| Endocrine disrupting compounds,one group of harmful substances,could lead to obesity and diabetes,induce female hormone-sensitive cancer and male prostate cancer,affect reproductive health,thyroid and neurodevelopment of men and women,etc.Because of extensive sources,it would be discharged into natural water bodies through certain channels,bringing about water pollution.In China,endocrine disrupting compounds are currently found in major lakes and rivers and detected in some drinking water sources and daily tap water.By liquid-liquid separation technique,polyethersulphone/modified attapulgite hybrid microspheres were prepared with acid,heat and organic modified attapulgite and polyethersulphone.Apparent characteristics of hybrid microspheres were analyzed by scanning electron microscope,BET surface analyzer and pH drift method.Effects of modified attapulgite dosage,initial solution pH,dosing amount and initial solution concentration on adsorption of bisphenol A(BPA)and sulfamethoxazole(SMX)on hybrid microspheres were investigated.Kinetic and thermodynamic principles were applied to describe adsorption process in depth.Results show:(1)Polyethersulphone embeded modified attapulgite forming into balls.Diameter of five kinds of hybrid microspheres ranged from 2.41 mm to 2.95 mm,and isoelectric point of hybrid microspheres with 2:1 dosing amount was 4.67.With increase of modified attapulgite dosing amount,porosity and total micropore volume of hybrid microspheres decreaseded,while specific surface area gradually increased.(2)Modified attapulgite played a major role in adsorption process,while polyethersulphone played a role of skeleton support embedding modified attapulgite.Under the same dosing amount,amount of BPA adsorbed on hybrid microspheres was higher than SMX,and BPA with lower solubility were preferentially adsorbed in mixed solutions of BPA and SMX.Hybrid microspheres had a better affinity for hydrophobic endocrine disruptors.Increase of pH was beneficial to adsorption of BPA and SMX on hybrid microspheres and had a greater influence on SMX than BPA.Adsorption of anionic endocrine disrupting compounds on hybrid microspheres was more effective than cationic ones.Increase of adsorbent dosage increased adsorption amount of endocrine disrupting compounds on hybrid microspheres,but adsorption amount per gram of adsorben decreased.Increase of initial endocrine disrupting compounds concentration increased adsorption amount of hybrid microspheres.Because of competition relationship between BPA and SMX in mixed solution,adsorption of BPA and SMX on hybrid microspheres in mixed solution had lower capacity for each component than unit system.(3)Adsorption kinetics analysis showed that endocrine disrupting compounds adsorption process of hybrid microspheres was more consistent with pseudo-secondorder kinetics model.Theoretically calculated equilibrium adsorption capacity is similar to the experimentally obtained equilibrium adsorption capacity.Adsorption process could be divided into two phases: Phase I was macroporosity diffusion process,which was completed in about 6 hours,and adsorption proceeded rapidly;Phase II was intragranular diffusion process,which adsorption equilibrium was reached in about 4 days,and adsorption proceeded slowly.Two-stage adsorption had similar removal rates of endocrine disrupting compounds.(4)Adsorption thermodynamic analysis showed that adsorption process of hybrid microspheres in single-component solutions fitted Langmuir adsorption thermodynamic model;adsorption process of hybrid microspheres for each component in mixed solution was consistent with extended Langmuir adsorption thermodynamic model;adsorption process of hybrid microspheres for BPA+SMX in mixed solution fitted Langmuir adsorption thermodynamic model.It showed that BPA and SMX adsorption process were uniform monolayer adsorption on hybrid microspheres surface and contains competitive adsorption.Adsorption process of hybrid microspheres was a spontaneous,exothermal reaction process and mainly physical adsorption.Also,it was preferential and relatively easy to carry out.Adsorption of BPA on hybrid microspheres was an entropy increasing process;adsorption of SMX was a process of entropy reduction;adsorption of BPA and SMX in mixed solution was an entropy increasing process.No matter whether it was in unit system or in binary system,hybrid microspheres for endocrine disrupting compounds have less been influenced by temperature.(5)After the fifth regeneration with ethanol,removal efficiency of endocrine disrupting compounds kept above 95%.Results show that hybrid microspheres had excellent reuse performance. |
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