Comparison of dynamic adsorption/desorption characteristics of toluene on different porous materials

Four different types of adsorbents, SBA-15, MCM-41, NaY and SiO₂, were used to study the dynamic adsorption/desorption of toluene. To further investigate the influence of pore structure on its adsorption performance, two SBA-15 samples with different microspores were also selected. It is shown that microporous material NaY has the largest adsorption capacity of 0.2873 mL/g, and the amorphous SiO₂ exhibits the least capacity of 0.1003 mL/g. MCM-41 also shows a lower break through capacity in spite of the relatively small pore diameter, because it can not provide the necessary small geometric confinement for the tiny adsorbates. However, the mesoporous SBA-15 silica with certain micropore volume shows relatively higher adsorption capacity than that of MCM-41 silica. The presence of micropores directly leads to an increase in the dynamic adsorption capacity of toluene. Although NaY has the highest adsorption capacity for toluene, its complete desorption temperature for toluene is high (>350℃), which limits its wide application. On the contrary, mesoporous silica materials exhibits a good desorption performance for volatile organic compounds at lower temperatures. Among these materials mesoporous SBA-15 samples, with a larger amount micropores and a lower desorption temperature, are a potentially interesting adsorbent for the removal of volatile organic compounds. This behavior should been related with the best synergetic effect of mesopores and micropores.     

两种介孔分子筛动态吸附VOCs的研究

采用模板剂法制备了孔道规整、大比表面积的2种介孔分子筛MCM-41和SBA-15,并以甲苯、二甲苯、三甲苯为吸附对象,考察了介孔分子筛动态吸附VOCs的性能.结果表明,增加VOCs分子尺寸和浓度,降低床层温度可大幅提高介孔分子筛吸附性能.SBA-15由于介孔壁上的微孔结构适合吸附低浓度、小分子VOCs;MCM-41更适合吸附高浓度、大分子VOCs.TPD脱附试验表明,VOCs在介孔材料表面150℃下就能基本脱附完全.     

介孔氮化碳对水中全氟辛烷磺酸的吸附去除研究

以SBA-15为模板、四氯化碳和乙二胺为前驱体,通过聚合反应制备了介孔氮化碳(Mesoporous Carbon Nitride,MCN).同时,采用X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、傅里叶红外光谱(FT-IR)、X射线光电子能谱(XPS)和元素分析等手段对MCN进行了表征分析,并考察了MCN对水中全氟辛烷磺酸(PFOS)的吸附性能.结果表明,MCN吸附PFOS的过程符合准二级动力学模型,其吸附行为遵循Langmuir等温线模型;MCN吸附去除PFOS的效率受溶液pH值、溶液温度及共存离子等因素的影响,其中,溶液pH值的影响最为显著,当溶液pH值分别为2.2和10.6时,MCN对PFOS的去除率分别为98.15%和5.59%;吸附PFOS饱和后的MCN可以用0.1 mol·L-1NaOH溶液进行解吸,经5次循环/再生后的MCN对PFOS的去除率仍在95%以上.与介孔碳(CMK-3)和活性炭(AC)相比,MCN对PFOS显示出更优越的吸附能力.     

表面包覆TiO_2材料的制备及光催化降解染料废水

以介孔硅基分子筛SBA-15为载体,采用溶胶-凝胶法在SBA-15分子筛表面包覆TiO_2。制备了不同TiO_2含量的链状二维六方形介孔复合材料。采用电子显微镜扫描仪、X射线衍射仪、傅立叶红外光谱、紫外-固体漫反射等技术对复合材料进行表征。SEM结果表明样品具有良好的包覆效果,UV-Vis光谱结果表明样品具有较好的光吸收能力。XRD结果表明复合材料表面包覆的TiO_2为锐钛矿和金红石的混合晶型,随载体用量的增加TiO_2的粒径逐渐减小。以光催化降解亚甲基蓝为目标,研究复合材料在煅烧温度、载体用量、底物溶液初始浓度等影响因素下的光催化效果。考察复合材料的再生光催化活性。研究表明:介孔TiO_2复合材料相比于市售P-25有较高的光催化活性。复合材料可进行回收利用,并且其介孔结构牢固不易崩塌。     

