An Investigation into the Adsorption Characteristics of Grafted Mesoporous Silicates for the Removal of Tetramethyl Ammonium Hydroxide from Aqueous Solution

Abstract

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.

Adsorption of Tetramethylammonium Hydroxide on Activated Carbon

“…A suitable fitting by Langmuir isotherm indicated formation of monolayer coverage of TMAH molecules at the adsorption sites of the adsorbent (Do 1998). Similar good correlation with Langmuir isotherm was also found by Kelleher et al (2001Kelleher et al ( , 2002 on their CMSs in the range of equilibrium concentration of about 0 to ca. 300 mg=L of TMAH.…”

“…Despite the versatile use of activated carbon, currently there is still no study about TMAH adsorption on activated carbon. The only study about adsorption of TMAH uses cubic mesoporous silicate (CMS) and modified CMSs as adsorbents (Kelleher et al 2001(Kelleher et al , 2002. The main objective of this study is to investigate the adsorption behavior of TMAH onto activated carbon.…”

Removal of Aniline from Waste Streams Using a Combined Adsorption and Catalytic Oxidation Approach

“…However, regeneration of the spent adsorbent material can be both intensive and costly (Shu et al 1997). This has led to a strong growth in interest in developing alternative adsorbents for the removal of organic pollutants from aqueous waste streams (Kelleher et al 2001(Kelleher et al , 2002Crini 2006).…”