Kyushu University Academic Staff Educational and Research Activities Database
List of Papers
Yabushita Akihiro Last modified date:2021.06.04

Associate Professor / Department of Advanced Materials Science and Engineering / Faculty of Engineering Sciences


Papers
1. Kosuke Watanabe, Shohei Matsuda, Carlos A. Cuevas, Alfonso Saiz-Lopez, Akihiro Yabushita, Yukio Nakano, Experimental Determination of the Photooxidation of Aqueous I
-
as a Source of Atmospheric I
2, ACS Earth and Space Chemistry, 10.1021/acsearthspacechem.9b00007, 3, 4, 669-679, 2019.04, The chemistry of iodine plays an important role in the oxidizing capacity of the global marine atmosphere. In this study, we experimentally determine the photooxidation parameters of iodide ions in aqueous phase (I
-

(aq)
) and estimate the subsequent emission of gaseous iodine molecules (I
2(g)
) into the atmosphere. The values of the molar absorption coefficient (ϵ
iodide
(λ)) and the photooxidative quantum yields (φ
iodide
(λ)) of I
-

(aq)
in the range of 290-500 nm were determined. The influence of pH and dissolved oxygen (DO) on the values of φ
iodide
(λ) was also investigated. The emission of I
2(g)
into the atmosphere following the photooxidation of I
-

(aq)
in deionized water solution (pH 5.6, DO 7.8 mg L
-1
) and artificial seawater solution (pH 8.0, DO 7.0 mg L
-1
) was estimated to be (2.2 × 10
-8
× [I
-

(aq)
]
sea
) and (1.8 × 10
-8
× [I
-

(aq)
]
sea
) mol L
-1
s
-1
, respectively. Using a global chemistry-climate model, we estimated that the photooxidation of I
-

(aq)
can increase the atmospheric iodine budget by up to ∼8% over some oceanic regions..
2. Fatin Hazwani M. Azahar, Sourav Mitra, Akihiro Yabushita, Akira Harata, Bidyut Baran Saha, Thu Kyaw, Improved model for the isosteric heat of adsorption and impacts on the performance of heat pump cycles, Applied Thermal Engineering, 10.1016/j.applthermaleng.2018.07.131, 143, 688-700, 2018.10, The isosteric heat of adsorption strongly associates with the energetics of the adsorption processes. Being a direct function of the uptake amount, accurate modelling of the isosteric heat of adsorption is crucial in the design and development of adsorption systems. The isosteric heat of adsorption is often calculated using the Clausius-Clayperon equation with the perfect gas assumption and negligible adsorbed phase volume. We present a thermodynamic model of the isosteric heat of adsorption that addresses the non-ideal behaviour and the variation in the adsorbed phase density. The model is first validated using experimental data in comparison with the available models in the literature that invoke the ideal gas assumption with negligible adsorbed phase volume. Using these models, the isosteric heat for adsorption processes is examined from partial vacuum to high pressure as well as adsorption temperatures above the critical point. The impact of the prediction by each model on the system performance is then assessed in terms of the theoretical COP. For the realistic evaluation of system COP, an improved equilibrium cycle model is developed and the system performance is investigated using various models for the isosteric heat of adsorption. For adsorption at partial vacuum conditions, the COP values predicted by the ideal model are up to 1.8% higher when compared to the calculations using the present model. For high-pressure adsorption below the critical temperature, for example, Maxsorb III + R134a pair, the present model predicts 13% lower COP than the models available in the literature. The variation in the adsorbed phase density addressed in the present model leads to a higher value of isosteric heat (3.8%–8.6%) for adsorption above the critical temperature..
3. S. Matsuda, M. Yamazaki, A. Harata, A. Yabushita, CO2formation yields from different states of CO adsorbed on amorphous solid water under 157 nm photoirradiation, Chemistry Letters, 47, 4, 468-471, 2018.04.
4. Kitae Kim, Akihiro Yabushita, Masanori Okumura, Alfonso Saiz-Lopez, Carlos A. Cuevas, Christopher S. Blaszczak-Boxe, Dae Wi Min, Ho-Il Yoon, Wonyong Choi, Production of Molecular Iodine and Tri-iodide in the Frozen Solution of Iodide: Implication for Polar Atmosphere, Environmental Science & Technology, 50, 1280-1287, 2016.01.
5. T. Hidemori, T. Nakayama, Y. Matsumi, T. Kinugawa, A. Yabushita, M. Ohashi, T. Miyoshi, S. Irei, A. Takami, N. Kaneyasu, A. Yoshino, R. Suzuki, Y. Yumoto, S. Hatakeyama, Characteristics of atmospheric aerosols containing heavy metals measured on Fukue Island, Japan, Atmospheric Environment, 97, 447-455, 2014.05.
6. P. D. Hamer, D. E. Shallcross, A. Yabushita, M. Kawasaki, V. Marécal, C. S. Boxe, Investigating the photo-oxidative and heterogeneous chemical production of HCHO in the snowpack at the South Pole, Antarctica, Environmental Chemistry, 11, 459-471, 2014.05.