The Experts below are selected from a list of 6516 Experts worldwide ranked by ideXlab platform
Yoshinori Kawase - One of the best experts on this subject based on the ideXlab platform.
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hydroxyl radical generation by zero valent iron cu zvi cu bimetallic catalyst in wastewater treatment heterogeneous fenton fenton like reactions by fenton reagents formed in situ under Oxic Conditions
Chemical Engineering Journal, 2018Co-Authors: Rina Yamaguchi, Moe Suzuki, Shunji Kurosu, Yoshinori KawaseAbstract:Abstract Zero-valent iron (ZVI) has been recognized as a heterogeneous Fenton/Fenton-like catalyst generating hydroxyl radical (OH radical). ZVI bimetallic catalysts modified by the deposition of transition metals on the ZVI surface have been proposed as alternatives to enhance the reactivity of ZVI catalyst. However, it is not clear from the literature whether OH radical is actively generated via the Fenton/Fenton-like reactions in ZVI bimetallic catalyst systems. To quantify the generation of OH radical by ZVI/Cu bimetallic catalysts, the amount of generated OH radical was measured under the Oxic Condition. Although the maximum amount of generated OH radical by ZVI/Cu bimetallic catalysts was obtained at pH 3 being an optimal pH for the Fenton reaction, OH radical generation by ZVI/Cu bimetallic catalysts was considerably restricted by the inadequate in-situ generation of H2O2 and the generation of OH radical was inhibited due to Cu deposition on ZVI surface. While the deposition of Cu on the ZVI surface enhanced the removal of Orange II via the facilitation of reductive degradation and the increase in adsorption capability on the surface of ZVI/Cu bimetallic catalysts, it could not stimulate the OH radical generation or the oxidative reactivity of heterogeneous Fenton/Fenton-like catalyst. The present study confirmed that the passivation of ZVI surface accelerated by the deposition of Cu on ZVI surface inhibited the OH radical generation. The kinetic models for OH radical generation by ZVI/Cu bimetallic catalysts were developed by considering the linkage of OH radical generation with eluted Fe and Cu ions. The model predictions could simulate the experimental results reasonably.
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Removal of antibiotic sulfamethoxazole by zero-valent iron under Oxic and anOxic Conditions: Removal mechanisms in acidic, neutral and alkaline solutions.
Journal of environmental management, 2017Co-Authors: Maki Kobayashi, Rina Yamaguchi, Shunji Kurosu, Yoshinori KawaseAbstract:Removal of antibiotic sulfamethoxazole (SMX) by zero-valent iron (ZVI) was examined in the range of pH from 3.0 to 11.0 under Oxic and anOxic Conditions to clarify mechanisms of SMX removal in acidic, neutral and alkaline solutions. SMX removal was affected by solution pH and related to the speciation of SMX. Under the Oxic Condition, the maximums of SMX removal efficiency and rate were obtained at pH 3.0. The SMX removal efficiency decreased from 100 to 32% with increasing pH in the acidic solutions (3 ≦ pH ≦ 5) and increased to 88% in neutral and moderately alkaline solutions (6 ≦ pH ≦ 10). In highly alkaline solution (pH = 11), the SMX removal was significantly suppressed due to the formation of passive layer on ZVI surface. The removal rate of SMX under the Oxic Condition significantly declined with increasing pH. Under the anOxic Condition, SMX removal was completed within 300 min in the acidic solutions and remained to less than 70% after 300 min in neutral and moderately alkaline solutions. For pH ≧ 10, no SMX removal practically occurred. The removal rate of SMX under the anOxic Condition approximately remained constant in the acidic solution and largely decreased in neutral and moderately alkaline solutions. SMX removal by ZVI was found to be dominated by the reductive degradation and adsorption under both the Oxic and anOxic Conditions. It was concluded that ZVI has the potential for effective removal of antibiotic SMX under the Oxic and anOxic Conditions. A kinetic model could reasonably simulate the dynamic profiles of SMX removal.
