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An increase in heavy metal soil contamination, especially lead, in the industrial area or near industrial areas has become a serious environmental problem. An industrial zone including paints, electrical plants, metal works, machining, and smelting factories, in the suburban of Ho Chi Minh City, was chosen as the study area. Soil samples were collected from the industrial area and in the residential area next to the industrial area for three experiments, namely, lead content in the surface soils, lead leachate into the water, and movement of lead in soil. Then, the results were compared to the values in the Soil Contamination Countermeasures Law of the Japan Ministry of Environment to assess the possibility of soil contamination which may cause health risks to a human living in that area. The results of the analysis show that the soil has been contaminated by lead. In particular, the lead concentrations of the surface soil samples are 23–35 mg kg-1, while the lead elution of soil samples is quite high, about 0.6 mg L-1. With these results, the soil can harm people by direct ingestion. More importantly, this work proves that lead species have been going down gradually. To assess the possibility of lead approaching groundwater, more further studies need to be achieved.

Landfills are substantial anthropogenic sources of greenhouse gases such as methane (CH4), carbon dioxide (CO2), and non-methane volatile organic compounds (NMVOCs). This study reports a simple and efficient method for determining the environmental loads of landfill gases (LFG) emitted from the Nam Binh Duong landfill, Vietnam, by applying the LandGEM and the IPCC first-order decay models (FOD model). The environmental LFGs loads were quantified based on both the relevant parameters of the generation potential (L0) of 81 m3/Mg and the generation rate (k) of 0.355 year−1 of methane (CH4) as well as the average measurement value of CH4 (57% by volume of the LFGs) obtained throughout the on-site measurements of the investigated landfill (Scenario 1). Then, the quantified emission results of the LFGs were compared to those of the Clean Air Act (CAA) default mode of the model (Scenario 2). During the period from 2004 to 2144, the projected landfill methane emissions add up to 116,377 t of CH4 with an average of 825 t of CH4/year. The paired t test conducted to compare the gas emissions obtained from both scenarios demonstrated that the on-site parameters significantly affect the yield of the LFGs. The estimated total LFG, methane, CO2, and NMVOCs recovery potential can serve as supporting data for policy making on obtaining renewable energy from landfills and minimizing the environmental issues caused by LFGs emissions.

Herein, Co3O4 was coated on N,S co-doped TiO2 to synthesize Co3O4/N,S–TiO2 nanocomposites applying for an advanced degradation of Direct Blue 71 (DB 71) under visible irradiation. N and S were used to incorporate into TiO2 matrix to decrease its energy band gap (Ebg) while Co3O4 was used to coat on N,S–TiO2 to further enhance its electron-hole separation efficiency. Therefore, these synthesized Co3O4/N,S–TiO2 exhibited novel photocatalytic ability efficiently degrading DB 71. The optimal Co3O4 coating ratio for maximum improving photocatalytic degradation ability of the N,S–TiO2 was 30 wt %. Above the optimal coating content, the excess Co3O4 would cover more N,S–TiO2 surface or prevent the contact of incident light to these particles resulting in decrease in the photocatalytic performance. The pH for zero point charge of the Co3O4/N,S–TiO2 was approximately 4.7 while the DB 71, which has negative charge sulfuric groups, favors to adsorb on positive surface. Thus, optimal pH for efficient decomposition of DB 71 by the Co3O4/N,S–TiO2 was 4. Finally, the study investigated that the sunlight was perfectively suitable source to excite for photocatalytic degradation of DB 71 by the synthesized Co3O4/N,S–TiO2.

In this study, sol–gel combining with hydrothermal methods were successfully used to synthesize N and S co-doped TiO2 nanotubes (N@S-TiO2 NTT) for efficient photocatalytic degradation of volatile organic compounds (VOCs). The obtained characterization results indicated that the synthesized N@S co-doped TiO2 existed as nanotubes. Specific surface areas of these synthesized nanotubes was greatly that of these nanoparticles. The largest surface area recorded at N@S-TiO2 nanotubes was 105.3 m3/g. FTIR spectrum results showed that the presence of N–H and S–O bond, which confirmed that nitrogen and sulfur were successfully doped into TiO2 lattice. We also investigated that N@S dopants significantly improved the photocatalytic activity of TiO2 nanotubes for efficient degradation of gaseous VOCs. Therefore, photocatalytic activity for VOCs degradation by the N@S-TiO2 nanotubes was greater than that by the undoped TiO2 nanotube. Optimized humidity for degradation of VOCs was medium condition (55–70%). Under dry conditions, lack of water for hydroxyl radical production led to decrease in photocatalytic activity. Under humidity conditions, the excess water molecules competed with VOCs for adsorbing on material surface leading to decrease in photocatalytic degradation efficiency. Under the optimized humidity, the highest photocatalytic efficiency of the synthesized N@S-TiO2 nanotubes for degradation of gaseous VOCs for 3 h was approximately 94%. The VOCs degradation capacity by the synthesized N@S-TiO2 nanotubes was approximately 90 (ppm/g h).

The coronavirus disease 2019 (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a global health concern. The development of vaccines with high immunogenicity and safety is crucial for controlling the global COVID-19 pandemic and preventing further illness and fatalities. Here, we report the development of a SARS-CoV-2 vaccine candidate, Nanocovax, based on recombinant protein production of the extracellular (soluble) portion of the spike (S) protein of SARS-CoV-2. The results showed that Nanocovax induced high levels of S protein-specific IgG and neutralizing antibodies in three animal models: BALB/c mouse, Syrian hamster, and a non-human primate (Macaca leonina). In addition, a viral challenge study using the hamster model showed that Nanocovax protected the upper respiratory tract from SARS-CoV-2 infection. Nanocovax did not induce any adverse effects in mice (Mus musculus var. albino) and rats (Rattus norvegicus). These preclinical results indicate that Nanocovax is safe and effective.

