**3.5 Nanodiamond purification method**

Nanodiamond integration frequently includes performance and after process procedures designed at purification residues. To deal with two of the most prevalent and most common pollutants, some types of carbon (particularly graphitic) and associated metals and oxides, a number of approaches have been devised. The overall purpose of carbon emissions refining is to discharge selective oxidation by characterized sp2 carbon reactivity in comparison to sp3 carbon in the diamond phase. Sustaining a maximum temperature of 400–430°C was used to select sp2 carbon [17]. In the situation of PLAL NDs, where metal contamination is avoided but the fraction of sp2 carbon is so high that it becomes a main reaction product, this approach provides a simple and effective solution. The most extensively utilized processes are liquid-phase oxidation reactions. Strong acids are typically used in these processes, which have the additional benefit of removing certain metal-based contaminants. Perchloric acid, concentrated nitric acid, sulfuric acid, hydrochloric acid coupled with nitric acid, and hydrogen fluoride are some examples. Because these therapies demand temperatures between 80 and 200°C, additional equipment is required, adding to the complexity and cost. However, particularly in detonation methods, when metal-based contaminants are included in substantial levels, this is important due to the equipment used in such processes, such as metal blasting rooms [18].
