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1.
采用尿素分解水热合成法制备Mg-Fe类水滑石,并通过XRD,FF-IR表征.利用Mg-Fe类水滑石焙烧产物对水中硫酸根离子进行一定条件的吸附去除.结果表明,Mg-Fe类水滑石层间阴离子为碳酸根,结晶效果较好.焙烧后Mg-Fe类水滑石在pH =4~8,温度为35℃,对初始浓度500 mg/L硫酸根离子具有较好的吸附能力,90 min可快速达到吸附平衡,吸附数据表明该吸附符合准二级动力学方程,吸附等温线符合Langmuir吸附模型,最大吸附量为151.51 mg/g. 相似文献
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由于人类活动和自然原因,重金属污染已经成为一个全球性问题。吸附法是一种极具可操作性和规模化推广的修复技术,因此,开发具有高选择性、高吸附量的吸附剂迫在眉睫。类水滑石是一类典型的阴离子插层材料,因其层板组成可调、层间阴离子可交换、结构记忆效应等特点已经在重金属污染治理领域得到了广泛关注。概述了盐湖镁资源高值化转化制备镁基水滑石材料并用于重金属污染治理方面的工作,介绍了镁基水滑石在重金属污染耕地原位修复方面的应用进展,讨论了超稳矿化过程中存在的问题并提出了建议,最后对镁基水滑石的应用前景进行了展望。 相似文献
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采用共沉淀法一步合成系列类水滑石负载磁性粒子的颗粒,经煅烧得到磁性焙烧产物.利用焙烧产物吸附水中腐殖酸,得到磁性焙烧态锌铝类水滑石去除腐殖酸效果较好.考察了磁性焙烧态锌铝类水滑石制备条件对腐殖酸去除效果的影响,通过正交试验优化了制备条件.静态吸附实验表明:吸附剂投加量0.2 g/L, 30 min内20 mg/L腐殖酸去除率为97.96%.X射线衍射(XRD)、红外光谱(FT-IR)、热重-差热(TG-DSC)和比表面积(SSA)表征结果表明:一定量的磁性基质掺入并没有破坏锌铝类水滑石典型的层状结构;焙烧态产物为氧化物,磁性保持良好;比表面积达80.00 m2/g.磁性焙烧态锌铝类水滑石在水中因"记忆效应"而结构重建通过表面吸附和腐殖酸结构中小尺寸的官能团插层快速去除腐殖酸. 相似文献
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实验合成了一种焙烧态Ca-Mg-Al类水滑石,通过吸附动力学、吸附热力学及pH值的影响实验研究其对As (V)的吸附性能;并通过X射线衍射(XRD)、比表面积及孔径(BET)、场发射扫面电子显微镜(FESEM)、傅里叶红外光谱(FTIR)和X射线光电子能谱(XPS)等测试对合成材料进行表征并分析其吸附机理.实验结果表明,焙烧态Ca-Mg-Al 类水滑石对As(V)具有较强的吸附能力,其最大吸附量为71.86 mg/g,其吸附行为较符合Freundlich吸附等温方程和准一级动力学方程,且在不同的pH值下均能保持较好的吸附能力.焙烧态Ca-Mg-Al 类水滑石吸附As(V)的吸附机理主要包括类水滑石晶体结构的重建以及其表面羟基官能团的络合作用. 相似文献
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实验合成了一种焙烧态Ca-Mg-Al类水滑石,通过吸附动力学、吸附热力学及pH值的影响实验研究其对As(Ⅴ)的吸附性能;并通过X射线衍射(XRD)、比表面积及孔径(BET)、场发射扫面电子显微镜(FESEM)、傅里叶红外光谱(FTIR)和X射线光电子能谱(XPS)等测试对合成材料进行表征并分析其吸附机理。实验结果表明,焙烧态Ca-Mg-Al类水滑石对As(Ⅴ)具有较强的吸附能力,其最大吸附量为71.86 mg/g,其吸附行为较符合Freundlich吸附等温方程和准一级动力学方程,且在不同的pH值下均能保持较好的吸附能力。焙烧态Ca-Mg-Al类水滑石吸附As(Ⅴ)的吸附机理主要包括类水滑石晶体结构的重建以及其表面羟基官能团的络合作用。 相似文献
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为了脱除水中的苯甲酸根,以苯甲酸作为吸附质,研究了水滑石及其焙烧产物的吸附作用。考察了吸附剂的镁铝摩尔比、初始pH值、苯甲酸浓度、吸附剂添加量、吸附时间和温度对吸附效果的影响,并对比考察水滑石和焙烧水滑石对苯甲酸的吸附。结果表明,水滑石及其焙烧产物对苯甲酸的最优吸附条件均为酸性环境下,镁铝摩尔比3∶1,吸附质浓度220 mg/L,吸附剂的量0.06 g;水滑石吸附时间20 h,吸附温度为60℃时,对苯甲酸的去除效果最好;而焙烧水滑石在室温下吸附苯甲酸8 h达到最高去除率;在同样条件下,水滑石焙烧产物比水滑石对苯甲酸的吸附大得多。 相似文献
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以氯离子为诱导的钢筋锈蚀是造成混凝土耐久性问题的主要原因,其本质是氯离子通过材料基体的多孔结构在水泥基材料中扩散,并逐步迁移到钢筋表面,发生不利的物理化学反应。水滑石即层状双金属氢氧化物(LDHs)是一种新型延缓钢筋锈蚀的外掺材料,具有独特的层状结构和离子交换性质,可在特定的介质溶液中将客体阴离子与层间阳离子进行交换,达到吸附氯离子、延长混凝土结构服役寿命的目的。本文介绍了水滑石的结构性质、制备方法及氯离子吸附机理,总结了不同类型水滑石的氯离子吸附能力及相关研究成果。研究结果表明:水滑石复合水泥基材料的氯离子吸附性能受LDHs材料制备工艺、水泥基材料中孔隙液pH值及氯离子浓度影响,高温焙烧处理的水滑石对氯离子吸附效果更好;当LDHs掺量控制在1%~3%(质量分数)时,有利于改善水泥基材料的抗氯离子渗透性能。 相似文献
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S. Abell F. Medina D. Tichit J. Prez-Ramírez J.E. Sueiras P. Salagre Y. Cesteros 《Applied catalysis. B, Environmental》2007,70(1-4):577-584
In this paper, activated Mg-Al hydrotalcites were used as catalysts in the aldol condensation of campholenic aldehyde and methyl ethyl ketone (MEK). These materials represent an attractive alternative to less environmentally friendly liquid bases in a number of base-catalyzed reactions involved in the pharmaceutical and fragrance industries. The presence of basic hydroxyl groups in the interlayer space leads to very active materials. However, the relation between the activity of reconstructed hydrotalcites and the rehydration procedure is still not well understood. Different rehydration protocols in combination with extensive characterization studies were performed, including XRD, SEM, IR spectroscopy and TPD of CH3CN and CH3NO2. The materials were tested as catalysts in the aldol condensation of campholenic aldehyde and MEK, and relationships between the catalytic performance of the activated hydrotalcites and the rehydration procedure were derived. Several factors may influence the activity and selectivity of this reaction, such as the reaction temperature, the molar ratio of the reactants and the degree of rehydration of the hydrotalcite-like catalysts. The selectivity towards the formation of the desired branched isomer increases when performing the reaction at low temperatures. 相似文献