高分子树脂与介孔分子筛吸附-脱附VOCs性能对比

采用溶剂热法制备介孔聚二乙烯基苯(PDVB)树脂,并以介孔分子筛MCM-41、SBA-15为参照,从吸附-脱附甲苯、邻二甲苯、均三甲苯性能和高湿度下的疏水性能方面对其进行对比研究.结果表明,PDVB具有最大的比表面积1219.1m2/g,其对低浓度甲苯吸附量约为介孔分子筛的2倍,同时吸附性能几乎不受水汽影响.随着VOCs分子尺寸增加,3种吸附剂对VOCs的饱和吸附量均有所增加,但PDVB的穿透吸附量明显高于分子筛.热重分析表明,在200℃以下3种吸附剂上吸附的有机分子均能脱附完全,具有优良的脱附再生性能.     

Rapid removal of bisphenol A on highly ordered mesoporous carbon

Bisphenol A (BPA) is of global concern due to its disruption of endocrine systems and ubiquity in the aquatic environment. It is important, therefore, that e orts are made to remove it from the aqueous phase. A novel adsorbent, mesoporous carbon CMK-3, prepared from hexagonal SBA-15 mesoporous silica was studied for BPA removal from aqueous phase, and compared with conventional powdered activated carbon (PAC). Characterization of CMK-3 by transmission electron microscopy (TEM), X-ray di raction, and nitrogen adsorption indicated that prepared CMK-3 had an ordered mesoporous structure with a high specific surface area of 920 m2/g and a pore-size of about 4.9 nm. The adsorption of BPA on CMK-3 followed a pseudo second-order kinetic model. The kinetic constant was 0.00049 g/(mg min), much higher than the adsorption of BPA on PAC. The adsorption isotherm fitted slightly better with the Freundlich model than the Langmuir model, and adsorption capacity decreased as temperature increased from 10 to 40°C. No significant influence of pH on adsorption was observed at pH 3 to 9; however, adsorption capacity decreased dramatically from pH 9 to 13.     

污泥基活性炭-甲醇工质对吸附/解吸特性

将市政生物污泥资源转化与吸附制冷能效提升相交叉融合,通过炭素前驱体进行复配、KOH催化炭化及磷酸催化活化相结合的压块炭改进工艺对污泥基活性炭的孔结构进行原位调控,制备了4种新型污泥基活性炭（WNC-4/3/2/1）;对比研究了以污泥炭和甲醇制冷剂为工质对的吸附制冷床的吸附/脱附循环、制冷量及制冷功率变化特性.结果表明： KOH和磷酸浸渍过程可分别促进微孔及中孔结构的发育,WNC-4的总孔、微孔及中孔容积分别达到0.6960,0.1641和0.5319cm³/g.比表面积与孔结构容积水平的同步提升与甲醇制冷剂吸附/脱附量呈良好的相关性（R²>0.90）.基于Langmuir吸附等温模型（R²=0.9939）计算的最大吸附量Q_L^*达到（552.67±23.83）mg/g;基于Sokoda-Suzuki方程计算的40min内的平衡吸附量和脱附量分别为（372.94±9.504）和（412.55±8.309）mg/g.脱附温度为100℃时,WNC-4吸附制冷系统的稳定脱附量、制冷量和制冷功率分别达到（328.81±10.74）mg/g,（300.34±9.81）kJ/kg和（600.68±19.62）kJ/（kg·h）.     

