【作者】 毛丽莉；

【导师】 王海增；

【作者基本信息】 中国海洋大学 ， 海洋化学工程与技术， 2014， 博士

【摘要】 本文研究了四种氧化镁基吸附材料：六硅酸镁、海泡石、凹凸棒石、层状氢氧化镁铝的成型和它们对水体污染物亚甲基蓝、氟离子、钴离子和生物柴油中游离脂肪酸的吸附性能，克服了粉末吸附剂流动性大、易堵塞、难回收等缺陷。利用傅里叶红外光谱仪(FT-IR)、冷场发射扫描电子显微镜(SEM)、差热-热重分析仪（TG-DTA）、扫描探针显微镜(AFM)等现代分析仪器和手段对成型前后的吸附材料进行表征，研究了它们的表面形态和分散程度，评价了它们对水体污染物和游离脂肪酸的吸附脱除性能，并通过动力学的讨论，初步探讨了吸附机理。主要研究结果如下：1.用焙烧法活化氧化镁基吸附材料，通过吸附性能的考察找出最佳焙烧温度，采用现代分析仪器和多种化学分析手段对活化前后的氧化镁基吸附材料的结构形貌进行了表征。分析结果表明，随着焙烧温度的升高，吸附材料表面发生了相应的变化，从而影响其吸附性能。2.将焙烧后的六硅酸镁、海泡石、凹凸棒石、层状氢氧化镁铝分别与聚醚砜用共混法制备成膜吸附材料，并通过吸附实验得出最佳吸附剂添加量分别为：吸附亚甲基蓝，六硅酸镁添加量为18%；吸附生物柴油中的游离脂肪酸，氧化镁基吸附材料添加量均为18%；吸附钴离子，海泡石添加量为14%，凹凸棒石为18%；吸附氟离子，层状氢氧化镁铝添加量为18%。将焙烧后的六硅酸镁、海泡石、凹凸棒石、层状氢氧化镁铝分别与聚偏氟乙烯用挤出法造粒，制备得到颗粒吸附材料，并通过吸附实验得出合适的吸附剂添加量分别为：吸附亚甲基蓝，六硅酸镁添加量为23%；吸附生物柴油中的游离脂肪酸，氧化镁基吸附材料添加量均为23%；吸附钴离子，海泡石添加量为19%，凹凸棒石为23%。3.对成型吸附材料进行分析和表征，发现这四种氧化镁基吸附剂均匀地分散在成型后的吸附材料中，高分子网络起到固定吸附剂颗粒的作用，随着吸附剂含量的增加，成型吸附剂单位质量的吸附能力也有所变化。4.六硅酸镁成型吸附材料用于吸附亚甲基蓝，考察了吸附时间、温度、污染物初始浓度及吸附剂投加量对吸附性能的影响。结果表明，在实验温度范围内，分别达到亚甲基蓝的最大吸附量为：六硅酸镁膜吸附材料157mg/g，六硅酸镁颗粒吸附材料85mg/g。对亚甲基蓝的吸附均遵循伪二级动力学模型，吸附过程可用Frendlich吸附等温式描述。5.氧化镁基成型吸附材料用于吸附生物柴油中的游离脂肪酸，在最佳吸附条件下游离脂肪酸的最大吸附量分别为：六硅酸镁膜吸附材料：210mg/g，海泡石膜吸附材料：250mg/g，凹凸棒石膜吸附材料：210mg/g，层状氢氧化镁铝膜吸附材料：455mg/g，六硅酸镁颗粒吸附材料：175mg/g，海泡石颗粒吸附材料：185mg/g，凹凸棒石颗粒吸附材料：145mg/g，层状氢氧化镁铝颗粒吸附材料：218mg/g。在实验温度范围内，Freundlich吸附模型可以较好地描述氧化镁基成型吸附材料对游离脂肪酸的吸附行为。对于六硅酸镁吸附材料，无论是膜状还是颗粒状，伪一级动力学数据都能较好地描述其对游离脂肪酸的吸附；对于层状氢氧化镁铝，无论是膜状还是颗粒状，伪二级动力学数据都能较好地描述其对游离脂肪酸的吸附；海泡石和凹凸棒石的膜吸附材料对游离脂肪酸的吸附均符合伪一级动力学模型，它们的颗粒吸附材料均符合伪二级动力学模型。对于氧化镁基颗粒吸附材料吸附游离脂肪酸来说，吸附过程主要受颗粒内扩散控制，但颗粒内扩散不是唯一的速率控制步骤。6.考察了海泡石、凹凸棒石的成型吸附材料对水溶液中钴离子的吸附性能，在最佳吸附条件下，钴离子的最大吸附量分别为：海泡石膜吸附材料13mg/g，凹凸棒石膜吸附材料12.7mg/g，海泡石颗粒吸附材料16.1mg/g，凹凸棒石颗粒吸附材料12.4mg/g。Langmuir吸附等温方程能够很好的描述凹凸棒石颗粒吸附材料对钴离子的吸附，Freundlich吸附等温方程能够很好的描述海泡石膜吸附材料和凹凸棒石膜吸附材料对钴离子的吸附，海泡石颗粒吸附材料吸附过程较为复杂，Langmuir和Freundlich等温式均不适用于描述其吸附行为。伪二级动力学方程能够很好地描述海泡石、凹凸棒石的成型吸附材料对水溶液中钴离子的吸附过程。颗粒内扩散方程的拟合说明颗粒内扩散不是唯一的控速步骤。7.考察了层状氢氧化镁铝膜吸附材料对水溶液中氟离子的吸附性能，发现随着膜吸附材料投加量的增加、时间延长，氟离子的脱除率随之增加。在最佳吸附条件下达到氟离子最大吸附量为2.65mg/g。Langmuir吸附等温方程能够很好的描述层状氢氧化镁铝膜吸附材料对氟离子的吸附，随着溶液pH值的升高，吸附能力下降。伪二级动力学方程能很好地描述层状氢氧化镁铝膜吸附材料对氟离子的吸附行为。颗粒内扩散方程的拟合说明吸附过程主要受颗粒内扩散控制，但颗粒内扩散不是唯一的速率控制步骤。上述研究结果表明，利用氧化镁基吸附材料成型制备的一系列吸附材料具有较好的吸附性能和广阔的应用前景。本研究中将有机聚合物作为载体固定吸附材料成型，并应用于生物柴油精制和污染物脱除领域，为粉末状吸附剂的大规模使用提供了新思路。更多还原

【Abstract】 Four kinds of Magnesium Oxide based adsorption materials (magnesium silicate,sepiolite, palygorskite, layered double hydroxides(LDHs)’) have been investigated inthe shaping and their adsorption performance on water pollutants such as methyleneblue, cobalt ion, fluorinion and free fatty acids in biodiesel, which can solve thedefects of powder adsorbent such as high dispersibility, cannot be recycled and tend tobecome clogged.The physicochemistry properties of the obtained samples were characterizedwith FT-IR spectrometers, Scanning electron microscope, thermogravimetry andatomic force microscope. Their adsorption properties of water contaminants and freefatty acid were