苯在改性活性炭上的脱附活化能

采用浸渍法制备了KH560/改性活性炭、1706/改性活性炭和A172/改性活性炭等3种活性炭,并利用程序升温脱附技术测定了苯在这3种改性活性炭上的脱附活化能. 结果表明,苯在经改性的活性炭上的脱附活化能均大于其在未改性活性炭上的脱附活化能,表明用有机硅烷改性活性炭可以提高其对苯的吸附能力. IGC分析结果表明,经硅烷改性的活性炭的特殊作用吸附自由能DGs均小于原始活性炭的DGs,这4种活性炭表面与苯的特殊作用吸附自由能DGs大小顺序与苯在这些活性炭上的脱附活化能大小顺序正好相反,这表明DGs越小,吸附质与活性炭表面形成的吸附越牢固,吸附质从其表面脱附所需的活化能越大.     

金属离子改性活性炭对二氯甲烷脱附活化能的影响

主要研究了金属离子改性活性炭对二氯甲烷脱附活化能的影响。通过浸渍法分别将6种不同金属离子负载在活性炭表面,采用ASAP 2010M测定该系列改性活性炭的孔径分布和比表面积,利用程序升温脱附技术测定了二氯甲烷在系列改性活性炭上的脱附活化能,应用软硬酸碱理论分析和讨论了活性炭表面负载不同金属离子对二氯甲烷脱附活化能的影响。结果表明,二氯甲烷在Al(Ⅲ)/SY-6AC、Li(Ⅰ)/SY-6AC、Mg(Ⅱ)/SY-6AC、Fe(Ⅲ)/SY-6AC和Ca(Ⅱ)/SY-6AC的脱附活化能高于其在原始活性炭上的脱附活化能,而它在 Ag(Ⅰ)/SY-6AC的脱附活化能低于在原始活性炭上的脱附活化能。根据软硬酸碱理论分类,二氯甲烷属硬碱,当活性炭表面分别负载了硬酸类金属离子Al³⁺、Li⁺、Mg²⁺、Fe³⁺和Ca²⁺,则增大了表面局部硬酸度,提高了对二氯甲烷的吸附能力; Ag⁺ 属软酸,当活性炭表面负载了Ag⁺,则降低了活性炭表面局部硬酸度,从而降低了对二氯甲烷的吸附能力。     

石英粉表面处理对硅树脂复合材料性能的影响

分别以六甲基二硅氮烷(HMDS)、γ-甲基丙烯酰氧基丙基三甲氧基硅烷(KH 570)、γ-(2,3-环氧丙氧)丙基三甲氧基硅烷(KH 560)、正十二烷基三甲氧基硅烷(WD-10)为改性剂,对2种粒径的石英粉进行表面改性,然后用于制备硅树脂复合材料。研究了石英粉用量、配比和改性剂种类对硅树脂复合材料性能的影响。结果表明,随着石英粉用量的增加,硅树脂复合材料的螺旋流动长度减小,当325目与3000目石英粉按质量比1∶1复配时材料弯曲强度最高。HMDS、KH 570、KH 560改性石英粉制得的硅树脂复合材料相较于未改性弯曲强度有所提升,吸水率下降。WD-10改性石英粉制得的硅树脂复合材料吸水率大幅下降,降幅最大为42. 91%。硅烷改性降低了石英粉表面极性,硅烷改性石英粉制备的硅树脂复合材料体积电阻率均升高,升幅最大为50%。     

纳米TiO2改性石质文物防水材料WD-10

为了改善防水材料WD-10(主要成分十二烷基三甲氧基硅烷)对石质文物的保护效果,以KH550(氨丙基三乙氧基硅烷)为偶联剂、OP-10(聚乙二醇辛基苯基醚)为乳化剂进行纳米Ti O2改性,并对改性材料的憎水性、透气性、耐盐性、耐光性、耐候性进行表征。结果表明,改性材料具有优异的憎水性和透气性,对水的接触角为140°,透湿率较WD-10提高8%。2次耐盐循环后,改性材料的质量损失率比WD-10减少了61.48%。光老化实验表明,未改性材料经816 h紫外老化后接触角降为0°,而改性材料接触角90°。通过对世界遗产重庆大足石刻细砂岩240 h实验室耐候性测试显示:改性材料的质量损失仅1.07%、接触角变化率10.38%,均小于WD-10的质量损失1.95%和接触角变化率24.34%。因此,纳米Ti O2改性石质文物防水材料WD-10的透气性、耐盐性、耐光性、耐候性比改性前有显著改善,且优异的憎水性能够长期保持。     

