The Effect Of Natural Organic Matters On The Adsorption And Stability Of ZnO Nanoparticles On Powdered Activated Carbon

Nanomaterials are widely used because of their excellent properties.During their production,use,transportation and disposal,nanomaterials will inevitably be released into the environment,thus posing potential threats to the ecological environment and human health.Nanoparticles will have adsorption and complexation with natural organic matter(NOM)which is widely existed in the water environment.Natural organic matter can influence the properties and behavior of nanoparticles in aquatic environments.Thus,understanding the effect of NOM on nanoparticles'physiochemical properties is critical for identifying an effective water treatment processes,and controlling the potential risk they pose to ecological and human health.In this study,systematically studies the effects of NOM(HA or BSA)on the physicochemical properties of ZnONPs and different ZnONPs forms adsorption by activated carbon in water environment were studied.Meanwhile,the rerelease characteristics and forms of ZnONPs adsorbed on activated carbon collected from different NOM conditions were discussed,which was of great significance to the ecological risk and health risk control of nanoparticles.The main research and results of this paper are as follows:1.Different ZnONPs simulated water samples were prepared by NOM(HA and BSA)mixed with ZnONPs dispersed liquid.The membrane filtration method was used to research the different simulation ZnONPs occurrence forms(including particulate,colloidal,and dissolved fractions)in water samples,and their surface charge and hydraulic particle size were characterized by Zetasizer Nano.The results showed that both HA and BSA increased the Zeta potential value of ZnONPs in water samples.While the Zeta potential value decreased sharply and the hydraulic particle size increased of simulated water samples with the increase of ionic strength and hardness in the water sample.In addition,the proportion of colloidal Zn at background of HA was higher than that BSA.2.The use of powder activated carbon(PAC)adsorption to remove ZnONPs in different water samples.By comparing the differences of occurrence forms of ZnONPs in water samples before and after adsorption treatment,to clarify the effect and mechanism of adsorption of different occurrence forms of ZnONPs by PAC.And,the morphology and composition of PAC adsorbed ZnONPs were analyzed by means of characterization to illustrates the effects of the physicochemical properties of typical NOM on the adsorption and removal of ZnONPs in different occurrence forms.The adsorption experiments demonstrated that both colloidal and dissolved Zn fractions can adsorb on the PAC's surface.As the HA concentration increased from 0 to 20 mg/L,the colloidal Zn fraction's adsorption efficiency decreased from 74.49%to 61.24%.However,BSA did not significantly influence the colloidal Zn fraction's adsorption.The increase of ionic strength and hardness of water sample inhibited the adsorption effect of PAC on ZnONPs,especially the adsorption efficiency of colloidal fraction.3.The release amount and release process of ZnONPs on waste activated carbon in water environment were studied by static dissolution experiment,and the influence of adsorption conditions on the occurrence form of ZnONPs release was discussed by using membrane filtration method.Furthermore,the changes of ZnONPs characteristics on the surface of the waste activated carbon and the morphology of the colloidal fraction were analyzed by means of SEM and XRD,and preliminarily clarified the The path and mechanism of ZnONPs rerelease from WAC.The leaching experiments showed that the colloidal Zn fraction would release from the PAC's surface,and most of them transferred to the dissolved Zn fraction.As the HA concentration increased from 0 to 20 mg/L,the Zn concentration leached from the PAC adsorbed ZnONPs reduced from 0.956 to 0.694 mg/g.Comparatively,the leached Zn concentration varied only slightly with an equal increase in BSA concentration.In addition,the adsorption environment with HA will change the morphology of leaching colloidal fraction,while BSA will not significantly affect the morphology of leaching colloidal fraction.