determined, moreover, the principle of kinetics in the adsorptionprocess was also studied, and the adsorption mechanism was discussed. The mainresearch contents and results are as follows:1. Prepared activated Magnesium Oxide based adsorption material by calcination,determined the suitable calcinate temperature after the investigation of adsorptionproperties, the physicochemistry properties of the obtained samples werecharacterized with modern analysis instruments, the results show that with theincrease of calcination temperature, the material surface changed, thus affecting theadsorption performance.2. Prepared hybrid membranes through blending calcinated magnesium silicate,sepiolite, palygorskite, layered double and PES/DMF respectively, and determinedsuitable proportion by the adsorption experiments：to adsorb methylene blue, sixmagnesium silicate added18%; to adsorb free fatty acid in biodiesel, magnesiumoxide based adsorption material adding amount is18%. To adsorb cobalt, sepiolitecontent is14%and attapulgite was18%; fluoride ion adsorption, Mg-Al layereddouble hydroxide added18%.Prepared molded particles through blending magnesium silicate, sepiolite, palygorskite, layered double and PVDF by extrusion granulation, and determinedsuitable proportion by the adsorption experiments: to adsorb methylene blue, sixmagnesium silicate added23%; to adsorb free fatty acid in biodiesel, magnesiumoxide based adsorption material adding amount is23%. To adsorb cobalt, sepiolitecontent is19%and attapulgite was23%.3. Through characterized with modern analysis instruments, we can foundmagnesium silicate, sepiolite, palygorskite and layered double hydroxides aredispersed in the adsorption material uniformly. The polymer plays the role of networkto fix adsorbent granules and with the increase of content of adsorbent, adsorptioncapacity changed accordingly.4. MB is selected as adsorption object to investigate the magnesium silicatemolded adsorbent’s adsorption, the effects of time, temperature, initial concentrationof MB and adsorbent dosage on adsorption properties were investigated. The resultsshow that, in the temperature range of the experiments, respectively, methylene blueadsorption maximum is: six magnesium silicate membrane:157mg/g, six magnesiumsilicate particles:85mg/g. The adsorption thermodynamics showed Frendlichadsorption model could describe the adsorption process and the studies of kineticsproved Pseudo second-dynamics equation could describe the adsorption behavior inthe experimental temperature range.5. Magnesium Oxide based molded adsorbent for the adsorption of free fattyacids in biodiese were investigated, we studied the effects of adsorption time,temperature, and adsorbent dosage on adsorption properties. Under the bestexperimental conditions, the maximum adsorption capacity is, respectively: sixmagnesium