Conversion of heavy metal adsorbents into catalysts for the degradation of rhodamine B by high temperature activation

In this work, calcium nitrate and sodium silicate were employed as the sources of calcium and silicon, respectively, to synthesize sheet calcium silicate hydrate (CSH) by simple chemical precipitation. The obtained sheet CSH exhibited fast adsorption rate and large adsorption capacity, the maximum adsorption capacity is 556.3 mg g −1 , for Cu(II) ions. The CSH after adsorption of Cu(II) ions (CSH-Cu) was characterized by XRD, FTIR, SEM, N 2 adsorption and XPS, and which could be converted into a catalyst for rhodamine B (RhB) degradation by a simple high-temperature activation process. The results showed that the catalyst give the excellent reusability, and after four cycles of the catalyst, more than 90% of the RhB could still be degraded within 240 min. The free radical trapping experiments showed that all of the ·OH, ·O 2 − and h + generated on the surface of the catalyst played an essential role in the degradation process, while h + made the largest contribution. Based on this, the degradation mechanism of RhB is also proposed.