Study On Separation Method Of Microplastics And Mechanism Of Antibiotic Adsorption

With the rapid development of science and technology,people have invented all kinds of plastic products,which brings great convenience to daily life and production,but also produces a series of environmental problems.Plastic waste in the environment is constantly broken and cracked to form microplastics(size < 5mm).Microplastics can absorb all kinds of pollution substances,which are absorbed by organisms and passed along the food chain and food web,and are enriched in organisms and affect the normal physiological functions of organisms.As an emerging pollutant,microplastics pose a great threat to the Marine ecological environment safety.At the same time,it can also be used as a carrier to enrich antibiotics and other pollutants,resulting in high local concentrations of antibiotics in the ocean.The plastic in the ocean will eventually settle to the seabed or remain on the beach under the action of waves and wind.The investigation of microplastic pollution on the beach is of great significance for the assessment of Marine microplastic pollution and the study of the impact of microplastics on the environment.In this paper,a set of methods for the separation of microplastics on sandy beaches were designed and used to investigate the microplastics pollution in four sandy beaches in Dalian City.According to the results of beach survey,the behavior and mechanism of microplastics adsorbing antibiotics were studied,and the influence of aging on the ability of microplastics adsorbing antibiotics was analyzed.The main contents are as follows:(1)In order to solve the problems of low manual efficiency,complex process and incomplete separation in the density separation flotation method of beach microplastics,a kind of automatic separation device for microplastics was designed.By means of microporous aeration and flotation liquid injection,the microplastics can be fully agitated in flotation solution.The efficient separation of microplastics from sand is realized by the good sedimentation performance of ceramic corrugated packing.The microplastics were collected by different diameter metal screens.By optimizing parameters such as specific surface area,aeration rate and reaction time of ceramic corrugated packing,the flotation efficiency of microplastics was further improved.In the separation recovery verification,the separation recovery rates of six kinds of microplastics standard products with different densities were 96% ～98%,which can provide stable and reliable technical and tool support for beach research.(2)Micro plastic separation method based on the design was carried out by the beach in dalian micro plastic,bathing beach in dalian micro plastic content,particle size range,statistics on the shape,color,composition,micro plastic pollution sources are analyzed,and according to the survey in dalian 4 sand micro plastic pollution to the ecological risk assessment.The results showed that the average content of microplastics in the beach of the four bathing beaches was 6562 N/m2.Through qualitative analysis,six kinds of microplastics,such as polystyrene(PS),were found,which mainly came from human activities such as manufacturing,tourism and fishery.Incomplete treatment of industrial waste water,household waste and sewage,as well as plastic waste produced by mariculture and tourism all lead to a large number of microplastics flowing into the Marine environment to varying degrees.The results of ecological risk assessment showed that the beach microplastics pollution in Dalian City was light,and the beach pollution level with high toxic microplastics pollution was higher.(3)Levofloxacin(LEV)and Norfloxacin(NOR)were selected as target antibiotics to study the theory of microplastics adsorption on microplastics based on the investigation of microplastics pollution in Dalian beach.It was found that the kinetic adsorption of antibiotics on microplastics was in line with Elovich equation and pseudo-second-order dynamic model,and the isothermal adsorption was in line with Langmuir model and Freundlich model.The microplastics before and after antibiotic adsorption were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy.The changes of two kinds of microplastics before and after aging were obtained.The effect of aging on microplastics adsorption of antibiotics was also investigated.