锆改性沸石对蔗糖溶液中没食子酸的吸附性能研究

Adsorption of Gallic Acid from Sucrose Solution on Zirconium-modified Zeolite

为降低制糖过程中蔗汁中没食子酸的含量,降低白砂糖的色值,以氧氯化锆和沸石为原料,通过共沉淀法制备锆改性沸石,研究改性前后沸石表面结构和基团的变化,考察时间、pH值、温度及没食子酸初始浓度等因素对改性沸石吸附蔗糖溶液中没食子酸的吸附效果的影响,并对吸附动力学模型、吸附等温模型和吸附热力学进行初步探讨。扫描电镜结果显示锆改性后沸石表面更加粗糙,红外光谱显示改性后沸石基团发生了改变,氧化锆成功的负载到改性沸石上。吸附试验结果表明锆改性沸石对没食子酸吸附量达到34.442 mg/g。改性沸石对蔗糖溶液中没食子酸吸附的最佳pH值为8.0,时间为600 min,吸附温度及没食子酸初始浓度的提高有利于提高吸附效果;吸附过程符合准二级吸附动力学模型和Langmuir等温吸附模型;通过热力学研究可知吸附过程为吸热过程,能自发进行。

In order to reduce the gallic acid content of sugarcane juice and the color value of white granulated sugar,zirconia-modified zeolite was prepared using a co-precipitation method with zirconia and zeolite as raw materials.The surface structure of zeolite and group changes before and after modification were studied,and the effects of time,pH,temperature,and initial gallic acid concentration on the adsorption of gallic acid from sucrose solution using the modified zeolite were investigated.In addition,adsorption kinetics,isotherm models,and thermodynamics were discussed.Scanning electron microscope observations revealed that the surface of the modified zeolite was rougher than that of the unmodified compound,and the infrared spectrum obtained indicated group changes in the modified zeolite and the successful loading of zirconia.The adsorption capacity of zirconium-modified zeolite for gallic acid was found to be 34.442 mg/g,whereas the optimum pH and time for modified zeolite adsorption of gallic acid from sucrose solution were 8.0 and 600 min,respectively.Furthermore,it was found that increasing the adsorption temperature and initial concentration of gallic acid was beneficial with respect to enhancing the adsorption effect,and that the adsorption process could be described in terms of quasi-second-order adsorption kinetic and Langmuir isothermal adsorption models,whereas thermodynamic analysis revealed that the adsorption process was endothermic and could be spontaneous.