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Removal of anionic surfactant sodium dodecyl benzene sulfonate (SDBS) from wastewaters by zero-valent iron (ZVI): predominant removal mechanism for effective SDBS removal.
Environmental science and pollution research international, 2017Co-Authors: Akari Takayanagi, Maki Kobayashi, Yoshinori KawaseAbstract:Mechanisms for removal of anionic surfactant sodium dodecyl benzene sulfonate (SDBS) in wastewaters by zero-valent iron (ZVI) were systematically examined. The contributions of four removal mechanisms, i.e., reductive degradation, oxidative degradation, adsorption, and precipitation, changed significantly with solution pH were quantified and the effective removal of SDBS by ZVI was found to be attributed to the adsorption capability of iron oxides/hydroxides on ZVI surface at nearly neutral pH instead of the degradation at acidic Condition. The fastest SDBS removal rate and the maximum TOC (total organic carbon) removal efficiency were obtained at pH 6.0. The maximum TOC removal at pH 6.0 was 77.8%, and the contributions of degradation, precipitation, and adsorption to TOC removal were 4.6, 14.9, and 58.3%, respectively. At pH 3.0, which is an optimal pH for oxidative degradation by the Fenton reaction, the TOC removal was only 9.8% and the contributions of degradation, precipitation, and adsorption to TOC removal were 2.3, 4.6, and 2.9%, respectively. The electrostatic attraction between dodecyl benzene sulfate anion and the iron oxide/hydroxide layer controlled the TOC removal of SDBS. The kinetic model based on the Langmuir-Hinshelwood/Eley-Rideal approach could successfully describe the experimental results for SDBS removal by ZVI with the averaged correlation coefficient of 0.994. ZVI was found to be an efficient material toward the removal of anionic surfactant at nearly neutral pH under the Oxic Condition.
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Hydroxyl radical generation linked with iron dissolution and dissolved oxygen consumption in zero-valent iron wastewater treatment process
Chemical Engineering Journal, 2016Co-Authors: Takuma Harada, Tomonori Yatagai, Yoshinori KawaseAbstract:Abstract In zero-valent iron (ZVI) wastewater treatments, organic pollutants are degraded by hydroxyl radical (OH radical) generated via the Fenton reaction besides by the reductive reaction. The generation of OH radical is initiated by the dissolution of ZVI. The strong linkage of OH radical generation by ZVI with eluted ferrous ion and dissolved oxygen (DO) through the iron dissolution and the formation of passive iron oxide/hydroxide layer on the ZVI surface was found. While OH radicals were gradually generated by microscale ZVI (mZVI) until the termination of iron dissolution, the OH radical generation by nanoscale ZVI (nZVI) was very quick at the initial phase, subsequently slowed down and terminated. Although the rate of OH radical generation with nZVI was much faster than that with mZVI, the amount of generated OH radical with nZVI was less than mZVI under the same iron dosage Conditions. With increasing ZVI dosage and controlled solution pH value, the amount of generated OH radical for both mZVI and nZVI increased and decreased, respectively. For nZVI under the Oxic Condition, the quick depletion of DO at the initial phase accompanied with the sequential recovery to the saturation concentration was found. A reaction kinetic model was developed to quantify a linkage of OH radical generation with the iron dissolution and the formation of passive iron oxide/hydroxide layer on the ZVI surface. The linkage could be reasonably simulated by the proposed kinetic model with the correlation coefficient of >0.828.
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Removal of cationic dye methylene blue by zero-valent iron: Effects of pH and dissolved oxygen on removal mechanisms.
