半焦条件优化对油页岩Cd^(2+)、Pb^(2+)吸附性能的影响

Effect of Optimize Semi Coke Conditions for the Ability ofOil Shale to Adsorb Cd^(2+)and Pb^(2+)

为深入研究温度对半焦油页岩Cd^(2+)、Pb^(2+)吸附性能的影响,以新疆巴里坤矿区油页岩(oil shale,OS)渣为原料,在200~800℃下半焦改性,制备出4种半焦油页岩(OS-200、OS-400、OS-600、OS-800)。使用扫描电子显微镜(scanning electron microscope,SEM)、透射电子显微镜(transmission electron microscope,TEM)、热重分析(thermogravimetric analysis,TGA)、X射线衍射分析(X-ray diffraction,XRD)、比表面积分析方法BET(Brunauer-Emmett-Teller)和傅里叶变换红外光谱分析(Fourier transform infrared spectroscopy,FTIR)等技术进行了物相表征,通过吸附试验研究了其对Cd^(2+)、Pb^(2+)的吸附性能。结果表明:通过不同温度的焦化,OS的物理性状、热重特性等均发生明显变化,在未改变其基本矿物成分的基础上改变了—OH、C O和Si—O—Si化学键的活性,增加了其比表面积。OS-600表现出更好的吸附性能,在pH=7,25℃的条件下,Langmuir方程及准二级动力学模型能够更好地拟合吸附过程。拟合结果显示OS-600理论Cd^(2+)最大吸附量为9.04 mg/g,Pb^(2+)最大吸附量为44.84 mg/g。实测OS-600对Cd^(2+)、Pb^(2+)的实测吸附量分别为6.69、35.42 mg/g,分别高出OS原样吸附量的53.44%、71.69%。OS半焦温度以400~700℃为宜,半焦时间不低于2 h,研究结果为半焦OS制备吸附材料时温度条件优化提供了理论支撑。

To investigate the effect of temperature on the adsorption performance of Cd^(2+)and Pb^(2+)in semi coke shale,four types of semi tar shale(OS-200,OS-400,OS-600,OS-800)were prepared by modifying the semi coke with oil shale(OS)residue from the Balikun mining area in Xinjiang at 200~800℃.The phase characterization was carried out using techniques such as scanning electron microscope(SEM),transmission electron microscope(TEM),thermogravimetric analysis(TGA),X-ray diffraction(XRD),Brunauer-Emmett-Teller(BET),and Fourier transform infrared spectroscopy(FTIR).The adsorption performance of Cd^(2+)and Pb^(2+)was studied through adsorption experiments.The results show that through coking at different temperatures,the physical and thermogravimetric properties of OS underwent significant changes.On the basis of not changing its basic mineral composition,the activity of—OH,C O,and Si—O—Si chemical bonds is changed,and its specific surface area is increased.OS-600 exhibits better adsorption performance,and the Langmuir equation and quasi second order kinetic model can better fit the adsorption process at pH=7 and 25℃.The fitting results show that the theoretical maximum adsorption capacity of OS-600 for Cd^(2+)is 9.04 mg/g,and the maximum adsorption capacity for Pb^(2+)is 44.84 mg/g.The measured adsorption capacities of OS-600 for Cd^(2+)and Pb^(2+)are 6.69 mg/g and 35.42 mg/g,respectively,which are 53.44%and 71.69%higher than the original adsorption capacity of OS.The optimal semi coke temperature for OS is 400~700℃,and the semi coke time should not be less than 2 hours.The research results provide theoretical support for optimizing the temperature conditions when preparing adsorbent materials using semi coke OS.