The Experts below are selected from a list of 237 Experts worldwide ranked by ideXlab platform
Satoshi Asaoka - One of the best experts on this subject based on the ideXlab platform.
-
Adsorption of phosphate onto lanthanum-doped coal fly ash-Blast Furnace Cement composite.
Journal of hazardous materials, 2020Co-Authors: Satoshi Asaoka, Kohei Kawakami, Hiroyuki Saito, Tsuyoshi Ichinari, Hideaki Nohara, Oikawa TakahitoAbstract:Abstract We develop a high-performance adsorbent for phosphate removal from water or wastewater by impregnating lanthanum (La) on a coal fly ash—Blast Furnace Cement composite (La-FACC). The optimized impregnation percentage of La and calcination conditions of the La-FACC were 1% and 800 ℃ for 2 h, respectively. The adsorption kinetics of phosphate onto the La-FACC was well fit by the intra-particle diffusion model, indicating that film and intra-particle diffusion were the rate-controlling step in the adsorption process of phosphate onto the La-FACC. The pseudo second-order kinetic model could also describe the adsorption kinetics of phosphate. Hence, adsorption of phosphate onto the La-FACC occurred mainly via chemisorption. The Langmuir isotherm was appropriate for describing the phosphate adsorption behavior onto the La-FACC. The monolayer maximum adsorption capacity was 24.9 mg-P g−1. The La-FACC showed high adsorption capacity and selectivity for phosphate with a wide range of pH, and with high concentrations of coexisting ions attributed to both formation of inner sphere complexes and electrostatic interaction. Magnesium ion slightly inhibited the adsorption of phosphate. Hence, the La-FACC developed in this study is a promising adsorbent for water treatment with a wide pH range and high ion strength.
-
Removal of hydrogen sulfide with granulated coal ash under aerobic and anaerobic conditions
Journal of environmental chemical engineering, 2018Co-Authors: Satoshi Asaoka, Waqar Azeem Jadoom, Takamichi Ishidu, Takahito Oikawa, Hideo Okamura, Kenji NakamotoAbstract:Abstract Annual emissions of fly ash from the burning of coal have increased to approximately 750 million tons. It is hoped that new applications utilizing by-products from coal-fired power plants will contribute to further waste reduction and set the standard for industrial-scale recycling. The purpose of this study was to evaluate the removal rate of hydrogen sulfide by a new recycled material called granulated coal ash, which is produced from coal fly ash from coal thermal electric power stations and Blast Furnace Cement. A batch experiment was carried out to evaluate the removal rate of hydrogen sulfide by granulated coal ash under both anaerobic and aerobic conditions. The granulated coal ash could remove hydrogen sulfide under both anaerobic and aerobic conditions. However, the maximum removal of hydrogen sulfide by granulated coal ash was only 5.1 mg-S g−1 under anaerobic conditions because the manganese oxide which oxidizes hydrogen sulfide to sulfur could not be regenerated under anaerobic conditions. In contrast, the rate constant for hydrogen sulfide under aerobic conditions was high due to the multiplier effect attributed to both increasing Eh and the regeneration of manganese oxide by dissolved oxygen.
-
Optimum reaction ratio of coal fly ash to Blast Furnace Cement for effective removal of hydrogen sulfide
Chemosphere, 2017Co-Authors: Satoshi Asaoka, Kyunghoi Kim, Kazutoshi Hino, Yuzuru Hatanaka, Takahito Oikawa, Hideo Okamura, Kenji Nakamoto, Shinjiro Hayakawa, Tetsuji OkudaAbstract:Reducing hydrogen sulfide concentration in eutrophic marine sediments is crucial to maintaining healthy aquatic ecosystems. Managing fly ash, 750 million tons of which is generated annually throughout the world, is another serious environmental problem. In this study, we develop an approach that addresses both these issues by mixing coal fly ash from coal-fired power plants with Blast Furnace Cement to remediate eutrophic sediments. The purpose of this study is to optimize the mixing ratio of coal fly ash and Blast Furnace Cement to improve the rate of hydrogen sulfide removal based on scientific evidence obtained by removal experiments and XAFS, XRD, BET, and SEM images. In the case of 10 mg-S L−1of hydrogen sulfide, the highest removal rate of hydrogen sulfide was observed for 87 wt% of coal fly ash due to decreased competition of adsorption between sulfide and hydroxyl ions. Whereas regarding 100 mg-S L−1, the hydrogen sulfide removal rate was the highest for 95 wt% of coal fly ash. However, for both concentrations, the removal rate obtained by 87 wt% and 95 wt% were statistically insignificant. The crushing strength of the mixture was over 1.2 N mm−2when the coal fly ash mixing ratio was less than 95 wt%. Consequently, the mixing ratio of coal fly ash was optimized at 87 wt% in terms of achieving both high hydrogen sulfide removal rate and sufficient crushing strength.
