Quantitation And Identification Of Nanoparticles In Wastewater And Adsorption Characteristics Of Antibiotics

Nanoparticles refer to crystalline or amorphous materials with dimensions of 1 to 100 nm in at least one dimension.Their environmental behavior has drawn much attention in the field of the environment in recent years.Nanoparticles with large specific surface area and surface activity,can be combined with the pollutants in the aqueous phase to enhance the migration of pollutants,is considered to be one of the key factors affecting chemical pollutants and bioavailability.In the traditional sewage treatment method,no special treatment process for the nano-particles is provided.The nanoparticles carrying the pollutants may escape from the sewage treatment process and cause potential harm to the water environment.Therefore,it is of great significance to study the characteristics of nanoparticulates in wastewater and their carrier and adsorption to other pollutants in order to control water quality risks and ensure water quality and safety.In this study,the effluent from each stage of municipal wastewater treatment plant was selected to separate,identify and quantify the nanoparticles in the water.Antibiotics were selected as the carriers and adsorbents for the nanoparticles to study the adsorption characteristics and influencing factors of antibiotics to the nanoparticles with different particle sizes in wastewater.The results are as follows:(1)The separation method of the nanoparticles in wastewater was established based on asymmetric flow field separation technology and the separation conditions were optimized.The separation method of nanoparticles in actual wastewater including the collection and preservation of water samples,pretreatment of water samples,asymmetric flow field separation of wastewater nanoparticles,quantification of nanoparticle in different size range.The results of using asymmetrical flow field flow fractionation to optimize the separation effect showed that: when the conditions were injection volume 100 ?L,horizontal flow rate 1 mL / min,flow rate of 2 mL / min,elution time of 40 min,10 KDa regenerated cellulose membrane as separation membrane and 10 mmol NaCl as carrier fluid,can get the best separation effect.(2)The separation,identification,quantitative analysis of the actual sewage nanoparticles and adsorption characteristics and influencing factors of antibiotics were studied.The results show that it is difficult to remove the nano-scale particles in the wastewater by the traditional biological treatment methods of urban sewage treatment plants.The maximum number of nanoparticles in the effluent of different stages from the actual WWTPs are in different size range.The influent and primary sendimentation are in the range of 40~60 nm,the secondary sendimentation and effluent are in the range of 60~80 nm,among which,the maximum number density of secondary sendimentation in the range of 60~80 nm were the highest,which can be 6.32 × 10 ^ 6 particles/ mL.On-line UV-visible spectroscopic detection of nanoparticles showed that among the nano-sized particles,the small particle size nanoparticles were the main carriers of the organic components in the particles.The three-dimensional fluorescence spectra showed that the major components were the aromatic proteins and microbial metabolites.Using EDS and TEM to detect the elementary composition of nanoparticles found that the main element of nanoparticles in wasterwater were Si,Al,O;The distribution of antibiotics on nanoparticles with different particle size was different,among which the distribution was the most on the nanoparticles in the range of 60~80 nm.(3)The effects of pH and ionic strength on the size distribution of actual wastewater nanoparticles and the adsorption of tetracycline were investigated.The results show that when the pH is close to the isoelectric point and the ion concentration is increased,the agglomeration behavior of the nanoparticles is obvious and the distribution of the number of particles in the smaller particle size decreases,with the increase of the pH,the DLS size of the nanoparticles firstly increase and then decrease;At pH = 5,the adsorption capacity of antibiotics on the nanoparticles was the largest.The ions in the adsorption system will compete with nanoparticles to adsorp tetracycline and the higher ionic strength will promote the agglomeration of nanoparticles,which are responsible for the decrease of the tetracycline distribution on the effluent nanopartides.This study provides a systematic analysis and detection method for the separation and quantification of nanoparticles in the actual sewage,and also provides some theoretical basis for the effective control of the environmental risk of effluent discharge into the water and the corresponding engineering and technical strategies.