The Coronavirus disease-2019 (COVID-19) pandemic caused by the Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2), has become a dire global health concern. The development of vaccines with high immunogenicity and safety is crucial for control of the global COVID-19 pandemic and prevention of further illness and fatalities. Here, we report development of SARS-CoV-2 vaccine candidate, Nanocovax, based on recombinant protein production of the extracellular (soluble) portion of the S protein of SARS-CoV-2. The results showed that Nanocovax induced high levels of S protein-specific IgG, as well neutralizing antibody in three animal models including Balb/C mice, Syrian hamsters, and non-human primate (Macaca leonina). In addition, the viral challenge study using the hamster model showed that Nanocovax protected the upper respiratory tract from SARS-CoV-2 infection. No adverse effects were induced by Nanocovax in swiss mice (Musmusculus var. Albino), Rats (Rattus norvegicus), and New Zealand rabbits. These pre-clinical results indicated that Nanocovax is safe and effective.

We successfully used Cu to dope into the NiWO4 crystal to prevent the fast recombination or increase the lifetime of the photo-induced h+ and e− of the material. Then, the synthesized Cu-NiWO4 was successfully hybridized with g-C3N4 to form Cu-NiWO4/g-C3N4 direct Z system for novel photocatalytic decomposition of n-hexane under vis-light. In the formed Cu-NiWO4/g-C3N4 Z direct system, photo-induced e− in Cu-NiWO4 CB associated with photo-induced h+ in g-C3N4 VB maintaining e− in g-C3N4 CB and h+ in Cu-NiWO4 VB, thereby synthesized photocatalysts formed abundant available e− and h+ amounts even excited by vis-light and the formed e− and h+ pairs exhibit suitable redox potentials for reactions with O2 and H2O, respectively, to produce strong oxidative radicals for advanced photocatalytic degradation of n-hexane. The highest removal efficiency and degradation degree of n-hexane photocatalyzed by Cu-NiWO4/g-C3N4 were 96.8 and 96.3%, respectively. The synthesized Cu-NiWO4/g-C3N4 material also demonstrated strongly stability during long time n-hexane removal.

This paper presents a one-step selective separation of polyvinyl chloride (PVC) from PVC/PET mixture based on hydrophilicity building on the PVC surface using H2O2/ultrasonication. After the combined treatment, the decrease of PVC contact angle (from 87.2° to 71.5°) is consistent with the increase in hydrophilic functional groups that is evidenced by Fourier transform infrared and X-ray photoelectron spectroscopy results on the PVC surface. The H2O2/ultrasonic treatment generates oxidizing agent and increases hydrophilicity on the PVC surface, which allows to selectively separate the treated PVC by its submerging on the reactor bottom. Meanwhile, the treated PET is easily floated off because it is not affected by the combined treatment and still maintains the hydrophobic surface. The combined treatment of H2O2 and ultrasonic irrigation obtains 100% purity and recovery of the PVC separation under the optimum conditions. The optimized separation conditions are H2O2 concentration 3%, ultrasonic irrigation time 30 min and temperature 30 °C, floating agent concentration 0.4 mg/L and intermittent mixing at 50 rpm. Reusing of H2O2 is also feasible to save cost and environmental benefits. The combination of ultrasonication and H2O2 is an effective and inexpensive method for PVC separation to improve plastic recycling quality.

Polyvinyl chloride (PVC) products comprise a large portion of plastic wastes and cause severe environmental burdens in thermal recycling such as toxic release and disposal difficulties. Selective separation methods for PVC containing hazardous chlorine are required for the development of suitable disposal or material recycling processes. However, separating PVC selectively from municipal plastic waste mixtures is difficult due to their similar hydrophobic surface and appearance densities. This study presents a one-step, selective separation technique for PVC using H2O2 solution under ultrasonic irrigation to promote the selective development of hydrophilicity only on the PVC surface. The combined treatment helped to decrease air bubbles attached on the PVC surface because of increased wettability, which allowed the treated PVC to settle on the bottom of the flotation reactor. However, the remaining plastic wastes were easily floated off because they maintained their hydrophobicity. The combined treatment with a low concentration of 3% H2O2 and ultrasonic irrigation for 30 min afforded 100% purity and recovery of the PVC separated from the municipal plastic waste mixture. This proposed treatment is therefore a promising and inexpensive way to improve plastic recycling quality through selective PVC separation by the selective development of hydrophilicity on its surface.

In this study, we firstly aimed to use Nb as dopant to dope into the TiO2 lattice in order to narrow band gap energy or enhance photocatalytic activity of the Nb-TiO2. Then, the prepared Nb-TiO2 was combined with g-C3N4 to establish Nb-TiO2/g-C3N4 direct Z-scheme system for superior reduction of CO2 into valuable fuels even under visible light. The obtained results indicated that the band gap energy of the Nb-TiO2 (2.91 eV) was lower than that of the TiO2 (3.2 eV). In the successfully established Nb-TiO2/g-C3N4 direct Z-scheme system, the photo-excited e− in the CB of the Nb-TiO2 combined with the photo-excited h+ in the VB of the g-C3N4 preserving the existence of e− in the CB of the g-C3N4 and h+ in the VB of Nb-TiO2, and thereby, the system produced numerous amount of available e−/h+ pairs for the reduction of CO2 into various valuable fuels. In addition, the produced e− of the Nb-TiO2/g-C3N4 existing in the CB of the g-C3N4, which the potential energy is approximately −1.2 V, would be strong enough for the reduction of CO2 to generate not only CH4 and CO but also HCOOH. Among established Nb-TiO2/g-C3N4 materials, the 50Nb-TiO2/50 g-C3N4 material was the best material for the CO2 reduction.