Tetsuji Okuda - One of the best experts on this subject based on the ideXlab platform.
-
Optimum reaction ratio of coal fly ash to Blast Furnace Cement for effective removal of hydrogen sulfide
Chemosphere, 2017Co-Authors: Satoshi Asaoka, Kyunghoi Kim, Kazutoshi Hino, Yuzuru Hatanaka, Takahito Oikawa, Hideo Okamura, Kenji Nakamoto, Shinjiro Hayakawa, Tetsuji OkudaAbstract:Reducing hydrogen sulfide concentration in eutrophic marine sediments is crucial to maintaining healthy aquatic ecosystems. Managing fly ash, 750 million tons of which is generated annually throughout the world, is another serious environmental problem. In this study, we develop an approach that addresses both these issues by mixing coal fly ash from coal-fired power plants with Blast Furnace Cement to remediate eutrophic sediments. The purpose of this study is to optimize the mixing ratio of coal fly ash and Blast Furnace Cement to improve the rate of hydrogen sulfide removal based on scientific evidence obtained by removal experiments and XAFS, XRD, BET, and SEM images. In the case of 10 mg-S L−1of hydrogen sulfide, the highest removal rate of hydrogen sulfide was observed for 87 wt% of coal fly ash due to decreased competition of adsorption between sulfide and hydroxyl ions. Whereas regarding 100 mg-S L−1, the hydrogen sulfide removal rate was the highest for 95 wt% of coal fly ash. However, for both concentrations, the removal rate obtained by 87 wt% and 95 wt% were statistically insignificant. The crushing strength of the mixture was over 1.2 N mm−2when the coal fly ash mixing ratio was less than 95 wt%. Consequently, the mixing ratio of coal fly ash was optimized at 87 wt% in terms of achieving both high hydrogen sulfide removal rate and sufficient crushing strength.
Marlinda Abdul Malek - One of the best experts on this subject based on the ideXlab platform.
-
effect of curing environments on strength porosity and chloride ingress resistance of Blast Furnace slag Cement concretes a construction site study
Construction and Building Materials, 2012Co-Authors: Howji Che, Shao Siang Huang, Chao Wei Tang, Marlinda Abdul MalekAbstract:� penetration than OPC concretes. abstract Durability of concrete structures in marine environments has become a major concern to the scientific community over the past several decades. Many publications have reported the excellent performance of concrete containing mineral admixtures (MAs), such as ground granulated Blast Furnace slag (GGBS) and pulverized fuel ash (PFA), in coastal marine environments. However, the rate of hydration or pozzo- lanic activity of MAs in the concrete is slow. As a result, the resistance offered to the penetration of chlo- ride ions also increases slowly with time. This paper reports the results of an experimental study conducted to evaluate the effect of curing conditions on the strength, porosity, and chloride ingress char- acteristics of concretes made with high slag Blast Furnace Cement (HBFC) and ordinary Portland Cement (OPC). A total of six different concrete mixtures were cast and tested. The experimental variables included water-to-binder ratio (W/B) ratios, curing environments, and curing durations. W/B ratios used were 0.33, 0.34, and 0.36. Two types of curing conditions are investigated: seawater immersion and marine atmo- spheric exposure during curing at 4, 7, 28, 90, 180, and 360 day intervals. The results indicated that the curing condition had pronounced effects on the related properties. Seawater-cured specimens showed a slightly higher early strength but a lower ultimate strength as compared with air-cured spec- imens. The HBFC concretes had lower MIP porosity than the corresponding OPC concretes with the same design strength. The chloride diffusion coefficient of the HBFC concretes was much lower than that of the corresponding OPC concretes. Therefore, it may be concluded that the HBFC concretes showed consider- ably better resistance to chlorides ion penetration than the OPC concretes.
