Improving Recovery of Diatoms Bio-Silica Using Chemical Treatment with VAUS^TM

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 M. nummuloides. 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 M. nummuloides. 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 M. nummuloides. Ultrasonic treatment and frequency adjustments were found to significantly impact the chemical removal of organic matter from M. nummuloides. Although vacuum application was initially considered, it did not demonstrate a statistically significant effect according to TOC analysis.