壳聚糖-沸石复合膜对茶汤中茶多酚的选择性吸附

将壳聚糖和沸石物理共混制成膜,以壳聚糖-沸石复合膜作为吸附剂,对茶汤中茶多酚进行吸附研究,考察了吸附剂用量、时间、温度、浓度、pH值等因素对吸附效果的影响,就壳聚糖-沸石复合膜对茶多酚的吸附动力学进行初步探讨,并用HPLC分析其对茶多酚和咖啡因的选择性吸附。结果表明,将4.0m L 4%壳聚糖和0.2%沸石的混合液制成的壳聚糖-沸石复合膜、25.00m L 1.049mg/mL原茶汤在吸附时间2h、温度30℃的条件下吸附,吸附率可达76.3%,吸附量为171.2mg/g;HPLC谱图表明,壳聚糖-沸石膜对EGCG具有很好的选择吸附性能。     

改性黏土负载多乙烯多胺对H_2S的高效捕集

以工业建材级黏土矿石粉为原料,经酸处理或煅烧改性后,利用其多孔性负载多乙烯多胺制得吸附材料,并考察了其硫化氢脱除性能.实验结果表明,经400℃煅烧改性的材料的硫化氢脱除效果最佳.考察了负载方法、吸附温度、水蒸气预处理和负载量等因素对吸附的影响,发现在较低温度以及预加湿的情况下,硫化氢的脱除效果最显著,脱除率接近100%.负载量为33.3%的吸附剂的穿透硫容及饱和硫容均优于其它负载量的吸附剂.再生实验表明,吸附剂可以在较低温度下轻易再生,且多次再生后脱硫效果无显著下降.红外光谱和比表面积测试结果表明,该吸附剂对硫化氢的吸附以化学吸附为主.     

AgCeY分子筛吸附剂的制备及性能研究

以NaY分子筛为载体,通过液相离子交换法制备了经Ag、Ce双金属离子改性的AgCeY吸附剂,并利用UV-vis、XRD、BET、ICP、XPS和FT-IR技术对吸附剂进行了表征。以噻吩/苯并噻吩/正辛烷/甲苯体系为汽油模拟体系,考察了制备条件和吸附条件对吸附剂脱硫性能的影响以及吸附剂再生性能。结果表明,AgCeY吸附剂上Ag、Ce这两种金属元素分别以Ag⁺、Ce⁴⁺形式存在,AgCeY吸附剂具有类似于AgY的高的脱硫性能,又具有类似于CeY的高的吸附选择性,AgCeY对噻吩(TP)和苯并噻吩(BT)的吸附选择性顺序为BT > TP;最适宜的制备条件为先交换Ag后交换Ce离子、离子交换24 h、Ce/Ag物质的量比为2.5、500 ℃焙烧;在原料20 mL、AgCeY吸附剂用量0.2 g、吸附温度50 ℃、吸附时间60 min下,噻吩脱硫率可达到59.0%,苯并噻吩脱硫率达到96.5%。     

镍/碳纳米管复合材料的合成及其吸附性能

本文以二氰二胺和硝酸镍为原料通过煅烧法在900℃合成了镍/碳纳米管(Ni-CNT)的复合材料,采用X射线粉末衍射(XRD),扫描电镜(SEM),透射电镜(TEM),傅里叶变换红外光谱(FTIR)等手段对产物进行了表征,并对其磁性进行了测量。探讨了不同条件下(吸附时间、吸附剂量、pH)产物对刚果红溶液吸附性能的影响。结果表明,当吸附时间达到20 min、吸附剂用量达到1.0 g·L~(-1)且pH值在8时产物对刚果红的吸附率最高,达到97.8%。循环实验表明其五次吸附后依然保持良好的吸附率,且在磁场作用下,吸附剂易与溶液分离。     

