ՊՏՈՒՂԲԱՆՋԱՐԵՂԵՆԱՅԻՆ ՀՈՒՄՔԱՏԵՍԱԿՆԵՐԸ ՉՈՐԱՑՄԱՆ ՆԱԽԱՊԱՏՐԱՍՏԵԼՈՒ ԱՅԼԸՆՏՐԱՆՔԱՅԻՆ ԵՂԱՆԱԿ

Drying is a fruit and vegetable processing technological procedure as a result of which food products with up to 1 year shelf life can be manufactured. Safety indices of the dried fruits and vegetables should comply with the stated standards. As a novelty, the raw material, to be dried, was treated with sodium pyrosulfite. The latter’s properties and chemical composition was studied, and after drying of fruits, expert examination was conducted. Unlike the sulfur powder, the processing with sodium pyrosulfite is much safer; besides the natural color of processed product is preserved and the drying time is reduced by 2-3 hours.

The Fluidity and Sprayability Characteristics of -200 Mesh Sulfur Powder

To study the fluidity and sprayability characteristics of sulfur powder, powder comprehensive characteristic tester was utilized. The results show that the fluidity was in not good level and prone to be sprayable. With the moisture content less than 1.2%, the fluidity property was also in not good level, and continuous increase in the moisture content or the charge-to-mass ratio tended to trigger off bad or even worse fluidity. When the moisture content of the wet basis was less than 0.7%, the sulfur powder was prone to spray. Raising the moisture content from 0.7% to 1.5%, or increasing the charge-to-mass ratio from -6.9 to -11.4 nC∙g-1 also led to may be sprayable tendency, while a further increase in one of the two parameters no sprayable tendency. It can be concluded that in the chemical industry, special treatment is needed for sulfur production equipment to improve its fluidity and sprayability.

Bioleaching of Heavy Metals from Municipal Solid Waste Incineration Fly Ash: Availability of Recoverable Sulfur Prills and Form Transformation of Heavy Metals

Bioleaching is an effective and promising approach for the recovery or removal of heavy metals from metal-laden municipal solid waste incineration fly ash. To exclude the risk of reacidification of the leached fly ash after bioleaching with sulfur powder, molded sulfur prills were used as energy substrate for sulfur oxidizing bacteria to examine the availability of reusing the recyclable sulfur forms. The chemical species of heavy metals during the bioleaching process were also investigated. Results showed that the pH reduction, sulfate production, and metal solubilization with sulfur prills were comparable to that with sulfur powder despite of the theoretically calculated smaller surface of the formers. After 15 days of bioleaching, 80.7–82.1% of Cd, 72.5–74.1% of Zn, 42.8–43.9% of Cu, 24.1–25.2% of Cr, and 12.4–13.0% of Pb were removed from the fly ash, respectively. During bioleaching, heavy metals in the acid extractable and reducible fraction were significantly removed, and metals in oxidizable from were partially reduced. The low leaching toxicity of heavy metals according to toxicity characteristic leaching procedure (TCLP) verified the effective detoxification of fly ash. Moreover, the comparable pH reduction and metal removal efficiencies of bioleaching process with recycled sulfur prills to that with fresh sulfur revealed the potential of reusing the recoverable sulfur prills in the bioleaching process for decontamination of heavy metals from municipal solid waste fly ash.

Explore the recycling of bioleaching functional bacteria and sulfur substrate using the sulfur-covered biochar particles

Background Bioleaching has been attracting attention recent years as an emerging sediment heavy metal pollution remediation technology. However, the use of sulfur powder as sulfur substrate causes the problem of “post-acidification”, and the free bioleaching functional bacteria which are susceptible to environmental impact during reactor operation cannot be used efficiently for multiple rounds. These problems can be solved if the sulfur substrate and the bioleaching functional bacteria can be recycled simultaneously after bioleaching. A new kind of sulfur substrate, the laboratory-made sulfur-covered biochar particles, were used in the bioleaching experiment, compared with sulfur powder and sulfur powder mixed with the surfactant rhamnolipid. Results The sulfur-covered biochar particles exhibited superior bioleaching performance, including faster acidification rate, SO 4 2- production rate and heavy metal bioleaching rate, and higher heavy metal solubilization percentage (Ni 33.76%; Cu 66.16%; Zn 65.494%), which was resulted from the acceleration of bioleaching reaction by the bioleaching functional bacteria immobilized on the biochar surface. Otherwise, the sulfur-covered biochar particles could be reused in the second round, and the heavy metal solubilization percentage (Ni32.84%, Cu69.93%, Zn67.17%) was comparable with that of the first round. Nevertheless, the sulfur content became the main limiting factor causing poor bioleaching performance during the third round. The sulfur mixed with the surfactant rhamnolipid did not show significant effect in promoting acidification and heavy metal solubilization due to high levels of organic matter and the impact of the low pH value. Conclusion The research indicated the laboratory-made sulfur-covered biochar particles could realize the dual immobilization of the bioleaching functional bacteria and the sulfur substrate to support their recycling and reuse in the second bioleaching round. In the future research, the way to maintain the reuse of the sulfur-covered biochar particle for more rounds will be explored.

