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1.
PLoS One ; 19(5): e0301984, 2024.
Article En | MEDLINE | ID: mdl-38771833

BACKGROUND: The prevalence of burnout among live streamers remains largely unknown. This study aims to investigate the prevalence and factors associated with burnout among Chinese live streamers. METHODS: A cross-sectional study recruited 343 full-time live streamers from 3 companies in Changsha city. Socio-demographic and occupational characteristics were collected using self-designed items. Job stress was assessed using the Job Content Questionnaire (JCQ-22), while supervisor and coworker support were evaluated using the last 8 items of the JCQ-22. Burnout was assessed using the 17-item Chinese version of the Maslach Burnout Inventory-Human Services Survey (MBI-HSS). RESULTS: Our findings revealed that 30.6% of live streamers experienced burnout. Lower levels of education (OR = 2.65 and 3.37, p = 0,005 and 0.003), higher monthly income (OR = 10.56 and 11.25, both p = 0.003), being an entertainment-oriented streamer (OR = 2.13, p = 0.028), continuous walking during live streams (OR = 2.81, p = 0.006), significant drop in follower count (OR = 2.65, P = 0.006), live streaming during the daytime (OR = 3.75, p = 0.001), and higher support from supervisors and coworkers (OR = 3.66, p = 0.001) were positively associated with burnout. However, the effects of education and drop in followers on burnout were not significant in the multivariate logistic models (p = 0.321 and 0.988). CONCLUSIONS: Burnout among Chinese live streamers is associated with income, being an entertainment streamer, engaging in continuous walking during live streams, conducting live streams during the daytime, and experiencing excessive support from supervisors and coworkers.


Burnout, Professional , Humans , Female , Male , Adult , China/epidemiology , Cross-Sectional Studies , Prevalence , Burnout, Professional/epidemiology , Burnout, Professional/psychology , Middle Aged , Surveys and Questionnaires
2.
Environ Technol ; 44(11): 1613-1625, 2023 Apr.
Article En | MEDLINE | ID: mdl-34792432

Hypersaline wastewater is a typical industrial wastewater produced by iron and steel metallurgy, food material processing and other industries. Aiming at a waste liquid produced by mechanical vapour recompression evaporation and concentration in Tianjin coastal industrial zone, an environment-friendly supercritical water oxidation technology was used to efficiently remove the high-content organic matter in the hypersaline wastewater concentrate (HWC). A comparison of the degradation effects of various oxidants in the supercritical state showed that hydrogen peroxide (H2O2) could be used as a suitable agent for processing the HWC. The reaction parameters were systematically optimised by single-factor experiment and response surface design. The degradation mechanism and reaction characteristics were analyzed using gas chromatography mass spectrometry. Solid residues were characterised by field emission scanning electron microscope. The results indicated that when the dosage of hydrogen peroxide was 6.39%, the reaction temperature was 380°C, the reaction time was about 90 min and the optimal total organic carbon removal rate was 96.22%. Furthermore, it was found that hydroxyl radicals produced by hydrogen peroxide initiated the bond breaking and ring-opening reactions in organic matter, which eventually degraded organic matter into water and carbon dioxide.


Wastewater , Water Pollutants, Chemical , Waste Disposal, Fluid/methods , Hydrogen Peroxide/chemistry , Organic Chemicals , Oxidation-Reduction , Water , Water Pollutants, Chemical/chemistry
3.
Environ Res ; 216(Pt 4): 114777, 2023 01 01.
Article En | MEDLINE | ID: mdl-36370818

Facile fabrication of porous carbon materials from waste halogenated plastic is highly attractive but frequently hampered due to potential release of halogenated organic pollutants. In this study, a novel type of carbon hybrid was tentatively synthesized from a real-world halogenated plastic as an inexpensive carbon source by sub/supercritical carbon dioxide carbonization technique. It was found that halogen-free carbon carrier was advantageously synthesized through carbonization of halogenated plastic without using catalysts due to zip depolymerization, random chain cracking and free radical reactions induced by sub/supercritical carbon dioxide technique. Exhibiting with more abundant functional groups including C-O, CO groups than pyrolytic carbon carrier, the derived carbon carrier demonstrated excellent performance in selective recovery of lithium from cathode powder with highest recovery efficiency of 93.6%. Mechanism study indicated that cathode powder was transformed into low-valence states of transition metals/metal oxides and released lithium as lithium carbonate due to collapse of oxygen framework via carbothermic reduction. This work provides an applicable and green process for synthesis of alternative carbon carrier from waste halogenated plastic and its application as carbothermic reductant in lithium recovery.


