The Study On Preparation Of Different Pore Sizes Activated Carbon Supported TiO₂ Composites And Removal Of 17?-ethynyl Estradiol

The control of endocrine disrupting chemicals?EDCs?has become a concern in the environmental field.The endocrine disruptor 17?-ethynyl estradiol?EE2?,which has the strongest estrogen effect,has been detected in different water environment.At present,most studies focus on photocatalytic degradation of endocrine disruptors in high concentration.However,there are a large number of inorganic ions and dissolved organic matter?DOM?coexisting in the actual water body,and the interference effect of these coexisting ions and DOM in the catalytic system is ignored,which makes it impossible to comprehensively judge the effective performance of photocatalysts.The main work is as follows:?1?Using 700 nm,1.2?m silica?SiO₂?and calcium carbonate?CaCO₃?as templates and glucose as the carbon source,three activated carbons with different pore sizes were prepared by the template method and compared with commercial activated carbons for EE2 adsorption removal.The structure,pore size of them were observed by SEM.The results showed that the pore sizes of AC₁,AC₂ and AC₃ were 559.51-616.84 nm,510.13-538.74 nm and 370.99-1231.86 nm,respectively.Commercial activated carbon is block-shaped with fine and dense pores on the surface.The equilibrium adsorption amounts of EE2 over AC₁,AC₂,AC₃,and AC₄ are 9.120 mg/g,7.925 mg/g,72.975mg/g and 23.496 mg/g,respectively.The adsorption rate constants fitted by the quasi-second-order kinetic equation are 0.0024 g/mg/min,0.0021 g/mg/min,0.0026g/mg/min,and 2.51 g/mg/min.?2?4 kinds of AC/TiO₂ composites with different pore diameters were prepared via hydrothermal method,the mass ratios of activated carbon to titanium dioxide was optimized according to the and adsorption,photocatalytic degradation and adsorption/photocatalytic degradation removal rates,and the structure of the prepared composites was characterized by SEM,XRD and BET method.the adsorption rates of EE2 over the optimized 85%AC₁/TiO₂,85%AC₂/TiO₂,10%AC₃/TiO₂,30%AC₄/TiO₂were22.76%,69.26%,48.55%,79.17%,and 81.30%after 120 min adsorption,the photocatalytic degradation rates were 36.18%,26.97%,44.61%,12.8%,and 11.8%after 120 illumination,The total removal rates were 58.94%,96.23%,93.16%,91.97%and 93.10%.The degradation rate constants of EE2 by TiO₂,85%AC₁/TiO₂,85%AC₂/TiO₂,10%AC ₃/TiO₂,30%AC₄/TiO₂ are 0.00505 min^-1,0.01659 min^-1,0.0158min^-1,0.00815 min^-1,0.00786 min^-1.The results showed that the photocatalytic degradation rate of EE2 over 85%AC₁/TiO₂ is 1.05 times,2.,03 times,2.11 times and 3.29 times thant those over 85%AC₂/TiO₂,,10%AC₃/TiO₂,AC₄/TiO₂ and pure TiO₂.Therefore,85%AC₁/TiO₂ composite has the best catalytic activity.The SEM images showed that the pore sizes of 85%AC₁/TiO₂,85%AC₂/TiO₂ and 10%AC₃/TiO₂ were374.19-423.81 nm,285.71-483.4 nm,295.24-919.05 nm,respectively.Compared with AC₁,AC₂,and AC₃,the pore sizes of them reduced accordingly.EDS element mapping showed that TiO₂ particles were dispersed on the activated carbon t.The specific surface areas of 85%AC₁/TiO₂,85%AC₂/TiO₂,10%AC₃/TiO₂,30%AC₄/TiO₂ are 34.28m²/g,27.632 m²/g,207.46 m²/g,83.13 m²/g,the average pore volumes were 0.1611cm³/g,0.1251 cm³/g,0.37 cm³/g,and 0.1668 cm³/g.Large specific surface area and pore volume of 10%AC₃/TiO₂ and 30%AC₄/TiO₂ will help to increase their adsorption capacity for pollutants,which accelerate the transfer rate of pollutants to the photocatalytic degradation sizes of the composite.?3?The effects of dissolved organic matter?DOM??HA,FA?which are widely present in actual water body,on the adsorption and degradation of EE2 by composites were studied.The results showed that HA and FA reduced the adsorption removal rates of 4 kinds ofcomposite materials due to competitive adsorption of them on the surface of the material;HA reduced the photocatalytic degradation removal rates of 85%AC₂/TiO₂,10%AC₃/TiO₂,and 30%AC₄/TiO₂ by 1.68%,4.46%and 0.2%,whereas the photocatalytic degradation removal rate of 85%AC₁/TiO₂ increased by 6.53%.However,FA increased the photocatalytic degradation removal rate of 85%AC₁/TiO₂,85%AC₂/TiO₂,10%AC₃/TiO₂,and 30%AC₄/TiO₂ by 12.57%,17.38%,14.36%,4.93%.Both HA and FA can reduce the adsorption removal rate of TiO₂.HA increases the photocatalytic degradation removal rate of TiO₂ by 6.21%,and FA reduces the photocatalytic degradation removal rate of TiO₂ by 11.88%.On the one hand,the reduction of the photocatalytic degradation removal rate by DOM may be because DOM competes with EE2 for active free radicals,thereby reducing the photocatalytic degradation of EE2;on the other hand,DOM increases the photocatalytic degradation removal rate,possibly because of the photosensitivity of DOM.?4?Cl^-and NO₃^-make the four composites and TiO₂ reduce the removal rates of EE2 and increase the removal rate of photocatalytic degradation.SO₄^2-reduces the removal rates of EE2 over 85%AC₁/TiO₂,85%AC₂/TiO₂,30%AC₄/TiO₂,and increases the removal rate of photocatalytic degradation;For the composite material10%AC₃/TiO₂,SO₄^2-makes its adsorption removal rate increase and photocatalytic degradation removal rate decrease;SO₄^2-reduced both the adsorption and photocatalytic degradation removal rates of TiO₂.