降低生物柴油中自由脂肪酸的吸附剂研究

以甘蔗渣为原材料,通过高温煅烧制备甘蔗渣吸附剂,用于降低生物柴油中的自由脂肪酸含量。采用SEM、热重分析仪对甘蔗渣吸附材料进行表征分析,研究不同煅烧温度对吸附剂吸附性能的影响,以及不同吸附条件对吸附效果的影响。结果表明,在实验条件下,当甘蔗渣吸附材料煅烧温度为600℃、吸附剂用量0.30 g、吸附温度25℃、吸附时间100 min时,可以将生物柴油原料油的酸值降至0.4 mg/g。     

羧甲基壳聚糖对胆红素的吸附性能研究

合成了不同取代度的羧甲基壳聚糖(CM-CTS)作为吸附剂，研究了不同条件对CM-CTS吸附胆红素性能的影响．结果表明：在实验条件下，随着羧甲基取代度的增加和体系温度的升高．最大吸附率和吸附速率均相应增加：在接近人体血液pH值的条件下，CM-CTS对胆红素的吸附性能较佳：人血清白蛋白和离子强度的增加对CM—CTS吸附胆红素有明显的抑制作用。     

浮石负载壳聚糖吸附去除水中丙溴磷

通过浮石负载壳聚糖制备了吸附剂壳聚糖/浮石复合物,采用扫描电子显微镜(SEM)、热重分析(TGA)、元素分析、傅里叶红外光谱(FT-IR)、X射线衍射(XRD)和X射线荧光光谱(XRF)等技术手段表征了吸附剂性质,考察了吸附剂量、吸附时间、溶液pH值、离子强度和温度对该吸附剂吸附去除水中丙溴磷的影响,研究了再生吸附剂的吸附性能。结果表明,负载在浮石上的壳聚糖占吸附剂总量的8.69%;在p H值3.0~7.0内,壳聚糖/浮石对丙溴磷的吸附率大于90%;这种吸附剂对丙溴磷的吸附受溶液离子强度影响较小,随温度升高而稍微减小。在溶液温度25℃、pH=7.0、丙溴磷浓度40 mg/L、壳聚糖/浮石剂量为0.7 g/L和吸附平衡时间为90 min条件下,此吸附剂对丙溴磷最大吸附率为93.3%(最大吸附量为53.4 mg/g)。壳聚糖/浮石连续经过3次吸附/再生循环,每次循环对丙溴磷的吸附率下降约12%。可见壳聚糖/浮石通过吸附可有效地去除水中的农药丙溴磷。     

低温一步法活性炭基脱硫剂的制备与评价

以木屑为原料,在低温条件下一步法制得活性炭基吸附剂,考察了吸附剂制备条件和液-固、气-固吸附条件对吸附剂脱硫性能的影响。结果表明,吸附剂的最佳制备条件为,浸渍液与木屑质量比为1：1,浸渍液中硝酸质量分率为30%、吸附剂表面NiO负载量为5%,常温下浸渍24 h,400℃焙烧3 h。该吸附剂在0.2 g吸附剂/10 mL模拟油、温度为40℃及时间为5 h的液-固吸附脱硫的条件下,脱硫率为28.36%,吸附四次后饱和吸附硫容量可达2.34 mgS/g;在气-固吸附温度为250℃、空速为6.3 h^-1的条件下,饱和吸附硫容量为2.37 mgS/g;高温气-固吸附脱硫对吸附剂的影响表明,与脱硫前相比,吸附剂在比表面积、总孔体积、微孔体积均有明显提高,这说明气-固吸附脱硫过程同时实现了活性炭的扩孔活化。甲苯溶剂再生实验表明,经五次再生后吸附剂的再生性能均可达90%以上。     

