粪产碱杆菌改性生物炭对水中U(VI)的去除性能与机理

Removal Performance of U(VI) from Aqueous Solutions by Pig ManureBiochar Modified with Alcaligenes faecalis and its Mechanism

制备了粪产碱杆菌改性猪粪生物炭(PMBC-A1、PMBC-A2、PMBC-A3)用于去除水中的铀。扫描电镜和能谱仪表征表明粪产碱杆菌被分泌的生物膜包埋固定在生物炭表面,并形成了高磷界面。批次试验表明PMBC-A2对铀的吸附性能更优异,且不易发生磷污染。当U(VI)初始质量浓度为5 mg/L时,PMBC-A2最佳的吸附条件是投加量为0.1 g/L,温度为30℃,反应时间为24 h,此时对铀的去除率最高达92.65%。PMBC-A2除铀过程符合拟二级动力学模型和Langmuir等温线模型,拟合最大吸附容量为338.52 mg/g。在干扰离子存在时PMBC-A2对铀的吸附具有良好的选择性。吸附—解吸试验表明PMBC-A2具有循环利用的潜力。傅里叶红外光谱、光电子能谱和X射线衍射等表征证明PMBC-A2对水中铀的去除机理主要是磷酸基团和羧基的表面络合吸附、生物磷酸盐矿化和生物还原。

Modified pig manure biochar(PMBC-A1,PMBC-A2,PMBC-A3)by A.faecalis was prepared for uranium removal from aqueous solutions.Scanning electron microscopy(SEM)and energy dispersive X-ray spectroscopy(EDS)characterizations revealed that Alcaligenes faecalis was embedded and fixed on the surface of biochar by secreted biofilm and formed a high phosphorus interface.Batch experiments demonstrated PMBC-A2 has better adsorption performance for uranium and is less likely to cause phosphorus pollution.When the initial concentration of U(VI)is 5 mg/L,the optimal adsorption conditions for PMBC-A2 are that the dosage is 0.1 g/L,the temperature is 30℃,the contact time is 24 h,and the removal rate of uranium is 92.65%.The process of uranium removal is conformed to the pseudo-second-order kinetic model and the Langmuir isotherm model,and the maximum fitting adsorption capacity is 338.52 mg/g.P MBC-A2 exhibited excellent selectivity for uranium adsorption in the presence of interfering ions.The adsorption-desorption test shows that PMBC-A2 has the potential of recycling.Characterizations including Fourier-transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS),and X-ray diffraction(XRD)confirmed that the uranium removal mechanism of PMBC-A2 from aqueous solutions is primarily the surface complexation adsorption of phosphate groups and carboxyl groups,biological phosphate mineralization and biological reduction.