【作者】 孙金香；

【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， 2010， 博士

【摘要】 本文以镁盐和商品活性炭为原料,运用过量浸渍法、等体积浸渍法、机械混合法和化学沉淀-原位复合法制备一系列氯化镁/活性炭复合材料、氢氧化镁/活性炭复合材料和氧化镁/活性炭复合材料。利用差热-热重分析仪、比表面积及孔结构分析仪、X射线衍射仪、红外光谱仪和扫描电镜等现代仪器对其进行了表征分析,并研究了该系列镁炭复合材料的吸湿性能、对废水中有机物和重金属离子的吸附脱除性能及对催化裂化汽油中硫化物的吸附脱除性能。运用过量浸渍法、等体积浸渍法、机械混合法和化学沉淀-原位复合法制得氯化镁/活性炭复合材料、氢氧化镁/活性炭复合材料和氧化镁/活性炭复合材料。发现：镁盐改性活性炭得到的复合材料的比表面积随着焙烧温度和焙烧时间的变化而变化,其平均孔径均大于2nm,具有中孔性质。镁盐负载在活性炭上之后,其特征峰峰强变弱,说明氯化镁负载在活性炭上之后,镁盐的晶体结构被破坏,在晶面上出现不同程度缺陷结构。在复合材料中,镁元素分别以氯化镁、氢氧化镁和氧化镁的形式存在,分散于活性炭的孔隙内外,镁组分和炭组分有一定的相互作用。研究了氯化镁/活性炭复合材料的吸湿性能。结果表明,氯化镁/活性炭复合干燥剂的吸湿量随着氯化镁含量的增加而增加；在氯化镁含量固定时,相对湿度越高,干燥剂的吸湿量越大。吸湿过程遵循伪二级动力学模型,再生性能好,可循环利用。研究了氯化镁/活性炭复合材料、氢氧化镁/活性炭复合材料和氧化镁/活性炭复合材料对水溶液中染料(弱酸性红2R、普拉红B、弱酸性艳蓝RAWL、亚甲基蓝、分散深蓝S-3BG、中性红2GL和碱性紫)的静态吸附和动态吸附性能。静态吸附实验结果表明：氧化镁基活性炭复合材料对染料的吸附均是快速吸附过程,在实验考察的温度范围内,对染料的吸附均遵循伪二级动力学模型,吸附过程分别可用Langmuir和Freundlich吸附等温式描述。在20～40℃吸附温度下,氯化镁/活性炭复合材料对弱酸性红2R的饱和吸附量为35.84～714.57mg·g-1；在20～40℃吸附温度下,氢氧化镁／活性炭复合材料对弱酸性红2R、普拉红B、弱酸性艳蓝RAWL、亚甲基蓝、分散深蓝S-3BG的饱和吸附量分别为178.57～125mg·g-1,32.57～31.55mg·g-1,37.88～34.82mg·g-1,166.67～212.72mg·g-1和120.48～192.3lmg·g-1；在20～40℃吸附温度下,氧化镁／活性炭复合材料对普拉红B和弱酸性艳蓝RAWL的饱和吸附量分别为63.69～59.17mg·g-1和105.26～70.42mg·g-1。热力学研究表明,氧化镁基活性炭复合材料对染料的吸附过程均可自发进行。动态吸附实验表明,弱酸性红2R和普拉红B溶液初始浓度增大,传质推动力增大,吸附量增大；随着柱高的增加,饱和吸附时间增加,饱和吸附百分率随着柱高的增加而增大；流速增大,穿透时间缩短,但改性复合吸附剂的饱和吸附量降低；改性复合吸附剂适用pH值范围很广,但在酸性条件下吸附性能最佳；吸附柱可以再生和重复利用,具有重要的实用应用价值。研究了氧化镁基活性炭复合材料对水溶液中重金属离子的吸附性能,考察了吸附时间、吸附温度、溶液初始pH值、吸附剂用量和初始浓度对吸附性能的影响。结果表明：该类复合材料对这几种重金属离子的吸附均为快速的吸附过程,吸附均遵循伪二级动力学模型。Cu2+在氧化镁/活性炭复合材料上的吸附和Ni2+在氢氧化镁/活性炭复合材料上的吸附均可用Langmuir线性吸附等温方程式很好的描述,而Cr(Ⅵ)在氧化镁/活性炭复合材料上的吸附则用Freundlich线性吸附等温方程式描述更为合适。在20～50℃吸附温度下,Cu2+和Cr(VI)在CACl(以氯化镁和造纸草浆黑液为主要原料制备)上的饱和吸附量分别为22.12～91.74mg·g-1和27.03～384.62mg·g-1；在25～45℃吸附温度下,Cu2+和Cr(VI)在DMC(以氯化镁和商品活性炭为主要原料制备)上的饱和吸附量分别为63.58～85.26mg·g-1和32.14～53.26mg·g-1；在20～50℃吸附温度下,Ni2+在氢氧化镁/活性炭复合材料上的饱和吸附量为27.86～34.36mg℃g-1。热力学数据表明,该类复合材料对这几种重金属离子的吸附过程是一个自发的吸热反应。氧化镁/活性炭复合材料吸附脱除FCC汽油中硫化物的实验表明,以硫酸镁和造纸草浆黑液为原料制得的氧化镁/活性炭复合材料(CAS)对FCC汽油脱硫的适宜条件为：固定床温度80℃,油剂比1.0,空速5h-1；以氯化镁和商品活性炭为原料制得的氧化镁/活性炭复合材料(DMC)对FCC汽油脱硫的适宜条件为：固定床温度90℃,油剂比1.0,空速5h-1。在相同的动态吸附条件下,氧化镁／活性炭复合材料比商品活性炭和氧化镁具有更大的硫容和更高的脱硫性能,复合材料CAS的初始脱硫能力高于DMC,而DMC的硫容明显大于CAS。在两种复合材料分别脱硫后的FCC汽油中,硫化物的含量和种类均明显减少,尤其是苯并噻吩基本完全脱除。氧化镁／活性炭复合材料在300℃下用氮气吹扫2h再生,再生后仍具有较高的脱硫能力：脱硫率达88.56%,穿透时间为110min。上述研究表明,镁盐改性活性炭得到的镁炭复合材料可以很好地应用于空气干燥、废水中有机物和重金属离子的吸附脱除等领域,对催化裂化汽油中硫化物的脱除也有很好地效果。该研究不仅得到了一系列性能优良的无机-有机复合多孔性环保材料,而且对于我国西部盐湖资源开发过程中镁盐的综合利用也具有非常重要的意义。更多还原

【Abstract】 In this paper, a series of compounds were prepared with magnesium salts and activated carbon as raw materials by plus-impregnation, incipient-impregnation, mechanical mixing and chemical precipitation & compounding in situ, such as magnesium chloride/activated carbon composites, magnesium hydroxide/ activated carbon composites and magnesia/ activated carbon composites. These compounds were analyzed and characterized by DTA-TGA, BET surface area and pore structure analyzer, X-ray diffraction, infrared spectroscopy and scanning electron microscopy and other modern instruments. The adsorption properties of magnesia-based activated carbon compounds were evaluated by moisture absorption, removal of organic matter and heavy metal ions in wastewater, sulfur compound from FCC