Adsorption And Removal Of Tetracylines In Water Environment By Magnetic Ordered Mesoporous Materials

Tetracycline antibiotics(TC)are a kind of common antibiotic drugs,and their residues in domestic water have caused significant threat to human health and the environment.Ordered mesoporous carbon materials(OMCs)have gradually showing a great advantage in the field of adsorption because of their unique physical and chemical properties.Although there are several preparation methods for mesoporous carbon,tailoring pore size is still a major challenge.In this paper,the effect of adding Dicyandiamide(DCDA)on pore size tailoring during the soft-templating synthesis of mesoporous carbon was studied systematically.Magnetic Fe3O4 particles were supported on the surface of mesoporous carbon to facilitate the repeated recycling.At the same time,the mesoporous carbon materials were characterized by a variety of test methods.The results showed that the addition of DCDA did not destroy the ordered structure of mesoporous carbon materials,and achieved the pore size from 2.98 nm to 9.42 nm.In addition,the magnetic Fe3O4 particles were uniformly supported on the mesoporous carbon surface,exhibiting a strong magnetic response.With the increase of DCDA,a large amount of functional groups(O-H,N-H and C = O)were added at the mesoporous carbon surface,which had a certain effect on adsorption.Secondly,the adsorption properties of minocycline were studied with H-NMC-X as adsorbent.The results showed that the adsorption could reach equilibrium at 10 minutes and pore sizes of 5.89 nm was much more favorable for the adsorption.In addition,the influence of different conditions on the adsorption of minocycline were studied.With the increasing of temperature and pH value of solution,the adsorption of minocycline increased at first and then decreased.The presence of natural organic matter did not have a significant effect on the adsorption results.Furthermore,the adsorption conditions were optimized by the corresponding surface method.The optimum conditions were as follows:the initial pH value was 6.40,the adsorption temperature was 298 K and the ionic strength was 25 g· L-1.At the same time,the circulation experiment also showed that the magnetic mesoporous carbon material had a better circular regenerating property.The adsorption of minocycline on Fe3O4-NMC-1.5 obey the pseudo-first order kinetic model at different temperatures.The maximum adsorption capacity were respectively 120.9 mg·g-1(283 K),207.4 mg·g-1(293 K)and 175.8 mg·g-1(303 K),being similar to the experimental results.The results of the liquid film diffusion and the intra-particle diffusion model indicated that the adsorption was a multi-step process.According to the analysis of isotherm and thermodynamics,the adsorption was spontaneous,endothermic and combined with physical and weak chemical adsorption processes,and can meet the Sips model well.The adsorption of eight kinds of tetracycline antibiotics by mesoporous carbon materials shows that the adsorption was not completely proportional to the molecular weight,but had a certain relationship with the functional groups.