生物硫铁复合材料对水中U(Ⅵ)的去除性能及作用机理

目前,生物材料处理含铀废水已成为研究热点,为此,对硫酸盐还原菌(SRB)产生的生物材料的性能进行研究。通过接种硫酸盐还原菌制备了生物硫铁复合材料,探讨了p H值、U(VI)初始质量浓度和温度对生物硫铁去除U(VI)的影响,对比了硫铁、活性生物硫铁和硫酸盐还原菌(SRB)对U(VI)的去除效果。采用环境扫描电镜(SEM)、傅里叶红外光谱仪(FTIR)、高分辨率透射电镜(TEM)-X射线能谱(EDS)分析了生物硫铁结构特性及其对U(VI)的去除机理。结果表明,当初始p H值为7.5、温度为35℃,U(VI)初始质量浓度为7.2 mg/L、生物硫铁投加量为0.1 g时对U(VI)的去除效果最好,12 h完成反应,去除率达99.5%。活性生物硫铁除U(VI)效果优于硫铁和SRB,表明活性生物硫铁中硫铁化合物和SRB同时对U(VI)产生吸附与还原作用,具有速度快、效率高等优点。生物硫铁中的硫铁化合物为无定形态和不规则角柱体,角柱体厚度为20~150 nm,长度为200 nm~1μm。TEM-EDS分析表明,生物硫铁除U(VI)机理有胞外吸附与胞内积累,铀占总元素的质量分数为9.70%,特征峰明显,生物硫铁具有良好的U(VI)去除能力。FTIR分析表明,与U(VI)作用的基团主要有羟基、羧基、磷酸基和C=O、C—N、P—O。

Mechanism and function of the biological iron sulfide composites for treating the U (Ⅵ) containing sewage

The present paper is aimed at making an exploration of the effects of the initial U(Ⅵ) concentration rate,the pH value and the temperatures on the removal of U (Ⅵ) by using the biological iron sulfide composites.As is known,it has been a hot topic for the biomaterials to be applied to treating the uraniumcontaining sewage,which.has pushed us to study their properties and functions produced by the sulfate-reducing bacteria (SRB).For the research purpose,we have analyzed the underlying removing mechanism by using the environmental electronic scanning microscope (SEM),the Fourier transform infrared spectroscopy (FTIR) and the high-resolution transmission electron microscopy (TEM) and X-ray spectroscopy (EDS).The results of our investigation and analysis indicate that the highest removal capacity can be obtained on the conditions when the initial pH is 7.5,at the initial concentration of U(Ⅵ) being 7.2 mg/L at the temperature of 35 ℃,with the biological sulfur iron composites being in a dosage of 0.1 g.What is more,we have gained the treating equilibrium for a test of 12h at the ultimate U (Ⅵ) removal rate of 99.5％.In addition,the U(Ⅵ) removing rate via the biological sulfur iron composites can prove to be more efficient than those of sulfur iron and SRB.Besides,sulfur iron and SRB in the activated biological sulfur iron composites can efficiently adsorb and reduce the U (Ⅵ) content due to their great advantages of high absorptive efficiency.Furthermore,the FTIR spectra indicate that all the four groups of hydroxyl,carboxyl,and phosphoric acid do involve the uranium deposition of C =O,C-N,and P-O.As is shown by the show the SEM images,the sulfide iron in the biological sulfide iron tend to turn to be amorphous in the irregular prisms,which is about 20-150 nm thick and 200 nm-1 μm long.That the U(Ⅵ) removal capability may tend to be a kindof extracellular adsorption and intracellular accumulation by TEM-EDS.What is also necessary to be mentioned is that the uranium characteristic peaks can obviously account for 9.70％ of the entire elemental mass fractions.This may demonstrate that the biological sulfur iron enjoys excellent U (Ⅵ) removal capacity,which can serve as a valuable reference for further studies on the uranium-rich sewage treatment with the biological sulfur-iron composites.