic hypermutation (SHM). As we have shown, estrogen boosts AID expression, which is critical for both CSR and SHM, through upregulation of HoxC4, which together with NF-κB critically mediates Aicda (AID gene) promoter activation. We contend here that additional regulation of Aicda expression by estrogen occurs through epigenetic mechanisms. As we have shown, histone deacetylase inhibitors (HDIs) short-chain fatty acid (SCFA) butyrate and propionate as well as the pharmacologic HDI valproic acid upregulate miRNAs that silence AID expression, thereby modulating specific antibody responses in C57BL/6 mice and autoantibody responses in lupus-prone MRL/Fas lpr/lpr mice. Here, using constitutive knockout Esr1 -/- mice and B cells as well as conditional knockout Aicda cre/cre Esr1 flox/flox mice and B cells, we showed that the HDI-mediated downregulation of Aicda expression as well as the maturation of antibody and autoantibody responses is reversed by estrogen and enhanced by deletion of ERα or E2 inhibition. Estrogen's reversion of HDI-mediated inhibition of Aicda and CSR in antibody and autoantibody responses occurred through downregulation of B cell miR-26a, which, as we showed, targets Aicda mRNA 3'UTR. miR-26a was significantly upregulated by HDIs. Accordingly, enforced expression of miR-26a reduced Aicda expression and CSR, while miR-26a-sponges (competitive inhibitors of miR-26a) increased Aicda expression and CSR. Thus, our findings show that estrogen reverses the HDI-mediated downregulation of AID expression and CSR through selective modulation of miR-26a. They also provide mechanistic insights into the immunomodulatory activity of this hormone and a proof-of-principle for using combined ER inhibitor-HDI as a potential therapeutic approach.

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