Journal of environmental science and health. Part A Toxic hazardous substances & environmental engineering, 2015Co-Authors: Xuan Sun, Moe Suzuki, Tomoyo Kurokawa, Minoru Takagi, Yoshinori KawaseAbstract:Effects of pH and dissolved oxygen on mechanisms for decolorization and total organic carbon (TOC) removal of cationic dye methylene blue (MB) by zero-valent iron (ZVI) were systematically examined. Decolorization and TOC removal of MB by ZVI are attributed to the four potential mechanisms, i.e. reduction, degradation, precipitation and adsorption. The contributions of four mechanisms were quantified at pH 3.0, 6.0 and 10.0 in the Oxic and anOxic systems. The maximum efficiencies of decolorization and TOC removal of MB were found at pH 6.0. The TOC removal efficiencies at pH 3.0 and 10.0 were 11.0 and 17.0%, respectively which were considerably lower as compared with 68.1% at pH 6.0. The adsorption, which was favorable at higher pH but was depressed by the passive layer formed on the ZVI surface at alkaline Conditions, characterized the effects of pH on decolorization and TOC removal of MB. The efficiencies of decolorization and TOC removal at pH 6.0 under the anOxic Condition were 73.0 and 59.0%, respectively, which were comparable to 79.9 and 55.5% obtained under the Oxic Condition. In the Oxic and anOxic Conditions, however, the contributions of removal mechanisms were quite different. Although the adsorption dominated the decolorization and TOC removal under the Oxic Condition, the contribution of precipitation was largely superior to that of adsorption under the anOxic Condition.
Ping Ning - One of the best experts on this subject based on the ideXlab platform.
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alternating anOxic Oxic Condition combined with step feeding mode for nitrogen removal in granular sequencing batch reactors gsbrs
Separation and Purification Technology, 2013Co-Authors: Fang-yuan Chen, Yong-qiang Liu, Joo-hwa Tay, Ping NingAbstract:Abstract Alternating anOxic/Oxic Condition combined with step-feeding mode (AASF) has been reported to be an efficient method for nitrogen removal in granular sequencing batch reactor by our previous work. As carbon/nitrogen (C/N) ratio is one of the key factors impacting nitrogen removal efficiency, batch experiments using granules with a mean size of 1.3 mm under AASF were carried out for nitrogen removal from synthetic wastewater with C/N ratio of 5:1 and 3:1, respectively. It was found that over 90% nitrogen efficiency could be achieved for both C/N of 5 and 3. Furthermore, over 2 months operation was maintained for treating the wastewater with C/N ratio of 5:1 to investigate the long-term stability of granules under the new operational strategy. The results showed that AASF mode in GSBR could achieve over 85% nitrogen removal efficiency with great stability for long-term stability. This indicated that alternating anOxic/Oxic Condition combined with step-feeding mode is an effective strategy for nitrogen removal even from wastewater with low C/N ratio in granular sequencing batch reactor.
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Alternating anOxic/Oxic Condition combined with step-feeding mode for nitrogen removal in granular sequencing batch reactors (GSBRs)
Separation and Purification Technology, 2013Co-Authors: Fang-yuan Chen, Yong-qiang Liu, Joo-hwa Tay, Ping NingAbstract:Abstract Alternating anOxic/Oxic Condition combined with step-feeding mode (AASF) has been reported to be an efficient method for nitrogen removal in granular sequencing batch reactor by our previous work. As carbon/nitrogen (C/N) ratio is one of the key factors impacting nitrogen removal efficiency, batch experiments using granules with a mean size of 1.3 mm under AASF were carried out for nitrogen removal from synthetic wastewater with C/N ratio of 5:1 and 3:1, respectively. It was found that over 90% nitrogen efficiency could be achieved for both C/N of 5 and 3. Furthermore, over 2 months operation was maintained for treating the wastewater with C/N ratio of 5:1 to investigate the long-term stability of granules under the new operational strategy. The results showed that AASF mode in GSBR could achieve over 85% nitrogen removal efficiency with great stability for long-term stability. This indicated that alternating anOxic/Oxic Condition combined with step-feeding mode is an effective strategy for nitrogen removal even from wastewater with low C/N ratio in granular sequencing batch reactor.
Fang-yuan Chen - One of the best experts on this subject based on the ideXlab platform.
