Examples of Adsorption

The book draws a first contrast with absorption before giving worked examples of adsorption itself: when cotton is dipped in water, the cotton becomes wet because water penetrates into the bulk of the fibres -- that is absorption, not adsorption, since the water is not merely sitting on the cotton's surface. (The printed heading for this section is worth flagging: it reads 'Examples of Absorption', but the numbered list underneath it -- and the reference to Table 11.1 that follows -- is entirely about adsorption examples, so this appears to be a heading/labelling slip in the source rather than a deliberate mismatch; this platform has kept the substance of the list, which is unambiguously about adsorption.) Three worked examples of adsorption are given: (i) gases like hydrogen and oxygen being adsorbed by finely divided metals such as platinum, palladium, copper and nickel; (ii) gases like nitrogen and carbon dioxide being adsorbed by activated charcoal; and (iii) removal of colouring matter, such as the organic dye methylene blue, from solution -- when charcoal is added to a methylene blue solution and shaken, the s …