Extraction of High Purity Silica from Amazonian Sponges

Silica has a variety of uses, including functioning as a catalytic support and utility in drug delivery systems. It is traditionally obtained from mineral sources through costly extraction processes, which has led to a search for alternative sources. One of the main features of freshwater sponges is that they contain spicules composed mainly of amorphous silica. The species Metania reticulata is found in the Negro river (Amazonas, Brazil) in great abundance, reaching volumes above 3 dm3. Different purification processes employing oxidizing solutions and subsequent heat treatment are proposed in order to extract high purity silica from freshwater sponges. With these processes, it was possible to obtain high purity (99.92%) amorphous silicon at a concentration higher than silica commercially used for column chromatography (99.71%) support material while eliminating the other elements present in the sponges (Fe, K, Ca, Ti and S). This study described low-cost techniques for the production and purification of high purity amorphous silica as alternatives to production methods currently in use.