Purification of biosilica from living diatoms by a two-step acid cleaning and baking method

Due to their sustainability, intact cell walls, availability of pure cultures, and others, living diatoms show a lot of promise for the application in various fields in particular for micro/nano-devices. In order to purify the biosilica structures of diatoms called frustules, a two-step acid cleaning and baking method was employed. By this path, organic matter and inorganic impurities can be removed very effectively. In addition, the highest quality of frustules was achieved when the samples were cleaned in an excess of boiling 10~15 % HCl and subsequently heated to 600 °C at a heating rate of 3 °C min −1 for 6 h. In our operation, the native frustule morphology was maintained completely, and dry frustules with more than 90 % SiO 2 in weight can be obtained, and furthermore, the surface area of them reached a good value of 48.47 m 2 g −1 .