Removal of Humic Substances from Water by Alumina-Based Pillared Clays

Abstract

This paper deals with the synthesis and use of alumina-pillared clays, Al-PILCs, for water treatment in removing humic substances. Al-PILCs represent a new class of adsorbents with an increased potential for the removal of colour generating compounds such as ‘humic’ and ‘fulvic acids’. High content Al-PILCs were synthesised. Various thermal treatment conditions, 453K and 673K, and the effect of ultrasonic treatment during the preparation of Al-PILCs were also explored. Comparative adsorption experiments were conducted with Montmorillonite, as the starting clay as a reference material, and several different batches of Al-PILCs. Adsorption of ‘humic acid’ from both distilled and tap water were studied. A maximum adsorption capacity of 23.4 mg g−1 of ‘humic acid’ on Al-PILCs was obtained with PILC-O-453 which represents Al-PILCs treated at 453K. Al-PILCs are more effective at removing ‘humic acid’ from tap water especially at high ‘humic acid’ concentrations. The adsorption process is described by Langmuir-type isotherms. It is shown by these experiments that Al-PILCs represents a valuable adsorbent for the removal of colour-generating compounds such as ‘humic acid’.