11种吸附剂上二噁英的热吸附/脱附性能评价

筛选在低温下高效捕集并在一定的高温下可以快速完全脱附二噁英的吸附/脱附材料是二噁英在线热捕集的关键。该研究以1,2,3,4-四氯代二苯并-对-二噁英(1,2,3,4-TCDD)和1,2,3,8,9-五氯代二苯并呋喃(1,2,3,8,9-PCDF)为二噁英模型物,以电子捕获检测器(ECD)作为检测器,利用填充柱气相色谱系统,测定了这两种二噁英单体在11种吸附剂上4~5个温度点下的保留体积,并建立了相应的范特霍夫方程。结果表明,11种吸附剂的线性方程决定系数(R²)均大于0.96。根据范特霍夫方程,预测了吸附剂在120、150、180 ℃时的气固分配系数(K_SA)。弗洛里硅土在120、150、180 ℃ 3个温度点下都具有最强的吸附能力,特别是在120 ℃时,1,2,3,4-TCDD、1,2,3,8,9-PCDF在弗洛里硅土上的K_SA分别高达1.82×10⁸ m³/g、1.46×10¹³ m³/g。碳基吸附剂的高分子多孔微球GDX系列的GDX-101、GDX-102、GDX-103、GDX-105、GDX-203在最高耐受温度270 ℃下都可以实现二噁英的热脱附,证实了碳基吸附剂作为二噁英热吸附/脱附的吸附剂的可行性。310 ℃下,在丝光沸石上1,2,3,4-TCDD可实现热脱附,而1,2,3,8,9-PCDF在相同条件下无法实现热脱附,体现了沸石对二噁英同系物的选择性吸附的特性。而硅藻土和蒙脱土对气相中的二噁英几乎没有吸附能力,不适合作为二噁英热捕集的吸附剂。弗洛里硅土、硅胶、氧化铝、GDX-102、GDX-103和GDX-203对1,2,3,4-TCDD、1,2,3,8,9-PCDF都具有很强的吸附能力,因此被初步选为二噁英的候选吸附剂。通过比较120 ℃下和270 ℃下二噁英在这6种吸附剂上的lnK_SA,发现弗洛里硅土在两个温度点下的保留体积都是最大的;在侧重低温下二噁英的热捕集性能时,弗洛里硅土是捕集二噁英的最佳吸附剂;而GDX-102是6种吸附剂中lnK_{SA,270 ℃}最小的,在侧重高温下二噁英的热脱附性能时,GDX-102是二噁英热脱附的最佳吸附剂。同时,硅胶、GDX-103和GDX-203的lnK_{SA,120 ℃}和lnK_{SA,270 ℃}与GDX-102相近,也可以作为快速热吸附/脱附的材料。该文通过系统评价1,2,3,4-TCDD和1,2,3,7,8-PCDF在11种吸附剂的热吸附/脱附性能,对简化二噁英的采样和制备过程提供了新的解决思路,为实现二噁英的热捕集提供了技术支撑。     

以聚乙烯基咪唑为配基的内毒素亲和吸附剂的研究

通过乙烯基咪唑(VI)在硅胶粒子表面的自由基接枝聚合制备了一种以聚乙烯基咪唑为配基的新型内毒素亲和吸附剂. 用FTIR检测样品中咪唑基的特征吸收, 用热重分析法(TGA)测定了PVI的接枝率. 实验发现, PVI在吸附剂中的含量对内毒素的吸附率影响很大. 当PVI的接枝率为2.5％左右时, 吸附剂对内毒素的去除率最大. 在离子强度小于1 mol/L和pH=7的中性条件下, PVI吸附剂对内毒素具有最佳的吸附性能. 该吸附剂具有良好的血液相容性. 内毒素在该亲和吸附剂上的吸附等温线符合Freundlich吸附方程, 其吸附动力学为二级反应.     