gasoline.The compounds such as magnesium chloride/activated carbon composites, magnesium hydroxide/ activated carbon composites and magnesia/ activated carbon composites were prepared by plus-impregnation, incipient-impregnation, mechanical mixing and chemical precipitation & compounding in situ. It showed that the specific surface area of these mesoporous compounds changed with changing the calcination temperature and time, the average pore size of whom larger than 2nm. After the magnesium salt load in the activated carbon, the peak intensity weaken, which indicated that the crystal structure of magnesium salt was destroyed. It was found that magnesium were inside and outside the pores in activated carbon, respectively, in the form of magnesium chloride, magnesium hydroxide and magnesium oxide. Mg and C have a certain fusion.It was showed that the water adsorption capacity increased with the content of magnesium chloride and the relative humidity increasing. The moisture adsorption onto the magnesium chloride/activated carbon composite was followed the pseudo-second order model. The adsobnet could be recycled and reused.The static and dynamic adsorption performance of dyes from aqueous solution on the magnesium oxide-based activated carbon composites(magnesium chloride/activated carbon composites, magnesium hydroxide/activated carbon composites and magnesia/activated carbon composite materials) were studyed. Static adsorption experiment results showed that the adsorption courses were all fast processes;the adsorption of all kinds of dyes onto the composites were followed the pseudo-second order model and could be described respectively by Langmuir or Freundlich isotherm; the adsorption capacities of Weak Acid Red 2R on magnesium chloride/activated carbon were 35.84～714.57mg·g-1 at the temperature of 20～40℃; the adsorption capacityes of Weak Acid Red 2R, Weak Acid Red B,Weak Acid Brilliant Blue RAWL, Methylene and Disperse Navy Blue S-3BG on magnesium hydroxide/activated carbon composites were 178.57～125mg·g-1,32.57～31.55mg·g-1, 37.88～34.82mg·g-1,166.67～212.72mg·g-1 and 120.48～192.31mg·g-1 under the temperature of 20～40℃, while those were 63.69～59.17mg·g-1 and 105.26～70.42mg·g-1 to Weak Acid Red B and Weak Acid Brilliant Blue RAWL on magnesia/activated carbon composites at the same temperature; thermodynamic studies have shown that the adsorption processes of dyes on the magnesium-based activated carbon composites were spontaneous.Dynamic adsorption experiments showed that the mass transfer driving force increased with increasing the initial concentration of dyes, which leaded to the adsorption amount of the Weak Acid Red 2R and the Weak Acid Red B;with the increase of column height and the saturation adsorption time increasing, the percentage of adsorption increased; with the flow rate increasing, through time and the adsorption capacity decreased; the composites prepared were well for a wide range of pH values, but best for acidic conditions; adsorption column could be recycled and reused, with important practical application.The magnesia-based activated carbon composites prepared were examined for the adsorption of heavy metal ions