摘 要
近年来，随着纺织、印刷等印染工业的快速发展，染料污染问题日趋严重，因此，开展印染废水治理工作尤为迫切。吸附法具有处理效果好、操作简便、适用范围广等特点，从而被广泛应用到污染物分离过程中。硅胶是常用的吸附材料，在污染物处理方面具有一定的应用价值。然而，目前我国工业化生产的硅胶粒径大且分散不均匀，对有机污染物的吸附性能不理想，限制了硅胶作为吸附剂在污染治理方面的应用。果胶是一类广泛存在于植物中的以 α-1,4-糖苷键链接的 D-半乳糖醛酸酸性杂多糖，分子内含有大量的羧基、羟基等活性基团，较多研究将果胶应用于吸附水中重金属等污染物，鲜有研究将果胶应用于碱性阳离子染料的吸附。
本文制备了一种新型果胶改性硅胶复合材料，研究了果胶改性硅胶复合材料对碱性阳离子染料的吸附性能。果胶改性硅胶，既利用果胶分子与阳离子作用的活性位点，又提高了果胶的机械稳定性及作用面积，同时改进硅胶的吸附性能。实验从废弃的柚子皮中提取果胶，利用果胶对自制多孔硅胶微球进行表面改性，得到一种新型的复合材料--P-硅胶，研究了材料的制备条件及吸附性能的影响因素，并将其应用到水中亚甲基蓝碱性染料的吸附分离中。主要内容包括：
（1）采用化学沉淀法，以硅酸钠和氯化铵为原料，在添加表面活性剂的情况下，制备多孔硅胶微球，通过傅立叶红外光谱和正置荧光显微镜对材料进行表征，研究了硅酸钠浓度、表面活性剂种类、表面活性剂浓度、分散剂无水乙醇用量等因素对所制备的多孔硅胶微球吸附性能的影响。研究表明，当氯化铵浓度 1.0 mol/L,硅酸钠浓度 0.5mol/L,表面活性剂十六烷基三甲基溴化铵（CTAB）浓度 0.1 mol/L,分散剂无水乙醇用量 5%时，制备出的多孔硅胶微球对亚甲基蓝的去除率最好，最大去除率可达 51%.
（2）以废弃的柚子皮为原料，采用酸提取法提取果胶，通过正交实验确定了果胶的最佳提取条件为：提取温度 95 °C,pH 值 1.5,料液比 1:15,提取时间 60 min,果胶提取率可达 5%以上。通过酸碱滴定法测得所提取的果胶的酯化度（DE）为 67.1% ,并且通过傅立叶红外光谱对其结构进行表征。
（3）用果胶改性多孔硅胶微球表面，制备出果胶改性硅胶复合材料P-硅胶，通过傅立叶红外光谱对 P-硅胶进行表征，并利用紫外分光光度法研究了 P-硅胶对亚甲基蓝的吸附性能。考察了原料投加量对所制备的P-硅胶吸附性能的影响并比较了以自制硅胶和商品薄层硅胶HG为原料所制备的 P-硅胶的吸附性能。结果表明，硅胶经过果胶改性后，其对亚甲基蓝的吸附容量由 30.35 mg·g-1增加到 41.33 mg·g-1,吸附性能明显提高。当果胶与硅胶质量比为 1:2 时，制备的 P-硅胶对亚甲基蓝的吸附性能较好，以自制硅胶为原料制备的 P-硅胶的吸附性能优于以硅胶 HG 为原料制备的 P-硅胶。
（4）研究了 P-硅胶吸附亚甲基蓝的最佳吸附条件，考察了 pH值、吸附剂 P-硅胶用量、吸附时间、温度、亚甲基蓝的初始质量浓度等因素对 P-硅胶吸附性能的影响。考察了不同洗脱剂（去离子水、无水乙醇、盐酸）对 P-硅胶重复利用的影响。P-硅胶对亚甲基蓝的吸附容量随着 pH、温度的升高而增大，碱性条件下有利于 P-硅胶对亚甲基蓝的吸附，结果显示：当 pH=7,P-硅胶用量为 5 mg,亚甲基蓝初始质量浓度为 12 mg·L-1, 吸附时间 120 min,吸附温度为 50 °C 时，制备出的 P-硅胶对亚甲基蓝染料溶液的吸附容量最大可达 57.75mg·g-1.动力学研究表明 P-硅胶对亚甲基蓝的吸附行为符合准二级动力学方程，P-硅胶吸附亚甲基蓝的过程以化学吸附为主。吸附等温线研究显示，实验数据拟合更符合 Langmuir 吸附等温模型。以乙醇洗脱再生的 P-硅胶，重复使用效果较好。研究了 P-硅胶对湖水及自来水等实际水样中亚甲基蓝的去除效果，去除率可达 90%以上。
关键词：果胶；改性；硅胶微球；亚甲基蓝；吸附
ABSTRACT
For the last few years, with the rapid development of dyeing and printing industry, thepollution from dyestuff is getting worse. As a consequence, it is sorely needed controlling thepollution from dyestuff. As is known to all, adsorption method has benificial advantages, such as,effective treatment, ease of operation, wide applicability, which was applied in the process ofpollutants separation Silica gel is a kind of typical adsorption materials and shows the hugepotential practical value in the aspect of pollutant treatment.However, owing to the larger particlessize and uneven distribution, silica gel that was utilized in the controlling the pollution fromdyestuff widely was restricted. Pectin is a family of complex heteropolysaccharides consisting ofα-1,4-glycosidic linked D-galacturonic acid residues, which widely exists in plants and containslarge amount of active groups such as carboxyl, hydroxyl. The pectin is usually used to adsorb theheavy metal pollutants in the water mostly. However, there is little research about application ofpectin into alkaline cationic dyes adsorption.
