硅胶键合醛基型吸附材料的制备及对重金属离子的吸附

摘要

以无机材料硅胶为基体,利用有机硅烷偶联剂KH550、乙二醛和戊二醛为原料进行希夫碱反应,分别合成含有C=N的硅胶键合醛基型吸附材料(乙二醛修饰的为SG-1、戊二醛修饰的为SG-2),并采用红外光谱、热重、扫描电子显微镜和孔结构等分析手段对吸附材料进行了表征.结果表明:(1)从微观上看,硅胶表面较光滑;SG-1、SG-2表面的粗糙度、孔隙率都较硅胶明显增加,有利于吸附实验的进行.(2)拟二级动力学方程更适合描述SG-1、SG-2对重金属离子的吸附行为,吸附过程由化学吸附过程决定.SG-1、SG-2对4种重金属离子的吸附热力学过程适合用Langmuir等温吸附方程解释,其过程是单分子层吸附.(3)SG-1、SG-2对4种重金属离子的静态饱和吸附量均表现为Cu(Ⅱ)＞Ni(Ⅱ)＞Pb(Ⅱ)＞Cr(Ⅵ).SG-1、SG-2对Cu(Ⅱ)静态饱和吸附量分别达至9.401、9.738 mg/g.(4)SG-1、SG-2对4种重金属离子解吸率与解吸液(5％(质量分数)硫脲+0.1 mol/L盐酸)体积并不呈现正相关,解吸率基本可达到90％,再生性能良好,当解吸液体积为6 mL时解吸率最大.%Composite adsorbents (SG-1 or SG-2) with C=N had been prepared using glyoxal or glutaric dialdehyde,silane coupling agent KH550 and silica gel as raw materials.The structures were characterized by infrared spectroscopy (IR),thermogravimetry (TG),scanning electron microscope (SEM) and porous structure analysis.The research results showed as follow:(1) microcosmicly,the surface of silica gel was relatively smooth while the surface roughness and porosity of SG-1 and SG-2 were obviously increased,which was favorable to the adsorption experiment.(2) The adsorption behavior on heavy metal ions of SG-1 and SG-2 were more suitable described by pseudo-second-order kinetic equation.The adsorption process was determined by chemical adsorption process.The adsorption behavior on 4 heavy metal ions of SG-1 and SG-2 was reasonably explained by Langmuir adsorption isotherm equation.(3) The saturation adsorption capacities of SG-1 and SG-2 on 4 heavy metal ions both showed Cu(Ⅱ)＞Ni(Ⅱ)＞Pb(Ⅱ)＞Cr (Ⅵ).The saturation adsorption capacities on Cu(Ⅱ) of SG-1 and SGr-2 reached 9.401,9.738 mg/g respectively.(4)The desorption ratio on 4 heavy metal ions of SG-1 and SG-2 was not positively correlated with the volume of desorption solution (5％ (mass fraction) thiourea +-0.1 mol/L hydrochloric acid).The desorption ratio was able to basically reach 90％,indicating good regeneration performance of SGr-1 and SG-2.The desorption ratio achieved a maximum value when the volume of desorption solution was 6 mL.