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alternating anOxic Oxic Condition combined with step feeding mode for nitrogen removal in granular sequencing batch reactors gsbrs
Separation and Purification Technology, 2013Co-Authors: Fang-yuan Chen, Yong-qiang Liu, Joo-hwa Tay, Ping NingAbstract:Abstract Alternating anOxic/Oxic Condition combined with step-feeding mode (AASF) has been reported to be an efficient method for nitrogen removal in granular sequencing batch reactor by our previous work. As carbon/nitrogen (C/N) ratio is one of the key factors impacting nitrogen removal efficiency, batch experiments using granules with a mean size of 1.3 mm under AASF were carried out for nitrogen removal from synthetic wastewater with C/N ratio of 5:1 and 3:1, respectively. It was found that over 90% nitrogen efficiency could be achieved for both C/N of 5 and 3. Furthermore, over 2 months operation was maintained for treating the wastewater with C/N ratio of 5:1 to investigate the long-term stability of granules under the new operational strategy. The results showed that AASF mode in GSBR could achieve over 85% nitrogen removal efficiency with great stability for long-term stability. This indicated that alternating anOxic/Oxic Condition combined with step-feeding mode is an effective strategy for nitrogen removal even from wastewater with low C/N ratio in granular sequencing batch reactor.
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Alternating anOxic/Oxic Condition combined with step-feeding mode for nitrogen removal in granular sequencing batch reactors (GSBRs)
Separation and Purification Technology, 2013Co-Authors: Fang-yuan Chen, Yong-qiang Liu, Joo-hwa Tay, Ping NingAbstract:Abstract Alternating anOxic/Oxic Condition combined with step-feeding mode (AASF) has been reported to be an efficient method for nitrogen removal in granular sequencing batch reactor by our previous work. As carbon/nitrogen (C/N) ratio is one of the key factors impacting nitrogen removal efficiency, batch experiments using granules with a mean size of 1.3 mm under AASF were carried out for nitrogen removal from synthetic wastewater with C/N ratio of 5:1 and 3:1, respectively. It was found that over 90% nitrogen efficiency could be achieved for both C/N of 5 and 3. Furthermore, over 2 months operation was maintained for treating the wastewater with C/N ratio of 5:1 to investigate the long-term stability of granules under the new operational strategy. The results showed that AASF mode in GSBR could achieve over 85% nitrogen removal efficiency with great stability for long-term stability. This indicated that alternating anOxic/Oxic Condition combined with step-feeding mode is an effective strategy for nitrogen removal even from wastewater with low C/N ratio in granular sequencing batch reactor.
Yong-qiang Liu - One of the best experts on this subject based on the ideXlab platform.
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alternating anOxic Oxic Condition combined with step feeding mode for nitrogen removal in granular sequencing batch reactors gsbrs
Separation and Purification Technology, 2013Co-Authors: Fang-yuan Chen, Yong-qiang Liu, Joo-hwa Tay, Ping NingAbstract:Abstract Alternating anOxic/Oxic Condition combined with step-feeding mode (AASF) has been reported to be an efficient method for nitrogen removal in granular sequencing batch reactor by our previous work. As carbon/nitrogen (C/N) ratio is one of the key factors impacting nitrogen removal efficiency, batch experiments using granules with a mean size of 1.3 mm under AASF were carried out for nitrogen removal from synthetic wastewater with C/N ratio of 5:1 and 3:1, respectively. It was found that over 90% nitrogen efficiency could be achieved for both C/N of 5 and 3. Furthermore, over 2 months operation was maintained for treating the wastewater with C/N ratio of 5:1 to investigate the long-term stability of granules under the new operational strategy. The results showed that AASF mode in GSBR could achieve over 85% nitrogen removal efficiency with great stability for long-term stability. This indicated that alternating anOxic/Oxic Condition combined with step-feeding mode is an effective strategy for nitrogen removal even from wastewater with low C/N ratio in granular sequencing batch reactor.