Carbon Dioxide , Lithium , Electric Power Supplies , Recycling , Plastics , Powders
4.
Waste Manag ; 153: 13-19, 2022 Nov.
Article En | MEDLINE | ID: mdl-36029533

The present study reports a sequential, non-acid process for effective recovery of copper and precious metals from mobile phone printed circuit boards. In this process, gold and silver were first enriched during the synthesis process of cuprous chloride and then leached by thiosulfate method. Results indicated that the distribution of gold and silver in the liquid and solid phases during the synthesis of cuprous chloride process was affected by the [Cu]/[Cu2+] ratio. Enrichment of gold and silver in the residue after the cuprous chloride synthesis could be achieved by the adjusting the [Cu]/[Cu2+] ratio. The silver and gold leaching rates of the residue after cuprous chloride synthesis (93.8 % silver and 99 % gold) were much higher than those of the raw PCB sample (27.0 % silver and 14.2 % gold) under the same conditions. This process has the advantages of high leaching efficiency, high leaching rate and avoiding the use of HNO3 or aqua regia commonly used for copper, gold and silver recovery. Thus, this study offers a promising and environmentally friendly method for recovering valuable metals from e-waste.


Cell Phone , Electronic Waste , Copper/chemistry , Electronic Waste/analysis , Gold/chemistry , Recycling/methods , Silver/chemistry , Thiosulfates/chemistry
5.
J Hazard Mater ; 432: 128746, 2022 06 15.
Article En | MEDLINE | ID: mdl-35339831

Upcycling of waste plastics as functional materials is a new approach for synthesizing low-cost and durable adsorbents with zwitterionic property. Herein, a facile process for recycling blending waste plastics to fabricate zwitterionic plastic-g-hydrogel (ZPH) for simultaneous adsorbing cationic and anionic heavy metals was developed. ZPH possessed high affinities for cations and anions in both acid and alkaline conditions owing to its zwitterionic property, and the maximum adsorption capacities of Pb2+, Cd2+, Ba2+, and Cr(VI) (Cr2O72-) were 132.13, 85.58, 69.92 and 85.15 mg/g, respectively. Mechanism study indicated the incompatibility of blending plastics was skillfully overcome through the crosslinking between sodium alginate (SA)/chitosan (CTS) and plastics. Cations were adsorbed onto ZPH via electrostatic interaction, cation exchange and coordination interactions with Cl/N/O-containing groups. Furthermore, the reduction of Cr(VI) to Cr(III) was another important path for ZPH to capture anionic Cr2O72-, and subsequently Cr(III) was adsorbed via coordination interaction and cation exchange. Moreover, the regeneration experiment showed ZPH possessed excellent reusability and stable structure. Accordingly, this research provides a profitable approach for recycling blending plastics, and ZPH has potentials for industrial application in wastewater treatment or contaminated site remediation with complex heavy metals pollution.


Metals, Heavy , Water Pollutants, Chemical , Adsorption , Anions , Cations/chemistry , Hydrogels/chemistry , Metals, Heavy/chemistry , Plastics , Water Pollutants, Chemical/chemistry
6.
Neurosci Lett ; 759: 136050, 2021 08 10.
Article En | MEDLINE | ID: mdl-34126179