低介电常数聚酰亚胺/多金属氧酸盐复合薄膜的制备及其性能

以带环氧官能团的3-环氧丙氧基三甲基硅烷(KH560)作为改性剂在酸性MeCN/H2O混合溶液中和多金属氧酸盐K8SiW11O39进行反应,制得了硅烷改性的多金属氧酸盐有机杂化物SiW11KH560,红外光谱、XPS等分析结果表明KH560与K8SiW11O39发生了反应。将改性后的K8SiW11O39添加到均苯四甲酸酐-二苯醚二胺的聚酰胺酸溶液中,热酰亚胺化制备了聚酰亚胺/多金属氧酸盐复合薄膜。EDS能谱分析表明多金属氧酸盐颗粒在聚酰亚胺基体中呈均匀分布,当复合薄膜中多金属氧酸盐有机杂化物SiW11KH560含量达到20%(wt)时,复合薄膜的介电常数从3.29降低至2.9。此外,随着SiW11KH560添加量的增加,复合薄膜的储能模量也显著提高,而复合薄膜的热性能没有受到严重影响。     

二种估算苯酚在改性活性炭上脱附活化能模型

应用程序升温吸附(TPD)技术分别测定了苯酚在空白活性炭以及负载Fe3+,Ag+的活性炭上TPD曲线,并采用理想TPD模型和改进的TPD模型估算苯酚在这些吸附材料上的脱附活化能,讨论了吸附材料表面负载Fe3+,Ag+对苯酚脱附活化能的影响。结果表明:采用改进的TPD模型估算得到的脱附活化能要低于理想TPD模型估算得到的活化能4.9%—5.9%,这是由于理想TPD模型忽略了脱附过程中可能出现的吸附质被再吸附现象。苯酚从负载硬酸Fe3+活性炭表面上脱附活化能大于其从原始活性炭表面脱附的活化能,而它从负载属于软酸的Ag+的活性炭表面上脱附所需的活化能小于其从空白活性炭表面脱附的活化能。     

季铵盐复配硅烷偶联剂改性蒙脱土的制备及表征

制备十八烷基三甲基氯化铵(OTAC)复配γ-氨丙基三乙氧基硅烷(KH550)改性蒙脱土(MMT),利用XRD、ICP、FTIR、TG和SEM对改性前后的蒙脱土进行表征.结果表明MMT层间距的扩大主要是由于OTAC与MMT层间阳离子交换的结果,质子化的KH550亦能与MMT进行离子交换但不影响OTAC对MMT的有机改性,而且KH550能与MMT表面羟基反应形成化学键而接枝于MMT表面.     

IGC技术表征HFC-134a在改性活性炭上的吸附特性

在323. 15～373. 15 K温度区间,采用反相气相色谱(IGC)技术分别测定了四氟乙烷(HFC-134a)在酸改性、碱改性、盐改性前后活性炭上的吸附热及脱附活化能,绘制了脱附曲线。结果表明,改性前,HFC-134a在活性炭上吸附热和脱附活化能分别为-31. 889,-31. 554 k J/mol;酸改性后,活性炭对HFC-134a的吸附热和脱附活化能分别为-49. 788,-51. 600 k J/mol;碱改性后,活性炭对HFC-134a的吸附热和脱附活化能分别为-46. 567,-57. 206 k J/mol;盐改性后,活性炭对HFC-134a的吸附热和脱附活化能分别为-42. 259,-43. 462 k J/mol。     

IGC技术表征HFC-134a在改性活性炭上的吸附特性

在323. 15～373. 15 K温度区间,采用反相气相色谱(IGC)技术分别测定了四氟乙烷(HFC-134a)在酸改性、碱改性、盐改性前后活性炭上的吸附热及脱附活化能,绘制了脱附曲线。结果表明,改性前,HFC-134a在活性炭上吸附热和脱附活化能分别为-31. 889,-31. 554 k J/mol;酸改性后,活性炭对HFC-134a的吸附热和脱附活化能分别为-49. 788,-51. 600 k J/mol;碱改性后,活性炭对HFC-134a的吸附热和脱附活化能分别为-46. 567,-57. 206 k J/mol;盐改性后,活性炭对HFC-134a的吸附热和脱附活化能分别为-42. 259,-43. 462 k J/mol。     