We successfully used V as dopant to enhance activity of TaON for visible light photocatalytic reduction of CO2 into valuable fuels. We investigated that the used V dopants existed in the TaON lattice and replaced several Ta elements in the lattice leading to decrease in the conduction band minimum and increase in the valence band maximum of the prepared V TaON. Hence, the band gap energy of the prepared V TaON was lower than that of prepared TaON or the prepared V TaON material could absorb significant amount of incident visible light for production of e− and h+ pairs, which participated in reactions with CO2 and H2O to generate CH4, CO, O2 and H2. We also investigated that the optimal V/Ta ratio (or optimal amount of V dopant) for maximum enhancing photocatalytic activity of TaON was 1.5 wt%. The prepared 1.5V TaON visible light photocatalytically converted CO2 with H2O to generate CH4, CO, O2 and H2 with generation rates of 673, 206, 1479 and 67 (µmol·g−1cat·h−1), respectively.

Polyaniline (PANI) and polythiophene (PTh) conducting polymers have been used to sensitize Tantalum Nitride (Ta3N5) to enhance its photocatalytic activity. The synthesized materials exhibited novel photocatalytic activity for overall water splitting to produce hydrogen and oxygen even excited by visible light irradiation. The used PANI and PTh sensitizers enhanced the charge transfer efficiency and minimized the high recombination rate of the photo-excited electrons (e-) and holes (h+) of the Ta3N5 photocatalyst (enhanced e-/h+ separation efficiency of the Ta3N5) leading to increase in its photocatalytic activity for efficient visible light water splitting. We also investigated that the used PANI and PTh completely covering the Ta3N5 particles could acted as charge acceptors for quick migration of the produced h+ to their surface and thus minimizing contact between the nitride of the Ta3N5 and the produced h+, which could oxidize the nitride. It means that the used conducting polymers also protected the Ta3N5 particles from self-photocorrosion. Therefore, the synthesized tantalum nitride sensitized/protected by PANI or PTh could be applied for long-term water splitting. The production rates of H2 and O2 generated from water splitting of Ta3N5/PANI were higher than that of the Ta3N5/PTh because the electric conductivity of the PANI was higher than that of the PTh.

The research was conducted to assess the satisfaction of tourists with local community-based tourism services in the My Hoa Hung (MHH) commune in Long Xuyen, An Giang, Vietnam. The research findings will be the scientific and practical basis for effective and sustainable tourism development in MHH. A mixed-method of qualitative and quantitative is used in this study. Tourist local officers and tourist providers were interviewed as key informants. Such samples of domestic and foreign tourists were interviewed using a questionnaire survey to collect and analyze the tourists' satisfaction with tourism services. The result shows that tourists visiting MHH come from different regions and countries, from different age groups, and occupations, so their needs and satisfaction with MHH's community-based tourism services are also very diverse. The study uncovers that tourists are most satisfied with the human factor, especially the enthusiasm attitude of the tourist service provider (reaching 4.07 points), and then environmental landscape (3.90 points), infrastructure (3.90 points), price (3.80 points), and the lowest security- safety factor (3.73 points). However, in each factor, there are still a number of criteria that tourists are not satisfied with, which should be paid attention to for sustainable tourism development, such as environmental sanitation, traffic safety, and English communication ability of tourists' service providers.

This study reports the selective hydrophilization of the ABS/PC blend surface using the peroxide-sonochemical system and then its selective separation by froth flotation technique from other ABS-based plastics (ABS, ABS/PMMA) and PS/HIPS in electronic shredder residue (ESR). FT-IR and XPS measurements confirm that the hydrophilic moiety development on the ABS/PC surface led to increasing the wettability of ABS/PC and then decreased its floatability. The confocal scanning results also support the enhancement of microscale roughness of the treated ABS/PC surface. The enhanced surface roughness is attributed to the oxidative process which degrades hydrophobic moieties and promotes hydrophilic functional groups on the ABS/PC surface using commercial oxidant peroxide and ultrasound. This study also investigated removal of Br-containing compounds on the ABS/PC surface. The optimum conditions for selectively ABS/PC separation are peroxide concentration 2%, power cycle 70%, treatment time 5 min, temperature 50 °C, floating agent concentration 0.4 mg/L, flotation time 2 min, and airflow rate 0.5 L/min. ABS/PC was selectively separated from ESR styrene plastics with high recovery and purity of 98.9% and 99.8%, respectively. Hence, the developed novel surface treatments having removal of hazardous Br chemicals and none-formation of secondary pollutants should be applied for upgrading plastic recycling quality.

