【作者】 杨雪静；

【导师】 杨亚玲；

【作者基本信息】 昆明理工大学 ， 生物化工， 2009， 硕士

【摘要】 本文以农业废弃物玉米芯(VC)为原料,采用微波法预处理玉米芯,再利用丁二酸酐与其进行酯化反应合成改性玉米芯(MC)。采用SEM、IR和XPS等对VC和MC的微观结构和表面化学形态进行表征,并对吸附机理进行了初步探讨。将MC应用于废水中稀有金属钯的处理,通过静态和动态实验,考察了MC对废水中Pd(Ⅱ)的吸附性能。同时,对MC的再生性能进行了研究。研究结果表明,采用微波的预处理方法,以丁二酸酐对其进行接枝改性的优化工艺条件为：微波800W功率的条件下6 min,m(玉米芯)：m(丁二酸酐)：V(吡啶)=1：1.5:20,回流60 min,饱和碳酸氢钠液中浸泡30 min。产品的质量提高百分数(WPG)为41.4%。结合SEM、IR和XPS分析,可知通过改性可使玉米芯表面形成多孔、疏松的结构,有利于钯离子的吸附。但其化学结构没有大的改变,说明改性过程不会对玉米芯的纤维结构造成破外。羧基的引入,使其含量增加到总含量的10.31%,说明丁二酸酐成功地偶联上玉米芯。在考察MC对废水中Pd(Ⅱ)的处理效果时,建立了一种测定Pd(Ⅱ)的催化动力学光度新方法。即在非离子表面活性剂Tween-20存在下,痕量Pd(Ⅱ)对K2S2O8氧化靛红的氧化还原反应具有明显的催化作用,使体系的反应速度加快,灵敏度提高。方法的线性范围为8×10-4～1.28×10-2μg/mL,检出限为5.3×10-9g/L,催化反应表观活化能为53.92 KJ/mol。静态吸附性能结果表明：与VC相比,MC的最大吸附量提高了5.5倍。Freundlich吸附等温式能较好地描述不同温度下的实验数据。吸附过程符合一级动力学模型。由吸附热力学参数可知,吸附属于自发的、吸热的和熵增加的过程。采用降流式单床吸附柱吸附装置,研究MC对废水中钯的动态吸附性能。发现穿透曲线强烈依赖实验条件,在其他条件不变的情况下,’流速越大,进口浓度越高,吸附剂用量越少,可使吸附床的床层穿透加快,穿透时间缩短。考察了MC的再生性能,结果表明该吸附剂经4次再生后仍保持较好的吸附性能。更多还原

【Abstract】 Using agriculture wasters-corncob(VC) as the raw material, this article applied microwave method to pretreat corncob and esterification method with succinic anhydride to synthesis the modified corncob(MC). The microstructure and surface chemical morphology of VC and MC had been studied by SEM, IR and XPS. Then the mechanism of adsorption was discussed preliminarily. MC was used to treat Pd(Ⅱ) in waster water. According to the static and dynamic adsorption experiment, the adsorption properties of Pd(Ⅱ) onto MC was investigated. Furthermore, the regeneration properties of MC was also studied.The results showed that, the optimum technological conditions of graft modification by microwave pretreatment and esterification method with succinic anhydride were as follows: the power of microwave was 800W for 6 min, m(corncob):m(succinic anhydride): V(pyridine)=1:1.5:20, refluxed for 1 h, stirred in a saturated sodium bicarbonate solution for half hour. The weight percent gain(WPG) of product was 41.4%.SEM spectra, IR spectra combined with XPS spectra revealed that, the surface of MC appeared porous and loose structure, which was conductive to adsorb Pd ions. The chemical structure didn’t have big change. The modification process didn’t damage the fiber structure of corncob. The introduction of carboxy groups made its content increase to 10.31% in total content. It proved that succinic anhydride had been coupled to corncob.When investigating the treatment effect of Pd(Ⅱ) onto MC in waste water, a new catalytic kinetic spectrophotometric method has been developed for the determination of palladium(Ⅱ). Based on the catalytic effect of the trace palladium(Ⅱ) on the oxidation reaction of indigo carmine by K2S2O8 in the Tween-20 medium, the reaction rate of system has been speeded up and the sensitivity has been improved. The linear range of determination is 8x10-4-1.28x10-2μg/mL, and the detection limit is 5.3x10-9 g/L. The apparent activation energy is 53.92 KJ/mol.The result of static adsorption properties showed that compared with VC, the maximum adsorption capacity of MC increased by 5.5 fold. Freundlich adsorption isotherm can better describe experimental data at different temperature. The adsorption process accord with Pseudo-first order kinetic model. The adsorption thermodynamics parameters indicated that adsorption was a spontaneous, endothermic and entropy increase process.By means of down-flow single bed adsorption column, the dynamic adsorption properties of Pd(II) onto MC in waster water was studied. The results showed that breakthrough curve was affected intensively by experiment conditions.In the case of other conditions remain unchanged, greater velocity, higher inlet concentration and less adsorbent can speed up breakthrough and shorten breakthrough time.The regeneration properties of MC was investigated. The results indicated that the adsorbent kept good adsorption properties after four regeneration.更多还原