Development of a hydroxyapatite-based composite: Sr-doped HAp/NiO proven to be an efficient nanocatalyst for photocatalytic degradation of organic dye and photoreduction of Cr()

In this research, Sr-doped hydroxyapatite, HAp and NiO nanoparticles were used to produce a novel nanocomposite, Sr-doped HAp/NiO. Various analytical and instrumentation techniques such as FTIR, PXRD, UV-DRS, SEM, TEM, and XPS were used to characterize the as synthesized composite material. The nanocomposite acts as an efficient photocatalyst and is able to degrade Congo red (CR) dye up to 95.6% within 40 min under solar light irradiation without any kind of external additive. The HR LC-MS spectrum was recorded to determine the degradation products of the chosen organic dye. Furthermore, the as prepared nanocatalyst also effectively reduced 98.7% of carcinogenic Cr( vi ) to Cr( iii ) within just 10 min. In order to propose the photocatalytic mechanism and to detect the active radicals present, a radical trapping experiment was conducted. As an appealing photocatalyst for wastewater treatment and reduction of toxic chemicals, the research concluded with a methodical and cost-effective process for producing the Sr-doped HAp/NiO nanocomposite. An efficient heterogeneous photocatalyst, Sr-doped HAp/NiO was utilized to degrade harmful Congo red dye and reduce carcinogenic Cr( vi ) to less hazardous Cr( iii ).