Synthesis of Novel Poly[2-(dimethylamino) ethyl methacrylate]/Pumice Stone Hydrogel Composite for the Rapid Adsorption of Humic Acid in Aqueous Solution

In this study, a novel hydrogel composite, poly[2-(dimethylamino) ethyl methacrylate]/pumice (PDMAEMA/Pmc) was designed and its sorption behavior for humic acid (HA) was produced by using batch adsorption techniques. FTIR results showed that pumice was well incorporated with the PDMAEMA matrix. A scanning electron microscopy (SEM) was used in order to determine the morphology of composite hydrogel. In the batch experiments, the adsorption capacity was evaluated depending on different variables such as ionic strength; initial HA concentration; pH and adsorbent dosage. The adsorption capacity was found to be 86.27 mg/g under the optimized conditions. The results revealed that HA adsorption onto PDMAEMA/Pmc was well expressed by the Freundlich isotherm model and the adsorption process was followed by the pseudo second order kinetic model. The reusability tests also indicated that novel PDMAEMA/Pmc adsorbent was an efficient and cost-effective adsorbent for removal of HA.     

The Adsorption of Herbicides and Pesticides on Clay Minerals and Soils. Part 1. Isoproturon

The adsorption of isoproturon and two model compounds, N,N-dimethylurea and4-isopropylaniline, on clay minerals (bentonite,montmorillonite and kaolinite), organic matter (humic acid) and soil (with and without organic matter) has been studied using FT-infrared spectroscopy (IR), thermogravimetric analysis (TGA), high pressure liquid chromatography (HPLC) and X-ray diffraction (XRD).N,N-dimethylurea interacted with bentonite and montmorillonite by the coordination of the carbonyl group, directly or indirectly through water molecules, with exchangeable cations. Adsorption on humic acid was due to hydrogen bonding with the active sites of the adsorbent. The amino group ofN,N-dimethylurea appears tobe relatively inactive during adsorption. The mechanisms involved in the adsorption of 4-isopropylaniline were hydrogen bonding and protonation. No adsorption of 4-isopropylaniline was observed on kaolinite. The investigation of isoproturon suggested that both the carbonyl and amino groups of isoproturon were involved in interactions with the active sites of the adsorbents. Both the clay minerals and organic matter of soil contribute to the adsorption of organic compounds on soil but the clay minerals bentonite and montmorillonite play a major role in their adsorption on soil.     

Generation and electrochemical nanogravimetric response of the third anodic hydrogen peak on a platinum electrode in sulfuric acid media

Platinum electrodes have been investigated in sulfuric acid solutions in the hydrogen adsorption–desorption region by electrochemical quartz crystal nanobalance (EQCN). It was found that a well-developed peak (the so-called third peak) between the two main peaks appeared when, following the cycling in the oxide region, the electrode was kept at potentials just more positive than the potential of hydrogen evolution under the same conditions. The extent of this third peak and its ratio to oxidation peaks of the strongly and weakly adsorbed hydrogen depend on the waiting time at potentials mentioned above as well as on the scan rate. Similarly to the other two peaks, the simultaneous EQCN response shows a slight mass increase which can be assigned to adsorption of HSO₄ ^? ions at the platinum surface. Because the third peak appears only after a potential excursion in the oxide region, it is related to the formation of specific surface sites on which hydrogen can be adsorbed with an energy which falls between the energies of the weakly and strongly bound hydrogen. The waiting time effect indicates that this adsorption is a slow process, and it is the very reason that it cannot be observed during the second cycle. The scan rate dependence can be elucidated by the transformation of this type of adsorbed hydrogen to the other two forms.     

Preferential adsorption of extracellular polymeric substances from bacteria on clay minerals and iron oxide

The adsorption of extracellular polymeric substances (EPS) from Bacillus subtilis on montmorillonite, kaolinite and goethite was investigated as a function of pH and ionic strength using batch studies coupled with Fourier transform infrared (FTIR) spectroscopy. The adsorption isotherms of EPS on minerals conformed to the Langmuir equation. The amount of EPS-C and -N adsorbed followed the sequence of montmorillonite>goethite>kaolinite. However, EPS-P adsorption was in the order of goethite>montmorillonite>kaolinite. A marked decrease in the mass fraction of EPS adsorption on minerals was observed with the increase of final pH from 3.1 to 8.3. Calcium ion was more efficient than sodium ion in promoting EPS adsorption on minerals. At various pH values and ionic strength, the mass fraction of EPS-N was higher than those of EPS-C and -P on montmorillonite and kaolinite, while the mass fraction of EPS-P was the highest on goethite. These results suggest that proteinaceous constituents were adsorbed preferentially on montmorillonite and kaolinite, and phosphorylated macromolecules were absorbed preferentially on goethite. Adsorption of EPS on clay minerals resulted in obvious shifts of infrared absorption bands of adsorbed water molecules, showing the importance of hydrogen bonding in EPS adsorption. The highest K values in equilibrium adsorption and FTIR are consistent with ligand exchange of EPS phosphate groups for goethite surface. The information obtained is of fundamental significance for understanding interfacial reactions between microorganisms and minerals.     