from aqueous solutions by varying the parameters of adsorption time, temperature, initial pH, adsorbent dosage and initial concentration. Studies showed that the adsorption courses were all fast processes; the adsorption of all kinds of heavy metal ions onto the composites were followed the pseudo-second order model;the adsorption of Cu2+ on the magnesia/activated carbon composite and Ni2+ on the magnesium hydroxide/activated carbon composite could be described by Langmuir isotherm, but the adsorption of Cr(VI) on the magnesia/activated carbon composite could be described by Freundlich isotherm; under the temperature of 20～50℃,the adsorption capacities of Cu2+ and Cr(Ⅵ) on CAC1 (CAC1 was prepared using magnesium chloride and straw pulp black liquor as main raw materials) were 22.12～91.74mg·g-1 and 27.03～384.62mg·g-1,but the adsorption capacities of Cu2+ and Cr(VI) on DMC (DMC was prepared using magnesium chloride and activated carbon as main raw materials) were 63.58～85.26mg·g-1 and 32.14～53.26mg·g-1 under the temperature of 25～45℃; the adsorption capacities of Ni2+ on magnesium hydroxide/activated carbon composite were 27.86～34.36mg·g-1 under the temperature of 20～50℃;the adsorption of all kinds of heavy metal ions was found to be endothermic.The removal performance of sulfur compounds from FCC gasoline by magnesium oxide/activated carbon composites with magnesium sulfate and straw pulp black liquor as raw materials (CAS) or with magnesium chloride and activated carbon as raw materials (DMC) was evaluated using dynamic adsorption method. It was found that when sorbent granularity at the range of 40～60 meshes, the best technological parameters of adsorption temperature, volume ratio of gasoline and space velocity to CAS and DMC were 80℃,1.0,5h-1 and 90℃,1.0,5h-1 respectively, sulfur removal efficiencies were higher. In the same conditions, the sulfur hold and desulfurization performance of magnesium oxide/activated carbon composites were higher than activated carbon and magnesium oxide, respectively; when the initial desulfurization capacity of CAS was higher than DMC, DMC had a greater sulfur hold significantly than CAS.GC-FPD chromatograms of gasoline desulfurized clearly showed that sulfur compounds, such as thiophene and 3-methyl-thiophene, in FCC gasoline were adsorbed by magnesia/activated carbon composites, and benzothiophene was removed completely. Magnesia/activated carbon composites after regeneration at 300℃for 2h with nitrogen purge still had a higher desulfurization capacity:desulfurization rate of 88.56%, and the penetration time was 110min.The studies showed that the composites prepared by magnesium salts modified activated carbon could be well applied to air dry, removal of organic matter, heavy metal ions in wastewater and sulfur compounds in FCC gasoline. The preparation of magnesia-based activated carbon composites by magnesium salts and activated carbon can serve two purposes. One hand, it can provide a new way for preparation of inorganic-organic porous material for environmental protection; but on the other hand, it’s very important for utilization of magnesium salts from salt lake’s of China’s western.更多还原