Characteristics of pellet-type adsorbents prepared from water treatment sludge and their effect on trimethylamine removal

We optimized the preparation method of pellet-type adsorbents based on alum sludge with the aim of developing a high-performance material for the adsorption of gaseous trimethylamine. Effects of calcination temperature on physical and chemical properties of pellet-type adsorbents were investigated. The porous structure and surface characteristics of the adsorbents were studied using N₂ adsorption and desorption isotherms, scanning electron microscope, X-ray diffraction, temperature-programmed desorption of ammonia, and infrared spectroscopy of adsorbed pyridine. The adsorbents obtained from the water treatment sludge are microporous materials with well-developed mesoporosity. The pellet-type adsorbent calcined at 500 °C had the highest percentage of micropore volume and the smallest average pore diameter. The highest adsorption capacity in trimethylamine removal attained over the pellet-type adsorbent calcined at 500 °C can be attributed to the highest number of acid sites as well as the well-developed microporosity.