Study On The Adsorption And Removal Behavior Mechanism Of Tetracycline Based On Renewable Biomass Charcoal

In this paper,biochar was synthesized by using cattle manure as precursor,and it was used to remove tetracycline hydrochloride from aqueous solution.The effects of p H value,initial concentration of tetracycline hydrochloride,contact time,solution temperature and other factors on the adsorption of tetracycline were determined,and the adsorption kinetics and isothermal adsorption model were analyzed.In view of the problem of adsorbent recycling,a detailed regeneration method for the spent adsorbent was proposed.The adsorbents were characterized by scanning electron microscope(SEM),specific surface area analyzer(BET),X-ray diffraction spectrometer(XRD),Raman spectrometer(Raman),Fourier infrared spectrometer(FTIR)and X-ray photoelectron spectroscopy(XPS).The conclusions of the above research are as follows:In the study of adsorption behavior of tetracycline,when the temperature is 25?,the dosage of adsorbent is 0.1 g/L,and the p H of solution is 4,the higher the initial concentration of tetracycline is,the higher the adsorption capacity is,and the maximum adsorption capacity corresponding to the initial concentration of 132mg/L is 412mg/g.According to the thermodynamic study,the Gibbs free energy of the process is negative,indicating that the process is a spontaneous reaction process;if the adsorption effect increases with the temperature,the reaction is endothermic.In addition,three kinetic models were used to fit the experimental adsorption data.From the fitting results,the adsorption process was in accordance with the pseudo second-order kinetic model.The fitting results of the internal diffusion model show that both the internal diffusion rate and the external diffusion rate are the factors affecting the adsorption rate.The Langmuir isotherm adsorption model and Freundlich isotherm adsorption model are used to simulate the experimental data.It can be concluded that the adsorption process is more suitable for Langmuir isotherm equation.The results of adsorption and regeneration experiments show that the best way to regenerate biochar is to use K2S2O8 solution with 1000 times of the concentration of tetracycline adsorbed on biochar.After one reuse,the adsorption capacity of biochar decreased to 75.4% of the initial adsorption capacity and the degradation effect was stable;after three reuse,the removal efficiency of biochar for tetracycline decreased,but it was still70.8% of the initial adsorption capacity,indicating that the prepared biochar had excellent recycling performance.At last,the characterization results show that the biochar prepared by solid waste(cow dung)has a well-developed pore structure,with a specific surface area of 1090.68m2/g,an average pore size of 2.24 nm and a pore volume of 0.61cm3/g.It is nano material with a large specific surface area.At the end of the paper,the mechanism of adsorption of tetracycline by biochar was discussed.