Atractylenolide III, a major component of the atractylodes macrocephala Koidz, derived from the rhizoma atractylodes, has been reported to produce various pharmacological effects including anti-aging, anti-inflammation, anti-tumor, and other effects. Growing evidence suggests that proinflammatory cytokines, such as interleukin (IL)-1, IL-6 and tumor necrosis factor (TNF)-α, are increased in depressed patients. The present study was aimed at investigating the antidepressant- and anxiolytic-like effects of atractylenolide III in lipopolysaccharide (LPS) challenge and chronic unpredictable mild stress (CUMS) rat model. We found that 30 mg/kg of atractylenolide III administered by oral gavage for 14 days, significantly reduced the immobility time in a forced swimming test (FST), but did not alter the number of crossings in an open field test (OFT), respectively. The results indicated that atractylenolide III has an antidepressant-like effect without affecting locomotor activity. We then used the LPS-induced depression model to assess the effects of atractylenolide III on behaviors in FST, sucrose preference test (SPT), and novelty-suppressed feeding test (NSFT). Interestingly, in addition to the antidepressant-like effects, 30 mg/kg of atractylenolide III also produced an anxiolytic-like effect. To further identify the antidepressant- and anxiolytic-like effects of atractylenolide III, we used the CUMS model with 28 consecutive days of the atractylenolide III treatment, followed by the SPT, FST, and NSFT. Atractylenolide III prevented CUMS-induced depressive- and anxiety-like behaviors in rats. To illustrate the underlying possible mechanisms of action of atractylenolide III, we measured the proinflammatory cytokines levels. The results showed that atractylenolide III decreased the proinflammatory cytokines levels in the hippocampus of CUMS exposed rats. In summary, our findings demonstrated that atractylenolide III produces antidepressant- and anxiolytic-like effects in rats, and these effects appear to be mediated by inhibition of hippocampal neuronal inflammation.


Anti-Anxiety Agents/pharmacology , Antidepressive Agents/pharmacology , Anxiety , Depression , Lactones/pharmacology , Sesquiterpenes/pharmacology , Animals , Anxiety/etiology , Behavior, Animal/drug effects , Cytokines/drug effects , Depression/etiology , Disease Models, Animal , Hippocampus/drug effects , Male , Rats , Rats, Sprague-Dawley , Stress, Psychological/complications
7.
Front Pharmacol ; 12: 652865, 2021.
Article En | MEDLINE | ID: mdl-33897438

Drug addiction is considered maladaptive learning, and drug-related memories aroused by the presence of drug related stimuli (drug context or drug-associated cues) promote recurring craving and reinstatement of drug seeking. The mammalian target of rapamycin signaling pathway is involved in reconsolidation of drug memories in conditioned place preference and alcohol self-administration (SA) paradigms. Here, we explored the effect of mTOR inhibition on reconsolidation of addiction memory using cocaine self-administration paradigm. Rats received intravenous cocaine self-administration training for 10 consecutive days, during which a light/tone conditioned stimulus was paired with each cocaine infusion. After acquisition of the stable cocaine self-administration behaviors, rats were subjected to nosepoke extinction (11 days) to extinguish their behaviors, and then received a 15 min retrieval trial with or without the cocaine-paired tone/light cue delivery or without. Immediately or 6 h after the retrieval trial, rapamycin (10 mg/kg) was administered intraperitoneally. Finally, cue-induced reinstatement, cocaine-priming-induced reinstatement and spontaneous recovery of cocaine-seeking behaviors were assessed in rapamycin previously treated animals, respectively. We found that rapamycin treatment immediately after a retrieval trial decreased subsequent reinstatement of cocaine seeking induced by cues or cocaine itself, and these effects lasted at least for 28 days. In contrast, delayed intraperitoneal injection of rapamycin 6 h after retrieval or rapamycin injection without retrieval had no effects on cocaine-seeking behaviors. These findings indicated that mTOR inhibition within the reconsolidation time-window impairs the reconsolidation of cocaine associated memory, reduces cocaine-seeking behavior and prevents relapse, and these effects are retrieval-dependent and temporal-specific.

