中药渣生物炭的制备及其对水中四环素的吸附特性研究

Preparation of Chinese Medicine Wastes Biochar and Its Adsorption Characteristics to Tetracycline in Water

以中药废渣为原料,四环素为目标污染物,采用限氧热解法在热解温度分别为300℃、500℃和700℃的条件下制备了不同中药渣生物炭(Biochar,BC),并采用比表面积分析仪(BET)、扫描电子显微镜(SEM)、傅里叶红外光谱分析仪(FTIR)、X射线光电子能谱仪(XPS)、X射线衍射仪(XRD)等手段对不同中药渣生物炭的物理化学性质进行了表征;通过中药渣生物炭对水中四环素(Tetracycline,TC)的吸附试验,研究了不同中药渣生物炭对水中四环素的吸附特性,考察了溶液初始浓度、吸附时间对溶液中四环素去除效果的影响,并结合吸附动力学、吸附等温线拟合结果探究了中药渣生物炭对水中四环素的吸附机制。结果表明:随着热解温度的升高,中药渣生物炭中有机物分解,含氧官能团种类及其相对含量发生变化,其中含氧官能团C—C的相对含量升高、C—H的相对含量降低,中药渣生物炭的芳香化程度增加,且700℃制备的中药渣生物炭对水中四环素的吸附性能更优;中药渣生物炭对水中四环素的吸附量依次为BC700(93.46mg/g)>BC500(76.32mg/g)>BC300(32.92mg/g),且中药渣生物炭对水中四环素的吸附过程遵循准二级吸附动力学模型和Langmuir吸附等温线模型,主要为单分子层吸附过程;中药渣生物炭对水中四环素的吸附机制主要涉及孔隙填充作用、氢键作用、静电作用和π-π作用。

In this study,Biochars(BC)are prepared from residue of Traditional Chinese Medicine Wastes(TCMWs)at 300℃,500℃and 700℃by oxygen-limited pyrolysis with tetracycline as the target pollutant.Through the adsorption test of tetracycline in water by biochar from Chinese medicine wastes,the study characterizes the physicochemical properties of different biochars from Chinese medicine wastes by BET,SEM,FTIR,XPS and XRD;it also investigates the adsorption characteristics of different biochars to Tetra-cycline(TC)in water,and the effects of initial solution concentration and adsorption time on the removal of TC in solution.Combined with the adsorption kinetics and adsorption isotherm fitting results,the study explores the adsorption mechanism of TCMWs biochar to Tetracycline in water.The results show that with the increase of pyrolysis temperature,the organic matters in TCMWs biochar are decomposed,the types and relative proportion of oxygen-containing functional groups reduced,the relative contents of C—C and C—H of oxygen-containing functional groups increased,and the aromatization degree of TCMWs biochar increased.The biochar prepared at 700℃has better adsorption efficiency for tetracycline.The adsorption experiments show that the adsorption capacity of tetracycline by TCMWs biochar is BC700(93.46 mg/g)>BC500(76.32mg/g)>BC300(32.92mg/g),and the adsorption process of TCMWs biochar to an-tibiotics follows the quasi-second-order adsorption kinetic equation and Langmuir adsorption isotherm mo-del.The adsorption mechanism of TCMWs biochar to Tetracycline mainly involves pore filling,hydrogen bonding,π-πinteraction and electrostatic interaction.