Study On The Competitive Adsorption And Impacting Factors Of Phenol And Bisphenol A On Bahe River Sediment

Phenolic Endocrine Disrupting Chemicals(EDCs)have been driving extensive research interests due to their prevalence and persistence in water and sediment.In order to study the adsorption of various phenolic EDCs on river sediments under natural conditions,analysing the pollution characteristics of phenol and bisphenol A(BPA)in the Bahe River water-sediment system first.The static adsorption experiments,which contained single or dual contaminant of phenol and bisphenol A(BPA)in the system,were carried out to characterize the adsorption of the two pollutants on the surface sediments in Bahe River for the pollution characteristics.The theory of site energy distribution was employed to interpret the experimental data,so as to understand the mechanisms based on the competitive adsorption of the two contaminants.The main and interaction effects of factors on the adsorption the two compounds in the dual-contaminant system were studied under particle size,humic acid concentration,pH and temperature.The main conclusions were as follows:(1)During Jan 2018 to Aug 2018,the concentration of phenol in the water of Bahe River was 0.012~10.815 ?g/L,while the concentration of bisphenol A was 0.068~0.700 ?g/L.The detection rates of pollutants were 44.44% and 72.22%.The phenol content in sediment was 0.362~4.879 mg/kg,and the concentration of bisphenol A was 0.077~0.387 mg/kg.The detection rates of pollutants in sediments were 100% and 94.44%.There was no significant correlation between the two pollutants in the water of Bahe River,but there was a significant negative correlation in sediment,especially in the wet season.(2)The adsorption of phenol and bisphenol A on sediments was more consistent with Elovich model in single-contaminant system;the adsorption process of phenol was more consistent with the pseudo-second-kinetic equation in dual-contaminant system,and bisphenol A was closer to Elovich model.(3)The Freundlich model was more appropriate for the adsorption of phenol and bisphenol A than the Langmuir model on sediment.The adsorption characteristics of phenol and bisphenol A on sediments under single and dual-contaminant system were analyzed by the site energy distribution theory.The results showed that the site energy of average and site energy heterogeneity of phenol in dual-contaminant system decreased by 0.867% and 3.473% at the same concentration(1~50 mg/L),respectively,and the number of adsorption sites decreased by 1.230%,the site energy of average and heterogeneity increased by 6.074% and 14.992%,and the number of adsorption sites increased by 6.389%.There is a certain competitive adsorption between phenol and bisphenol A,and the bisphenol A is in a competitive advantage.(4)The results of response surface methodology showed that the effects of single factor and interaction of multi-factor on the adsorption of pollutants was different.Only the humic acid concentration had signifiant effect on the adsorption of phenol on the sediment among four single factors.At the same time,the interaction of humic acid concentration and temperature promoted the adsorption of phenol significantly under the interaction of multiple factors.The order of influence of four single factors on the adsorption amount of bisphenol A was particle size,humic acid concentration,pH and temperature.The particle size inhibited the adsorption of bisphenol A significantly on the sediment.The second-order interaction promotion is marked of particle size and pH.