Springer Science and Business Media LLCActa Medica Okayama1438-49572542023Sequential flotation of 4 components in silicon-based waste solar cells24072416ENMamiMizukawaDepartment of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama UniversityNorikoNishimuraDepartment of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama UniversityMd. AzharUddinDepartment of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama UniversityYoshieiKatoDepartment of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama UniversityYu-ichiUchidaDepartment of Applied Chemistry, Faculty of Fundamental Engineering, Nippon Institute of TechnologySi, Al, Cu, and Ag particlesf mixture which mainly composes pulverized silicon-based waste solar cells were individually separated by the batch flotation experiments with high recovery and content, and then a general flow chart of the sequential flotation procedure of n-component was postulated including 2-, 3-, and 4-components. The n-component mixture was separated to 1: n-1 or i: j (i + j = n) by a flotation procedure and n-1 times operation was necessary to divide into the individual component. The first flotation process to separate Al into the froth layer was carried out with a collector of SDS solution after dipping Si, Al, Cu, and Ag mixture into the SDS solution. Si was separated in the froth by the second flotation with a collector of a commercial neutral detergent after Al etching by HCl, and Si, Cu and Ag mixture dipped in the detergent. The Cu and Ag mixture was calcinated at 673 or 773 K and dipped into the detergent, and the third flotation with the collector of the detergent led to Cu in the froth and Ag in the sediment. The 4-component mixture was successfully separated into each component by the 3-consecutive flotation processes.No potential conflict of interest relevant to this article was reported.Springer Science and Business Media LLCActa Medica Okayama1438-49572522022Flotation kinetics of aluminum powders derived from waste crystalline silicon solar cells and its comparison between batch, continuous and column flotation practices826834ENYoshieiKatoDepartment of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama UniversityShoHaradaDepartment of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama UniversityNorikoNishimuraDepartment of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama UniversityMd. AzharUddinDepartment of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama UniversityYu-ichiUchidaDepartment of Applied Chemistry, Faculty of Fundamental Engineering, Nippon Institute of TechnologyIn this study, floatability rate of aluminum (Al) powders was analyzed for the purpose of separating valuable resources from residual materials in waste photovoltaic (PV) solar cells, and equations for flotation recovery were developed for various flotation types according to the rate-determining steps of the gas flowrate and feed rate. The flotation rate became a zero-order reaction at the rate-determining step of the gas flow rate and had the same form between a batch and continuous typed practices by substituting residence time with real time. Under the rate-determining step of the feed rate, the flotation rate was expressed by the linear combination of the first-order reaction of an even group material. The flotation recovery rate of Al powders was analyzed by the data of a batch floatability experiment and indicated by the linear expression of the first-order reaction of two groups due to the rate-determining step of the feed rate. The calculated separation recovery of n-cell type device increased as the number of cells increased and approached that of the batch and column types.No potential conflict of interest relevant to this article was reported.Iron and Steel Institute of JapanActa Medica Okayama0915-15596162021Effect of Impeller and Gas Stirring on Agglomeration Behavior of Polydisperse Fine Particles in Liquid17751783ENAkitoYamaguchiDepartment of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama UniversityHitoshiOkanoDepartment of Material and Energy Science, Graduate School of Environmental ScienceSyunsukeSumitomoDepartment of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama UniversityMd. AzharUddinDepartment of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama UniversityYoshieiKatoDepartment of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama UniversityAgglomeration, coalescence and flotation of non-metallic inclusions in steel melt are effective for obtaining gclean steel.h In this study, the agglomeration and breakup behaviors of particles with a primary particle size distribution (hereinafter, polydisperse particles) in a liquid under impeller and gas stirring were compared by numerical calculations and model experiments. The particle-size-grouping (PSG) method in the numerical agglomeration model of particles was combined with a breakup term of agglomeration due to bubble bursting at the free surface. Polydisperse and monodisperse polymethylmethacrylate (PMMA) particles were used in the agglomeration experiments. The agglomeration rate of the polydisperse particles under impeller stirring was increased by an increasing energy input rate, whereas the agglomeration rate under gas stirring decreased under this condition due to the larger contribution of the breakup of agglomerated particles during bubble bursting in gas stirring. At the same energy input rate, agglomeration of polydisperse particles was larger under impeller stirring than under gas stirring. The agglomeration rate of polydisperse particles was larger than that of monodisperse particles under both impeller and gas stirring at the same energy input rate. The computational temporal changes in the total number of particles were in good agreement with the experimental results. This means that the difference in the agglomeration behaviors observed in impeller and gas stirring can be explained by the turbulent coagulation and subsequent agglomerated particle breakup in gas stirring. The computational temporal change in the number of each group approximately agreed with the experimental change in both impeller and gas stirring.No potential conflict of interest relevant to this article was reported.ElsevierActa Medica Okayama1387-70031242021Effect of ultrasonic irradiation on -Fe2O3 formation by co-precipitation method with Fe3+ salt and alkaline solution108400ENHayatoKoizumiDepartment of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama UniversityMd. AzharUddinDepartment of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama UniversityYoshieiKatoDepartment of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama UniversityThe effect