Explore the recycling of bioleaching functional bacteria and sulfur substrate using the sulfur-covered biochar particles

Background Bioleaching has been attracting attention recent years as an emerging sediment heavy metal pollution remediation technology. However, the use of sulfur powder as sulfur substrate causes the problem of “post-acidification”, and the free bioleaching functional bacteria which are susceptible to environmental impact during reactor operation cannot be used efficiently for multiple rounds. These problems can be solved if the sulfur substrate and the bioleaching functional bacteria can be recycled simultaneously after bioleaching. A new kind of sulfur substrate, the laboratory-made sulfur-covered biochar particles, were used in the bioleaching experiment, compared with sulfur powder and sulfur powder mixed with the surfactant rhamnolipid. Results The sulfur-covered biochar particles exhibited superior bioleaching performance, including faster acidification rate, SO 4 2- production rate and heavy metal bioleaching rate, and higher heavy metal solubilization percentage (Ni 33.76%; Cu 66.16%; Zn 65.494%), which was resulted from the acceleration of bioleaching reaction by the bioleaching functional bacteria immobilized on the biochar surface. Otherwise, the sulfur-covered biochar particles could be reused in the second round, and the heavy metal solubilization percentage (Ni32.84%, Cu69.93%, Zn67.17%) was comparable with that of the first round. Nevertheless, the sulfur content became the main limiting factor causing poor bioleaching performance during the third round. The sulfur mixed with the surfactant rhamnolipid did not show significant effect in promoting acidification and heavy metal solubilization due to high levels of organic matter and the impact of the low pH value. Conclusion The research indicated the laboratory-made sulfur-covered biochar particles could realize the dual immobilization of the bioleaching functional bacteria and the sulfur substrate to support their recycling and reuse in the second bioleaching round. In the future research, the way to maintain the reuse of the sulfur-covered biochar particle for more rounds will be explored.

Effect of heat treatments on the electronic properties of indium sulfide films

The optical and electrical properties of indium sulfide films with different heat treatments are investigated. Indium sulfide films are heat treated in Ar gas in a temperature range of 100–400 °C. Some annealed samples are heat treated at 300 °C with sulfur powder. The indium sulfide films show a band gap of 1.9–2.3 eV, an electrical resistivity in the range of 5.5 × 100–6.0 × 103 Ωm, and n-type electrical conduction. The resistivity decreases by three orders of magnitude by heat treatment at 300 °C in Ar gas and recovers almost to the initial state by heat treatment at 300 °C with sulfur powder. The Seebeck coefficient and subgap absorption at 1 eV show similar changes and recovery. The experimental results reveal the possible control of the density of states and of the Fermi level position by heat treatment and, hence, the feasibility of carrier control.

Explore the recycling of bioleaching functional bacteria and sulfur substrate using the sulfur-covered biochar particles

Background Bioleaching has been attracting attention recent years as an emerging sediment heavy metal pollution remediation technology. However, the use of sulfur powder as sulfur substrate causes the problem of “post-acidification”, and the free bioleaching functional bacteria which are susceptible to environmental impact during reactor operation cannot be used efficiently for multiple rounds. These problems can be solved if the sulfur substrate and the bioleaching functional bacteria can be recycled simultaneously after bioleaching. A new kind of sulfur substrate, the laboratory-made sulfur-covered biochar particles, were used in the bioleaching experiment, compared with sulfur powder and sulfur powder mixed with the surfactant rhamnolipid.Results The sulfur-covered biochar particles exhibited superior bioleaching performance, including faster acidification rate, SO 4 2- production rate and heavy metal bioleaching rate, and higher heavy metal solubilization percentage (Ni 33.76%; Cu 66.16%; Zn 65.494%), which was resulted from the acceleration of bioleaching reaction by the bioleaching functional bacteria immobilized on the biochar surface. Otherwise, the sulfur-covered biochar particles could be reused in the second round, and the heavy metal solubilization percentage (Ni32.84%, Cu69.93%, Zn67.17%) was comparable with that of the first round. Nevertheless, the sulfur content became the main limiting factor causing poor bioleaching performance during the third round. The sulfur mixed with the surfactant rhamnolipid did not show significant effect in promoting acidification and heavy metal solubilization due to high levels of organic matter and the impact of the low pH value.Conclusion The research indicated the laboratory-made sulfur-covered biochar particles could realize the dual immobilization of the bioleaching functional bacteria and the sulfur substrate to support their recycling and reuse in the second bioleaching round. In the future research, the way to maintain the reuse of the sulfur-covered biochar particle for more rounds will be explored.