Preparation Of Nano-MgO/SiO₂ Charge Membrane And Its Removal Of Tetracycline In Water

In recent years, due to the extensive use of antibiotics, antibiotic wastewater discharge problems are becoming increasingly prominent. Antibiotics lead to the emergence of a large number of drug-resistant pathogens, which has brought a threat for the ecological environment and human health, and the residual antibiotics in the environment have a strong inhibitory effect on the microorganisms, so that the process of antibiotic wastewater treatment is more complex, high cost, the effect of instability and so on. Therefore, in the research of antibiotic wastewater treatment, it is of great significance to control the content of antibiotics in the environment, to seek more simple and quick, high removal efficiency and environmental protection technology.In this paper, the preparation of positively charged microporous ceramic membranes and the composition and surface electrical properties were studied. The removal efficiency of tetracycline in water was studied, and the separation mechanism was explored.Simultaneously, the practical application of the charged positive microporous ceramic membrane was also discussed.The surface of the diatomite base membrane was modified by impregnation-thermal decomposition method to obtain the nano-MgO/SiO2 positive charge microporous ceramic membrane using diatomite ceramic membrane as base membrane, magnesium chloride and urea as raw materials. The composition of the membrane was characterized by FT-IR, XRD,EDS, TEM and SEM. The results show that the positively charged MgO coating exhibits cubic crystal grains and uniformly adhered to the surface of the base film without blocking the pores of the membrane. The pore structure of charged membrane was studied by mercury porosimeter, and the results showed that the membrane had porous structure with an average pore diameter of 1.9?m and the pore structure of the membrane remained intact.The adhesion between MgO and ceramic basement membrane was studied by XPS. The results showed that new chemical bond was formed between nano-MgO and base membrane, and the nano-MgO coating adhered firmly to the surface of base membrane.The zeta potential of the charged membrane was analyzed. The results show that the charged membrane has high electrical properties and is positively charged in a wide pH range. The isoelectric point of the charged membrane is 10.8, which can adsorb negatively charged small molecules.Finally, the removal of tetracycline with nano-MgO/SiO2 positive charge microporous ceramic membrane was studied. The results show that the charged membrane has a good removal effect on tetracycline in water, and the removal rate is up to 99.9% under certain experimental conditions. The influence of tetracycline initial concentration, solution pH,operating pressure and coexisting ions on the removal of tetracycline were studied. It was found that the pH value of the solution had a great effect on the removal of tetracycline, the removal rate of tetracycline was over 96% when the pH value of the solution ranged from 6.0 to 10.2. High concentration of tetracycline is easy to make the charged membrane to adsorption saturation, affecting the life of charged membrane. When the surface area of the charged membrane is 2.8cm2 and the thickness is 5mm, the adsorption saturation of tetracycline is l.45 mg/cm3. Operating pressure affects the contact time of the solution with the membrane, thus affecting the adsorption of tetracycline on the charged membrane. The higher the operating pressure, the shorter the contact time, and the lower the removal rate of tetracycline. Therefore, it is possible to improve the removal of tetracycline with the charge membrane performance by increasing the membrane size and reduce the operating pressure.The coexisting ions in the solution had little effect on the adsorption of tetracycline. The removal mechanism of tetracycline showed that the positively charged microporous ceramic membrane adsorbed tetracycline molecules through electrostatic adsorption. The results show that low concentration tetracycline solution is more suitable for the long-term use of positively charged ceramic membrane.Therefore, the preparation of positively charged microporous ceramic membrane by impregnation-thermal decomposition has the advantages of low cost and simple process,and the nano-MgO is uniformly distributed on the surface of the charged membrane. The strong binding force between the base membrane and the charge agent. It can adsorb and separate tetracycline molecules by mutual attraction of positive and negative charges, and the tetracycline has a good removal effect. The positively charged microporous ceramic membrane has many advantages, such as high separation performance, large flux, long service life, simple operation and low cost. It has a good application prospect in drinking water purification, domestic wastewater treatment and other fields.