海藻酸纤维对阳离子染料吸附性能的研究

【作者】 郭春香；

【导师】 夏延致；

【作者基本信息】 青岛大学 ， 材料学， 2011， 硕士

【摘要】 我国海域辽阔,海洋生物资源相当丰富,尤其是藻类资源。目前除天然海洋海藻,世界人工栽培海藻技术也非常成熟。我国海藻酸盐产量居世界第一并且应用日益广泛。海藻酸分子链上含有大量的羧基和羟基,在水溶液中失去氢离子而带有负电荷,与阳离子物质有较强的结合能力。以海藻酸钠为原料,通过湿法纺丝工艺制备的海藻酸纤维是一种理想的绿色生物质吸附材料,具有吸附面积增大,吸附速度较快快,吸附过程易于操作和处理,吸附后吸附剂可生物降解,不会对环境造成二次环境污染等综合优点。本文以实验室自制的海藻酸纤维为生物吸附剂,研究了海藻酸纤维对染料的吸附行为,重点研究了海藻酸纤维对亚甲基蓝染料MB和阳离子蓝染料CB的静态吸附行为和海藻酸纤维对亚甲基蓝染料MB的动态纤维。在海藻酸纤维对亚甲基蓝染料MB和阳离子蓝染料CB的静态吸附研究中主要研究了时间、染料溶液的浓度、染料溶液酸碱值、温度等因素对吸附过程的影响,并利用等温吸附方程(Langmuir模型、Freundlich模型、Temkin模型)、动力学模型(准一级动力学模型、准二级动力学模型和粒子扩散模型)、热力学方程等分析了吸附过程,探讨了吸附机理。静态吸附实验的结果表明,海藻酸纤维对亚甲基蓝染料和阳离子蓝染料的吸附在很短的时间内就能达到平衡,且随时间延长吸附量变化不大；海藻酸纤维吸附两种染料的最佳pH为7.0；随离子浓度的增大,海藻酸纤维的吸附量增大,达到吸附平衡的时间缩短；温度升高,纤维的平衡吸附量降低。海藻酸纤维吸附两种染料的动力学过程符合Freundlich模型、Temkin模型、准二级动力学模型描述,粒子扩散模型,说明此吸附过程并非一个单分子层的吸附,纤维表面不均匀且吸附时纤维表面的能量分布不均匀。吸附反应的△G0的值都小于零,说明海藻酸纤维吸附两种染料的过程是自发进行的。吸附过程的焓变(△H)小于零,表明该吸附过程是放热的。熵变(△S)小于零,表明随着吸附的进行,染料在海藻酸纤维表面排列的无规性降低。在海藻酸纤维对亚甲基蓝染料MB动态吸附研究中主要研究了时间和染料溶液对吸附过程的影响,并利用Thomas模型和Nelson-Yoon模型对动态吸附柱吸附过程进行了探讨。结果表明,海藻酸纤维吸附柱对亚甲基蓝染料MB的吸附均具有良好的动力学特性,吸附效果很好。在给定的实验条件下,Thomas方程和Yoon-Nelson方程与实验结果均可以较好地拟合,由模型参数计算出来的数据与实验数据有很高的拟合度。更多还原

【Abstract】 China owns vast sea areas and is rich in marine biological resources, especially in algae resources. In addition to natural sea algae products, nowadays the technology of culturing algae has been matured. In our country, the outputs of alginate top first in the world and is applied intensively. There are abundant of carboxyl and hydroxyl groups in alginate molecule, and the hydrogen ions of the groups are tend to lose in aqueous solution and hence the alginate fibers bear negative charges. The negative charged fibers are easy to combine positive substance. The alginate fibers manufactured through wet spinning with sodium alginate as raw material is a kind of green marine material, showing comprehensive advantages, such as large specific areas, fast adsorption, easiness to handle and operate, and biodegradation after adsorption, which avoids the environmental pollution.The alginate fibers are made in our laboratory and used as biological adsorbent and its adsorption behavior of dyes are investigated; especially adsorption process of methylene blue dye (MB), cationic blue dye (CB) and dynamic adsorption of methylene blue dye (MB) onto alginate have been studied.In the study of adsorption behavior of methylene blue dye (MB) and cationic blue dye (CB), variables such as time, concentration of solution, pH and temperature are investigated. The isothermal models (Langmuir model, Freundlich model and Temkin model) and kinetic models (pseudo-first-order kinetic model, pseudo-second-order model and Intraparticle diffusion model) and thermodynamic model are applied to further study the adsorption process and mechanism. The studies show the alginate fibers adsorption of both MB dye and CB dye reach equilibrium in a few minutes and adsorption capacity varies little as time extends. The optimal pH of both dye solution is 7. The adsorption capacity increases and the time required for equilibrium adsorption decrease as the concentration of dye solution within experimental range. The adsorption capacity decreases as temperature increases. The adsorption process accord with Freundlich model, Temkin model, pseudo-first-order model and Intraparticle diffusion model, which indicate that alginate fibers adsorption of both dyes is not a monolayer adsorption and the surface of the fiber is not uneven and the adsorption surface energy of the fibers is not homogenous. The negative adsorption valuesΔG show the adsorption process of both dyes is spontaneous. The negative values ofΔH indicate the adsorption process is exothermic and the negative values ofΔS show the randomness of the adsorption system decreases. In the study of dynamic adsorption behavior of methylene blue dye (MB), the effect of time and concentration of dye solution are investigated and the Thomas model and Nelson-Yoon model are applied. The study shows that the adoption behavior of alginate fibers column exhibits obvious dynamic column adsorption characteristics. The adsorption curves accord with the Thomas model and Nelson-Yoon model with high correlation coefficients.更多还原