Carbon dioxide capture using polyethylenimine-loaded mesoporous carbons

A high efficiency sorbent for CO2 capture was developed by loading polyethylenimine (PEI) on mesoporous carbons which possessed well-developed mesoporous structures and large pore volume. The physicochemical properties of the sorbent were characterized by N2 adsorption/desorption, scanning electron microscopy (SEM), thermal gravimetric analysis (TG) and Fourier transform infrared spectroscopy (FT-IR) techniques followed by testing for CO2 capture. Factors that affected the sorption capacity of the sorbent were studied. The sorbent exhibited extraordinary capture capacity with CO2 concentration ranging from 5% to 80%. The optimal PEI loading was determined to be 65 wt.% with a CO2 sorption capacity of 4.82 mmol-CO2 /g-sorbent in 15% CO2 /N2 at 75°C, owing to low mass-transfer resistance and a high utilization ratio of the amine compound (63%). Moisture had a promoting effect on the sorption separation of CO2 . In addition, the developed sorbent could be regenerated easily at 100°C, and it exhibited excellent regenerability and stability. These results indicate that this PEI-loaded mesoporous carbon sorbent should have a good potential for CO2 capture in the future.     

氨基改性SBA-15有序介孔材料对Cd(Ⅱ)的吸附热力学特征研究

以硅酸钠为硅源,三嵌聚合物Pluronic P123为模板剂,采用水热-后期接枝的合成方法,制备出氨基改性SBA-15.用透射电镜、X射线衍射、氮气吸附-解吸和红外光谱等手段对其结构进行了表征.在此基础上,以改性SBA-15为吸附剂,通过批实验讨论了吸附时间、体系初始pH值和温度等对水溶液中Cd2+吸附的影响,并讨论了...     

苯基改性的介孔分子筛SBA-15的合成与表征

采用一步法在酸性条件下以聚乙氧基聚丙氧基聚乙氧基三嵌段共聚物(P123)为模板剂,用正硅酸乙酯(TEOS)和苯基三甲氧基硅烷(PTMS)直接缩合制备了苯基改性介孔分子筛Ph-SBA-15,并用红外光谱(FTIR)、小角X射线衍射(SAXRD)、热重分析(TGA)、透射电镜(TEM)和氮气吸附-脱附对样品进行了表征。结果表明,制备的样品不仅保持了高度有序的SBA-15的二维六角结构,而且具有较高的热稳定性,较大的比表面,孔容和孔径。     

介孔TiO2纤维的制备及其光催化性能

采用溶胶-凝胶和水蒸气活化热处理技术制备了介孔TiO2纤维,考察了各种因素对介孔TiO2纤维光催化活性的影响,并对介孔TiO2纤维结构进行了表征。介孔TiO2纤维的最佳制备条件：n（TBOT）∶n（C6H10O3）∶n（H2O）∶n（C3H8O）=1∶0.4∶2.0∶16,搅拌时间80min,Si与Ti的摩尔比为0.15,采用分段程序升温工艺,活化温度为700℃。所得介孔TiO2纤维比表面积为127.7m2/g,最可几孔径为7.3nm,具有极高的热稳定性及抗晶型转变能力,反应时间75min时活性艳红X-3B降解率为99.3%。     

中孔分子筛Al-MCM-41催化裂解聚烯烃反应研究

采用水热合成法制备了不同硅铝比的中孔分子筛A l-MCM-41,将其应用于高密度聚乙烯(HDPE)和聚丙烯(PP)的催化裂解反应。通过改变硅铝比、反应温度和催化剂用量,对A l-MCM-41催化HDPE和PP裂解反应的规律进行了探讨,研究表明,HDPE裂解反应受硅铝比的影响较大;而对于PP裂解反应,硅铝比在一定范围内对催化剂活性的影响不明显。另外,与热裂解和HZSM-5小孔分子筛的催化裂解结果进行了比较,结果证明A l-MCM-41具有较高的催化活性和较高的液体产物收率,尤其适合于空间位阻较大的PP的催化裂解反应。     

Adsorptive removal of mercury from acid mine drainage: a comparison of silica and maghemite nanoparticles

Mercury adsorption by silica and maghemite nanoparticles (NPs) was studied with the aim of comparing their performance in the remediation of acid mine drainage (AMD) contaminated water. Calculated distribution coefficients (K_d) showed that both NPs are exceptional adsorbents. However, adsorbate coverage per unit area was 30 times higher for maghemite than for silica NPs, despite the latter having a surface area ～15 times greater. Maghemite adsorbed 75% of available Hg compared to 56% by silica, making it a more efficient sorbent than silica under AMD conditions. Kinetics and isotherm data for both adsorbents were fitted by the pseudo-second-order (R² = 1) and the Freundlich (R² ≥ 0.98) models, implying that adsorption to both NP types was by chemisorption. Adsorption increased with NP concentrations and pH and was enhanced in the presence of manganese and sulfate ions although adsorption to silica was inhibited in 1:2 Hg-to-Mn systems. Importantly, trends in simulated wastewater were replicated in actual AMD-contaminated water samples. This study highlights the fact that properties besides surface area and charge of adsorbents determine adsorbent performance, and superior attributes may not always lead to higher adsorption efficiencies.     