of ultrasonic irradiation on direct maghemite (-Fe2O3) preparation by a co-precipitation method with Fe3+ salt (Fe(NO3)3) and an excess amount of alkaline (KOH) solution without going through the conventional magnetite (Fe3O4) formation route was explored in comparison with impeller stirring. The preparation procedure for obtaining iron oxide nanoparticles was designed using the sequential processes of precipitation, decantation, drying and thermal dehydration, and ultrasonic irradiation or impeller stirring was done during the precipitation process. -ferric oxyhydroxide (-FeOOH) was partially formed in addition to -ferric oxyhydroxide (-FeOOH) and thermally dehydrated to -Fe2O3 and hematite (-Fe2O3) by ultrasonic-assisted co-precipitation of Fe3+ salt and the excess KOH solution, whereas only -FeOOH and -Fe2O3 were synthesized by impeller stirring. The difference between the products of the two methods was explained by the Lamer model associated with the nucleation and growth of FeOOH. Magnetization increased as the crystallite diameter decreased, which is estimated to facilitate partial formation of magnetic -Fe2O3. Magnetization was enhanced by a lower ultrasonic frequency due to the stronger shock wave induced by the cavitation effect.No potential conflict of interest relevant to this article was reported.SpringerActa Medica Okayama0049-697923212021Enhancement of Zinc Ion Removal from Water by Physically Mixed Particles of Iron/Iron Sulfide17ENYuyaKambaDepartment of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama UniversityMiharuUetaDepartment of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama UniversityMd. AzharUddinDepartment of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama UniversityYoshieiKatoDepartment of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama UniversityZinc (Zn) removal by physically mixed particles of zero-valent iron (Fe) and iron sulfide (FeS) was investigated as one technology for Zn removal from waste groundwater. The effects of the Fe/FeS mass ratio, including a single Fe and FeS particles, and pH on changes in the concentrations of Zn, Fe, and S were examined by a batch test and column tests, and the mechanism of Zn elimination was discussed. Among all the mixing fractions of Fe and FeS, Zn was eliminated most effectively by 3Fe/7FeS (mass ratio of Fe/FeS = 3/7). The Zn removal rate decreased in the order of 3Fe/7FeS, FeS, and Fe, whereas the Fe concentration decreased in the order of Fe, FeS, and 3Fe/7FeS. The S concentration of FeS was larger than that of 3Fe/7FeS. The Zn removal rate by physically mixed 3Fe/7FeS particles was enhanced by a local cell reaction between the Fe and FeS particles. The electrons caused by Fe corrosion moved to the FeS surface and reduced the dissolved oxygen in the solution. Zn2+, Fe2+, and OH| ions in the solution were then coprecipitated on the particles as ZnFe2(OH)6 and oxidized to ZnFe2O4. Moreover, Zn2+ was sulfurized as ZnS by both the Fe/FeS mixture and the simple FeS particles. The Zn removal rate increased with increasing pH in the range from pH 3 to 7. From a kinetic analysis of Zn removal, the rate constant of anode (Fe)/cathode (FeS) reaction was almost the same as that of ZnS formation and slightly larger than that of Fe alone.No potential conflict of interest relevant to this article was reported.WileyActa Medica Okayama0008-40349912020Suspension pattern and rising height of sedimentary particles with low concentration in a mechanically stirred vessel410420ENYuichiroTokuraDepartment of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama UniversityKeitaMiyagawaDepartment of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama UniversityMd. AzharUddinDepartment of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama UniversityYoshieiKatoDepartment of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama UniversityIn this study, the effects of impeller rotation speed, off]bottom clearance, blade angle, types of solid and liquid, etc., on the suspension pattern of sedimentary particles and particle rise height in liquid were investigated with a hemispherical vessel without baffles under low particle concentration. The transition conditions of suspension pattern between regimes I and II, and regimes II and III, were observed visually, and their non]dimensional equations were expressed with an acceptable correlation by varying the above operation factors a great deal. Here, regime I is stagnation of particles on a vessel bottom, II is partial suspension, and III is complete suspension in liquid. The non]dimensional equation of the maximum particle rise height was also successfully obtained. The combination of the non]dimensional equations of transition and maximum particle rise height permitted us to determine the adequate solid/liquid mixing operation conditions without collision of particles with device parts.No potential conflict of interest relevant to this article was reported.ElsevierActa Medica Okayama0141-39101792020Simultaneous degradation and dechlorination of poly (vinyl chloride) by a combination of superheated steam and CaO catalyst/adsorbent109225ENHarukaNishibataGraduate School of Environmental and Life Science, Okayama UniversityMd. AzharUddinGraduate School of Environmental and Life Science, Okayama UniversityYoshieiKatoGraduate School of Environmental and Life Science, Okayama UniversityIn order to explore the possibility of efficient chlorine removal from the poly (vinyl chloride) (PVC) containing waste plastics, simultaneous degradation and dechlorination of PVC at a relatively low temperature was investigated by changing the atmosphere gas and metal oxide as catalyst and/or adsorbent (catalyst/adsorbent). 5.0 g of PVC and various metallic oxides such as CaO, Fe3O4, SiO2, Al2O, Ca(OH)2, MgO were used under the superheated steam and nitrogen atmosphere of 473 K. The degradation rate of the PVC sample was small and the chlorine conversion to inorganic chloride was not observed without catalyst/adsorbent in the presence of either superheated steam or nitrogen atmosphere. Under the superheated steam atmosphere, the CaO catalyst/adsorbent resulted in much larger rates of degradation and dechlorination than any other metal oxides such as Fe3O4, SiO2, Al2O, Ca(OH)2, MgO compared with nitrogen atmosphere. The calcium compounds such as CaCl₂, CaClOH and Ca(OH)₂ were formed in the sample by the combination of CaO catalyst/adsorbent and superheated steam. The rates of PVC degradation and chlorine conversion to inorganic chlorides were dramatically enhanced beyond the stoichiometric CaO amount for the CaCl₂ formation reaction with PVC under the superheated steam atmosphere.
