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用Ar~+激光器的488nm单色光研究了UO_2(NO_3)_2-30％TBP-煤油体系中U(Ⅵ)的光化学行为。实验表明:光照后TBP有机相内含有还原生成的U(Ⅳ)和TBP的主要降解产物DBP和丁醛;生成U(Ⅳ)的量子产额与酸度、温度、TBP浓度有关。光照合0.1mol/l U(Ⅵ),0.2mol/l HNO_3的30％TBP-煤油溶液时U(Ⅳ)的量子产额为0.18。温度大于30℃光照时,会产生显著量的亚硝酸。亚硝酸的生成量与光照功率和U(Ⅵ)的浓度成正比,当酸度大于0.1mol/l时,其量随酸度增加而减少。还初步探讨了U(Ⅵ)在TBP中光化还原的机理。
The photochemical behavior of U (Ⅵ) in UO_2 (NO_3) _2-30% TBP-kerosene was investigated by monochromatic light of Ar ~ + laser at 488 nm. The experimental results showed that the photodegradation products of DBP and butyraldehyde, the main degradation products of U (Ⅳ) and TBP, contained in TBP organic phase. The quantum yields of U (Ⅳ) were related to acidity, temperature and TBP concentration. The quantum yield of U (Ⅳ) was 0.18 when irradiated with 30% TBP-kerosene solution containing 0.1 mol / l U (Ⅵ) and 0.2 mol / l HNO 3. At temperatures greater than 30 ° C, significant amounts of nitrous acid are produced. The formation amount of nitrous acid is proportional to the light power and the concentration of U (Ⅵ). When the acidity is higher than 0.1mol / l, the amount decreases with the increase of acidity. The mechanism of U (Ⅵ) photoreduction in TBP was also discussed.