In this paper, a new kind of composite materials was prepared by modifying porous silica gelwith pectin, and the alkaline cationic dyes adsorption property of composite materials was studied.
The adsorption property of Silica gel was increased through modified by pectin,which used themolecule interact between active group in the pectin and silicon hydroxyl in the silica gel andincresed the action area of pectin and enhanced the mechanical stability of pectin.The new kind ofadsorption materials （P-Silica gel） was prepared by modifying porous silica gel with pectinextracted from the waste pomelo peel. The preparation conditions of materials and the influencefactors of adsorption property was investigated.The P-Silica gel was applied in the adsorptionseparation of methylene blue in the watrer.The main content of this paper is as follows:
（1） The porous silica gel was obtained from ammonium chloride and sodium silicate byadding the surfactant. The materials were characterized by Fourier transform infrared （FT-IR）spectroscopy and fluorescence microscope. The effects of the Na2SiO3concentration, differentkinds of surfactant, the concentration of surfactant, the amount of disperser ethyl alcohol on theadsorption properties of the porous silica gel were examined.The study showed the best conditionas follows:the concentration of NH4Cl was 1 mol/L, the concentration of Na2SiO3was 0.5 mol/L,concentration of CTAB was 0.1 mol/L, the amount of ethyl alcohol was 5%. The porous silica gelprepared in this condition showed the largest removal rate of MB and the best removal rate mayreach 51%.
（2） The pectin was extracted from the waste pomelo peel by acid hydrolysis. According to theorthogonal experiment, the optimum extraction conditions were ascertained: extractiontemperature 95 °C, extraction pH 1.5,solid-liquid ratio 1:15, extraction time 60 min. In thiscondition, the extraction ratio of pectin was more than 5%. The degree of esterification to theextracted pectin was 67.1% measured by acid-base titration and the structure of pectin wascharacterized by Fourier transform infrared （FT-IR） spectroscopy.
