| Cephalosporin antibiotic is a widely used antibiotic drug,and the pollution leaded by the residue in water environment is very harmful to people’s health and ecosystem.Zeolite imidazole framework materials(ZIFs)have received more attention in adsorption field due to their high physical properties such as high stability and high porosity.At present,a variety of ZIFs materials have been successfully synthesized and widely used,but the pore structure is an important factor limiting the adsorption of macromolecule pollutants.This paper aims to improve the pore structure of ZIFs and load magnetic particles for adsorbing the trace antibiotics in water.In this paper,Hexadecyl trimethyl ammonium Bromide(CTAB)and sodium laurate(SL)were used as template to control the pore size,and the magnetic Fe3O4@＠SiO2 particles were loaded on ZIF-8 to make it magnetic,which was convenient for recycling.In addition,the adsorbent was characterized by various test methods.The test results showed Fe3O4@Si02@ZIF-8 material was successfully synthesized with uniform particle size and high stability.Added template agent would increase the adsorption capacity and increase the pore size of the material from 2.07 nm to 10.01 nm.Magnetic Fe3O4 particles supported on the surface of the adsorbent exhibited strong magnetic.Moreover,the introduction of the templating agent brought lots of functional groups such as O-H,C=O,C=N,N-H,C-N etc.on the surface of the adsorbent promoting the adsorption.The adsorption experiment results showed that the adsorption capacity reached the maximum at 5.17 nm,and almost reached the adsorption equilibrium at 15 min.In addition,the effects of various influencing factors on the adsorption of ceftazidime on Fe3O4@SiO2@ZIF-8 were studied.With increasing the initial pH,temperature and ionic strength,the adsorption capacity increased first and then decreased.The addition of humic acid would reduced the adsorption amount.These three factors including temperature,initial solution pH and ionic strength were optimized by response surface methodology.The adsorption capacity was best when the adsorption conditions were:the adsorption temperature was 294.62 K,the initial pH value was 6.27,the ionic strength was 0.37 g·L-1.The adsorption capacity of 1 mg·L-1 ceftazidime solution reached 96.84 mg·g-1.Multiple regeneration experiments had shown the Fe3O4@SiO2@ZIF-8 has good recycling properties.The utilization rate of five times was still over 90%.At different temperatures,the adsorption accorded with the pseudo-second order kinetics model,and the difference between the adsorption capacity and the actual value was small.The intra-particle diffusion model showed the adsorption process was a multi-step speed control process.And the process better satisfied the Sips isotherm adsorption model,indicating the process was not a single molecule adsorption but a complex mixed adsorption mechanism.Adsorption thermodynamic studies had shown that the adsorption process was spontaneous and exothermic.By establishing QSPR model,analyzing the adsorption data that eight kinds of cephalosporin antibiotics adsorbed by Fe3O4@SiO2@ZIF-8 had shown the adsorption performance was negatively correlated with the relative molecular weight of antibiotics and positively correlated with the polar surface area,molar volume and density. |