Kenji Nakamoto - One of the best experts on this subject based on the ideXlab platform.
-
Removal of hydrogen sulfide with granulated coal ash under aerobic and anaerobic conditions
Journal of environmental chemical engineering, 2018Co-Authors: Satoshi Asaoka, Waqar Azeem Jadoom, Takamichi Ishidu, Takahito Oikawa, Hideo Okamura, Kenji NakamotoAbstract:Abstract Annual emissions of fly ash from the burning of coal have increased to approximately 750 million tons. It is hoped that new applications utilizing by-products from coal-fired power plants will contribute to further waste reduction and set the standard for industrial-scale recycling. The purpose of this study was to evaluate the removal rate of hydrogen sulfide by a new recycled material called granulated coal ash, which is produced from coal fly ash from coal thermal electric power stations and Blast Furnace Cement. A batch experiment was carried out to evaluate the removal rate of hydrogen sulfide by granulated coal ash under both anaerobic and aerobic conditions. The granulated coal ash could remove hydrogen sulfide under both anaerobic and aerobic conditions. However, the maximum removal of hydrogen sulfide by granulated coal ash was only 5.1 mg-S g−1 under anaerobic conditions because the manganese oxide which oxidizes hydrogen sulfide to sulfur could not be regenerated under anaerobic conditions. In contrast, the rate constant for hydrogen sulfide under aerobic conditions was high due to the multiplier effect attributed to both increasing Eh and the regeneration of manganese oxide by dissolved oxygen.
-
Optimum reaction ratio of coal fly ash to Blast Furnace Cement for effective removal of hydrogen sulfide
Chemosphere, 2017Co-Authors: Satoshi Asaoka, Kyunghoi Kim, Kazutoshi Hino, Yuzuru Hatanaka, Takahito Oikawa, Hideo Okamura, Kenji Nakamoto, Shinjiro Hayakawa, Tetsuji OkudaAbstract:Reducing hydrogen sulfide concentration in eutrophic marine sediments is crucial to maintaining healthy aquatic ecosystems. Managing fly ash, 750 million tons of which is generated annually throughout the world, is another serious environmental problem. In this study, we develop an approach that addresses both these issues by mixing coal fly ash from coal-fired power plants with Blast Furnace Cement to remediate eutrophic sediments. The purpose of this study is to optimize the mixing ratio of coal fly ash and Blast Furnace Cement to improve the rate of hydrogen sulfide removal based on scientific evidence obtained by removal experiments and XAFS, XRD, BET, and SEM images. In the case of 10 mg-S L−1of hydrogen sulfide, the highest removal rate of hydrogen sulfide was observed for 87 wt% of coal fly ash due to decreased competition of adsorption between sulfide and hydroxyl ions. Whereas regarding 100 mg-S L−1, the hydrogen sulfide removal rate was the highest for 95 wt% of coal fly ash. However, for both concentrations, the removal rate obtained by 87 wt% and 95 wt% were statistically insignificant. The crushing strength of the mixture was over 1.2 N mm−2when the coal fly ash mixing ratio was less than 95 wt%. Consequently, the mixing ratio of coal fly ash was optimized at 87 wt% in terms of achieving both high hydrogen sulfide removal rate and sufficient crushing strength.
P. Pichniarczyk - One of the best experts on this subject based on the ideXlab platform.
-
Correlation factor between heat of hydration and compressive strength of common Cement
Construction and Building Materials, 2017Co-Authors: Tomasz Baran, P. PichniarczykAbstract:Abstract In this paper the results of the research of common and special Cements were presented. The scope included about 200 samples of industrial Cements produced in 9 manufacturing plants in Poland according to Cement standard PN-EN 197-1. Obtained results indicate that for different Cement plants strong correlation between the results of heat of hydration tests and the compressive strength after 28 days of hardening of Portland Cement CEM I without mineral additions is observed, irrespectively from strength class of that Cement. Even better correlation is observed for particular Cement plant. However, in the case of Blast Furnace Cement such relationships are in the borderline between weak and moderate for different Cement plants and moderate within one manufacturing plant. Achieved for particular Cement plant high correlation factors allow to estimate with very low error the standard compressive strength of Cement after 28 days of hardening on the basis of heat of hydration tests just after 3 days. It especially applies for Portland Cement CEM I.