凹凸棒石与硫酸亚铁协同吸附铀

Synergistic Treatment of Uranium-containing Wastewater by Attapulgite and FeSO_4

通过静态吸附实验,研究了pH值、吸附时间、铀初始质量浓度、吸附剂用量等因素对凹凸棒石及凹凸棒石与硫酸亚铁协同吸附铀的影响,从热力学和动力学方面对吸附过程进行了分析,并通过红外光谱(IR)和扫描电镜(SEM)探讨了其吸附机理。结果表明,当温度为25℃、pH值为5.0、凹凸棒石投加量为15g/L、铀初始质量浓度为100mg/L、吸附反应30min时,凹凸棒石对UO22+的吸附率达89.5%,饱和吸附量可达40.8mg/g以上;加硫酸亚铁后,凹凸棒石和硫酸亚铁协同吸附铀的效果大幅提高,在25℃、pH值为6.5、凹凸棒石用量20g/L、FeSO4用量1g/L、铀初始质量浓度为100mg/L、吸附时间30min时,凹凸棒石和硫酸亚铁协同对UO22+的吸附率达99.9%以上,经处理的含铀废水能达国标排放。凹凸棒石对UO22+的吸附遵循Langmuir吸附等温线;凹凸棒石及其协同体系对UO22+的吸附动力学模型符合准二级动力学方程。凹凸棒石吸附铀前后的红外光谱表明,凹凸棒石主要是通过羟基、胺基等基团与铀络合进行吸附的。

By static adsorption experiments, the effects of pH, adsorption time, urani- um＇s initial concentration and adsorbent dosage were studied on biosorption capacity of attapulgite and cooperative adsorption of attapulgite and ferrous sulfate for uranium. The adsorption process was analyzed in thermodynamics and kinetics, and the adsorp- tion mechanism was analyzed by infrared spectroscopy and scanning electron micro- scope. The results show that the adsorption rate of attapulgite on UO＋ reaches 89.5 and the saturated adsorption capacity of attapulgite is up to 40.8 mg/g in 30 min at 25 ℃ pH=5.0, 15 g/L of attapulgite dosage and 100 mg/L of uranium initial concen- tration. When the attapulgite dosage is 20 g/L, the uranium initial concentration is 100 mg/L, and the ferrous sulfate dosage is 1 g/L in 30 rain at 25 ℃and pHi6.5, theuranium initial system of attapulgite and ferrous sulfate on uranium is greatly improved, and the adsorption rate of UO2＋ on attapulgite and ferrous sulfate is more than 99.9%and the treated uranium-bearing wastewater can reach the national standard discharge. The adsorption by attapulgite of uranium follows Langmuir adsorption isotherm. In addition, the adsorption by attapulgite and synergistic system are in line with quasi- second order equation. IR micrograph before and after attapulgite adsorbed uranium indicates that the attapulgite is mainly composed of hydroxyl and amido, and the main way of adsorption of uranium is the surface complexing.