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[PPS07-15] Effect of ultraviolet C irradiation on surface alteration of basalt due to evaporation of sulfuric acid
Keywords:Mars, ultraviolet rays C, sulfuric acid, trivalent iron, evaporation
A large amount of iron oxide, sulfate, chloride, etc. have been detected on the surface of Mars, which is the cause of the reddish-brown color of the surface of Mars. Also, much evidence has led to the belief that liquid water once existed widely.
As an research activity of the science club in the junior high school, the author has irradiated basalt and iron olivine soaked in water or an acidic aqueous solution with ultraviolet rays and investigated their changes (Komori, 2020). Studies related to weathering of the surface of Mars include Golden et al. (2005) and Cole (2015). No experimental research has been conducted to investigate changes in basalt in sulfuric acid while irradiating with ultraviolet rays.
Ⅰ Research purpose
In the process of drying basalt soaked in sulfuric acid aqueous solution, the effect of ultraviolet rays C on the alteration of basalt is investigated and compared with related studies.
Ⅱ Method
1 Immerse two shaped basalt samples in sulfuric acid for 24 hours. Sulfuric acid is a mixture of boiled purified water and a stock solution of sulfuric acid.
2 Take out the two basalt samples from sulfuric acid and put them in separate test tubes with the surface wet. Replace the air with nitrogen.
3 Set the two test tubes in the ultraviolet irradiator. The ultraviolet irradiator is a bundle of four 20W germicidal lamps, and irradiates the sample with ultraviolet C of about 20W / m2. One of the two test tubes was directly irradiated (UVC) and the other was covered with aluminum foil so that it was not irradiated (N).
4 Every few days after the ultraviolet irradiation, the test tube was taken out from the ultraviolet irradiator, and the basalt sample was visually observed and photographed. After that, the air in the test tube was replaced with nitrogen and returned to the ultraviolet irradiator.
5 After the experiment, the analysis of the brown powder generated on the sample surface was analyzed by XRD. The surface of the sample was photographed with a digital microscope.
Ⅲ Result
UVC produced a powdery substance on the surface of the basalt. XRD revealed that the brown powder formed on the sample UVC surface was ferric sulfate, mainly metahomanite, and the white powder was gypsum. In the sample N, it seems that a slight amount of gypsum was formed on the entire surface.
Ⅳ Discussions
On Mars in the past, it is possible that irradiation of ultraviolet C produced minerals containing Fe3+, such as metahomanite, in the process of drying basalt soaked in the sea of sulfuric acid due to regression.
As an research activity of the science club in the junior high school, the author has irradiated basalt and iron olivine soaked in water or an acidic aqueous solution with ultraviolet rays and investigated their changes (Komori, 2020). Studies related to weathering of the surface of Mars include Golden et al. (2005) and Cole (2015). No experimental research has been conducted to investigate changes in basalt in sulfuric acid while irradiating with ultraviolet rays.
Ⅰ Research purpose
In the process of drying basalt soaked in sulfuric acid aqueous solution, the effect of ultraviolet rays C on the alteration of basalt is investigated and compared with related studies.
Ⅱ Method
1 Immerse two shaped basalt samples in sulfuric acid for 24 hours. Sulfuric acid is a mixture of boiled purified water and a stock solution of sulfuric acid.
2 Take out the two basalt samples from sulfuric acid and put them in separate test tubes with the surface wet. Replace the air with nitrogen.
3 Set the two test tubes in the ultraviolet irradiator. The ultraviolet irradiator is a bundle of four 20W germicidal lamps, and irradiates the sample with ultraviolet C of about 20W / m2. One of the two test tubes was directly irradiated (UVC) and the other was covered with aluminum foil so that it was not irradiated (N).
4 Every few days after the ultraviolet irradiation, the test tube was taken out from the ultraviolet irradiator, and the basalt sample was visually observed and photographed. After that, the air in the test tube was replaced with nitrogen and returned to the ultraviolet irradiator.
5 After the experiment, the analysis of the brown powder generated on the sample surface was analyzed by XRD. The surface of the sample was photographed with a digital microscope.
Ⅲ Result
UVC produced a powdery substance on the surface of the basalt. XRD revealed that the brown powder formed on the sample UVC surface was ferric sulfate, mainly metahomanite, and the white powder was gypsum. In the sample N, it seems that a slight amount of gypsum was formed on the entire surface.
Ⅳ Discussions
On Mars in the past, it is possible that irradiation of ultraviolet C produced minerals containing Fe3+, such as metahomanite, in the process of drying basalt soaked in the sea of sulfuric acid due to regression.