8.
Waste Manag ; 124: 283-292, 2021 Apr 01.
Article En | MEDLINE | ID: mdl-33640668

Recycling of spent Li-ion batteries is crucial for achieving sustainable development of battery industry. Current recycling processes mainly focus on valuable metals but less attention has been paid to spent graphite, which generally ends up as secondary waste. In this study, a process for preparing graphene and recovering Li in anode as a by-product from spent graphite was developed. The key point was to re-charge the spent LIBs to generate lithium graphite intercalation compounds. The lithium graphite intercalation compounds were then subjected to a hydrolysis procedure and graphene could be produced through ultrasonic treatment via the expansion/micro-explosion mechanism. Experimental results demonstrated that 1-4 layered graphene could be efficiently produced when spent Li-ion batteries with beyond 50% capacity were re-charged. The prepared graphene showed high quantity containing few defects (ID/IG = 0.33, C/O = 13.2 by energy dispersive spectroscopy and C/O = 8.8 by X-ray photoelectron spectroscopy). In addition, Li was simultaneously recovered in the form of battery-grade lithium carbonate in the above process. Economic analysis indicated that the graphene production cost was extremely low ($540/ton) compared to that of commercial graphene.


Graphite , Lithium , Electric Power Supplies , Electrodes , Recycling
9.
J Hazard Mater ; 395: 122614, 2020 Aug 05.
Article En | MEDLINE | ID: mdl-32302882

Recovery of high-content and valuable elements including phosphorus (P) is critical for recycling of spent LiFePO4 battery, but P recovery is challengeable due to the poor solubility of lithium phosphate and iron phosphate. This study compared two strategies to recover P by adopting sulfide salt to induce P dissolution, i.e., recovery of P directly from LiFePO4, and step-by-step recovery of Li then P. The results revealed that the second strategy was more efficient because of the higher recovering efficiency and selectivity. Accordingly, an acid-free process to recover P was successfully demonstrated. Li-recovery efficiency of 97.5 % was reached at a leaching time of 65 min, and nearly 100 % P-recovery efficiency was reached at 5 h. Mechanism analysis revealed that the transforming of delithiated LiFePO4 crystal to NaFeS2 was mainly responsible for P dissolution. Thermodynamic analysis and density functional theory calculation further proved the transformation reaction, and a stepwise-transformation mechanism was proposed. In addition, P was reclaimed in the form of soluble phosphate salts. The process is especially appealing due to its environmental and economic benefits for recycling spent LiFePO4 batteries.

10.
J Hazard Mater ; 382: 121140, 2020 01 15.
Article En | MEDLINE | ID: mdl-31518770

Electronic display housing plastics contain a high amount of halogenated compounds such as brominated flame retardants (BFRs) and polyvinyl chloride (PVC). Compared with moderate critical conditions of conventional eco-friendly sub/supercritical carbon dioxide (Sc-CO2), a novel and sustainable procedure by using improved Sc-CO2 was developed for disposal of this type of plastic. The main merit of the process was that complex halogen-containing plastics were safely disposed and halogen-free products were recycled without using catalysts or additives. It was discovered that additive BFRs were initially extracted by Sc-CO2 technique and then it decomposed accompanied with PVC rapidly to form HBr and HCl, which could be separated by traditional bromine stripping techniques from seawater. Based on response surface methodology (RSM), the maximum debromination and dechlorination efficiencies were achieved at 99.51% and 99.12% respectively. After the treatment, halogen-free products such as solid carbon materials and organic chemical feedstocks were obtained. Mechanism study elucidated that free radicals reaction involving chain initiation, growth and termination induced the polymer decomposition to form these products. This study provides an applicable and green approach for disposal and recovery of halogen-containing plastics.

11.
J Hazard Mater ; 386: 121633, 2020 03 15.
Article En | MEDLINE | ID: mdl-31740301

Impurity Fe could severely damage the performance of resynthesized cathode material, and therefore, LiFePO4 cathode should be removed from the mixed spent LIBs for materials recycling. In this research, a non-hydrometallurgy method has been developed to separate LiFePO4 by selectively peeling-off the LiFePO4 cathode material and the peeling-off process was well explained by theoretical modeling. The peeling-off efficiency of LiFePO4 was approximate 100 % and that of LiMn2O4/LiCoO2/Li(Ni, Co, Al)O2/Li(Ni, Mn, Co)O2 was only 0.08 %. That is, the separating selectivity was 1250. Mechanism study revealed that the peeling-off was achieved through selective destruction of the LiFePO4 crystal and the matrix of polyvinylidene fluoride (PVDF) binder. Particularly, the crystal structure of LiFePO4 was firstly destructed by sulfide, thus LiFePO4 particles were detached from the matrix of PVDF binder. Then, the PVDF binder without LiFePO4 particles filling were more susceptible to be brittlely peeled off by the micro-explosion force of hydrogen from the reaction of Al foil with water due to the weakened mechanical strength. The process is suitable for recycling varied types of spent LIBs, having a strong potential for industrial application.

