Reply to the comments on "Facilely synthesized cobalt doped hydroxyapatite as hydroxyl promoted peroxymonosulfate activator for degradation of Rhodamine B" by Zuo et al.

In a Co-HAP/PMS system, catalytic degradation process of RhB was accompanied by the gradual leaching of cobalt ion. The results of additional experiments showed that leached cobalt ion indeed contributed to active PMS for RhB degradation, which was not addressed in the previous study. The finding of the contribution from leached cobalt ion to PMS activation was reported due to the valuable comments of Zuo et al., what will be concerned in the future work. Importantly, Co-HAP still showed a significant contribution to PMS activation for RhB degradation at the initial stage. Fortunately, the release of Co from Co-HAP was slow, the secondary pollution could not be addressed due to the slightly release of Co ion that the Co concentration is lower than the standard of the discharge wastewater. Furthermore, the mechanism of non-radical reaction in the Co-HAP/PMS system was reported to confirm the heterogeneous catalysis of a Co-HAP/PMS system.