土壤中球孢枝孢对铀（Ⅵ）的吸附

从拟作为低放射性废物处置填埋场土壤中分离出一种霉菌，经过鉴定为链孢霉目黑霉科球孢枝孢，并考察该菌对UO₂²⁺的吸附行为。实验结果表明：铀初始质量浓度为10mg/L，加入5g/L的新鲜湿菌体，其吸附平衡时间约为24h，最终吸附率约94.1%，吸附符合准二级动力学模型；吸附最适宜pH=5～9，当pH≤2时，菌体几乎不吸附UO₂²⁺；铀初始质量浓度为2~10mg/L时，吸附率均在90%左右；吸附近似符合Langmuir吸附经验公式；菌体累积吸附6次吸附量可达6.6mg/g；Ca²⁺会降低微生物对铀的吸附；柠檬酸、硝酸和EDTA对吸附的铀均具有一定的解吸能力，其中柠檬酸最高为67%。采用红外吸收光谱分析，显示吸附后出现UO₂²⁺的吸收峰，表明铀主要以UO₂²⁺的形式被菌体吸附。

Sorption of Uranium by Cladosporium Sphaerospermum Isolated From Soil

A kind of fungus, which was identified by molecular biology technology as cladosporium sphaerospermum, was isolated from the soil in a potential site for disposal of low radioactive waste.The sorption behavior of uranium by this living fungus was investigated. When the initial concentration of uranyl ion is 10 mg/L, the sorption efficiency for uranium is 94.1%. Sorption equilibrium time is about 24 h.The experimental data can be described with the pseudo-second order equation with much high regression coefficient.The uranium adsorbability is closely in connection with its pH value of which the best range is from 5 to 9. When pH ≤2, the thalli scarcely adsorb uranium. The relationship between sorption capacities and concentration of uranium in aqueous solutions can be described by the Langmuir adsorption equation. The accumulating adsorbing capacities finally reach to about 6.6 mg/g. Except Ca²⁺, coexistent ions such as Na⁺, K⁺, HCO₃^-, CO₃^2- and SO₄^2-_scarcely inhibite the sorption of uranium on the fungus. Three desorption agents was investigated. Citric acid is found to be the best desorbent with a desorption rate of up to 67%, followed by HNO₃ about 60%, and lastly EDTA about 40%. Additionally, the bacteria were observed by infrared spectroscopy. The results show that uranium is absorbed in the form of UO₂²⁺.