双功能介孔吸附材料的制备及其同时吸附废水中Cd2+和Cr2O72-的研究

采用直接法和后嫁接法成功制备出骨架掺杂Al原子,孔道表面接枝大位阻含胺基基团的双功能介孔硅基吸附材料.采用SAXRD、TEM、FTIR、NH3-TPD等手段对合成材料进行表征,结果表明合成的双功能AN-SBA-15具有有序的二维六方介孔结构,孔道表面的Al-OH与胺基不会发生自发复合反应.对模拟废水中Cd~(2+)和Cr_2O_7~(2-)的同时吸附去除实验研究表明AN-SBA-15具备同时吸附废水中Cd~(2+)和Cr_2O_7~(2-)离子的能力,吸附最佳pH值为5.0,吸附在40 min就达到平衡.AN-SBA-15对Cd~(2+)和Cr_2O_7~(2-)离子的吸附符合Langmuir模型,属于单层吸附.由Langmuir模型拟合出的AN-SBA-15对Cd~(2+)和Cr_2O_7~(2-)离子的最大吸附容量分别为125.9 mg·g~(-1)和156.5 mg·g~(-1).此外AN-SBA-15具备良好的脱附再生能力.     

高效舱室空气净化可再生介微孔吸附材料

目的针对目前舰船舱室内空气封闭性强、污染物来源多、成分复杂且高温、高湿的特点,研发高效可再生介微孔吸附材料,以解决目前吸附法存在的选择性及再生困难问题。方法研究选取SBA-15为载体,并将金属氧化物催化剂负载在SBA-15上制备介微孔吸附材料,以甲醛、甲苯和醇类有机物为处理对象评价材料性能。结果在催化剂质量分数为0.12%时,负载催化剂的介微孔材料的有机物容量达到最高,112.3 mg苯/g催化剂,119.7 mg甲苯/g催化剂,147.3 mg甲醛/g催化剂,184.l mg乙醇/g催化剂,为活性炭吸附容量的1.5倍以上。吸附饱和再生30 min后有机物容量为,98.6 mg苯/g催化剂,106.3 mg甲苯/g催化剂,132 mg甲醛/g催化剂,169.7mg乙醇/g催化剂,说明其具有良好的再生性能。结论能够在广泛进气浓度和停留时间条件下使得处理后的污染物浓度低于严格的《民用建筑工程室内环境污染控制规范(GB 50325—2001)》所允许的浓度,并且在高温高湿条件下可以高效再生、重复使用。     

原位载铁中孔活性炭吸附As和天然有机物效能

采用配煤、原位浸渍和两步活化法制备了4种原位载铁活性炭（FGL1/2/3/4）,并以空白炭C-GL为基础的表面铁浸渍后改性炭（Fe-GL-2/3/4）为对照,研究了原位载铁炭对水中As和腐植酸（HA）的同步吸附效能.结果表明,炭化料原位载铁促进了比表面积（S_BET）和中孔结构的发育.其中,原位载铁炭FCL4（载铁量6.51%）在45Å~480Å的范围内的中孔容积（V_mes）比C-GL增加了0.1146cm³/g;而后改性载铁则造成S_BET和V_mes的显著降低.原位载铁同时促进了表面碱度的增加,保证了中性条件下更好的As离子吸附能力;FCL4对As（Ⅲ）和As（V）的Langmuir最大吸附量（L-Q_max）分别达到2.566和2.825mg/g.原位载铁炭进一步发育的中孔结构促进了对HA（<10mg DOC/L）的吸附效能,FGL4对HA的Langmuir最大吸附量（Q_HA）达到46.25mg DOC/g.As-HA共存体系内FGL4对各组分的吸附容量有所降低,但As（Ⅲ）和As（V）的吸附容量仍达到2.325和2.675mg/g.     

Potential applications of porous organic polymers as adsorbent for the adsorption of volatile organic compounds

Volatile organic compounds (VOCs) with high toxicity and carcinogenicity are emitted from kinds of industries, which endanger human health and the environment. Adsorption is a promising method for the treatment of VOCs due to its low cost and high efficiency. In recent years, activated carbons, zeolites, and mesoporous materials are widely used to remove VOCs because of their high specific surface area and abundant porosity. However, the hydrophilic nature and low desorption rate of those materials limit their commercial application. Furthermore, the adsorption capacities of VOCs still need to be improved. Porous organic polymers (POPs) with extremely high porosity, structural diversity, and hydrophobic have been considered as one of the most promising candidates for VOCs adsorption. This review generalized the superiority of POPs for VOCs adsorption compared to other porous materials and summarized the studies of VOCs adsorption on different types of POPs. Moreover, the mechanism of competitive adsorption between water and VOCs on the POPs was discussed. Finally, a concise outlook for utilizing POPs for VOCs adsorption was discussed, noting areas in which further work is needed to develop the next-generation POPs for practical applications.     