In this study, Cu2V2O7/g-C3N4 direct Z-scheme system was prepared for visible light photocatalytic conversion of CO2 into valuable fuels. As compared to the single Cu2V2O7 and g-C3N4, the established Cu2V2O7/g-C3N4 exhibited great increases in the CO2 conversion efficiency. When Cu2V2O7 was combined with g-C3N4 to establish a direct Z scheme system, both Cu2V2O7 and g-C3N4, which are narrow band-gap material, could absorb visible light for excitation of electrons from the valence band (VB) to the conduction band (CB). Then, the excited electrons existed in the CB of the Cu2V2O7 could return to holes in the VB of the g-C3N4 to prevent recombination of excited holes and electrons in each materials. Thus, the established direct Z scheme Cu2V2O7/g-C3N4 system produced significant amount of available holes and electrons. Finally, the produced holes and electrons reacted with H2O and CO2 to generate CO, CH4 and O2. The 50Cu2V2O7/50g-C3N4, which the Cu2V2O7 mole was equal to the g-C3N4 mole, produced enough electrons and protons for selective CO2 conversion into CH4 rather than CO. The generation rates of CH4, CO and O2 generated from the visible light photocatalytic conversion of CO2 by 50Cu2V2O7/50g-C3N4 were 305, 166 and 706 (µmol g−1 cat. h−1), respectively.

We successfully synthesized niobium-doped tantalum nitride sensitized/protected by polypyrrole (Nb Ta3N5/PPy) for efficient overall photocatalytic water splitting to produce hydrogen and oxygen under visible light. Niobium as a dopant was incorporated into the Ta3N5 lattice to act as an intermediate band between the valence band (VB) and the conduction band (CB) of Ta3N5 to enhance the electron-hole pair separation efficiency, thereby enhancing its photocatalytic activity. PPy, a conducting polymer with an extended π-π* conjugated electron system, was used as a sensitizer to enhance the charge transfer efficiency for migration of the photogenerated electrons and holes to its surface to prevent the recombination of the pairs and thus increase their lifetime. The migration of the photogenerated holes to the PPy surface also prevented the self photocorrosion of Ta3N5 (via reaction between the generated holes and nitrides in Ta3N5) in the electrolyte solution and thus enhanced its stability. Therefore, the synthesized Nb Ta3N5/PPy photocatalyst exhibited very high photocatalytic activity and stability for overall water splitting to produce H2 and O2 even under visible light at production rates of 65.1 and 32.8 μmol g−1cat. h−1, respectively.

This study reports a simple froth flotation method to separate plastic wastes of acrylonitrile–butadiene–styrene (ABS) and high impact polystyrene (HIPS) after initial hydrophilization by coating the plastics with ZnO and microwave treatment. ABS and HIPS are typical styrene-based WEEE plastics having similar density and hydrophobicity, which hinders their separation for recycling. After coating with ZnO, 2-min microwave treatment rearranged the ABS surface and thus changed its molecular mobility and increased its hydrophilicity. The combined ZnO coating/microwave treatment facilitated the selective separation of ABS and HIPS with 100% and 95.2% recovery and 95.4% and 100% purity in froth flotation, respectively. The combination of ZnO coating-microwave treatment and froth flotation can be utilized as a selective ABS/HIPS separation technique for improved recycling of WEEE plastics.

This study reports a simple and facile method to separate plastic wastes of acrylonitrile–butadiene–styrene (ABS) and ABS-based plastics (blends of ABS) in waste electronic and electrical equipment (WEEE) by froth flotation after inducing hydrophilization by ZnO coating under microwave treatment. ABS-based plastics containing brominated flame retardants (BFRs) can release hazardous substances, such as hydrogen bromide and brominated dioxins, during disposal or recycling activities. ABS and ABS-based plastics are typical styrene plastics with similar properties and it is, therefore, difficult to separate them selectively for recycling. We used 2-min microwave treatment to rearrange and change the molecular mobility on the surface of the ZnO-coated ABS with increased hydrophilic surfaces, which eased the selective separation of the ABS/polycarbonate (PC) blend containing BFRs from the remaining plastics. Therefore, the combined ZnO coating and microwave treatments can facilitate the selective separation of ABS/PC blend plastics with a recovery and purity of 100% and 91.7%, respectively, in a short flotation time of 2 min. Based on these findings, the combination of ZnO coating-microwave treatment and froth flotation can be applied for the selective separation of ABS-based plastics, leading to improved plastic recycling quality.

Acrylonitrile-butadiene-styrene (ABS) is one of hazardous halogenic plastics which containing brominated flame-retardants (BFRs) is considered as toxic wastes due to releasing hydrogen bromide and brominated dioxins through incineration or disposal activities. In present, recycling is aimed as a sustainable plastic waste management of ABS containing BFRs in ways that minimize the potential impact on human health and environment. This study was conducted to facilitate the separation of ABS plastics from heavy plastic mixture by froth flotation after surface rearrangement of ABS with mild heat treatment for its recycling. Hydrophilic moieties would be more likely to develop on the mild heat-treated ABS surfaces than on other plastics perhaps due to the difference of molecular mobility. This provides an excellent base for selective separation of ABS by froth flotation technique. As a result of froth flotation after mild heat treatment, about 97% of ABS with 100% purity was selectively separated from heavy plastics. The detailed mechanism for the selective separation of the ABS in the treatment (froth flotation after mild heat treatment) was discussed. Finally, this study facilities selective separation application effective and inexpensive method for of ABS from waste plastics.

Polyvinyl chloride (PVC) containing chlorine can release highly toxic materials and persistent organic pollutants if improperly disposed of. The combined technique of powder activated carbon (PAC) coating and mild heat treatment has been found to selectively change the surface hydrophobicity of PVC, enhancing its wettability and thereby promoting its separation from heavy plastic mixtures included polycarbonate (PC), polymethyl methacrylate (PMMA), polystyrene (PS) and acrylonitrile butadiene styrene (ABS) by means of froth flotation. The combined treatments helped to rearrange the surface components and make PVC more hydrophobic, while the remaining plastics became more hydrophilic. After the treatments at 150 °C for 80 s the contact angle of the PVC was greatly increased from 90.5 to 97.9°. The SEM and AFM reveal that the surface morphology and roughness changes on the PVC surface. XPS and FT-IR results further confirmed an increase of hydrophobic functional groups on the PVC surface. At the optimized froth flotation and subsequent mixing at 150 rpm, 100% of PVC was recovered from the remaining plastic mixture with 93.8% purity. The combined technique can provide a simple and effective method for the selective separation of PVC from heavy plastics mixtures to facilitate easy industrial recycling.