（3） The composite materials （P-Silica gel） was prepared by modifying porous silica gel withpectin.The materials were characterized by Fourier transform infrared （FT-IR） spectroscopy. Itsapplication to Methylene Blue （MB） removal from wastewater was investigated by UVspectrophotometry. The adsorption property of P-Silica gel prepared by self-made silica gel andpurchased silica gel HG was compared. The result showed that the adsorption property of poroussilica gel was improved significantly after modified by pectin in the condition of the pectin withsilica gel mass ratio of 1:2, and its adsorption capacity increased from 30.35 mg·g-1to 41.33mg·g-1. The adsorption property of P-Silica gel prepared by self-made silica gel was better thanpurchased silica gel HG.
（4） The effects of the pH, the amount of P-Silica gel, the adsorption time, the temperature, theinitial concentration of MB on the adsorption properties of P-Silica gel were examined. And therecyle of P-Silica gel was investigated through eluted by Deionized water, ethanol, hydrochloricacid. With the increase of the solution pH and temperature, the adsorption capacity of P -Silica geladsorbing methylene blue was increased, and it was conducive for the adsorption of methyleneblue in the alkaline conditions. The optimized adsorption condition was as follows: pH=7, theamount of P-Silica gel was 5 mg, the initial concentration of Methylene Blue was 12 mg·L-1. Andthe maximum adsorption capacity of P-Silica gel to Methylene Blue was 57.75 mg·g-1at 50 ?C.
Kinetic studies showed that the adsorption kinetics illustrated the suitability of employing thepseudo-second-order kinetic model, which indicated that the process of P-silica gel adsorbingmethylene blue was given priority to chemical adsorption. Adsorption isotherms showed thatLangmuir model was more suitable for the experimental data fitting.The P-Silica gel eluted byethanol showed the best effect of recyle using. The removal rates of MB were more than 90 % inthe lake water samples and tap water samples with using P-Silica gel as adsorbent.
KEY WORDS:pectin; modify; silica gel; methylene blue; adsorption
目 录
摘 要
ABSTRACT
目 录
第一章 绪论
1.1 引言
1.2 染料废水的主要治理方法
1.2.1 生物法
1.2.2 光催化法
1.2.3 膜分离法
1.2.4 吸附法
1.3 硅胶
1.3.1 硅胶微球的制备
1.3.2 硅胶微球的改性
1.4 果胶
1.4.1 果胶的结构
1.4.2 果胶的来源
1.4.3 果胶的性质
1.4.4 果胶的提取方法
1.4.5 果胶去除重金属离子国内外研究现状
1.5 论文的研究背景和主要内容
第二章 多孔硅胶微球的制备
2.1 前言
2.2 实验部分
2.2.1 试剂和仪器
2.2.2 实验原理
2.2.3 多孔硅胶微球的制备
2.2.4 多孔硅胶微球的表征
2.2.5 多孔硅胶微球的吸附性能
2.3 结果与讨论
2.3.1 多孔硅胶微球的表征
2.3.2 实验影响因素分析
2.4 本章小结
第三章 果胶的提取
3.1 前言
3.1.1 酸提取法
3.1.2 微波提取法
3.1.3 离子交换法
3.1.4 酶提取法
3.1.5 果胶沉淀方法
3.2 实验部分
3.2.1 试剂和仪器
3.2.2 果胶的提取
3.2.3 果胶提取步骤
3.2.4 果胶提取正交实验
3.2.5 果胶提取率计算
3.2.6 果胶酯化度的测定
3.2.7 果胶红外分析
3.3 结果与讨论
3.3.1 果胶提取正交实验
3.3.2 果胶酯化度的测定
3.3.3 果胶的红外光谱分析
3.4 本章小结
第四章 果胶改性硅胶的制备及其对亚甲基蓝的吸附性能
4.1 前言
4.2 实验部分
4.2.1 试剂和仪器
4.2.2 果胶改性硅胶的制备
4.2.3 样品的红外表征
4.2.4 亚甲基蓝吸附实验
4.3 结果与讨论
4.3.1 样品的红外表征
4.3.2 制备条件对 P-硅胶吸附性能的影响
4.3.3 实验条件对 P-硅胶吸附性能影响
4.4 本章小结
第五章 结论与展望
5.1 结论
5.2 展望
参考文献
致 谢