12.
J Hazard Mater ; 375: 43-51, 2019 Aug 05.
Article En | MEDLINE | ID: mdl-31039463

Recycling of spent lithium-ion batteries (LIBs) has aroused extensive attentions with the expanding demand of electric vehicles. Two considerable challenges of LIBs recycling were separating electrode materials from metallic foils and reclaiming hazardous electrolyte. In the current study, an environmentally benign process was developed to recovery electrode materials and hazardous electrolyte. The main merits were that no strong acid or alkali was applied in the process, and the electrode materials were reclaimed in flaky form. A special complex aqueous peeling agent, namely exfoliating and extracting solution (AEES) was manufactured and applied in the process. The results indicated that cathode material could be exfoliated from Al foil by weakening the mechanical interlocking force and Coulomb force between cathode materials and foils. Ethylene carbonate (EC) and propylene carbonate (PC) could be extracted from electrodes and separators and recovered via distillation. LiPF6 could be precipitated from EC and PC and recovered via filtration. The conditions could be precisely controlled by optimizing the concentration of AEES. The recovery efficiencies of electrolyte, Al foil, Cu foil and electrode materials were 95.6%, 99.0%, 100% and near 100%, respectively. The process efficiently avoided infiltration of impurities into the electrode materials and is environmentally friendly for industrial application.

13.
J Environ Manage ; 219: 332-339, 2018 Aug 01.
Article En | MEDLINE | ID: mdl-29753241

In the current study, the possibility of incorporating various industrial wastes into fireproofing materials was investigated. It was found that the newly developed materials showed excellent air sealing and fireproofing performance, with air permeability coefficients 3 to 4 orders of magnitude smaller than traditional fire prevention materials. The influence of different parameters on the air permeability was investigated, and the air sealing mechanisms were clarified through microstructure analysis. In addition, the workability and mechanical properties of the fireproofing materials for practical application in coal mine were studied. The new materials derived from industrial wastes had a compact and monolithic structure, and the excellent air tightness could be attributed to the pozzolanic activity of the industrial wastes and the film-forming property of organic polymers. Among the industrial wastes examined, a special coal fly ash with high pozzolanic activity and little free calcium oxide derived the best product with air permeability coefficient, tensile strength and breaking elongation of 4.17 × 10-8 m2/s, 2.14 MPa and 48.90%, respectively. This study provides an economical, environmentally friendly and promising approach for industrial wastes recycling.


Coal Ash , Industrial Waste , Recycling , Coal , Construction Materials
14.
Waste Manag ; 68: 490-497, 2017 Oct.
Article En | MEDLINE | ID: mdl-28743577

The present study reports a mechanochemical (MC) process for effective recovery of copper (Cu) and precious metals (i.e. Pd and Ag) from e-waste scraps. Results indicated that the mixture of K2S2O8 and NaCl (abbreviated as K2S2O8/NaCl hereafter) was the most effective co-milling reagents in terms of high recovery rate. After co-milling with K2S2O8/NaCl, soluble metallic compounds were produced and consequently benefit the subsequent leaching process. 99.9% of Cu and 95.5% of Pd in the e-waste particles could be recovered in 0.5mol/L diluted HCl in 15min. Ag was concentrated in the leaching residue as AgCl and then recovered in 1mol/L NH3 solution. XRD and XPS analysis indicated that elemental metals in the raw materials were transformed into their corresponding oxidation state during ball milling process at low temperature, implying that solid-solid phase reactions is the reaction mechanism. Based on the results and thermodynamic parameters of the probable reactions, possible reaction pathways during ball milling were proposed. Suggestion on category of e-waste for ball milling process was put forward according to the experiment results. The designed metal recovery process of this study has the advantages of highly recovery rate and quick leaching speed. Thus, this study offers a promising and environmentally friendly method for recovering valuable metals from e-waste.


