KGM基吸附材料的制备及其吸附性能研究

发布时间：2018-06-28 23:52

本文选题：魔芋葡甘聚糖 + 多巴胺　；参考：《西南科技大学》2017年硕士论文

【摘要】：随着工业化的快速推进,水污染问题,尤其是水的重金属离子污染日益严重,时刻威胁着环境安全及人类健康。研究表明饮用铅、镉离子含量超标的水,会严重影响人类的身体健康,污染自然环境。因此,有效减少或去除水中的铅、镉离子显得尤为重要。本文采用环境友好型天然高分子材料为原料,通过吸附法去除水中的铅、镉离子。吸附法具有操作便捷,成本低廉,去除效果好等特点。吸附剂作为吸附法的核心组成部分,是环境科学和材料科学研究的重点问题之一。当前,处理重金属水污染的吸附剂有矿物吸附剂,微生物类,生物质类吸附剂等,但由于资源短缺,二次污染等问题,急需要寻找新型吸附剂。魔芋葡甘聚糖是一种生物质材料,资源丰富,可再生,易降解,无毒性,成本低廉,且富含官能团及易改性。通过对魔芋葡甘聚糖水热改性制备出魔芋葡甘聚糖生物碳(KGMB),对其羧甲基化及多巴胺化学修饰改性制备出多巴胺修饰的羧甲基魔芋葡甘聚糖微球(CMKGM-PDA)吸附材料。通过重金属离子静态吸附实验及常规材料表征手段系统的研究了两种吸附材料对铅、镉的静态吸附行为;通过吸附脱附实验系统地研究了这两种吸附剂的循环再利用性能。结合傅立叶红外光谱仪(FT-IR)、热重分析仪(TG)、扫描电子显微镜(SEM)、X射线色散能谱(EDX)及X射线光电子能谱(XPS)等表征技术对两种吸附剂的铅、镉吸附行为及机理进行了分析探讨,为拓展两种吸附材料的应用范围提供一定的理论基础。结果表明:1.KGMB对铅、镉的吸附特性:当反应温度为25℃,吸附质浓度为50mg/g,pH为5.7,吸附剂量为5 mg,反应时间为24 h的条件下,KGMB吸附铅离子的最大容量为202.84 mg/g,吸附镉离子的最大吸附容量为137.55 mg/g。吸附过程均符合Langmuir模型,动力学均符合准二级动力学模型。温度在298.15到338.15 K之间,吸附过程属于自发、放热反应。在吸附剂再生实验中,经过三次吸附-解吸附的循环后,铅离子吸附量依然达69.34 mg/g,镉离子吸附量也能达71.06 mg/g。2.通过TG分析知KGMB的热稳定性较改性前有所提高;通过等电点测试可知,当pH2.3时,KGMB表面呈负电性,有利于金属离子的吸附;利用FT-IR,SEM-EDX及XPS探究KGMB吸附铅、镉离子的机理。结果表明,Pb(Ⅱ)和Cd(Ⅱ)与KGMB上-O H中氢离子发生离子交换,与氧发生静电吸引。3.CMKGM-PDA对铅离子的吸附特性:当pH为6.0,铅离子浓度为50mg/g,吸附剂量为25 mg,反应时间为24 h的条件下,CMKGM-PDA在反应温度为25℃时吸附铅的容量为75.19 mg/g,在反应温度为45℃时吸附铅的容量为153.37 mg/g;吸附过程符合准二级动力学模型及Langmuir模型,反应温度为25℃时,拟合最大铅吸附量为95.2 mg/g,吸附铅的量随着温度的增大而增大。温度在288到318 K之间,吸附过程是熵增的过程,属于自发、吸热反应。在吸附剂再生实验中,当溶液浓度为18 mg/g时,经过五次循环利用后,铅离子吸附量仍然可以达到27.5 mg/g。4.通过TG分析知CMKGM-PDA的热稳定性较改性前有所提高;通过等电点测试可知,当pH3.65时,CMKGM-PDA表面带负电,有利于金属离子的吸附;通过FT-IR,SEM-EDX及XPS探究CMKGM-PDA吸附铅的机理。结果表明,当pH3.65时,吸附铅主要以铅与-NH2的螯合作用;当pH3.65时,吸附铅主要以铅与-OH中氧的螯合作用。5.CMKGM-PDA对镉的吸附研究表明:当镉离子浓度为50 mg/g,pH为6.0,吸附剂量为25 mg,反应时间为24 h的条件下,CMKGM-PDA在反应温度为25℃时吸附镉的容量为21.5 mg/g。吸附过程符合准二级动力学模型及Langmuir模型,反应温度为15℃时,拟合最大镉吸附量为18.18 mg/g,反应温度为45℃时,拟合最大镉吸附量为50.51 mg/g,吸附镉的量随着温度的增大而增大。温度在288到308 K之间,属于自发、放热反应。在吸附剂再生实验中,当溶液浓度为50 mg/g时,经过五次循环利用后,镉离子吸附量仍然可以达到17.2 mg/g。6.通过TG分析知CMKGM-PDA的热稳定性较改性前有所提高;通过等电点测试可知,当pH3.65时,CMKGM-PDA表面带负电,有利于金属离子的吸附;通过FT-IR,SEM-EDX及XPS探究CMKGM-PDA吸附镉的机理。结果表明,当pH3.65时,吸附镉主要以镉与-OH中氧的螯合作用;当pH3.65时,吸附镉主要以镉与-N-H和-OH的螯合作用。以魔芋葡甘聚糖为基础材料,经过改性后得到的两种吸附材料KGMB和CMKGM-PDA对水中铅镉离子的去除有较好的效果,在处理铅镉污水领域有一定的应用潜力。
[Abstract]:With the rapid progress of industrialization, water pollution, especially heavy metal ion pollution in water, is becoming more and more serious, threatening environmental safety and human health. The research shows that drinking lead and cadmium ion content can seriously affect human health and pollution of natural environment. Therefore, it can effectively reduce or remove lead and cadmium ions in water. In this paper, the environment friendly natural polymer materials are used as raw materials to remove lead and cadmium ions in water by adsorption. The adsorption method has the characteristics of convenient operation, low cost and good removal effect. As one of the key components of adsorption method, adsorbents are one of the key problems in Environmental Science and material science. The adsorbents for water