Improving Recovery of Diatoms Bio-Silica Using Chemical Treatment with VAUSTM

High-temperature baking is a typical method to remove organic matter from diatoms, but it is not suitable for bio-silica because of the high crystallinity. This study provides a method using the VAUS^TM to remove organic matter from diatoms more quickly and biocompatibly. The optimal frequency for organic matter removal was investigated for domestically produced <i>M. nummuloides</i>. The removal efficiency of TOC/TN was calculated and analyzed. The C and Si elements were analyzed in EDS, and organic matter removal was analyzed by XRD. TOC RE% at a frequency of 35 kHz exhibited the highest value, indicating a statistically significant difference. XRD analysis demonstrated that the organic matter was nearly entirely removed using NaOCl compared to high-temperature-baked <i>M. nummuloides</i>. In the EDS analysis, there were significant differences in the C and Si elements with respect to frequency. This is very similar to the values from the positive control group, high-temperature-baked <i>M. nummuloides</i>. Ultrasonic treatment and frequency adjustments were found to significantly impact the chemical removal of organic matter from <i>M. nummuloides</i>. Although vacuum application was initially considered, it did not demonstrate a statistically significant effect according to TOC analysis.