铁改性蓝藻生物炭去除水中四环素效能及机理

Study on the efficiency and mechanism of iron-modified cyanobacteria biochar in removing tetracycline from water

以蓝藻为原料制备生物炭,通过考察不同温度制备的蓝藻生物炭对四环素的吸附效能,筛选最优制备温度。采用液相还原法制备不同铁炭比的铁改性蓝藻生物炭,研究其对四环素的去除效能、影响因素及去除机理。结果表明:在700℃、铁炭质量比为1∶1条件下制备的铁改性蓝藻生物炭对四环素具有高效去除能力,60 min去除率可达87.2%,为改性前的1.2倍,吸附类型符合伪二级动力学方程(R^(2)>0.99)。通过傅里叶红外光谱、扫描电镜、X射线光电子能谱、X射线衍射探讨铁改性蓝藻生物炭去除四环素性能与其结构的关系。结果表明,铁改性蓝藻生物炭对四环素的去除机理主要为吸附和化学降解作用,零价铁作为电子供体促进氧化还原反应的发生,含氧官能团作为电子转移桥梁在吸附降解过程中起着重要作用。影响因素试验结果表明,阴离子对铁改性蓝藻生物炭去除水中四环素效能的影响程度为SO_(4)^(2−)>Cl^(−),阳离子影响程度为Ca^(2+)>Na^(+),有机质黄腐酸相对于离子强度影响程度较弱。铁改性蓝藻生物炭对四环素类抗生素具有良好的去除能力,可为蓝藻资源化提供思路。

Using cyanobacteria as raw material to prepare biochar,the adsorption efficiency of cyanobacteria biochar on tetracycline at different temperatures was investigated and the optimal preparation temperature of cyanobacteria biochar was screened.Cyanobacteria biochar modified with different Fe/C mass ratios was prepared by the liquid phase reduction method.The removing efficiency,influencing factors and removing mechanism of the iron-modified cyanobacteria biochar for tetracycline were studied.The results showed that the iron-modified cyanobacteria biochar had a high removing capacity for tetracycline at 700℃and an iron-carbon mass ratio of 1∶1,and the removing rate reached 87.2%in 60 min,which was 1.2 times of that before modification.The adsorption type was in accordance with the pseudo-second-order kinetic equation(R^(2)>0.99).The relationship between the iron-modified cyanobacteria biochar tetracycline removal performance and its structure was discussed by Fourier transform infrared spectroscopy(FTIR),scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS)and X-ray diffraction(XRD).It was proved that the main removal effects of tetracycline were adsorption and chemical degradation,the zero-valent iron as the electron donor promoted the redox reaction,and the oxygencontaining functional groups as the bridge of electron transfer played an important role in the adsorption and degradation process.The test results of influencing factors showed that the influence degree of anions was in the order of SO_(4)^(2−)>Cl^(−),the influence degree of cations was Ca^(2+)>Na^(+),and the influence degree of organic fulvic acid(FA)was weak relative to ionic strength.The iron-modified cyanobacteria biochar had good removal efficiency on tetracycline antibiotics,which could provide a new idea for cyanobacteria resource utilization.