Insight into the adsorption of tetracycline onto amino and amino–Fe functionalized mesoporous silica: Effect of functionalized groups

In order to study the influences of functionalized groups onto the adsorption of tetracycline (TC), we prepared a series of amino and amino–Fe^3 + complex mesoporous silica adsorbents with diverse content of amino and Fe^3 + groups (named N,N-SBA15 and Fe-N,N-SBA15). The resulting mesoporous silica adsorbents were fully characterized by X-ray powder diffraction, Fourier transform infrared spectrometer and N₂ adsorption/desorption isotherms. Furthermore, the effects of functionalized groups on the removal of TC were investigated. The results showed that the periodic ordered structure of SBA-15 was maintained after modification of amino/Fe^3 + groups. The functionalized amino groups decreased the adsorption capacity while the coordinated Fe^3 + increased the adsorption capacity. The adsorption kinetics of TC fitted pseudo-second-order model well and the equilibrium was achieved quickly. The adsorption isotherms fitted the Langmuir model well and with the Fe^3 + content increased from 3.93% to 8.26%, the Q_max of the adsorbents increased from 102 to 188 mmol/kg. The solution pH affected the adsorption of TC onto amino complex adsorbents slightly while influenced the adsorption onto Fe-amine complex adsorbents greatly. The adsorption of TC on SBA15 and N,N-SBA15 may be related to the formation of outer-sphere surface complexes, while the adsorption of TC onto Fe-N,N-SBA15 was mainly attributed to the inner-sphere surface complexes. This study could offer potential materials that have excellent adsorption behavior for environmental remediation and suggested useful information for the preparing other adsorbents in environmental applications.     

Photocatalytic degradation of paraquat using nano-sized Cu-TiO2/SBA-15 under UV and visible light

Photocatalytic degradation of paraquat using mesoporous-assembled Cu-TiO₂/SBA15 under UV and visible light was investigated. The catalyst was synthesized by impregnation of Cu-TiO₂ colloids onto SBA-15. The colloids of Cu-TiO₂ were prepared via sol-gel method while the mesoporous support was prepared using hydrothermal technique. The catalyst was characterized using X-ray diffraction, nitrogen adsorption-desorption, transmission electron microscopy, UV diffuse reflectance spectroscopy, Zeta potential and X-ray adsorption spectroscopy. Results from characterizations showed that Cu doped TiO₂ had a small crystalline size and was well-dispersed on SBA-15. The inclusion of SBA-15 significantly enhanced the photocatalytic activity of the catalyst. Among the three types of undoped catalyst in this study (P25, TiO₂, TiO₂/SBA-15), TiO₂/SBA-15 yielded the highest degradation of paraquat for all pH under UV illumination. Meanwhile 2 wt.% Cu-TiO₂/SBA-15 yielded the highest activity under visible light.     

Effect of chlorine content of chlorophenols on their adsorption by mesoporous SBA-15

Studies on the effect of the chlorine content of chlorophenols (CPs) on their adsorption from aqueous solution by mesoporous SBA-15 are important in understanding the mechanisms of CP adsorption. In this study, three CPs with different degrees of chlorine content (i.e., 2-chlorophenol, 2,6-dichlorophenol and 2,4,6-trichlorophenol) were investigated. The effects of parameters such as temperature and solution pH were studied. The results showed that CP adsorption by SBA-15 increased with increasing number of chlorine substituents and depended strongly on the temperature and solution pH. Thermodynamic parameters such as Gibbs free energy change (ΔG⁰), enthalpy change (ΔH⁰) and entropy change (ΔS⁰) were also calculated. By comparison of the adsorption coefficient of CPs with varying physical-chemical properties (size, hydrophobicity and electron density), we propose that hydrophobic interactions between CPs and the SBA-15 surface, as well as electron donor-acceptor (EDA) complexes between oxygen of the siloxane surface of SBA-15 (e^--donor) and the πup-system of the CPs (e^--acceptor), were dominant adsorption mechanisms.     