氯化镁改性硅胶的吸水等温线及脱附性能

用氯化镁改性硅胶制备复合干燥剂,在相对湿度为20%～90%的条件下研究氯化镁改性硅胶对水蒸气的吸附,采用FHH(Frenkel–Halsey–Hill)模型研究复合干燥剂表面的粗糙程度,测定水在改性硅胶上的程序升温脱附曲线,考察复合干燥剂的再生温度、再生次数及氯化镁改性对硅胶吸湿性能和水的脱附活化能的影响。结果表明:在相同条件下,氯化镁含量为1%时,改性硅胶的吸水量约为未改性硅胶的10倍,改性硅胶吸水符合第Ⅳ型等温线。通过FHH模型分析说明改性后硅胶的大片状固体颗粒被部分破坏,形成更为精细的孔隙分布,硅胶表面更加粗糙和不规则。程序升温脱附研究表明氯化镁改性硅胶的脱附活化能较小,脱附容易进行。脱附再生3次后,改性硅胶仍具有较高的吸水量,复合干燥剂具有较好的再生性能。     

相对湿度对甲醛在改性活性炭上吸附的影响

This work mainly involves the study of effect of relative humidity on adsorption of formaldehyde on the activated carbons modified with organosilane solution. Modification of activated carbons was carded out by impregnating activated carbon with organosilane/methanol-containing solutions. The breakthrough curves of formaldehyde in the packed beds of original and modified activated carbons were measured, respectively, at relative humidity of 30%, 60%, and 80%. Temperature-programmed desorption （TPD） experiments were used to estimate the activation energy for desorption of formaldehyde from the activated carbon. Results showed that the relative humidity had strongly influence on breakthrough curves of formaldehyde in the packed beds. The higher the relative humidity of gas mixtures through the packed beds was, the smaller the breakthrough time of formaldehyde became. The use of organosilane compounds to modify surfaces of the activated carbon can enhance the interaction between formaldehyde and the surfaces, and as a result, the breakthrough times of formaldehyde in the packed beds of the modified activated carbon were longer than that in the packed bed of the unmodified activated carbon.     

吸附于CuO/AC及其AC上的苯胺和苯的TPD研究

以苯胺和苯为模型,考察了其在载体活性炭(AC)和炭基金属吸附-催化剂(CuO/AC)上的吸附行为,并对吸附了苯胺和苯的AC和CuO/AC进行程序升温脱附实验(TPD).结果表明,CuO/AC的苯胺脱附量显著小于AC,且起始脱附温度高于AC的脱附温度.CuO的担载改变了苯胺的吸附状态,使得苯胺和CuO/AC之间的吸附更加牢固;CuO担载前后的苯的脱附行为差别不大,表明其吸附状态没有变化.     

High performance sorbents for diesel oil desulfurization

Sorbents with different Ni loading supported on silica–alumina (SiAl) and activated carbon (AC) were synthesized and tested for removal of sulfur compounds from a model diesel oil, containing nearly 250 ppmw S as benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT). A state-of-art Commercial Ni-based sorbent and two Norit activated carbons were also tested for comparison. Moreover, the influence on sorbents uptake capacity of the presence of aromatics in amounts representative of real diesel oils was studied. Both commercial and home-made materials performed worse in presence of aromatic compounds. Probably, the latter competed with the refractory sulfur compounds (DBT and 4,6-DMDBT) in the adsorption on active sites. As a first important result of the investigation the sorbents carrying 45% and 30% of Ni on SiAl showed a breakthrough uptake capacity of nearly, respectively, 2 and 2.6 times higher than Commercial sorbent as a consequence of their higher Ni dispersion and surface area. Moreover, activated carbons and the sample with 28%Ni on AC showed an even higher breakthrough uptake capacities. In particular, the deposition of nickel on activated carbon is an innovative approach which takes advantage of the selectivity of Ni towards S-species and the high adsorptive capacity of AC support.     