pollution of heavy metals include mineral sorbents, microbes, and biomass sorbents, but due to the shortage of resources and the two pollution problems, it is urgent to find new adsorbents. The konjac glucomannan is a kind of biomass material, which is rich in resources, renewable, easy to be degraded, non-toxic, low cost, and rich in functional group and easily modifier. Konjac glucomannan bio carbon (KGMB) was prepared by hydrothermal modification of konjac glucomannan. Carboxymethyl and dopamine modified konjac glucomannan microspheres (CMKGM-PDA) adsorbents were prepared by carboxymethylation and dopamine modification. By static adsorption experiments of heavy metal ions and conventional material characterization, two of the adsorption materials were studied. The adsorption behavior of Pb and Cd on the adsorbents was investigated. The cyclic reutilization properties of the two kinds of adsorbents were studied by adsorption and desorption experiments. The two kinds of absorption techniques, such as the Fu Liye infrared spectrometer (FT-IR), the thermogravimetric analyzer (TG), the scanning electron microscope (SEM), the X ray dispersive energy spectrum (EDX) and the X ray photoelectron spectroscopy (XPS), were studied. The adsorption behavior and mechanism of lead and cadmium were analyzed and discussed to provide a theoretical basis for expanding the application range of two kinds of adsorbents. The results showed that 1.KGMB adsorbed lead and cadmium on the adsorption properties of lead and cadmium: when the reaction temperature was 25, the concentration of adsorbate was 50mg/g, pH was 5.7, the adsorption dose was 5 mg, and the reaction time was 24 h, KGMB adsorbed lead The maximum capacity of the ion is 202.84 mg/g, the adsorption capacity of the adsorbed cadmium ion is 137.55 mg/g. and the adsorption process conforms to the Langmuir model, and the kinetics conform to the quasi two kinetic model. The temperature is between 298.15 and 338.15 K. The adsorption process belongs to the spontaneous and exothermic reaction. In the adsorbent regeneration experiment, the adsorption desorption is followed by three sorbents. After the ring, the adsorption amount of lead ion still reaches 69.34 mg/g, and the adsorption amount of cadmium ion can reach 71.06 mg/g.2.. The thermal stability of KGMB is improved by TG analysis. Through isoelectric point test, it is found that when pH2.3, the surface of KGMB is negative, and is beneficial to the adsorption of metal ions; FT-IR, SEM-EDX and XPS explore KGMB to adsorb lead and cadmium ions by KGMB. The results show that Pb (II) and Cd (II) and the hydrogen ions in -O H on KGMB are exchanged with hydrogen ions, and the adsorption properties of.3.CMKGM-PDA to lead ions are attracted by the electrostatic precipitation with oxygen. When pH is 6, the concentration of lead ion is 50mg/g, the adsorption dose is 25 Mg, and the reaction time is 24 h, the capacity of the