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Koichi Kakimoto - One of the best experts on this subject based on the ideXlab platform.
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Modeling the Non-Equilibrium Process of the Chemical Adsorption of Ammonia on GaN(0001) Reconstructed Surfaces Based on Steepest-Entropy-Ascent Quantum Thermodynamics.
Materials, 2017Co-Authors: Akira Kusaba, Guanchen Li, Michael R. Von Spakovsky, Yoshihiro Kangawa, Koichi KakimotoAbstract:Clearly understanding elementary growth Processes that depend on surface reconstruction is essential to controlling vapor-phase epitaxy more precisely. In this study, ammonia chemical adsorption on GaN(0001) reconstructed surfaces under metalorganic vapor phase epitaxy (MOVPE) conditions (3Ga-H and Nad-H + Ga-H on a 2 × 2 unit cell) is investigated using steepest-entropy-ascent quantum thermodynamics (SEAQT). SEAQT is a thermodynamic-ensemble based, first-principles framework that can predict the behavior of non-Equilibrium Processes, even those far from Equilibrium where the state evolution is a combination of reversible and irreversible dynamics. SEAQT is an ideal choice to handle this problem on a first-principles basis since the chemical adsorption Process starts from a highly non-Equilibrium state. A result of the analysis shows that the probability of adsorption on 3Ga-H is significantly higher than that on Nad-H + Ga-H. Additionally, the growth temperature dependence of these adsorption probabilities and the temperature increase due to the heat of reaction is determined. The non-Equilibrium thermodynamic modeling applied can lead to better control of the MOVPE Process through the selection of preferable reconstructed surfaces. The modeling also demonstrates the efficacy of DFT-SEAQT coupling for determining detailed non-Equilibrium Process characteristics with a much smaller computational burden than would be entailed with mechanics-based, microscopic-mesoscopic approaches.
Akira Kusaba - One of the best experts on this subject based on the ideXlab platform.
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Modeling the Non-Equilibrium Process of the Chemical Adsorption of Ammonia on GaN(0001) Reconstructed Surfaces Based on Steepest-Entropy-Ascent Quantum Thermodynamics.
Materials, 2017Co-Authors: Akira Kusaba, Guanchen Li, Michael R. Von Spakovsky, Yoshihiro Kangawa, Koichi KakimotoAbstract:Clearly understanding elementary growth Processes that depend on surface reconstruction is essential to controlling vapor-phase epitaxy more precisely. In this study, ammonia chemical adsorption on GaN(0001) reconstructed surfaces under metalorganic vapor phase epitaxy (MOVPE) conditions (3Ga-H and Nad-H + Ga-H on a 2 × 2 unit cell) is investigated using steepest-entropy-ascent quantum thermodynamics (SEAQT). SEAQT is a thermodynamic-ensemble based, first-principles framework that can predict the behavior of non-Equilibrium Processes, even those far from Equilibrium where the state evolution is a combination of reversible and irreversible dynamics. SEAQT is an ideal choice to handle this problem on a first-principles basis since the chemical adsorption Process starts from a highly non-Equilibrium state. A result of the analysis shows that the probability of adsorption on 3Ga-H is significantly higher than that on Nad-H + Ga-H. Additionally, the growth temperature dependence of these adsorption probabilities and the temperature increase due to the heat of reaction is determined. The non-Equilibrium thermodynamic modeling applied can lead to better control of the MOVPE Process through the selection of preferable reconstructed surfaces. The modeling also demonstrates the efficacy of DFT-SEAQT coupling for determining detailed non-Equilibrium Process characteristics with a much smaller computational burden than would be entailed with mechanics-based, microscopic-mesoscopic approaches.
Shalini Sikarwar - One of the best experts on this subject based on the ideXlab platform.
