Effects of radiation of co2 laser on natural dolomite for thedegradation of azo dye reactive black 5 by photocatalysis

Abstract

In the present work, changes in Natural Dolomite (ND) produced by calcination using aCO2 (carbon dioxide) laser radiation were analysed, as well as the effect on the degradation and decolourisation of the dye, Reactive Black 5 (RB5), when ND was used as a catalyst. The power density of the CO2 laser and the duration of irradiation was varied. A mineral analysis was carried out using a scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The EDS analysis revealed the presence of elements such as magnesium (Mg), silicon (Si), aluminium (Al), calcium (Ca), oxygen (O), iron(Fe), zinc (Zn) and sodium (Na), while the X-ray diffraction analysis suggested that the treated dolomite samples experienced changes in their crystalline structure when calcined with the CO2 laser. However, there were no changes in the main phase of the dolomite. Additionally, a photocatalytic study was performed on the degradation and decolourisation of the RB5 in an acid aqueous medium, using ND and ND calcined with the CO2 laser radiation. Ultraviolet-visible spectrophotometry (UV/VIS) was used for the characterisation of the photocatalytic tests. An increase of 20% in the decolourisation and 19.6% in the degradation of the RB5 was observed.