Adsorption Of Congo Red In Aqueous Solution By Hydroxyapatite And Hydroxyapatite-Carbon Composites

Hydroxyapatite has become a hot topic because of its good adsorption performance and biocompatibility, and has attracted wide attention from researchers. Here, hydroxyapatite and its carbon composites obtained from waste bone discarded from food processing were prepared and applied to wastewater purification.First of all, in order to achieve the effective utilization of resources and improve the adsorption properties of the materials, hydroxyapatite and hydroxyapatite-carbon composites were prepared from bone raw materials within which there is high content of hydroxyapatite by means of the advantages of nature composite materials and bovine bones, in which carbon can effectively inhibit the agglomeration of hydroxyapatite. It was found that the effect of hydroxyapatite-carbon composite on Congo red adsorption was better than that of hydroxyapatite, which laid the foundation for the development of high performance dye adsorbent.Secondly, the adsorption behavior of bovine bone hydroxyapatite on Congo red was systematically studied. The results show that the adsorption capacity of hydroxyapatite obtained by calcination at 600 ? is strong, and the maximum adsorption capacity can reach 389.lmg·g-1, which is much higher than that of commercially nano-hydroxyapatite. The adsorption capacity of the hydroxyapatite product calcined at 700? to Congo red was the second. With the increasing of the calcination temperature, the ability of products to adsorb Congo red was declining, but it was very low in the experimental range, such as the sample calcined at 800?was similar to that of calcined at 900?, and both of them were better than commercial nano-hydroxyapatite. The results show that the adsorption process of the hydroxyapatite on Congo red is in accordance with the Langmuir isothermal adsorption model.Finally, the adsorption behavior of hydroxyapatite-carbon composites in Congo red was studied. At the initial concentration of Conge red in 200 mg·L-1,the removal rate was 99%. The adsorption properties of products are different at different calcination temperatures. In the experimental range the maximum adsorption capacity of sample calcined at 600? is the highest which is reached 423.72mg·g-1 . The adsorption capacity of the product calcined at 800?was relatively lowest. However, the maximum adsorption capacity of it was still 2.3 times higher than that of the commercial nano-hydroxyapatite. The results show that the adsorption behavior is in accordance with the quasi-second - order kinetics model, and the adsorption process has both physical adsorption and chemical adsorption.