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adsorptive and desorptive studies on toxic dye amaranth onto de oiled mustard from wastewater
Desalination and Water Treatment, 2011Co-Authors: Rajeev Jain, Shalini SikarwarAbstract:De-oiled mustard, an oil mill waste, was treated as an adsorbent for Amaranth, an azo dye currently used in paper and textile industries. The presence of Amaranth in these effluents causes obvious environmental and health problems. Kinetic studies of adsorption of Amaranth to de-oiled mustard were conducted in batch conditions at 30°C. The paper incorporates effect of pH, temperature, amount of adsorbent, contact time, concentration of adsorbate, particle size on adsorption. The adsorption Process followed a pseudo-first order model. The Equilibrium Process showed to be well described by both Freundlich and Langmuir models, at 30°C, 40°C and 50°C. Thermodynamic parameters like free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) of the systems, respectively, were calculated by using Langmuir constant. The estimated values for ΔG° were –8.027 ×?103 and –1.5322 ×?103 over activated carbon and activated de-oiled mustard at 303 K (30°C), indicate toward a spontaneous Process. Desorption studies indicate that elut...
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Adsorptive removal of Erythrosine dye onto activated low cost de-oiled mustard.
Journal of Hazardous Materials, 2008Co-Authors: Rajeev Jain, Shalini SikarwarAbstract:Abstract The present paper is aimed to investigate and develop cheap adsorption methods for colour removal from wastewater using waste material de-oiled mustard as adsorbent. De-oiled mustard, a biosorbent, was successfully utilized for removing a water-soluble xanthene dye, Erythrosine from wastewater. Kinetic studies of adsorption of Erythrosine at de-oiled mustard were carried out at 30 °C, using aqueous solutions with 5 × 10 −5 M concentration of Erythrosine. The adsorption Process followed a pseudo-first order model. The Equilibrium Process can be well described by both Freundlich and Langmuir models, at 30, 40 and 50 °C. Free energy of adsorption (Δ G °), enthalpy (Δ H °), and entropy (Δ S °) changes were calculated to predict the nature of adsorption. The estimated values for Δ G ° were −12.81 × 10 3 and −12.57 × 10 3 over activated carbon and activated de-oiled mustard at 203 K (30 °C), indicate toward a spontaneous Process. The positive value for Δ H ° indicates that the adsorption of Erythrosine dye to de-oiled mustard is an endothermic Process.
Jiunnfwu Lee - One of the best experts on this subject based on the ideXlab platform.
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fourier transform infrared spectroscopic analysis of fruit peels before and after the adsorption of heavy metal ions from aqueous solution
Journal of Chemical & Engineering Data, 2011Co-Authors: Munusamy Thirumavalavan, Yiling Lai, Jiunnfwu LeeAbstract:For orange peel (OP), lemon peel (LP), and banana peel (BP) as adsorbents for removal of heavy metal ions such as Cu2+, Ni2+, Cd2+, Pb2+, and Zn2+ from aqueous solution, a simple FT-IR technique was used and discussed to study the variation in functional groups upon modification. Metal−carbon bond formation was witnessed by FT-IR during metal ion adsorption. All of these adsorbents were characterized by FT-IR, BET, and SEM. The presence of carboxylic and hydroxyl groups was confirmed by FT-IR. The FT-IR spectrum of lemon peel cellulose (LPC) showed well resolved peaks for carboxylic acid and hydroxyl groups compared to LP indicating the appreciable contents of carboxylic acid and hydroxyl groups in LPC. The widely used Langmuir adsorption isotherms were used to describe the adsorption Equilibrium Process. The adsorption capacity of the metal ions such as Cu2+ and Ni2+ was found to be more than those of other metal ions. Upon comparison of the adsorbents, surface modified LPC (LPCACS) was found to show enh...