负载型铜酞菁的制备及其催化氧化巯基乙醇

以3-(环己氧基)-邻苯二腈和氯化铜为原料,通过钼酸铵固相法合成了一种烷氧基取代的铜酞菁配合物α-四(环己氧基)铜酞菁(CuPc),采用浸渍法将其负载在MCM-41和SBA-15介孔分子筛中,制备了CuPc/MCM-41和CuPc/SBA-15催化剂,并且负载后的酞菁还能回收利用,仍然具有催化效果。采用紫外-可见吸收光谱(UV-vis)、红外光谱(IR)对目标产物进行表征,并用TG对酞菁进行热稳定性分析,结果表明酞菁在200℃时开始失重,350℃时失重率最大为58%;通过氮气吸附对催化剂进行表征,证明酞菁已经进入到分子筛孔道,孔容积分别从0.132 cm3/g减至0.055 cm3/g和0.420 cm3/g减至0.202 cm3/g。研究了2种催化剂在不同pH、催化剂浓度下对巯基乙醇(ME)催化氧化性能的影响,结果表明,CuPc/SBA-15对巯基乙醇(ME)具有较高的催化活性,且2种催化剂的活性在pH=12时都达到最大。     

硫脲改性猪粪生物质炭对模拟农田径流中镉和草甘膦吸附特征

为同时去除农田地表径流中的重金属和农药,利用猪粪制备未改性猪粪生物质炭（简称"未改性生物质炭"）和硫脲改性猪粪生物质炭（简称"改性生物质炭"）,分析比较硫脲改性对生物质炭的pH、元素组成、表面含氧官能团和巯基含量等理化性质的影响,并系统地研究了单一和复合污染体系中初始浓度对两种生物质炭吸附水溶液中镉（Cd）和草甘膦效率的影响.结果表明:①与未改性生物质炭相比,改性生物质炭的pH、O/C（原子比）和H/C（原子比）降低,比表面积增大,含氧官能团和巯基含量增加.②与未改性生物质炭相比,改性生物质炭对Cd和草甘膦的吸附能力增强,最大表观吸附量（Q_max）增加了近3倍;随着Cd和草甘膦初始浓度的增加,未改性和改性生物质炭对Cd和草甘膦的吸附量逐渐增加,增加量最高分别达18.52%和7.60%.③单一污染体系中两种生物质炭对Cd或草甘膦的吸附更符合Langmuir等温吸附模型,说明其对Cd或草甘膦的吸附机理是单分子层的吸附起主导作用.④复合污染体系中,未改性和改性生物质炭对Cd的吸附能力分别增加了25.28%和21.26%,未改性生物质炭对Cd的最大表观吸附量增加了29.34%,但改性生物质炭对Cd的最大表观吸附量降低了47.28%;未改性和改性生物质炭对草甘膦的吸附能力减弱,但最大表观吸附量分别增加了2.63和3.45倍.研究显示,硫脲改性猪粪生物质炭作为一项有前景的新技术,为解决实际环境中的复合污染问题提供了经济环保的技术手段.      

Preparation and evaluation of aminopropyl-functionalized manganese-loaded SBA-15 for copper removal from aqueous solution

