Extraction And Purification Of Persimmon Tannin And Its Application In Treating Water Polluted By Tetracycline

China produces a large number of persimmons each year,the puckery persimmons account for about 20%of the total production which have been abandoned for the other persimmons get riped.Persimmon tannin has significant antioxidant,antibacterial,and anti-radiation effects,but its application and promotion still have problems such as low extraction purity and complex purification procedures,which limit its high-value utilization.Recently,due to the large number of using antibiotics in disease treatment,animal husbandry,aquaculture,etc.,the antibiotic pollution has become one of the most worrying health threats.The Hangzhou G20 Summit in 2016 clearly pointed out the impact of antibiotic resistance on health.Based on the above considerations,this paper uses persimmon waste（sparse persimmon fruit）as a raw material to carry out research on the extraction and purification technology of persimmon tannins,which provides the possibility for subsequent drug research and development based on high-purity persimmon tannins;Use crude persimmon tannins to prepare magnetic adsorbent materials,research on the treatment of tetracycline（TC）polluted water bodies,explore the mechanism of its enrichment,and provide support for the development of green and efficient antibiotic adsorbent materials.The research conclusions of this paper are as below:（1）Ultrasonic-assisted extraction（UAE）is used to extract persimmon tannins from puckery persimmons.The best extraction condition is as follows:80%methanol aqueous solution is selected as the extraction solution,the extraction temperature is 80℃,and 300W is selected as the ultrasonic power.Under the optimal conditions with a material ratio of 1:15 and an extraction time of 2 h,the purity of the persimmon tannin extract obtained is 13.5%.（2）The further purify was using macroporous resin method and membrane separation method.The best process condition is as follows:select HPD500 type macroporous resin,the sample concentration is 1 g/L,and the eluent is 60%methanol aqueous solution which the flow rate is 1.0 m L/min.Under these circumstances,the content of the purified persimmon tannin is 50%.After separation by ultrafiltration membrane,the purity of persimmon obtained is 91.23%.（3）Using persimmon tannin（PT）and nitrogen-doped graphene（NG）as raw materials,iron oxide（Fe₃O₄）as a magnetic core,a magnetic persimmon tannin-nitrogen-doped graphene composite material was prepared by a hydrothermal method（Fe₃O₄/PT/NG）.The study found that when pH=6.5,TC concentration is 50mg/L,temperature is 318K,and dosage is 0.6 g/L,the adsorption capacity for TC reached 315.65 mg/g.we have used a variety of characterization methods to analyze the morphology,element composition,and group changes of the adsorbent,which showed the specific surface area of the prepared adsorbent,the average pore size was 82.7724m²/g and 16.36 nm,and the surface showed Irregular hole-like structure.（4）When the pH is 6.4,the TC concentration is 50 mg/L,the temperature is 318K,and the dosage is 0.6 g/L,the adsorption capacity of（Fe₃O₄/PT/NG）composite material for TC reaches the maximum（315.65 mg/g）,adsorption is an endothermic reaction,and the Freundlich model and the pseudo-second-order kinetic model can explain the adsorption process.The adsorption mechanism shows that the pore filling,hydrogen bond interaction,π-πinteraction and electrostatic interaction are the main mechanism between the TC molecule and the adsorbent material.Moreover,the magnetic properties of the adsorbent material help to efficiently separate the adsorbent material from the aqueous solution.