adsorbed lead at the reaction temperature of 25 is 75.19 m. G/g, the adsorption capacity of lead at 45 C is 153.37 mg/g; the adsorption process conforms to the quasi two stage kinetic model and the Langmuir model. The maximum lead adsorption amount is 95.2 mg/g when the reaction temperature is 25, and the amount of the adsorbed lead increases with the increase of temperature. The temperature is from 288 to 318 K, and the adsorption process is the process of entropy increasing. In the experiment of adsorbent regeneration, when the concentration of the solution is 18 mg/g, after five cycles of recycling, the adsorption amount of lead ion can still reach 27.5 mg/g.4. by TG analysis. It is known that the thermal stability of CMKGM-PDA is higher than that before the modification. By isoelectric point test, when pH3.65, the CMKGM-PDA surface is negatively charged to the metal. The adsorption of ions by FT-IR, SEM-EDX and XPS is used to explore the mechanism of CMKGM-PDA adsorption of lead. The results show that when pH3.65, the adsorption lead is mainly the chelation of lead and -NH2; when pH3.65, the adsorption lead is mainly based on the chelation of lead and oxygen in -OH, the adsorption of cadmium is clear: the concentration of cadmium ion is 50 mg/g, pH is 6, adsorption dose is 25 mg, the reaction time is 24 h, the adsorption capacity of CMKGM-PDA at the reaction temperature of 25 C is 21.5 mg/g. adsorption process conforms to the quasi two class kinetic model and Langmuir model. When the reaction temperature is 15, the maximum cadmium adsorption capacity is 18.18 mg/g and the reaction temperature is 45 C, the maximum cadmium adsorption capacity is 50.51 mg/g, and cadmium adsorbed cadmium. The temperature increases with the increase of temperature. The temperature is between 288 and 308 K, which belongs to spontaneous and exothermic reaction. In the experiment of adsorbent regeneration, when the concentration of the solution is 50 mg/g, after five recycling, the adsorption amount of cadmium ion can still reach 17.2 mg/g.6. by TG analysis, and it is known that the thermal stability of CMKGM-PDA is improved before the modification; through so on, The electrical point test shows that when pH3.65, the CMKGM-PDA surface is negatively charged to the adsorption of metal ions, and the mechanism of adsorption of cadmium by CMKGM-PDA is explored through FT-IR, SEM-EDX and XPS. The results show that when pH3.65, the adsorption cadmium is mainly the chelation of cadmium and oxygen in -OH; when pH3.65, the adsorption of cadmium mainly on the chelation of cadmium and -N-H and -OH. Two kinds of adsorbents, KGMB and CMKGM-PDA, have good effect on the removal of lead and cadmium ions in water, and there are some potential applications in the field of treatment of lead and cadmium sewage.
【学位授予单位】：西南科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O647.3

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