Herein, Cu was incorporated into ZnO lattice to reduce its band gap as well as to extend its visible radiation response. The obtained Cu-ZnO was continuously integrated with g-C3N4 to create Cu-ZnO/g-C3N4 Z-direct scheme photocatalyst for advanced atrazine removal. Radical scavenging experiments have been also conducted to clearly figure out photocatalytic mechanism for degradation of atrazine by the synthesized photocatalyst. The synthesized Cu-ZnO only utilized the generated h+ for atrazine degradation (direct and indirect via formation hydroxyl radicals (•OH)) and the g-C3N4 only utilized the generated e− for atrazine degradation (indirect via reaction with O2 to form superoxide anion, which needed to continuously react with H2O to form •OH). Therefore, the photocatalytic atrazine degradation by synthesized Cu-ZnO material was greater than that by synthesized g-C3N4 material. Cu-ZnO/g-C3N4 utilized both generated e− and h+ for degradation of atrazine. Thus, the photocatalytic atrazine degradation by the synthesized Cu-ZnO/g-C3N4 was greater than those of single g-C3N4 or Cu-ZnO materials. Finally, the conducted recycling experiments indicated great stability of synthesized Cu-ZnO/g-C3N4 during long-term atrazine degradation process opening new era for application of the material in practical systems.

In the study, Fe was used as a dopant to enhance photocatalytic activity of TiO2. Then, the Fe-doped TiO2 was deposited on bentonite, which was pillared by Fe. The synthesized materials were characterized by SEM, XRD, UV-Vis, BET, and point of zero charge (pHPZC). Then, the synthesized materials were used for diazinon removal under both dark and visible light conditions to investigate adsorption and photocatalytic degradation abilities of the synthesized materials. The maximum diazinon adsorption capacity of the synthesized Fe-TiO2/Bent-Fe was 27.03 mg/g. The obtained results indicated that the Fe-TiO2/Bent-Fe exhibited high photocatalytic degradation activity for removal of diazinon even under visible light. The diazinon removal experiments were also conducted using different photocatalyst dosages, under different pH and light sources to figure the optimal conditions for removal processes. The obtained results indicated that optimal photocatalyst dosage and pH were 0.5 g/L and 4.5, respectively. Finally, the natural light generated from solar could be suitable used for diazinon removal by the synthesized Fe-TiO2/Bent-Fe.

This study reports simple, selective, and sustainable separation of chlorinated plastic (polyvinyl chloride, PVC) and acrylonitrile butadiene styrene (ABS) containing brominated flame retardants (BFRs) from mixed waste electrical and electronic equipment (WEEE) plastics using microwave and/or mild-heat treatment. Microwave treatment after plastic coating with powdered activated carbon (PAC) selectively increased the hydrophilicity of the PVC surface, which facilitated PVC separation (100% recovery and purity) from the WEEE plastic mixture under the optimum flotation conditions. A further mild-heat treatment for 100 s facilitated selective separation with the highest recovery and purity (100%) of PAC-coated ABS containing BFRs from the remaining plastic mixture due to selective formation of a twisted structure with a lower density than water and the untreated ABS. Mild-heat treatment only of PAC-coated WEEE plastic mixture resulted in successful recovery of (100%) the ABS and PVC. However, the recovered PVC had slightly reduced purity (96.8%) as compared to that obtained using the combined heat and microwave treatments. The combination of both treatments with flotation facilitated selective and sustainable separation of PVC and ABS from WEEE plastics to improve their recycling quality.

Herein, g-C3N4 and NiMoO4, which are moderate energy band gap semiconductors, have been effectively hybridized to create Z scheme heterojunction for successful visible-light photocatalytic converting CO2 into valuable products including CH4, CO, O2 and HCOOH. Ni(NO3)2·6H2O and (NH4)6Mo7O24·4H2O were used as precursors to synthesize NiMoO4 photocatalyst, which was continuously mixed with melamine before calcinating at 520 °C for 6 h to get NiMoO4/g-C3N4 Z scheme heterojunction. We explored that NiMoO4 intimately contacted with g-C3N4. These band positions of the NiMoO4 were also perfectly matched with those of the g-C3N4. Therefore, these photo-induced e− on conduction band of the NiMoO4 could easily travel to h+ on valence band of the g-C3N4 (recombination); thereby, minimize h+ and e− recombination in each material. Therefore, the NiMoO4/g-C3N4 direct Z-scheme heterojunctions could produce significant available h+ on the valence band of the NiMoO4 and e− on the conduction band of the g-C3N4. These e−/h+ have suitable redox potential to effectively convert CO2. Finally, the optimized g-C3N4 mole ratio for maximum enhancing photocatalytic efficiency of the NiMoO4/g-C3N4 heterojunction was 60%. When the g-C3N4 content increased to 70%, the excess g-C3N4 amount would entirely cover NiMoO4 surface leaded to form dense and closed shell. The formed closed shell decreased contact between NiMoO4 and CO2 as well as the interface charge transfer, which reduced the e− and h+ separation and transfer leading to decrease in photocatalytic conversion efficiency.