silicate membrane:210mg/g, sepiolite membrane:250mg/g, attapulgitemembrane:210mg/g, Mg-Al layered double membrane:455mg/g, six magnesiumsilicate particles:175mg/g, sepiolite particles:185mg/g, attapulgite particles:145mg/g, Mg-Al layered double hydroxide particles:218mg/g.The adsorptionthermodynamics showed Frendlich adsorption model could describe the adsorptionprocess. For magnesium silicate, both the hybrid membrane and shaped particles canbe described their adsorption behavior by Pseudo first-dynamics equation, and for LDHs, both the hybrid membrane and shaped particles can be described theiradsorption behavior by Pseudo second-dynamics equation. For sepiolite andpalygorskite, their hybrid membranes can be described by Pseudo first-dynamicsequation, and their shaped particles can be described their adsorption behavior byPseudo second-dynamics equation. Particle dispersion was the major controlling stepof adsorption rate but intra-particles diffusion was not the unique control step.6. Cobalt ion is selected as adsorption object to observe the molded adsorbent’sadsorption of sepiolite and palygorskite. Under the best experimental conditions, theadsorption of cobalt is, respectively: sepiolite membrane:13mg/g, attapulgitemembrane:12.7mg/g, sepiolite particles:16.1mg/g, attapulgite particles:12.4mg/g.The adsorption thermodynamics showed Langmuir adsorption model coulddescribe the adsorption process of palygorskite shaped particles and Frendlichadsorption model could describe the adsorption process of sepiolite and palygorskitehybrid membranes. For sepiolite, neither Langmuir nor Frendlich adsorption modelcould describe t the shaped particles for its complicated adsorption process. Thestudies of kinetics proved Pseudo second-dynamics equation could describe theadsorption behavior in the experimental temperature range and intra-particlesdiffusion was not the unique control step.7. Fluorinion adsorption on LDHs hybrid membranes was investigated. Theresults proved the rate of removal increased with increasing adsorbent dosage andadsorb time, and it was decreased with increasing pH value. Under the bestexperimental conditions, the maximum adsorption capacity of fluoride ions is2.65mg/g. The studies of kinetics proved Pseudo second-dynamics equation coulddescribe the adsorption behavior in the experimental temperature range andintra-particles diffusion was not the unique control step.The results of the study show that, a series of shaped Magnesium Oxide basedadsorption materials were prepared and they have good adsorption performance andwide application prospect. The organic polymer employed as network to fix theadsorption material, and the shaped Magnesium Oxide based adsorption materialsused to biodiesel refining and pollutant removal, which provides a new idea for the widely utilized of powder adsorbent.更多还原