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Four cubic mesoporous silicates (CMS), one unmodified and three grafted with amine, carboxylic and cyano surface functional groups, were prepared, characterised and compared as adsorbents for tetramethyl ammonium hydroxide (TMAH) from aqueous solution. The adsorption process was studied as a function of molecular size and CMS pore volume. Sorption on the unmodified, cyano- and carboxylic-grafted adsorbents closely followed the Langmuir model while adsorption on the amine-treated silicate conformed to the Freundlich model. A comparison of the adsorbent pore volume and the volume of sorbed TMAH molecules suggested that monolayer sorption occurred, there being some evidence that surface functional groups influenced the adsorption process. The presence or absence of structural order, as defined by X-ray diffraction analysis, had no significant influence on the adsorption, as all materials, both ordered and disordered, had relatively high adsorption capacities.

A cubic mesoporous silicate (CMS) was prepared, characterised and assessed as an adsorbent for quaternary ammonium hydroxides (QAHs) from aqueous solution. The adsorption process was studied as a function of molecular size and CMS pore volume. Sorption closely followed the Langmuir model. A comparison of the CMS pore volume and the volume of the sorbed molecules suggested that monolayer sorption occurred and that the number of molecules sorbed was a function of the size of the quaternary ammonium hydroxide molecule and the threshold area capable of being occupied by this molecule.