In current study, Cu capped Cu2O nanoparticles (Cu-Cu2O) was synthesized using trioctylamine which is playing a dual role as a hydrolyzing agent as well as capping agent. Temperature and time dependent studies were also performed to monitor different phase formation. As synthesized material was characterized by X-ray diffraction (XRD) for phase determination, crystalline size and morphological investigation. Transmission electron microscopy (TEM) images revels the morphology of the nanoparticles was cubic which leads to spherical at higher temperature. Photocatalytic mineralization studies were carried out in the presence of Congo Red (CR) dye, organic molecules decontamination from aquatic environment with 98.7% mineralization.

Polyvinyl chloride (PVC) products comprise a large portion of plastic wastes and cause severe environmental burdens in thermal recycling such as toxic release and disposal difficulties. Selective separation methods for PVC containing hazardous chlorine are required for the development of suitable disposal or material recycling processes. However, separating PVC selectively from municipal plastic waste mixtures is difficult due to their similar hydrophobic surface and appearance densities. This study presents a one-step, selective separation technique for PVC using H

In this study, we firstly aimed to use Nb as dopant to dope into the TiO

The recovery of precious metals from automotive shredder residue (ASR) dust/combustion residue is an option that is not usually considered due to the lack of available information. Therefore, before any disposal or recovery application can be considered, it is necessary to determine the significance of the levels and distribution of precious metal in ASR dust/ASR combustion residue. In the present study, quantitative analysis of precious metals (Pt, Pd, Au, Ag and Cu) in the ASR residue samples was performed using energy dispersive X-ray (EDX) fluorescence spectrometer. With the fundamental parameter (FP) method, the X-ray intensity is obtained and the quantitative analysis is performed using theoretical calculation. This method is very effective for quantitative analysis of unknown samples without standard samples. Further, in order to analyse the precious metal distribution within the ASR combustion residues, the microstructural characterisation and elemental mapping were also carried out with the aid o...

In the present study, feasibility of the selective surface hydrophilization of polyvinyl chloride (PVC) by microwave treatment was evaluated to facilitate the separation from automotive shredder residue (ASR), by the froth flotation. The combination of 60 sec microwave treatment with PAC, a sharp and significant decrease about 16.5° contact angle of PVC was observed in ASR plastic compared with other plastics. The microwave treatment with the addition of PAC resulted in a synergetic effect for the froth flotation, which may be a result of the 90% selective separation of PVC from ASR plastics, with 82% purity. While, simple mixing with a nanometallic Ca/CaO/PO4 dispersion mixture immobilized 95-100% of heavy metals in ASR soil/residues. The quantity of heavy metals leached from thermal residues after treatment by nanometallic Ca/CaO/PO4 was lower than the Korean standard regulatory limit for hazardous waste landfills. Microwave treatment can be a simple and effective method for PVC separation from ASR plastics., {"references":["Solving the E-Waste Problem (StEP) Initiative, StEP E-waste World\nMap. (2014) http://www.step-initiative.org/step-e-waste-worldmap.\nhtml","C. P. Balde, R. Kuehr, K. Blumenthal, S. Fondeur Gill, M. Kern, P.\nMicheli, E. Magpantay, J. Huisman (2015), E-waste statistics: Guidelines\non classifications, reporting and indicators. United Nations University,\nIAS - SCYCLE, Bonn, Germany. (2015)","Y. C. Jang, Waste electrical and electronic equipment (WEEE)\nmanagement in Korea: generation, collection, recycling systems, J.\nMater. Cycles Waste. Manag. 12 (2010) 283–294.","Korea Ministry of Environment (Korea MOE) (2007) The Act on the\nResource Recycling of Waste Electrical Electronic Equipment (WEEE)\nand End-of-life Vehicles (ELVs), The Ministry, Gwacheon.","T. Takoungsakdakun, S. Pongstabodee, Separation of mixed\npost-consumer PET-POM-PVC plastic waste using selective flotation,\nSep. Purif. Technol. 54 (2007) 248-252.","S. Moriwaki, M. Machida, H. Tatsumoto, Y. Otsubo, M. Aikawa, T.\nOgura. Dehydrochlorination of poly(vinyl chloride) by microwave\nirradiation. Applied Thermal Engineering 26 (2006) 745–750.","M. Ito, K. Ushida, N. Nakao, N. Kikuchi, R. Nozaki, K. Asai, M. Washio.\nDechlorination of poly (vinyl chloride) by microwave irradiation I:A\nsimple examination using a commercial microwave oven. Polymer\nDegradation and Stability 91 (2006) 1694e1700.","Bacalogulu R., Fish MH, Kaufhold J., Sander H. J. In: Zweifel H., editor.\nPlastics additives handbook. Cincinnati: Hanser Gardner Publications;\n2001. p. 427 (chapter 3).","D. A. Jones, T. P. Lelyveld, S. D. Mavrofidis, S. W. Kingman, N. J.\nMiles. Microwave heating applications in environmental engineering—a\nreview. Resources, Conservation and Recycling 34 (2002) 75–90.\n[10] J. A. Menéndez, A. Arenillas, B. Fidalgo, Y. Fernández, L. Zubizarreta,\nE. G. Calvo, J. M. Bermúdez. Microwave heating processes involving\ncarbon materials, Fuel Processing Technology 91 (2010) 1–8.\n[11] Y. Mitoma, S. R. Mallampati, H. Miyata, M. Kakeda, Decomposition of\nPolychlorinated Biphenyls in Soil With a Dispersion Mixture of Metallic\nCalcium and Calcium Oxide, Arch. Environ. Contam. Toxicol. 64 (2013)\n180–186.\n[12] Mallampati S. R., Mitoma Y., Okuda T., Sakita S., Kakeda M. (2012a)\nHigh immobilization of soil cesium using ball-milling with nano-metallic\nCa/CaO/NaH2PO4: implications for the remediation of radioactive soils.\nEnviron Chem Lett 10:201–207.\n[13] Mallampati, S. R., T. Okuda, Y. Mitoma, S. Sakita, and M. Kakeda.\n2012b. Enhanced heavy metal immobilization in soil by grinding with\naddition of 595 nanometallic Ca/CaO dispersion mixture. Chemosphere\n89:717–723. doi:10.1016/j.chemosphere.2012.06.030.\n[14] M. S. Reddy, T. Okuda, K. Kurose, T. Y. Tsai, S. Nakai, W. Nishijima,\nM. Okada, Surface ozonation of polyvinyl chloride for its separation from\nwaste plastic mixture by froth flotation, J. Mater. Cycles. Waste., 12\n(2010) 326-331.\n[15] T. Okuda, K. Kurose, W. Nishijima, M. Okada, Separation of polyvinyl\nchloride from plastic mixture by froth flotation after surface modification\nwith ozone, Ozone-Sci. Eng., 29 (2007) 373-377.\n[16] Regulatory of waste management (Ministry of Environment Report,\nSeoul, Republic of Korea) (2000) 2-5."]}

