Adsorption Behavior And Mechanism Of Typical Endocrine-disrupting Compounds And Antibiotics Onto Different Resin

In our country,extensively applications of endocrine-disrupting compounds and antibiotics lead them become emerging polluting sources in many waters,and they are line with increasing environmental risk.Aiming at the typical EDCs and antibiotics,the adsorption behaviors on hyper-crosslinked resins(HP-1,HP-2),aminated resins(MQ-1,MQ-2),were studied in this paper,which could offer theoretical support in treating and recycling emerging pollutants from wastewater.The main study contents were listed as follows:1.Comparison of adsorption of the three phenolic compoundsAmong the four resins,HP-1 presented the largest adsorption capacity of NPEOn(n=10,14,30),and those of NPEOn on the other resins have no obvious difference.The adsorption capacity of NPEOn was larger for surfactants with shorter EO chains than longer EO chains,which indicated that the hydrophobic interactions and steric hindrance played an important role.The results showed that adsorption of NPEOn were dominated by surface area and pore size distribution,and no obvious correlation with the functional groups.The adsorption isotherms of NPEOn fitted the Langmuir and double Langmuir models well.Adsorption dynamics confirmed that the adsorption process involved two plateaus which were attributed to the formation of a monolayer and a bi-layer.Comparing the adsorption of Phenol,Bisphenol A and NPEO10,HP-1 presented the largest adsorption capacity for the three phenolic compounds,indicating that the interactions between the phenolic compounds and the surface of resins,especial microspore surface area and pore size distribution,were the key factors to their adsorption affinity.The adsorption affinity of Bisphenol A was higher than that of phenol and NPEO10,which may be ascribed to its lower value of water solubility and ?-?interaction between Bisphenol A and the resin with benzene rings,so the values of adsorption coefficients Kd was higher.The thermodynamic results showed that the adsorption of Bisphenol A and NPEO10 was thermodynamically favorable and generally endothermic whereas the adsorption process of phenol was exothermic.The adsorption amounts of phenol and Bisphenol A had a similar trend to the function of pH values;the adsorption amounts of NPEO10 remain practically constant within the tested pH range,indicating that there could be different interactions contributing to their adsorption process.2.Adsorption of tetracycline and sulfonamide antibiotics onto the four resinsThe results of static adsorption kinetics showed the adsorption data of tetracycline and sulfonamide antibiotics were fitted to the pseudo-second-order kinetic model by nonlinear regression(R2>0.99),indicating the pore size was the main effect on the adsorption rate.The equilibrium time for mesoporous resin D-lwas the shortest,while the equilibrium time for activated carbon was the longest because of its high microporosity.The equilibrium times for HP-1 and MQ-2 were between those because of their bimodal pore size distribution.The effect of solution chemistry on the adsorption behavior and mechanism had been studied by static adsorption experiments in this paper:(1)the effect of pH:it was found that the higher percentages of neutral species in the solution,the more adsorption amount of tetracycline and sulfonamide antibiotics on the adsorbents,which indicated the contribution of force between the molecules(such as?-?-EDA interaction,hydrophobic effects)was stronger than those between the functional groups on the adsorption process;(2)the effect of ion concentration:adsorption amounts increased with the rise of sodium chloride concentration.This might largely result from the well-known salting out effect and electrostatic interactions.And in this process,the IR spectra of resins showed hydrogen bonding,electrostatic effect and ?-? conjugate made great contribution to the adsorption process;(3)the effect of temperature:adsorption isotherms of antibiotics on resins could be better fitted with Freundlich model(R2>0.99).And the adsorption coefficient(Kd)of D-1 decreased with the rise of temperature,which showed the hydrophobic effect played a main role on the adsorption process.The adsorption amount of those two antibiotics on the HP-1 was largest.It was observed that the high surface area and bimodal pore size distribution of resins appeared to be important for the adsorption of antibiotics.The adsorption capacity of HP-1 was more than that of MQ-2 because of its higher surface area,so the functional groups of MQ-2 were not the main interaction in adsorption process.3.The adsorption of mixed pollutants onto resins prepared in our labBy optimizing the synthesis of a series of amino resin(GD2J,GD3J and GD2Y),and commercial resins(MQ-2,HP-1 and D-1)to adsorb the mixed solution of polyether NPEO10 nonylphenol,bisphenol A,phenol,tetracycline and sulfopyridine in equal molar ratio:The use of non-toxic materials to prepare resin,greatly reduce the pollution caused by the resin synthesis process.Exchange capacity,adsorption amounts and aminating agent dose are proportional.the resin GD2J with the largest specific surface area has the best adsorption performance compared with commercial resin,such as the relatively dispersed functional groups,a maximum initial adsorption rate,the shortest equilibrium time and maximum adsorption capacity.HP-1 has a higher specific surface area,but less surface functional groups,with a relatively high initial adsorption rate,low adsorption capacity.MQ-2,the specific surface area is small,the surface has more amino groups,and its adsorption capacity is slightly higher with the lower initial adsorption rate.D-1 has no advantages in specific surface area,pore size and functional groups,and the adsorption rate and adsorption capacity are the least.Because of its structural advantages,GD2J resin has excellent adsorption performance after multiple adsorption elution cycles.