Removal Of Representative Perfluorochemicals In Wastewater By Micro Particles Adsorption/desorption-ultrasound

Perfluorooctane sulfonate(PFOS)and perfluorooctanoic acid(PFOA)are widely used in industrial production because of their unique physical and chemical properties,released into the environment in an important way of the discharge of industrial wastewater.Currently,there are two main treatment methods including chemical degradation and absorption for removing PFOS and PFOA from wastewater.Due to low concentration of PFOS and PFOA in wastewater,it is not efficient that chemical degradation is directly used to break up PFOS and PFOA.However,adsorption only transfer PFOS and PFOA from aqueous phase to solid phase rather than destruct it.Therefore,a suitable treatment method to efficiently remove PFOS and PFOA from wastewater is desired.In this study,PFOS and PFOA in water are firstly enriched by an adsorbent,which has predominant adsorbent capabilities,is easy to disperse and collect,and is able to regenerate.Afterwards,high frequency ultrasonic degradation is applied to degrade the enrichment of PFOS and PFOA.We explore the preparation of two types of magnetic beads,and characterize them.Secondly,we verify their adsorption efficiency,survey its impact on treatment ability by p H and other coexistence common compounds,and measure their recycling ability.Then,we explore its action mechanisms.Finally,the degradation efficiency of PFOS and PFOA by high frequency ultrasound is investigated,the factors affecting the degradation efficiency are investigated,and the degradation mechanism is discussed.Through the characterizations and adsorption tests of embedded/ coated micro particles,the results showed that embedded micro particle was superparamagnetic,and micron-sized,and could efficiently remove PFOS and PFOA from water,and 97% removal efficiency was achieved for 0.1,1.0,10 mg/L PFOS and PFOA.The adsorption was dominated by multiple layers,and there existed ion exchange and hydrophobic interaction.Co-SO42-and nonionic surfactants affected the adsorption performance of PFOS,and PFOA removal was affected by nonionic surfactants and anions.The coated micro particle was superparamagnetic,and micron-sized,and could effectively adsorb PFOS and PFOA under acidic conditions.When the initial concentration of PFOS and PFOA was 0.1,1.0,10 mg/L,and p H was 4,the removal rates of PFOS and PFOA were 90% and 70%,respectively.The adsorption was dominated by monolayer layers,and there existed electrostatic adsorption and hydrophobic interaction.Co-anions,organic compounds and anionic and nonionic surfactants affected the adsorption performance of PFOS,however,cationic surfactants had no effect on PFOS.PFOA removal was affected by anions,organic matters and surfactants.Micro particles had good adsorption properties for PFOS and PFOA,then,the regeneration performance was further investigated.The results showed that embedded micro particles had a higher recovery rate and good recycling performance for PFOS and PFOA.The coated magnetic beads had a higher desorption rate of PFOS and PFOA,however,its recycling ability was unsatisfactory because of amino shedding.The results of the enrichment of PFOS and PFOA by ultrasound showed that ultrasound could effectively degrade PFOS and PFOA.The initial concentration of PFOS and PFOA was higher,the removal rate was lower,but the absolute removal rate was greater.