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《Separation and Purification Technology》2002,26(2-3):195-205
In this review, the adsorption of carbon dioxide on adsorbent materials at high temperature is examined critically. Adsorbent materials including carbon-based adsorbents, metal oxide sorbents, zeolites and hydrotalcite-like compounds (HTlcs) for carbon dioxide at high temperature are discussed. Research areas, which may make a significant impact in future are put forward. 相似文献
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Chunxia Chen Jinsong Peng Bin Li Zhongqin Hu Hua Zhang Fali Qiu 《Journal of Porous Materials》2009,16(2):233-238
Under microwave irradiation, a series of hydrotalcite-like compounds (HTL) were prepared in a short time of 10 min. The thus
synthesized samples were applied to the catalytic transesterification of dimethyl oxalate (DMO) with phenol, CuNi-containing
hydrotalcites (CuNi-HTLR) were found to exhibit good catalytic properties. When the reaction was performed with phenol/DMO
molar ratio of 4:1 and 1.9% CuNi-HTLR based on the total weight of reactants as catalyst, at 180 °C for 10 h, the conversion
of DMO and the selectivity of MPO + DPO reached over 66% and 95%, respectively. 相似文献
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水滑石及类水滑石材料的合成及应用新进展 总被引:13,自引:0,他引:13
水滑石及类水滑石材料具有很好的热稳定性和较大的比表面积,可以作为催化剂或催化剂载体。介绍了水滑石及类水滑石材料的合成方法以及作为催化剂、添加剂、吸附剂在有机合成反应、石油化学、塑料工业、水处理等方面的应用。 相似文献
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采用共沉淀法制备了系列不同Zr4+含量的Mg/Al/Zr三元类水滑石材料,研究了其对废水中磷酸根离子的吸附性能。采用XRD、DRIFTS、氮气吸脱附实验等手段对材料的结构及织构性质进行了表征,并研究了溶液初始pH以及竞争阴离子对磷吸附量的影响。结果表明:掺杂Zr4+能提高类水滑石层板正电荷密度以及增大层间距,有利于磷酸根阴离子的吸附;Mg/Al/Zr类水滑石对磷的吸附过程符合准二级动力学模型,吸附等温线符合Langmuir模型,当n(Zr4+)/(Al3++Zr4+)为0.3时,理论饱和吸附量最大,达到76.6 mg/g,比Mg/Al水滑石高出28.7%;酸性环境有利于磷酸根的吸附,而二价阴离子的竞争吸附作用会显著降低磷吸附效果。Mg/Al/Zr类水滑石对磷的吸附机理为静电吸引和阴离子交换协同作用。 相似文献
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Esteban López-Salinas Mayela García-Sánchez Ma. Luisa Ramón-García Isaac Schifter 《Journal of Porous Materials》1996,3(3):169-174
A series of Ga-containing hydrotalcite-like materials (GaHTs), [Mg1-x
Ga
x
(OH)2](CO3)
x/2 ·mH2O wherex = 0.072 0.35 (Mg/Ga = 12.9 1.8), was synthesized by a coprecipitation method. The resulting solids were characterized by means of X-ray diffraction, thermal gravimetric and infrared analyses. All GaHTs showed diffraction patterns typical of Mg-Al hydrotalcites. Small amounts of brucite, Mg(OH)2, were detected only in the GaHT with Mg/Ga = 12.9. Attempts to obtain Ga-richer hydrotalcites, Mg/Ga < 1.8, resulted in solids with an invariably constant Mg/Ga = 1.8 ratio, which appears to be the maximum Ga content limit. Judging from the TGA pattern of a GaHT (Mg/Ga = 7.7), the layered structure is stable up to ca. 573 K, and at 873 K the resulting solid shows a MgO-like diffraction pattern, suggesting that Ga3+ may be replacing some Mg2+ ions in MgO. Once their layered structure collapses (i.e., at 873 K), GaHT can be easily converted back into the original layered material by treating in a carbonate-containing aqueous solution, i.e., they show the memory effect typical of Mg-Al hydrotalcites. 相似文献