This study evaluated to facilitate separation of ABS plastics from other waste plastics by froth flotation after surface hydrophilization of ABS with heat treatment. The mild heat treatment at 100oC for 60s could selectively increase the hydrophilicity of the ABS plastics surface (i.e., ABS contact angle decreased from 79o to 65.8o) among other plastics mixture. The SEM and XPS results of plastic samples sufficiently supported the increase in hydrophilic functional groups and decrease contact angle on ABS surface, after heat treatment. As a result of the froth flotation (at mixing speed 150 rpm and airflow rate 0.3 L/min) after heat treatment, about 85% of ABS was selectively separated from other heavy plastics with 100% of purity. The effect of optimum treatment condition and detailed mechanism onto separation efficiency in the froth floatation was also investigated. This research is successful in giving a simple, effective, and inexpensive method for ABS separation from waste plastics., {"references":["F. Burat, A. Güney, M. O. Kangal, Selective separation of virgin and\npost-consumer polymers (PET and PVC) by flotation method, Waste\nManagement, 29 (2009) 1807–1813.","I. C. Nnorom, O. Osibanjo, Sound management of brominated flame\nretarded (BFR) plastics from electronic wastes: State of the art and\noptions in Nigeria, Resources, Conservation and Recycling, 52 (2008)\n1362–1372.","Flame retardants & PVC in electronics, in: Green Chemistry Vs Toxic\nTechnology, Electronics TakeBack Coalition, A Project of the Tides\nCenter, http://www.electronicstakeback.com/toxics-in-electronics/flameretardants-\npvc-and-electronics/.","P. A. Wäger, R. Hischier, Life cycle assessment of post-consumer\nplastics production from waste electrical and electronic equipment\n(WEEE) treatment residues in a Central European plastics recycling\nplant, Science of The Total Environment, 529 (2015) 158–167.","R. C. Thompson, C. J. Moore, F. S. vom Saal, S. H. Swan, Plastics, the\nenvironment and human health: current consensus and future trends,\nPhilosophical Transactions of the Royal Society B, 364 (2009) 2153–\n2166.","P. M. Subramanian, Plastics recycling and waste management in the US,\nResources, Conservation and Recycling, 28 (2000) 253-263.","J. Hopewell, R. Dvorak, E. Kosior, Plastics recycling: challenges and\nopportunities, Philosophical Transactions of the Royal Society B:\nBiological Sciences, 364 (2009) 2115-2126.","S. M. Al-Salem, P. Lettieri, J. Baeyens, Recycling and recovery routes\nof plastic solid waste (PSW): A review, Waste Management, 29 (2009)\n2625–2643.","O. O. Leah, B.. M. van Vliet, A. P. J. Mol, Managing plastic waste in\nEast Africa: Niche innovations in plastic production and solid waste,\nHabitat International, 48 (2015) 188–197.\n[10] Korea Environmental Corporation, Present situation of waste generation\nand treatment, (2013).\n[11] C. Wang, H. Wang, Q. Liu, J. Fu, Y. Liu, Separation of polycarbonate\nand acrylonitrile-butadiene-styrene waste plastics by froth flotation\ncombined with ammonia pretreatment, Waste Management, 34 (2014)\n2656-2661.\n[12] S. Pongstabodee, N. Kunachitpimol, S. Damronglerd, Combination of\nthreestage sink-float method and selective flotation technique for\nseparation of mixed post-consumer plastic waste, Waste Management,\n28 (2008) 475-483.\n[13] R. D. Pascoe, Investigation of hydrocyclones for the separation of\nshredded fridge plastics, Waste Management, 26 (2006) 1126-1132.\n[14] D. S. Achilias, C. Roupakias, P. Megalokonomos, A. A. Lappas, E. V.\nAntonakou, Chemical recycling of plastic wastes made from\npolyethylene (LDPE and HDPE) and polypropylene (PP), Journal of\nHazardous Materials, 149 (2007) 536-542.\n[15] G. Pappa, C. Boukouvalas, C. Giannaris, N. Ntaras, V. Zografos, K.\nMagoulas, A. Lygeros, D. Tassios, The selective\ndissolution/precipitation technique for polymer recycling: a pilot unit\napplication, Resources, Conservation and Recycling, 34 (2001) 33-44.\n[16] M. S. Reddy, T. Okuda, K. Kurose, T. Y. Tsai, S. Nakai, W. Nishijima,\nM. Okada, Surface ozonation of polyvinyl chloride for its separation\nfrom waste plastic mixture by froth fl oatation, Journal of Material\nCycles and Waste Management 12 (2010) 326–331.\n[17] M. S. Reddy, T.Yamaguchi, T. Okuda, T. Y.Tsai, S. Nakai, W.\nNishijima, M. Okada, Feasibility study of the separation of chlorinated\nfilms from plastic packaging wastes, Waste Management, 30 (2010)\n597–601.\n[18] H. Wang, X. L. Chen, Y. Bai, C. Guo, Z. Li, Application of dissolved air\nflotation on separation of waste plastics ABS and PS, Waste\nManagement, 32 (2012) 1297–1305.\n[19] T. Takoungsakdakun, S. Pongstabodee, Separation of mixed postconsumer\nPET–POM–PVC plastic waste using selective flotation,\nSeparation and Purification Technology, 54 (2007) 248–252.\n[20] S. Bigot, G. Louarn, N. Kébir, F. Burel, Facile grafting of bioactive\ncellulose derivativesonto PVC surfaces, Appl. Surf. Sci., 283 (2013)\n411-416.\n[21] N. Fraunholcz, Separation of waste plastics by froth flotation-a review,\nPart I, Minerals Engineering, 17 (2004) 261-268.\n[22] H. Alter, The recovery of plastics from waste with reference to froth\nflotation, Resources, Conservation and Recycling, 43 (2005) 119-132.\n[23] H. Shen, E. Forssburg, R.J. Pugh, Selective flotation separation of\npolymers by particle control, Resources Conservation and Recycling, 33\n(2001) 37-50.\n[24] K. Kojio, S. Kugumia, Y. Uchiba, Y. Nishino, M. Furukaw, The\nmicrophase-separated structure of polyurethane bulk and thin films,\nPolymer Journal, 41 (2009) 118-124.\n[25] S. Bigot, G. Louarn, N. Kébir, F. Burel, Facile grafting of bioactive\ncellulose derivativesonto PVC surfaces, Applied Surface Science, 283\n(2013) 411-416.\n[26] R. D. Pascoe, B. O'Connell, Flame treatment for the selective wetting\nand separation of PVC and PET, Waste Management, 23 (2003) 845-850.\n[27] M. S. Reddy, K. Kurose, T. Okuda, W. Nishijima, M. Okada, Separation\nof polyvinyl chloride (PVC) from automobile shredder residue (ASR) by\nfroth flotation with ozonation, Journal of Hazardous Materials, 147\n(2007) 1051-1055.\n[28] M. S. Reddy, K. Kurose, T. Okuda, W. Nishijima, M. Okada, Selective\nrecovery of PVC-free polymers from ASR polymers by ozonation and\nfroth flotation, Resources Conservation and Recycling, 52 (2008) 941-\n946.\n[29] T. Okuda, K. Kurose, W. Nishijima, M. Okada, Separation of polyvinyl\nchloride from plastic mixture by froth flotation after surface\nmodification with ozone, Ozone: Science and Engineering, 29 (2007)\n373-377.\n[30] K. Kurose, T. Okuda, S. Nakai, T.-Y. Tsai, W. Nishijima, M. Okada,\nHydrophilization of polyvinyl chloride surface by ozonation, Surface\nReview and Letters, 15 (2008) 711-715.\n[31] C. Q. Wang, H. Wang, B. X. Wu, Q. Liu, Boiling treatment of ABS and\nPS plastics for flotation separation, Waste Management, 34 (2014) 1206-\n1210."]}

