Study On The Application Of Modified TiO₂ Remove Atenolol In Water

In recent years,the problem of remnants of drugs and personal care products in the environment has attracted more and more attention.Atenolol?ATL?is a?1-receptor selective antagonist mainly used against cardiovascular diseases.It has been used for more than thirty years.Besides,ATL is one of the most widely used hypertension drugs.This kind of drug is widely dected in surface waters due to its extensive usage and water solubility.Furthermore,many studies have reported that the growth of human embryonic cells could been inhibited by ATL and was also found to be ecotoxic to freshwater species.ATL keeps steady in water for its processing of natural degradation is slow under natural condition.In addition,Conventional wastewater treatments and ecological restoration treatments are not effective.Therefore,the study of efficient and effective methods to remove ATL in water environment is of great significance for the stability of the ecological environment and the development of biological health.In this paper,two aspects was mainly carried out.One is the study of TiO₂ modification methods to prepare high-efficiency catalysts under visible light.The other is the study of photocatalytic reactors for in-situ remediation of water to determine the loading of catalysts and photocatalytic floating beds'design parameters.In the former,transition metal iron?Fe?,copper?Cu?,zinc?Zn?,manganese?Mn?and tungsten?W?modified TiO₂ were firstly prepared.Different dopants?different doping amount and calcination temperature were investigated to analysis the degradation of ATL according to their photocatalytic properties.Choosing out the better screening doped metal species and the microstructure and properties of selected catalysts were characterized by using instruments such as XRD,UV-vis,BET,as well as SEM.Secondly,the visible light degradation of ATL was studied by using the selected modified catalysts.The influencing factors included catalyst concentration,initial substrate concentration,variation of light source and pH.At the same time,the degradation mechanism of ATL was studied.The latter,the study simulated a photocatalytic floating bed.The catalytic activity,influencing factors,reaction kinetics and the stability of immobilized TiO₂ were studied.The main results are described below.1.Study on the photocatalytic degradation of ATL by different metal doped TiO₂.Compared with P25,the doping of Fe,Cu,Zn,Mn and W can increase the visible light response of TiO₂.And all of modified catalysts can improve the photocatalytic properties of ATL in different degrees.The degree of improvement is as follows:W>Zn>Fe>Cu>Mn.2.Study on the photocatalytic degradation of ATL by W-doped TiO₂.W doping can significantly enlarge the TiO₂ visible light absorption range,as well as increasing the specific surface area of catalyst.Moreover,W doping can maintain a good crystal structure.10%W-TiO₂?molar ratio?calcined at 500 ⁰C for 4 hour possess the best photo-degradation performance.The degradation efficiency of 10 mg/L ATL could reach to92%after 240 minutes visible light irradiation in the presence of 1 g/L 10%W-TiO₂-500.In addition,holes?h⁺?and hydroxyl radical?OH·?are determined to be the predominant reactive species during photocatalysis by means of scavenger experiments.By HPLC-MS and TOC test results,the degradation pathway of ATL was deduced.The degradation pathways of atenolol degradation mainly included the ether bond cleavage,?multiple?hydroxylation of the parent compounds,formation of benzaldehyde derivatives,and the elimination of functional groups,intermolecular cyclization and rearrangement.3.Study on the photocatalytic degradation of ATL by immobilized W-doped TiO₂.The glass fiber cloth was determined as the load material by adsorption experiment and photocatalytic degradation experiment.The study showed that 10 mg/cm² was the optimal catalyst loading.The height of liquid surface experiments showed that the lower the liquid surface height on the immobilized catalyst surface,the greater the number of photons reaching the catalyst surface,and the faster the photocatalytic degradation rate of ATL.The experimental results of the light intensity showed that higher degradation rate of ATL was achieved while the light intensity was higher.Photocatalysis degradation rate of ATL under different light intensities was as follows:1000 W Xenon lamp>500 W Xenon lamp>300 W Xenon lamp>26 W LED white lamp.Under the irradiation of sunlight from 10:00 a.m.to 14:00 p.m.,which average irradiance was 700 W/m²,the degradation of ATL reached to 52.71%.With the perturbation intensity ranging from 0 to 6,the degradation rate of ATL was improved because of the big amount of dissolved oxygen and the high mass transfer rate.4.Study on the design parameters of photocatalytic floating bed reactors.The photocatalytic floating bed designed in this study is suitable for the remediation of ATL-contaminated water bodies.The shape of the floating bed is regular rectangle and the loading catalyst of photocatalytic floating bed per unit area is 100 g/m².The concentration of ATL in water sets as 10 mg/L,and the immersion depth of floating bed is 1 cm The degradation rate from 10:00 a.m.to 14:00 p.m.reaching to 50%,which is the strongest sunlight irradiation in one day,is taken as the basis.The hydraulic load is 0.047 g ATL/?m²·d?.The area of the photocatalytic floating bed is determined based on the area of the repaired water body.