The CaO addition contributed to both of the PVC degradation as a catalyst and the reactant with HCl as an adsorbent, whereas the superheated steam played a role of the sample temperature increase to promote the PVC degradation through the exothermic reaction with CaO.
No potential conflict of interest relevant to this article was reported.The Minerals, Metals & Materials SocietyActa Medica Okayama2199-382362020Alkali Elution Behavior of Steelmaking Slag Packed in an Open Channel Vessel in Seawater132141ENYamatoMatsudaDepartment of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama UniversityMd. AzharUddinDepartment of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama UniversityYoshieiKatoGraduate School of Environmental and Life Science, Okayama UniversityYasuhitoMiyataSlag & Refractories Research Department, Steel Research Laboratory, JFE Steel CorporationEijiKisoMarketing Development, Slag & Cement Division, Nippon Steel CorporationThe alkali elution behavior of steelmaking slag in seawater was kinetically investigated and simulated under continuous flow in an open channel vessel with packed bed of steelmaking slag. Two types of steelmaking slags, viz. decarburization slag and dephosphorization slag, were used in this study. The alkali elution rate of decarburization slag was larger than that of dephosphorization slag due to larger free CaO content. The pH value for dephosphorization slag was almost the same as the seawater pH value in 3–4 days, whereas that for decarburization slag was stabilized in 3 days although the pH value was slightly larger than that of seawater. The capacity coefficients of alkali elution for dephosphorization and decarburization slags decreased together in an exponential manner with time. Based on a regression equation on the mass transfer capacity coefficient change with time, the alkali elution behavior was simulated and the calculated results agreed well with the experimental ones. The temporal pH change was predicted by changing slag surface area and seawater flow rate as a parameter. According to the simulation results for dephosphorization slag, the seawater pH value did not reach a high level in the ocean area.No potential conflict of interest relevant to this article was reported.SpringerActa Medica Okayama2199-3823542019Separation Between Silicon and Aluminum Powders Contained Within Pulverized Scraped Silicon-Based Waste Solar Cells by Flotation Method551560ENShoHaradaDepartment of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama UniversityMd. AzharUddinDepartment of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama UniversityYoshieiKatoDepartment of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama UniversityTakanoriKawanishiWet Process Division, Toho Kasei Co., LtdYoshiakiHayashiWet Process Division, Toho Kasei Co., Ltd There are few study examples on the separation of metals by floating method. In this study, separation of silicon and aluminum, which are the main components of silicon-based solar cell module, was carried out by floating method in order to purify silicon from waste solar cell module. The selection of surfactant, control of electric charge, wettability of the solid particles, surface tensions, and bubble surface area are important for separation of solids by floating method. Sodium dodecyl sulfate (SDS) can increase the hydrophobicity of aluminum powder due to the difference of surface potentials between silicon and aluminum. SDS behaves as a collector of aluminum as well as a frothing agent to decrease the bubble size. At a SDS concentration of 2 g/L and sample dipping time of 10 min, 80.1 mass% of aluminum was floated and separated, and the sedimentary silicon reached a purity of 90.7% from a mixture of 50 mass% aluminum and 50 mass% silicon. Finally, at a pH value of 7.0, SDS concentration between 1.0 and 2.5 g/L and air flow rate of 2.5 L/min (STP) were suitable experimental conditions to purify silicon from a mixture of silicon and aluminum by flotation separation method.No potential conflict of interest relevant to this article was reported.