A simple and rapid in situ separation and preconcentration method for the determination of molybdenum in environmental waters has been developed based on solid-phase extraction using a Sep-Pak CM cartridge loaded with zirconium (Zr-SP), followed by the determination of molybdenum with GFAAS. The adsorption and desorption behaviors of molybdenum on a Zr-SP were strongly affected by the pH of the solution. Molybdenum in the solution was quantitatively adsorbed on a Zr-SP at lower than pH 7. On the other hand, the desorption of molybdenum adsorbed on the Zr-SP was quantitatively made with solutions of higher than pH 12. A molybdenum solution adjusted to 0.2 mol L⁻¹ nitric acid was passed through a Zr-SP at a flow rate of 10 mL min⁻¹ for the adsorption of molybdenum. In field work, a guraduated syringe was used for the collection of molybdenum to make these operations simple and easy by hand in a short time. A mixture of 0.05 mol L⁻¹ sodium hydroxide and 0.05 mol L⁻¹ potassium sodium tartrate as an elute was found to more easily eluent molybdenum from Zr-SP than a 0.05 mol L⁻¹ sodium hydroxide solution. Therefore, the molybdenum adsorbed on the Zr-SP was eluted by passing 9 mL of a mixture of 0.05 mol L⁻¹ sodium hydroxide and 0.05 mol L⁻¹ potassium sodium tartrate through the Zr-SP at a flow rate of 0.5 mL min⁻¹. The eluted molybdenum was determined with GFAAS after adjusting the acidity with nitric acid. The established method was successfully applied to river water samples taken from some rivers in the eastern area of Shimane Prefecture, Japan. Relatively high concentrations of molybdenum were found in river water samples near molybdenum mines located in this area.

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種々の塩類共存下における水酸化アルミニウム,水酸化鉄(III)に対するクロム(III),(VI),モリブデン(VI),タングステン(VI)の共沈挙動を検討した.クロム(III)は種々の無機塩が共存する溶液からpH5～9で定量的に共沈するが,有機酸共存下では影響を受ける.クロム(VI)はpH5～6で最大共沈率を示し,塩基性溶液で共沈率は急激に減少した.アルミニウム(III),鉄(III)イオンに対する配位能の大きい陰イオンほどクロム(VI)の共沈率を低下させた.クロム酸,モリブデン酸,タングステン酸のpK値と共沈挙動から,これら金属水酸化物に共沈するVIB族オキソ酸イオン種はHMO₄^-形イオンであると推定した.水酸化アルミニウム,水酸化鉄(III)の各種pHにおけるゼータ電位を測定し,VIB族オキソ酸イオンの共沈が水酸化物表面の荷電に基づく共沈よりもむしろ錯形成による共沈の可能性の大きいことを見いだした.

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セルロースアセテート膜を用いる電気泳動法によって各種pHにおけるクロム酸イオン,モリブデン酸イオン,タングステン酸イオンの泳動挙動を解析し,泳動距離-pH曲線より,これら陰イオンの酸解離定数を決定した.クロム(VI):190V,25分間,モリブデン(VI):190V,30分間,タングステン(VI):300V,45分間の通電条件で各溶存化学種に対応する泳動スポットを得た.泳動距離-pH曲線より,クロム(VI),モリブデン(VI)及びタングステン(VI)の酸解離平衡HMO₄^-〓MO₄^2-+H⁺のpK_a値としてそれぞれ6.5,5.1,10.1という値を得た.

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The promotion of DX, which aims to reform corporate operations by utilizing digital technology, is one of the important issues for companies. Developing in-house engineers is an important issue for promoting DX. In this paper, we propose a practical DX propulsion training method by implementing prototype system construction. Specifically, we will propose a method for developing DX promotion capabilities using four prototypes for IoT, AI, big data, and cloud utilization, which are necessary for DX promotion. In addition, we propose a method for developing DX promotion capabilities by utilizing a prototype that integrates these four technologies, and discuss the practice and evaluation of these training methods.

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