Metal-oxide adsorbents granular

The granular metal-oxide adsorbents discussed in this chapter are activated alumina (AAl), modified activated aluminas, iron-oxide-coated sand (IOCS), granular ferric hydroxide (GFH or GEH), and proprietary filter media such as ADI. Although they differ in physical appearance, they all involve hydrous oxides of iron or aluminum that remove arsenic by a process of ligand exchange. Generally, they are employed in packed beds or small filters containing 28 X 48 mesh (0.6-... 

The expected influence of silica on other metal oxide adsorbents, such as granular ferric hydroxide, is similar to its negative effect on alumina. Phosphate and fluoride are other strong ligands commonly found in groundwater that exhibit a negative influence similar to that of silicate on the arsenic capacity of alumina and GFH (5,12). Thus, the concentrations of these ions must be known before a reasonable estimate of arsenic capacity can be made. 

Metal-oxide adsorption using packed beds of activated alumina, modified activated alumina, granular ferric hydroxide, iron-oxide coated sands, and other specialty adsorbents... 

Our research conducted at Cincinnati have been primarily focused on sol-gel synthesis of alumina, zirconia, titania and silica. These metal oxides not only are commonly used as adsorbent or catalyst support but also have recently emerged as excellent materials for ceramic membranes. The objective of this article is to report synthesis and properties of these sol-gel derived adsorbent materials with emphasis on development of a sol-gel granulation method and the properties of the sol-gel derived granular adsorbents. 

---