Characterization of waste fish bones (Heteropneustes fossilis and Otolithoides pama) for photocatalytic degradation of Congo red dye

Abstract

Heteropneustes fossilis (Shing) and Otolithoides pama (Poa) fish bones were chosen as the waste source of photocatalysts which are found in the confined water and the Sea. The bones of these fish are composed of calcium phosphate hydroxide (CPH) which is composed of phosphate and hydroxyl groups and these groups are effective for the photocatalytic activity. The fish bones are characterized by X-ray diffraction (XRD), Field Emission Electron Microscopy (FESEM), Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), Fourier-transformed infrared spectroscopy (FTIR), Optical bandgap, Particle size analyzer, etc. Crystallographic information was evaluated using the XRD data focusing on the crystallinity index, lattice parameters, microstrain, crystallite size, dislocation density, degree of crystallinity, β-TCP percentage, HAp percentage, volume fraction of β-TCP, specific surface area, relative intensity, and preference growth. The crystallite size of the natural bones was estimated from the XRD data engaging a number of model equations. Photocatalytic activity of the Shing and Poa fish bones was evaluated by degrading Congo Red dye varying different reaction parameters such as pH, interaction time, catalyst dose, and dye concentration.