Synthesis of Thiiranes from Epoxides in the Presence of Thiourea in a Weakly Hydrated Organic Medium

Reactivity of thiourea in the absence or in the presence of ethanol, towards several furanic, aromatic, aliphatic, and cyclic epoxides is studied. These results are compared to other ones obtained in the same conditions with another sulfured agent: KSCN.     

沸石吸附储氢研究进展

沸石类微孔材料作为储氢介质的研究已成为近年来储氢领域中备受关注的热点问题,但对于其储氢机理、储氢容量及其影响因素的文献报道不尽一致。本文从吸附实验测定和理论计算模拟方面综述了各种结构类型沸石的吸附储氢的研究结果。重点分析了沸石的结构类型、硅铝比、阳离子类型及吸附实验条件差异对储氢量的影响,并讨论了超临界吸附理论模型的发展状况,最后探讨了沸石作为储氢材料的可行性和发展方向。     

氨氮与磷在三种人工湿地填料上的吸附动力学

利用吸附动力学实验研究了浮石、陶结和陶粒对氨氮和磷的吸附动力学特征.结果表明:浮石对氨氮与磷的吸附容量明显比陶结和陶粒的大.人工湿地填料浮石和陶粒对氨氮与磷,以及陶结对氨氮的等温吸附动力学特征均可以用准一级、准二级和Bangham模型加以描述.其中浮石对氨氮和磷以及陶结对氨氮的吸附以化学吸附反应控制为主,而陶粒对磷的吸附过程则以扩散反应控制为主.三种填料对氨氮和磷的吸附均以表面吸附为主.     

Interaction of radium with freshwater sediments and their mineral components

Radiotracer method has been used for investigation of the adsorption and desorption of traces of radium on kaolinite and montmorillonite under conditions similar to those prevailing in waste and surface waters. It has been found that adsorption depends on the pH and ionic strength of the solution, and the character of these dependences is different for kaolinite and montmorillonite. Sulfates at concentration 60 mg·l^–1 have negligible effect on the adsorption. Montmorillonite represents better adsorbent for radium than kaolinite, but both minerals may significantly affect the form and migration of radium in surface waters, if present as (major) components of freshwater sediments. Radium can be quantitatively desorbed by 1M HCl from kaolinite but not from montmorillonite. The desorption by 0.1M NaCl is generally lower and depends on the pH during the preliminary adsorption. Mechanisms of radium adsorption on both minerals and the character of the adsorption sites are discussed.     

应用吸附势理论研究氢在沸石上的超临界吸附

针对吸附势理论描述气体超临界吸附所面临的问题, 采用经验方法求取了临界温度以上且较宽的压力范围内氢在微孔沸石上吸附的虚拟饱和蒸汽压和该吸附体系的亲合势系数茁i,j, 并通过对ln(W/W0)与(着i,j/茁i,j) (W,W0分别为吸附相体积及吸附剂的饱和吸附容量, 着i,j为吸附势)的相关性分析得到了一般吸附函数的表达式. 研究结果表明, 茁i,j与吸附热qi,j具有线性关系, 因此可将吸附热作为一般吸附函数的参数应用于吸附势理论的研究. 利用一般吸附函数对本实验条件下的吸附数据的拟合分析证实该函数可较好地表述氢在微孔沸石上的超临界吸附.