Selective Photoelectrocatalytic Removal Of Typical Endocrine Disrupting Chemicals

The removal of environmental endocrine disrupting chemicals（EDCs）and the inhibition of their toxicity are one of the most important hot-spots and crucial issues in the field of environmental chemistry.EDCs possess the characteristics of low concentration and high toxicity,and may still bring adverse environmental risks even at the concentration level of ng L^-1～μg L^-1.Although the traditional water pollution control technology can meet the needs of some overall indicators,it is difficult to effectively remove EDCs and eliminate its toxicity.Even in some advanced oxidation technologies（AOPs）,the removal of EDCs is still not satisfactory due to the inherent molecular structure characteristics,physicochemical properties and the interference of high-concentrated and low-toxic organic compounds in complex water matrices.This undoubtedly puts forward updated requirements for the high efficiency,selectivity and anti-interference ability of upcoming water pollution control technology.In this study,the photoelectrocatalytic（PEC）technology with high-efficiency oxidation ability is employed.Based on this,efficient PEC systems with selectivity for EDCs were constructed combined with surface modification,molecular imprinting and dummy-templates,realizing selective and accurate removal of typical EDCs in complex water matrices.The mechanisms of PEC and selective degradation were revealed by in-situ electron paramagnetic resonance（EPR）spectroscopy,in-situ infrared spectroscopy and X-Ray absorption fine structure.The main innovative results are as shown below:（1）Selective monocrystal titania nanorod arrays E2-TiO₂-NRs photoelectroanode was constructed,achieving selective removal of 1μg L^-1 trace amount of 17β-estradiol（E2）to below 0.1 ng L^-1 concentration with elimination of its estrogenic activity in a circulating flow photoelectrocatalysis（CF-SPEC）system under the interference of natural organic matter（NOM）at a concentration of 10 mg L^-1.The CF-SPEC enhances the selectivity to the targeting E2.The difference of adsorption capacity between NOM and E2 on E2-TiO₂-NRs is magnified by 5.6 times.And,the removal of E2 and the estrogenic activity increases by 58.7%and 5.8 times,respectively.In addition,higher generation rate of hydroxyl radicals（^·OH）and a lower toxic degradation pathway in CF-SPEC were observed,which leads to more thorough elimination of estrogen activity.Even in complex actual water matrices such as tap water and river water,selective removal of concentration and estrogen activity of target E2 was also achieved.（2）Selective Multi-TiO_2,{001}anode with highly exposed{001}facets of anatase phase was successfully constructed by multi-template method to realize the selective removal of three typical phthalic esters of DMP,DBP and DOP that belong to the priority control blacklist of China.Under the interference of 10 mg L^-1 NOM,the removal of the three typical PAEs reached 92.3%～95.6%,and the apparent kinetic constant(K_app)was 0.0118～0.0137 min^-1.It was shown in response surface analysis and in-situ multiple total reflection Fourier-transform infrared spectroscopy that Multi-TiO_2,{001}mainly promotes the selective enrichment and removal of target PAEs through the interaction between carbonyl C=O lone electron pairs and photoelectric anode.Finally,the selective removal of three PAEs and the complete elimination of aquatic toxicity and estrogen activity were realized in complex water matrices.（3）The selective PS-PAEs-TiO₂ photoanode for group-targeting pollutants was constructed by dummy-templates method.PS-PAEs-TiO₂realized the selective PEC removal of target PAEs by the accurate identification of PAEs characteristic structures of phthalate carbonyl and benzene ring.Under the interference of organic matter in the effluent of secondary treatment,the selective removal of nine PAEs reached 90%～99%.Quartz crystal microbalance（QCM）and photoelectrochemical analysis showed that the selectivity of PAEs may be derived from the preferential adsorption and enrichment,and the K_app of PAEs degradation increased by about two times.The results of solid-state NMR and IR spectra show that this selective recognition comes from the interaction ofπ-electrons and C=O functional groups of phthalate benzene ring between5c-Ti and oxygen vacancy,as well as the high matching of specific spatial positions.The results of apparent isotope kinetics and mass spectrometry show that the degradation of PAEs on the PS-PAE-TiO₂ photoanode is more prone to side chain scission,which reduces the production and accumulation of risky by-products.Finally,approximately 100%of estrogenic activity and acute aquatic toxicity of the simulated wastewater were eliminated,and genotoxicity was reduced by 92.5%.（4）The Ag_NDs⁰/TiO₂ photoanode modified with Ag nanodots with localized surface plasmon resonance（LSPR）effect was constructed,which realized the efficient and selective PEC removal of typical thiol-containing pollutants（TCPs）.Investigation of microstructure and nano photoelectric properties confirmed the high-efficient PEC performance and LSPR effect of Ag_NDs⁰/TiO₂.Under the condition of 5 wt%silver loading,the saturated adsorption capacity of typical TCPs increased significantly from5.2μg cm^-2 to 53.3μg cm^-2,the K_app increased by 5.8 times,and the selectivity factor increased by approximately 9 times.QCM and in-situ Raman imaging revealed that this selectivity come from the specific adsorption.And,further studies of infrared and Raman spectroscopy revealed the Ag-S chemical bond interaction between TCPs and the photoanode.This selective Ag_NDs⁰/TiO₂ photoanode based on Ag-S chemical bond interaction was adopted in actual wastewater and achieved removal of typical TCPs,realizing 92%～99.5%removal of targets.（5）A novel electrochemical system was constructed based on boron-doped diamond（BDD）electrode,which realized the high-efficient electrochemical in-situ generation of sulfate radicals（SO₄^-·）.High-efficiency and selective removal of atrazine（ATZ）,a typical EDCs,was achieved with the ability of selective oxidation of SO₄^-·.Compared with the traditional AOPs mainly based on^·OH,this novel system shows higher anti-interference ability,realizing 100%removal of ATZ even under the interference of 1000 times NOM.Given by in-situ electrochemical EPR spectroscopy,mechanism of in-situ generation,migration and transformation of radicals was revealed.The selective removal comes from the reaction characteristics of SO₄^-·,which is faster with the targets and slower with NOM.The production and accumulation of highly toxic by-products was clarified and the toxicity removal mechanism of ATZ was revealed at molecular level based on the structure-activity relationships.The energy consumption analysis results show that this selective electrochemical system has higher mineralization current efficiency.Given by accurate design and construction of the surface/interface of PEC materials,selective methods were established to realize the efficient and preferential removal of typical EDCs in complex water matrices.For different targets and complex water matrices,tailored selective interaction methods were employed,such as cyclic-flowing combined with molecular imprinting on single crystal surface,multi templating,dummy-templating,Ag-S chemical bond interactions and regulation of oxidize species.The customized and efficient treatments of EDCs in actual wastewater matrices are thus realized.The selective mechanisms of different selective PEC methods were further investigated,revealing the mechanisms of catalytic oxidation and changes of toxicity.It provides a theoretical basis and new research ideas for the efficient and selective PEC oxidation removal of typical EDCs pollutants in complex and actual water matrices.