Analysis Of Characteristics On The Adsorption Relationship Between Different Size Typical Clay Minerals And Roxithromycin In The Water

As a new kind of emerging organic micropollutants,antibiotics can be absorbed by the particles in water,which will pose a serious threat to human health.Study on the coexisting between the antibiotics and particulate matters will not only provide theoretical basis for the improvement of drinking water treatment technology,but also be of certain reference-significance to the formulation of water quality indexes in the future.Two kinds of typical inorganic clay mineral,montmorillonite and diatomite,were selected as the representative of the particles,while roxithromycin as the representative of the antibiotics in water,respectively.Combining with solid-phase extraction,microwave extraction,OECD guideline 106 batch-balance method,quasi-two-stage adsorption kinetic equation and UPLC/MS/MS detection method,the adsorption mechanism,as well as the adsorption time,pH value,ion concentration and cation types in the adsorption of roxithromycin by different particle sizes of typical clay minerals were studied.Educe the conclusion as below:（1）Determination method of roxithromycin were established on the basis of the UPLC/MS/MS,whose recovery rate is 94.4%.And the correlation coefficient R² of standard curve of antibiotics is 0.9995,with the linear range from 5 to 1000 ng/L.（2）In the adsorption experiments of roxithromycin being adsorbed by these two kinds of inorganic clay minerals,the continuous adsorption experiments have reached balance both in 24h.The analysis of roxithromycin adsorption dynamics shows that the pseudo-second-order model fits the adsorption behavior well（R²>0.99）.（3）The pH is an important factor which can affect the adsorption.Adsorption mechanism mainly include electrostatic interactions and competitive adsorption.In the experiments of adsorption,different kinds of cation have different performance.When there is K⁺and Na⁺in the water,the adsorption quantity is much higher with small particles,and when there is Mg²⁺and Ca²⁺in the water,the adsorption quantity is much higher with big particles.However,in the experiments of ion concentration,it can be found that the increase ion concentration will inhibit the adsorption of roxithromycin by montmorillonite and diatomite.