This study was conducted to synthesize and apply a nano-size calcium dispersed reagent as an immobilization material for heavy metal-contaminated automobile shredder residues (ASR) dust/thermal residues in dry condition. Simple mixing with a nanometallic Ca/CaO/PO4 dispersion mixture immobilized 95–100% of heavy metals in ASR dust/thermal residues (including bottom ash, cavity ash, boiler and bag filter ash). The quantity of heavy metals leached from thermal residues after treatment by nanometallic Ca/CaO/PO4 was lower than the Korean standard regulatory limit for hazardous waste landfills. The morphology and elemental composition of the nanometallic Ca/CaO-treated ASR residue were characterized by field emission scanning election microscopy combined with electron dispersive spectroscopy (FE-SEM/EDS). The results indicated that the amounts of heavy metals detectable on the ASR thermal residue surface decreased and the Ca/PO4 mass percent increased. X-ray diffraction (XRD) pattern analysis indicated that the main fraction of enclosed/bound materials on ASR residue included Ca/PO4− associated crystalline complexes, and that immobile Ca/PO4 salts remarkably inhibited the desorption of heavy metals from ASR residues. These results support the potential use of nanometallic Ca/CaO/PO4 as a simple, suitable and highly efficient material for the gentle immobilization of heavy metals in hazardous ASR thermal residue in dry condition.

The aim of this Bachelor thesis is to analyze subsequent integration of Vietnamese entrepreneurs in the Czech Republic with the focus on Prague. Moreover, the thesis deals with the impacts of this integration. The thesis is divided into two parts. In the theoretical part I am trying to describe the history of the arrival of Vietnamese citizens to the Czech Republic and their subsequent integration. In the practical part I have used a document analysis, secondary analysis and semi-structured interview to clarify the situation. The collected data is interpreted on a theoretical background. To sum up, the outcome of this thesis will enable the reader to better understand Vietnamese people living in the Czech Republic