Electronic Waste , Recycling , Copper , Environment , Metals
15.
Waste Manag ; 67: 232-239, 2017 Sep.
Article En | MEDLINE | ID: mdl-28502601

In the present study, cathode materials (C/LiCoO2) of spent lithium-ion batteries (LIBs) and waste polyvinyl chloride (PVC) were co-processed via an innovative mechanochemical method, i.e. LiCoO2/PVC/Fe was co-grinded followed by water-leaching. This procedure generated recoverable LiCl from Li by the dechlorination of PVC and also generated magnetic CoFe4O6 from Co. The effects of different additives (e.g. alkali metals, non-metal oxides, and zero-valent metals) on (i) the conversion rates of Li and Co and (ii) the dechlorination rate of PVC were investigated, and the reaction mechanisms were explored. It was found that the chlorine atoms in PVC were mechanochemically transformed into chloride ions that bound to the Li in LiCoO2 to form LiCl. This resulted in reorganization of the Co and Fe crystals to form the magnetic material CoFe4O6. This study provides a more environmentally-friendly, economical, and straightforward approach for the recycling of spent LIBs and waste PVC compared to traditional processes.


Electric Power Supplies , Lithium , Polyvinyl Chloride , Recycling , Metals
16.
Waste Manag ; 60: 643-651, 2017 Feb.
Article En | MEDLINE | ID: mdl-27876566

In this study, supercritical methanol (SCM) process was successfully used for the preparation of ultrafine copper materials from waste printed circuit boards (PCBs) after nitric acid pretreatment. Waste PCBs were pretreated twice in nitric acid. Sn and Pb were recovered by the first nitric acid pretreatment. The leach liquor with a high concentration of copper ions after the second nitric acid leaching was subjected to SCM process. The mixture of Cu and Cu2O with poor uniformity of particle size was formed due to the effect of ferric iron contained in the leach liquor of waste PCBs, while more uniform and spherical Cu particles with high monodispersity and smaller size could be prepared after the removal of Fe. The size of Cu particles increased obviously with the decline of SCM temperature, and particles became highly aggregated when the reaction temperature decreased to 300°C. The size of Cu particles decreased markedly with the decrease of initial concentration of copper ion in the leach liquor of waste PCBs. It is believed that the process developed in this study is simple and practical for the preparation of ultrafine copper materials from waste PCBs with the aim of recycling these waste resources as a high value-added product.


Copper/isolation & purification , Electronic Waste , Recycling/methods , Waste Products , Copper/chemistry , Iron/isolation & purification , Methanol/chemistry , Nanostructures/chemistry , Temperature
17.
J Hazard Mater ; 318: 216-223, 2016 Nov 15.
Article En | MEDLINE | ID: mdl-27427888

The current study was carried out to develop an environmental benign process for direct recovery of palladium (Pd) and silver (Ag) from waste printed circuit boards (PCBs) powder. The process ingeniously combined supercritical water oxidation (SCWO) and supercritical carbon dioxide (Sc-CO2) extraction techniques. SCWO treatment could effectively enrich Pd and Ag by degrading non-metallic component, and a precious metal concentrate (PMC) could be obtained, in which the enrichment factors of Pd and Ag reached 5.3 and 4.8, respectively. In the second stage, more than 93.7% Pd and 96.4% Ag could be extracted from PMC by Sc-CO2 modified with acetone and KI-I2 under optimum conditions. Mechanism study indicated that Pd and Ag extraction by Sc-CO2 was a complicated physiochemical process, involving oxidation, complexation, anion exchange, mass transfer and migration approaches. Accordingly, this study established a benign and effective process for selective recovery of dispersal precious metals from waste materials.

