Preparation Of Cobalt Oxide/Biochar Composite Materials And Their Adsorption Properties For Tetracycline Hydrochlorideby

With the continuous high-quality development of modern medical and health services,antibiotics are widely used in the prevention and treatment of diseases due to their function of inhibiting the growth of bacteria or killing bacteria.Among them,tetracycline hydrochloride,as a typical antibiotic,is widely used in the prevention and treatment of epidemic typhus,tsutsugamushi disease,relapsing fever,cholera and other diseases,it is worth pointing out that careless application of tetracycline hydrochloride can easily cause pollution to the environment and accumulate in the environment to cause a series of ecotoxicological effects.At present,the methods of treating antibiotic wastewater mainly include advanced oxidation,membrane treatment technology and adsorption method,among which the adsorption method has been widely concerned because of its advantages of high efficiency,economy and environmental protection.Based on the above,this study prepared a cobalt oxide/biochar composite material,and analyzed the material properties by means of scanning electron microscope(SEM),transmission electron microscope(TEM),Fourier infrared spectroscopy(FT-IR),and Tetracycline hydrochloride is the target pollutant.The adsorption performance,thermodynamic and kinetic characteristics of tetracycline hydrochloride were analyzed,and the adsorption mechanism was discussed.The main contents and conclusions of this study are as follows:(1)In this study,the walnut shell biochar Y was prepared by using the high-temperature calcination method with the discarded walnut shell as the original material.On this basis,different cobalt oxide/biochar composites Y1,Y2,Y3 and Y4 were prepared by controlling the ratio of cobalt chloride hexahydrate(Co Cl₂.6H₂O)to Y(the mass ratio of Co Cl₂.6H₂O to biochar were 0.3 and 0.5,0.7,0.9).Subsequently,a series of modern characterization methods such as transmission electron microscopy(TEM),scanning electron microscopy(SEM),and Fourier infrared spectroscopy(FT-IR)were used to characterize and analyze the above materials.(2)The adsorption effect of the prepared materials on tetracycline hydrochloride was investigated,and Y2 was taken as an example to investigate the factors affecting its adsorption process,as well as its adsorption process and mechanism.The results show that the adsorption effect of Y on tetracycline hydrochloride is not significant,only 12.83 mg/g.But the removal effect of cobalt oxide/biochar composite material on tetracycline hydrochloride is better,and with the increase of cobalt content,the maximum adsorption capacity of tetracycline hydrochloride shows,the maximum adsorption capacities of TC for Y1,Y2,Y3 and Y4 were 56.52,139.78,144.31 and151.43 mg/g,respectively.In addition,as the pH of the solution increases,the amount of tetracycline hydrochloride adsorbed by the cobalt oxide/biochar composite material increases first and then decreases.When the pH is 6,the adsorption is most favorable(q_e=154.86 mg/g).Adsorption kinetics and adsorption isothermal simulation results show that the adsorption of tetracycline hydrochloride by the cobalt oxide/biochar composite material conforms to the quasi-second adsorption kinetics and Langmuir isotherm model.The analysis of the intragranular diffusion model proves that its adsorption of tetracycline hydrochloride is divided into fast adsorption and slow adsorption stages.The results of thermodynamic model analysis show that the adsorption process of cobalt oxide/biochar composites on tetracycline hydrochloride is a spontaneous endothermic process,which shows that an appropriate increase in ambient temperature will facilitate this adsorption process to be carried out more efficiently.This conclusion is also consistent with the results of exploring the effect of temperature on the adsorption effect.In the adsorption process,the cobalt oxide in the material and the oxygen-containing functional groups on the surface of the material play an important role.(3)The material has certain recycling performance.Taking Y2 as an example,0.1%NaOH solution was used in this study to analyze it.After three cycles of experiments,the removal rate of tetracycline hydrochloride still exceeded 50%.