Preparation of diatomite-modified wood ceramics and the adsorption kinetics of tetracycline

Abstract

Taking corn straw as the main raw material, diatomite-modified wood ceramics were prepared by carbonizing a phenolic resin-corn straw powder composite under vacuum. The structure and properties of as-prepared materials were characterized by a scanning electron microscope, X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FT-IR), Scanning electron microscope(SEM) and Mercury injection. Using tetracycline as the target pollutant, the adsorption isotherms and adsorption kinetics of the samples on tetracycline were investigated. Results indicated that the diatomite-modified wood ceramics were mainly amorphous, containing a small amount of quartz phase and crystalline graphite. The pore size range, the porosity, and the specific surface area of the wood ceramics were 1000 nm to3800 nm, 48.6 %, and 7.83 m2/g respectively. According to the correlation coefficient R2, a Langmuir isothermal adsorption model could better describe the adsorption process of tetracycline on wood ceramics than the Freundlich model (0.999 versus 0.975). Adsorption kinetics of tetracycline (initial concentration 5 mg/L) on wood ceramics were analyzed at pH values of 3, 5, 7, and 9. Results of the kinetic model fitting showed that the quasi-second-order kinetic model parameter (R2 > 0.98) could better fit the adsorption process of tetracycline. After repetitive use of the wood ceramics, the removal efficiency decreased due to blockage of pores. After regeneration, the removal efficiency for tetracycline exceeded 90%.