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effective adsorption of heavy metal ions cu2 pb2 zn2 from aqueous solution by immobilization of adsorbents on ca alginate beads
Toxicological & Environmental Chemistry, 2010Co-Authors: Yiling Lai, Munusamy Thirumavalavan, Jiunnfwu LeeAbstract:The performance of adsorbent system consisting of orange peel cellulose (OPC), banana peel cellulose (BPC), orange peel cellulose immobilized Ca-alginate beads (OPCCA) and banana peel cellulose immobilized Ca-alginate beads (BPCCA) for the removal of Cu2+, Pb2+, and Zn2+ from an aqueous solution was tested. The widely used Langmuir isotherm model was utilized to describe the adsorption Equilibrium Process. OPC and BPC were characterized by SEM and Fourier transform infrared spectroscopy (FT–IR) techniques. The concentration of metal ions was varied in order to obtain optimum concentration level. The effect of pH was studied at different pH values. The role of cellulose in the case of OPC and BPC and the role of alginate in OPCCA and BPCCA were well understood leading to two different mechanisms in native and immobilized cellulose. OPC was found to be a better adsorbent among OPC and BPC, and Cu2+ was considered to be adsorbed more effectively than Pb2+ and Zn2+. The extent of enhancement of adsorption cap...
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cellulose based native and surface modified fruit peels for the adsorption of heavy metal ions from aqueous solution langmuir adsorption isotherms
Journal of Chemical & Engineering Data, 2010Co-Authors: Munusamy Thirumavalavan, Yiling Lai, Lingchu Lin, Jiunnfwu LeeAbstract:A viable and cost-effective technology was explored in this present task for removal of heavy metal ions such as Cu2+, Ni2+, Zn2+, Cd2+, and Pb2+ from aqueous solution using three fruit peels such as orange peel (OP), lemon peel (LP), and banana peel (BP). The surface of the LP and lemon peel cellulose (LPC) was chemically modified. All these adsorbents were characterized by FT-IR, BET, and SEM. The widely used Langmuir adsorption isotherms were used to describe the adsorption Equilibrium Process. The adsorption capacity of metal ions such as Cu2+ and Ni2+ was found to be more than that of other metal ions. Upon comparison of the adsorbents, surface modified LPC (LPCACS) was found to show enhanced adsorption activity. A comparative study of adsorption was carried out with activated carbon (AC) also from which it was inferred that the order of the adsorption capacity is as follows: LPCACS > LPC > AC > LP.
Guanchen Li - One of the best experts on this subject based on the ideXlab platform.
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Modeling the Non-Equilibrium Process of the Chemical Adsorption of Ammonia on GaN(0001) Reconstructed Surfaces Based on Steepest-Entropy-Ascent Quantum Thermodynamics.
Materials, 2017Co-Authors: Akira Kusaba, Guanchen Li, Michael R. Von Spakovsky, Yoshihiro Kangawa, Koichi KakimotoAbstract:Clearly understanding elementary growth Processes that depend on surface reconstruction is essential to controlling vapor-phase epitaxy more precisely. In this study, ammonia chemical adsorption on GaN(0001) reconstructed surfaces under metalorganic vapor phase epitaxy (MOVPE) conditions (3Ga-H and Nad-H + Ga-H on a 2 × 2 unit cell) is investigated using steepest-entropy-ascent quantum thermodynamics (SEAQT). SEAQT is a thermodynamic-ensemble based, first-principles framework that can predict the behavior of non-Equilibrium Processes, even those far from Equilibrium where the state evolution is a combination of reversible and irreversible dynamics. SEAQT is an ideal choice to handle this problem on a first-principles basis since the chemical adsorption Process starts from a highly non-Equilibrium state. A result of the analysis shows that the probability of adsorption on 3Ga-H is significantly higher than that on Nad-H + Ga-H. Additionally, the growth temperature dependence of these adsorption probabilities and the temperature increase due to the heat of reaction is determined. The non-Equilibrium thermodynamic modeling applied can lead to better control of the MOVPE Process through the selection of preferable reconstructed surfaces. The modeling also demonstrates the efficacy of DFT-SEAQT coupling for determining detailed non-Equilibrium Process characteristics with a much smaller computational burden than would be entailed with mechanics-based, microscopic-mesoscopic approaches.