Synthesis Of Flower-like Hydroxyapatite And Its Degradation In Malachite Green And Crystal Violet

Hydroxyapatite?HAP?, with compositions of stoichiometric Ca₁₀?PO₄?₆?OH?₂, is one of the foremost bioactive ceramic materials similar to the main inorganic constituent of human teeth and bones. The experimental results indicated that different dosage of expanded graphite had an impact on the morphology of HAP. Due to its efficient ability of degrading the dyes, the flower-like morphology of samples was used as catalyst of Fenton-like system. In this research, malachite green and crystal violet were used as reaction substrate to study the catalytic oxidization performance of HAP/H₂O₂ Fenton-like system.The main contents of this research include the following:?1? HAP is prepared by chemical precipitation in the presence of various contents of EG and characterized by TG, XRD, FT-IR, SEM and BET.?2? By comparing the ability of degradation dyes to different morphology hydroxyapatite, the best performance of sample was selected as catalyst during the following experiments.?3? The influence of initial concentration of dyes, dose of catalyst and oxidant etc. on the degrading property of malachite green and crystal violet by HAP/H₂O₂ Fenton-like system were discussed.?4? A study of the kinetic equations of reaction process was carried out.?5? The used catalyst was analyzed by XRD, FT-IR and SEM to explore its stability during the degradation process.The following conclusions were acquired:?1? The XRD patterns of as-prepared samples is essentially the same as the standard pattern of hydroxyapatite, no characteristic peak of impurity was found in the patterns.?2? When the dosage of expanded graphite was 0.5wt%, the as-synthesized product had the morphology of flower-like and efficiently ability of degrading the dyes.?3? When the catalyst dosage is 0.1 g/L and H₂O₂ dosage is 1 m L/L, the removal efficiency of malachite green?10 mg/L? could reach to 98.7% at the initial pH value of solution and room temperature. The removal efficiency of crystal violet?30 mg/L? could reach to 97.2% when the catalyst dosage is 0.1 g/L, H₂O₂ dosage is 1 mL/L, reaction time is 38 min.?4? Kinetic study indicates that the degradation processes of malachite green and crystal violet by HAP/H₂O₂ Fenton-like system can be better described by the pseudo-second-order model with a relatively well correlation.?5? The structure and morphology of the used catalyst had not obvious changes and indicated its higher stability.