A novel material, aminopropyl-functionalized manganese-loaded SBA-15 (NH₂-Mn-SBA-15), was synthesized by bonding 3-aminopropyl trimethoxysilane (APTMS) onto manganese-loaded SBA-15 (Mn-SBA-15) and used as a Cu^2 + adsorbent in aqueous solution. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction spectra (XRD), N₂ adsorption/desorption isotherms, high resolution field emission scanning electron microscopy (FESEM) and X-ray photoelectron spectroscopy (XPS) were used to characterize the NH₂-Mn-SBA-15. The ordered mesoporous structure of SBA-15 was remained after modification. The manganese oxides were mainly loaded on the internal surface of the pore channels while the aminopropyl groups were mainly anchored on the external surface of SBA-15. The adsorption of Cu^2 + on NH₂-Mn-SBA-15 was fitted well by the Langmuir equation and the maximum adsorption capacity of NH₂-Mn-SBA-15 for Cu^2 + was over two times higher than that of Mn-SBA-15 under the same conditions. The Elovich equation gave a good fit for the adsorption process of Cu^2 + by NH₂-Mn-SBA-15 and Mn-SBA-15. Both the loaded manganese oxides and the anchored aminopropyl groups were found to contribute to the uptake of Cu^2 +. The NH₂-Mn-SBA-15 showed high selectivity for copper ions. Consecutive adsorption–desorption experiments showed that the NH₂-Mn-SBA-15 could be regenerated by acid treatment without altering its properties.     

挥发性有机物(VOCs)吸附材料的研究进展

目前,我国面临严重的挥发性有机物（VOCs）污染问题。吸附法是研究与应用最为广泛的VOCs治理技术。主要介绍了吸附净化VOCs原理和几种常见的VOCs吸附材料,包括活性炭、新型多孔炭材料、沸石分子筛、黏土基吸附剂、金属有机框架和介孔硅。详述了各吸附材料的VOCs吸附能力和优缺点,判断了其应用价值,并指出了为提升大规模工业化应用潜力,后续研发的VOCs吸附材料应满足高吸附量、高疏水性、高热稳定性和再生能力强4个特征。     

硅藻类粗多糖生物剂的制备及其对Cd2+的吸附性能

为了考察粗多糖对Cd2+的吸附性能,采用不同方法（稀酸法、稀碱法及超声-冻融-加热法）由海洋硅藻提取粗多糖,并进一步揭示硅藻粗多糖对Cd2+的吸附潜力.通过对比不同方法下粗多糖的组分质量分数（总糖、蛋白质和硫酸基）及其对Cd2+的吸附量,筛选出优质的粗多糖吸附材料,利用FTIR（傅里叶变换红外光谱）和SEM（扫描电镜）浅析粗多糖对Cd2+的吸附机制,采用吸附动力学和吸附等温模型详细探讨其对Cd2+的吸附特性.结果表明:①超声-冻融-加热法比稀酸法、稀碱法所提取的粗多糖的总糖质量分数高,分别为31.39%（480 nm）、26.74%（490 nm）;蛋白质杂质质量分数为7.09%,硫酸基质量分数为2.86%.②硅藻类细胞壁具有微孔结构,主要是由硅藻壳、多糖、蛋白质和脂肪组成,提取出的粗多糖表面均含有氨基、酰胺基、羰基、羟基等官能团,为其吸附重金属离子提供可能性.③超声-冻融-加热法在3倍体积乙醇沉淀时提取的粗多糖对Cd2+吸附量最大,为353.12 mg/g;该粗多糖对Cd2+的吸附更符合伪二级动力学模型,表明吸附过程有化学吸附参与;相比于Freundlich等温吸附模型,吸附数据更符合Langmuir等温吸附模型,表明该粗多糖对Cd2+的吸附主要为单层吸附.研究显示,利用超声-冻融-加热法提取出的硅藻粗多糖对Cd2+的吸附量为353.12 mg/g,是一种很有应用潜力的生物吸附材料.      

中孔结构对活性炭吸附卷烟烟气中有机物的影响

卷烟烟气中复杂化合物对大气环境的污染已经引起了全世界的关注.因此,本文以颗粒活性炭为原料,通过硝酸钙、水蒸气调控得到比表面积、微孔容量丰富且含有较高中孔率的介孔活性炭,研究了孔结构对三醋酸甘油酯和挥发性有机物吸附的影响.结果表明:活性炭对三醋酸甘油酯的吸附主要受到比表面积和微孔的影响,中孔对其吸附性能没有太明显的作用;中孔结构对苯、甲苯、丙酮的吸附可以起到明显的通道效应,大大提高了活性炭对挥发性有机物的去除能力.