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Alternating anOxic/Oxic Condition combined with step-feeding mode for nitrogen removal in granular sequencing batch reactors (GSBRs)
Separation and Purification Technology, 2013Co-Authors: Fang-yuan Chen, Yong-qiang Liu, Joo-hwa Tay, Ping NingAbstract:Abstract Alternating anOxic/Oxic Condition combined with step-feeding mode (AASF) has been reported to be an efficient method for nitrogen removal in granular sequencing batch reactor by our previous work. As carbon/nitrogen (C/N) ratio is one of the key factors impacting nitrogen removal efficiency, batch experiments using granules with a mean size of 1.3 mm under AASF were carried out for nitrogen removal from synthetic wastewater with C/N ratio of 5:1 and 3:1, respectively. It was found that over 90% nitrogen efficiency could be achieved for both C/N of 5 and 3. Furthermore, over 2 months operation was maintained for treating the wastewater with C/N ratio of 5:1 to investigate the long-term stability of granules under the new operational strategy. The results showed that AASF mode in GSBR could achieve over 85% nitrogen removal efficiency with great stability for long-term stability. This indicated that alternating anOxic/Oxic Condition combined with step-feeding mode is an effective strategy for nitrogen removal even from wastewater with low C/N ratio in granular sequencing batch reactor.
Joo-hwa Tay - One of the best experts on this subject based on the ideXlab platform.
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alternating anOxic Oxic Condition combined with step feeding mode for nitrogen removal in granular sequencing batch reactors gsbrs
Separation and Purification Technology, 2013Co-Authors: Fang-yuan Chen, Yong-qiang Liu, Joo-hwa Tay, Ping NingAbstract:Abstract Alternating anOxic/Oxic Condition combined with step-feeding mode (AASF) has been reported to be an efficient method for nitrogen removal in granular sequencing batch reactor by our previous work. As carbon/nitrogen (C/N) ratio is one of the key factors impacting nitrogen removal efficiency, batch experiments using granules with a mean size of 1.3 mm under AASF were carried out for nitrogen removal from synthetic wastewater with C/N ratio of 5:1 and 3:1, respectively. It was found that over 90% nitrogen efficiency could be achieved for both C/N of 5 and 3. Furthermore, over 2 months operation was maintained for treating the wastewater with C/N ratio of 5:1 to investigate the long-term stability of granules under the new operational strategy. The results showed that AASF mode in GSBR could achieve over 85% nitrogen removal efficiency with great stability for long-term stability. This indicated that alternating anOxic/Oxic Condition combined with step-feeding mode is an effective strategy for nitrogen removal even from wastewater with low C/N ratio in granular sequencing batch reactor.
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Alternating anOxic/Oxic Condition combined with step-feeding mode for nitrogen removal in granular sequencing batch reactors (GSBRs)
Separation and Purification Technology, 2013Co-Authors: Fang-yuan Chen, Yong-qiang Liu, Joo-hwa Tay, Ping NingAbstract:Abstract Alternating anOxic/Oxic Condition combined with step-feeding mode (AASF) has been reported to be an efficient method for nitrogen removal in granular sequencing batch reactor by our previous work. As carbon/nitrogen (C/N) ratio is one of the key factors impacting nitrogen removal efficiency, batch experiments using granules with a mean size of 1.3 mm under AASF were carried out for nitrogen removal from synthetic wastewater with C/N ratio of 5:1 and 3:1, respectively. It was found that over 90% nitrogen efficiency could be achieved for both C/N of 5 and 3. Furthermore, over 2 months operation was maintained for treating the wastewater with C/N ratio of 5:1 to investigate the long-term stability of granules under the new operational strategy. The results showed that AASF mode in GSBR could achieve over 85% nitrogen removal efficiency with great stability for long-term stability. This indicated that alternating anOxic/Oxic Condition combined with step-feeding mode is an effective strategy for nitrogen removal even from wastewater with low C/N ratio in granular sequencing batch reactor.
