Iron phosphate complex with silica

The simplest version of the iron (III) coagulation-microflltration process is by nature more complex and costly than the simplest versions of the ion-exchange and metal-oxide adsorbent processes. Furthermore, as is the case with the MOA processes, high feed pH, and the presence of signiflcant silica, phosphate, and fluoride concentrations will decrease the arsenic-removal efficiency of the C-MF process. Nevertheless, C-MF is attractive for arsenic removal because of lower chemical consumption and less waste production. 

Examination of the infrared spectrum of a pure well-crystallized clay mineral can yield considerable information on its structure and composition in some instances, a species can be more quickly and more fully defined in structure and composition by this technique than by any other single technique. Few soil clays, however, are single species. In general, they are a complex mixture, which may include several layer silicates (either interstratified or as separate species), feldspars, various forms of silica, oxides and hydroxides of iron and aluminum, carbonates, sulphates, and phosphates. These minerals may well be poorly ordered, and associated with varying amounts of amorphous material. Not infrequently amorphous components predominate. As isolated, the clays may contain considerable amounts of organic matter, firmly combined with the inorganic constituents. 

---