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shan1027

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[交流] 关于物理吸附方面的汉译英求高手

吸附作用一般可以分为两类，一类是物理吸附（吸附质分子和吸附剂之间相互作用主要是范德华力），另一类为化学吸附（吸附质分子和吸附剂之间形成了化学键）。这里我们主要讨论利用惰性气体（一般为N2或Ar）物理吸附方法来表征介孔材料。它也是最常用、最有效的介孔材料表征方法之一。由此，人们可以得到材料的比表面积、孔容、孔径分布，甚至一些表面性质等信息。吸附等温线一般可以分为六种类型（IUPAC）。I型等温线在低压段吸附量存在一个明显的增加，随后达到吸附饱和。一般被认为这是单层（多层）吸附和微孔（< 2 nm）被气体分子填充时得到的吸附等温线。有时，介孔孔道表面经过有机官能团修饰后的氮气吸附等温线也会呈现I型曲线，因为此时有机基团会缩小介孔孔径，到达微孔范围。非孔或大孔材料（孔径 > 50 nm）表面可发生多层吸附一般会得到II和III型吸附等温线。III型等温线是由于吸附质分子在固体表面发生弱的气－固相互作用形成的，一般不常见。不规则的介孔材料一般也会产生II和III型吸附等温线。也有人报道，未除去表面活性剂的介观材料的吸附等温线为II型。III型吸附等温线则常见于水分子在疏水性介孔材料中的吸附。IV和V型吸附等温线的特点表现为多层吸附后紧接着吸附量急剧增加的毛细管凝结。它们是介孔材料典型的吸附等温线类型。毛细管凝结段的吸附量变化越陡峭，表明孔径分布越均匀。IV和V型吸附等温线的不同主要表现在多层吸附段，形成原因与II和III型等温线差别的原因一样，都是材料的表面性质不同造成的。VI型等温线来源于均匀非孔表面的依次多层吸附。

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1楼 2011-03-19 19:40:50

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zxs1989

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Adsorption is generally classified as physisorption (van der Waals forces dominate between adsorbates and adsorbents) and chemisorption (chemical bonding exists between adsorbates and adsorbents). Here we mainly discuss the utilization of physisorption of inert gasses (generally N2 or Ar) to characterize mesoporous materials. It’s one of the most popular and effective methods for mesoporous material characterization. Such information as specific area, pore volume, pore size distribution and some surface characteristics of the tested material can be obtained using this method. Adsorption isotherms are generally divided into six types (IUPAC). Type I isotherms show an obvious increase of adsorption capacity at low pressure and the subsequent plateau due to saturation of adsorption capacity. Type I isotherms are generally indicative of filling of micropores (< 2 nm) by monolayer gas molecules, but adsorption of N2 onto functional-group-modified mesopores also exhibits this shape sometimes due to the reduction of pore size to the range of micropores by grafting functional groups. Multilayer adsorption can occur on the surfaces of nonporous or macroporous materials, generally showing Type II or III isotherms. Type III isotherms are attributed to weak gas-solid interactions on the solid surface and are not common. Disordered mesoporous materials also generate Type II or III isotherms in general. It has been reported that mesoporous materials with residual surfactants display Type II isotherms. Type III isotherms are commonly obtained when water molecules are adsorbed onto hydrophobic mesoporous materials. Type IV and V isotherms have the characteristics of drastic increase of adsorption capacity caused by capillary condensation after multilayer adsorption and they are typical for mesoporous materials. The more abrupt the change caused by capillary condensation is, the pore size distribution is more uniform. The difference between Type IV and V isotherms mainly lies in the multilayer adsorption stage, and as the difference between Type II and III isotherms, results from different surface properties of solid materials. Type VI isotherms are attributed to successive multilayer adsorption onto homogeneous nonporous surfaces.