活性炭的改性条件及其对硫化氢吸附性能的影响

以工业活性炭为载体制备改性活性炭,对比研究了未改性活性炭,NaOH、Na2CO3、Fe(NO3)3、Cu(Ac)2改性活性炭及挂膜硫氧化细菌后活性炭在相同条件下对硫化氢穿透时间及吸附容量的影响。结果表明：在相同控制条件下,NaOH改性活性炭明显优于其它改性剂;不同梯度改性剂条件下,20% NaOH改性活性炭对硫化氢的吸附效果最好,吸附穿透容量为78.25 mg/g,穿透时间可以达到2000 min以上;不同改性剂挂膜硫氧化细菌后对硫化氢均有一定的处理效果,其中对已达到饱和吸附的NaOH改性活性炭挂膜后的再生效果可以达到100%以上,说明挂膜硫氧化细菌活性炭对硫化氢的处理具有很好的效果。     

High saturation capacity of activated carbons prepared from mesophase pitch in the removal of volatile organic compounds

A series of binderless activated carbon monoliths (ACMs) have been prepared from petroleum pitch and using KOH as activating agent. Characterization shows that these activated carbons combine a large “apparent” surface area (up to S_BET ∼ 3000 m²/g) together with a well-developed narrow micropore size distribution. Dynamic column adsorption experiments using different volatile organic compounds (VOCs), ethanol and benzene, show that these activated carbons prepared from mesophase-based materials exhibit a superior saturation capacity compared to conventional carbon materials. The total amount adsorbed reaches values as high as 18 g/100 g AC and 40 g/100 g AC, for ethanol and benzene, respectively. These are the best results reported in the literature. The total amount adsorbed for both molecules correlates with the total volume of narrow micropores, thus confirming the pore size specificity required for the adsorption of VOC molecules. Regeneration studies show that ethanol can be easily desorbed at room temperature by flowing clean air through the adsorbent whereas benzene requires a further heating for complete desorption/regeneration.     

Adsorption and desorption of small molecule volatile organic compounds over carbide-derived carbon

Carbide-derived carbon (CDC) was prepared by selective extraction of titanium from titanium carbide in a flow of freshly prepared chlorine. The dynamic adsorption and desorption performance of CDC of small molecule volatile organic compounds (VOCs) including methanol, acetaldehyde and acetone, was investigated and compared with that of two types of commercial activated carbons. The physicochemical properties of carbons were characterized by nitrogen adsorption, temperature programmed desorption, Raman spectroscopy and transmission electron microscopy. It was observed that the CDC could adsorb much more VOCs than commercial activated carbons (especially for the less polar methanol). The desorption behavior of VOCs from the saturated CDC was similar to that of commercial activated carbons, with adsorbed VOCs desorbed in the maximum degree at 110–150 °C, which indicated that the adsorption sites for the VOCs on the three carbon adsorbents were similar and the saturated CDC could be effectively regenerated by simple heat treatment just like commercial activated carbons. Based on the characterizations, the large adsorption capacity of CDC was attributed to its larger micropore volume, narrower pore distributions (0.7–1.5 nm), as well as higher specific surface area than those of two commercial activated carbons.     

Competitive adsorption of a benzene-toluene mixture on activated carbons at low concentration

Previous studies of the adsorption of benzene and toluene at low concentration showed that both porosity and surface chemistry of the activated carbon play an important role. This paper analyses the adsorption behaviour of a mixture of VOCs (benzene-toluene) on AC, due to the lack of information regarding the adsorption of mixtures. Thus, the performance of chemically activated carbons, physically activated carbon with steam and commercial samples is studied. This study shows that chemically activated carbons have better performance than the other samples, showing much higher adsorption capacities, breakthrough times and separation times. Porosity is a key factor and those activated carbons with higher volumes of micropores exhibit higher adsorption capacities and breakthrough times. This work also analyses the state of the adsorbed phase resulting from the mixture adsorption and comparison of the composition of the adsorbed hydrocarbons with that predicted by the ideal adsorption solution theory (IAST), shows good agreement.     

Adsorption from binary and ternary mixtures on activated carbons containing different amounts of chemically bonded oxygen

The adsorption process from the gas and liquid phase on activated carbons was investigated. Unmodified and chemically modified activated carbon Norit RKD-3 with different contents of chemisorbed oxygen were used. The surfaces were characterized by their content of surface functional groups, and the pore structure was characterized on the basis of adsorption-desorption isotherms of benzene vapor. Surface excess isotherms from binary and ternary mixtures of dioxane, n-heptane, and benzene were also determined. The influence of the chemical composition of the carbon surface on the adsorption from the gaseous and liquid phase is discussed.