介孔碳修饰石墨电极处理模拟硝基苯废水

采用水热合成—高温碳化—涂饰的方法制备了介孔碳修饰石墨电极,并将其用于模拟硝基苯废水的电化学处理,考察了废水pH、电流密度、电解质投加量对处理效果的影响。表征结果显示,修饰电极表面具有丰富的介孔结构,因而比石墨电极具有更高的硝基苯去除率和苯胺生成量。实验结果表明,在废水pH为7.0、电流密度为15 mA/cm~2、电解质硫酸钠投加量为1.775 g/L的条件下处理初始硝基苯质量浓度为100 mg/L的模拟废水,电解3.0 h时的硝基苯去除率高达99.6%,苯胺生成量最高达45.54 mg/L。     

Surface modification of mesoporous silica nanoparticle with 4-triethoxysilylaniline to enhance seawater desalination properties of thin-film nanocomposite reverse osmosis membranes

• Mesoporous silica nanoparticle was modified with 4-triethoxysilylaniline. • AMSN-based TFN-RO membranes were prepared for seawater desalination. • Water transport capability of the AMSN was limited by polyamide. • Polyamide still plays a key role in permeability of the TFN RO membranes. Mesoporous silica nanoparticles (MSN), with higher water permeability than NaA zeolite, were used to fabricate thin-film nanocomposite (TFN) reverse osmosis (RO) membranes. However, only aminoalkyl-modified MSN and low-pressure (less than 2.1 MPa) RO membrane were investigated. In this study, aminophenyl-modified MSN (AMSN) were synthesized and used to fabricate high-pressure (5.52 MPa) RO membranes. With the increasing of AMSN dosage, the crosslinking degree of the aromatic polyamide decreased, while the hydrophilicity of the membranes increased. The membrane morphology was maintained to show a ridge-and-valley structure, with only a slight increase in membrane surface roughness. At the optimum conditions (AMSN dosage of 0.25 g/L), when compared with the pure polyamide RO membrane, the water flux of the TFN RO membrane (55.67 L/m²/h) was increased by about 21.6%, while NaCl rejection (98.97%) was slightly decreased by only 0.29%. However, the water flux of the membranes was much lower than expected. We considered that the enhancement of RO membrane permeability is attributed to the reduction of the effective thickness of the PA layer.     

铁掺杂介孔氧化硅-石墨化炭复合物对橙黄Ⅱ的吸附

利用水热法合成铁掺杂介孔氧化硅-石墨化炭复合物(Fe MS),并对其进行结构表征,发现其具有介孔结构,且高铁含量的Fe MS含有明显的石墨化炭物种.比较了传统吸附剂活性炭、SBA-15及Fe MS分别对橙黄Ⅱ的吸附性能,考察了初始p H、投加量、初始浓度、吸附时间对吸附的影响,并对吸附过程进行了动力学研究和吸附等温模型的模拟.结果表明:Fe MS对橙黄Ⅱ有很好的吸附性能,且高铁含量的Fe MS吸附量优于低铁含量;Fe MS吸附橙黄Ⅱ的最佳p H值为7,最高吸附量能达到1108 mg·g-1;初始浓度对橙黄Ⅱ吸附效率有明显的影响;对低浓度的橙黄Ⅱ,可在120 min内达到吸附平衡;Fe MS对橙黄Ⅱ的吸附动力学数据符合准二级动力学模型;Fe MS对低浓度橙黄Ⅱ的吸附符合Henry等温模型,饱和吸附量与橙黄Ⅱ的浓度有关.     

Adsorption of benzene,cyclohexane and hexane on ordered mesoporous carbon

Ordered mesoporous carbon (OMC) with high specific surface area and large pore volume was synthesized and tested for use as an adsorbent for volatile organic compound (VOC) disposal. Benzene, cyclohexane and hexane were selected as typical adsorbates due to their different molecular sizes and extensive utilization in industrial processes. In spite of their structural differences, high adsorption amounts were achieved for all three adsorbates, as the pore size of OMC is large enough for the access of these VOCs. In addition, the unusual bimodal-like pore size distribution gives the adsorbates a higher diffusion rate compared with conventional adsorbents such as activated carbon and carbon molecular sieve. Kinetic analysis suggests that the adsorption barriers mainly originated from the difficulty of VOC vapor molecules entering the pore channels of adsorbents. Therefore, its superior adsorption ability toward VOCs, together with a high diffusion rate, makes the ordered mesoporous carbon a promising potential adsorbent for VOC disposal.