18.
Waste Manag ; 56: 423-30, 2016 Oct.
Article En | MEDLINE | ID: mdl-27287009

This work investigated various supercritical water oxidation (SCWO) systems, i.e. SCWO1 (only water), SCWO2 (water+H2O2) and SCWO3 (water+H2O2/NaOH), for waste printed circuit boards (PCBs) detoxification and recycling. Response surface methodology (RSM) was applied to optimize the operating conditions of the optimal SCWO3 systems. The optimal reaction conditions for debromination were found to be the NaOH of 0.21g, the H2O2 volume of 9.04mL, the time of 39.7min, maximum debromination efficiency of 95.14%. Variance analysis indicated that the factors influencing debromination efficiency was in the sequence of NaOH>H2O2>time. Mechanism studies indicated that the dissociated ions from NaOH in supercritical water promoted the debromination of brominated epoxy resins (BERs) through an elimination reaction and nucleophilic substitution. HO2, produced by H2O2 could induce the oxidation of phenol ring to open (intermediates of BERs), which were thoroughly degraded to form hydrocarbons, CO2, H2O and NaBr. In addition, the alkali-silica reaction between OH(-) and SiO2 induced the phase transformation of glass fibers, which were simultaneously converted into anorthite and albite. Waste PCBs in H2O2/NaOH improved SCWO system were fully degraded into useful products and simultaneously transformed into functional materials. These findings are helpful for efficient recycling of waste PCBs.


Electronic Waste/analysis , Epoxy Resins/chemistry , Glass/chemistry , Waste Management/methods , Water/chemistry , Halogenation , Hydrogen Peroxide/chemistry , Oxidation-Reduction , Sodium Hydroxide/chemistry
19.
J Hazard Mater ; 315: 102-9, 2016 09 05.
Article En | MEDLINE | ID: mdl-27179704

In this study, a novel reutilization method for waste printed circuit boards (PCBs) as flame retardant and smoke suppressant for poly (vinyl chloride) (PVC) was successfully testified. A supercritical water oxidation (SCWO) process was applied to treat waste PCBs before they could be used as flame retardants of PVC. The results indicated that SCWO conditions had a significant effect on the flame retarding and smoke suppressing properties of waste PCBs for PVC. Cu2O, CuO, and SnO2 were the main active ingredients in waste PCBs-derived flame retardants. A conversion of Cu elements (Cu(0)→Cu(+)→Cu(2+)) during SCWO process with the increase of reaction temperature was found to be the key influence factor for the flame retarding properties of SCWO-treated PCBs. The experiment results also showed that there was a synergistic effect of flame retardancy between Cu(+) and Cu(2+). After the optimized SCWO treatment, SCWO-treated PCBs significantly improved the flame retardancy and smoke suppression of PVC. Limiting oxygen index (LOI) and char yield (CY) increased with increasing SCWO-treated PCBs content in PVC, while smoke density rating (SDR) and maximum smoke density (MSD) decreased markedly. The mechanical properties of PVC samples were influenced in different degree by adding different content SCWO-treated PCBs.

20.
J Hazard Mater ; 316: 19-25, 2016 10 05.
Article En | MEDLINE | ID: mdl-27209515

In this work, an effective and environmentally friendly process for the recovery of cobalt (Co) and lithium (Li) from spent lithium-ion batteries (LIBs) and simultaneously detoxification of polyvinyl chloride (PVC) in subcritical water was developed. Lithium cobalt oxide (LiCoO2) power from spent LIBs and PVC were co-treated by subcritical water oxidation, in which PVC served as a hydrochloric acid source to promote metal leaching. The dechlorination of PVC and metal leaching was achieved simultaneously under subcritical water oxidation. More than 95% Co and nearly 98% Li were recovered under the optimum conditions: temperature 350°C, PVC/LiCoO2 ratio 3:1, time 30min, and a solid/liquid ratio 16:1 (g/L), respectively. Moreover, PVC was completely dechlorinated at temperatures above 350°C without any release of toxic chlorinated organic compounds. Assessment on economical and environmental impacts revealed that the PVC and LiCoO2 subcritical co-treatment process had significant technical, economic and environmental benefits over the traditional hydrometallurgy and pyrometallurgy processes. This innovative co-treatment process is efficient, environmentally friendly and adequate for Co and Li recovery from spent LIBs and simultaneous dechlorination of PVC in subcritical water.

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