Study On The Adsorption Of Florfenicol In Water By Graphene And Graphene-Polysulfone Adsorption Hybrid Membrane

With the increasing pollution of water by antibiotics,people’s health and the stability of ecosystems are threatened.Adsorption and membrane filtration are research hotspots applied to advanced treatment of high-concentration organic wastewater in recent years.In order to remove the veterinary antibiotic florfenicol in water,the widely used carbon-based adsorbent graphene is used to remove florfenicol in water.The effects of p H,anions,and other antibiotics on the adsorption of florfenicol on graphene were investigated by static adsorption experiments.And the adsorption kinetics and adsorption isotherms were studied.The structure and composition of graphene were analyzed by some material characterization methods to explore the mechanism of its adsorption.However,graphene is in powder form and is prone to agglomeration in water,so graphene must be fixed on the carrier.Combining adsorption and membrane filtration,using polysulfone as the organic phase,a graphene-polysulfone adsorption hybrid membrane with simple,high stability and high adsorption capacity was prepared by the simplest blending method.Dynamic filtration removal of florfenicol in water by adsorption hybrid membrane.The main results of the study are as follows:The adsorption effect of graphene on florfenicol was better in the p H range of 2-8.When the p H was greater than 9,the adsorption capacity was greatly reduced due to the existence of electrostatic repulsion.The florfenicol adsorption was not affected by anions such as SO₄^2-and Si O₃^2-,while Cl^-can slightly inhibit the adsorption on graphene.All three antibiotics had a certain influence on the adsorption.And the same class of antibiotics of florfenicol had a greater effect on adsorption.The degree of influence was chloramphenicol>lincomycin hydrochloride>ampicillin.The kinetics confirmed to the pseudo-first-order kinetic model,and the adsorption process may be dominated by physical adsorption.The adsorption rate was extremely fast in the first three minutes,then continued to adsorb slowly,and finally reached the adsorption equilibrium in 10min.The q_e calculated by the pseudo-first-order model was 7.68 mg/g.Langmuir model can well describe florfenicol adsorption on graphene.The maximum adsorption capacity was 12.10 mg/g,which was the upstream level among other reported adsorbents.Graphene can be recycled and regenerated after adsorbing florfenicol.After five regeneration cycles,the total regeneration rate can still reach more than 55%.Through a series of characterizations by SEM,EDS,FTIR and XPS,graphene had serious agglomeration,which can affect the adsorption capacity.At the same time,it was found that the graphene surface contains a small amount of organic oxygen-containing groups,which was beneficial to adsorption.In the study of the adsorption mechanism of florfenicol on graphene,it was found that the main adsorption mechanisms were intermolecular attraction,π-πinteraction and hydrogen bonding.The graphene-polysulfone adsorption hybrid membranes were prepared by blending method.Aiming at the pure water flux,the thickness of the pure polysulfone membrane was optimized to be 200μm,and the basic components were determined to be 14 wt%polysulfone,85.5 wt%DMAc,0.5 wt%PVP.Four kinds of graphene-polysulfone adsorption hybrid membranes were successfully prepared,which were M0.05,M0.1,M0.2 and M0.5,respectively.Through FTIR,SEM,and EDS analysis of M0.2,the adsorption hybrid membrane can be uniformly scraped,mainly composed of a dense layer and a porous layer.As the amount of graphene added increases within a certain range,the porosity of the membranes increased from 40.76%to 49.09%,and the average pore size increased from 32.2 nm to 35.9 nm.When too much graphene was added,there was a downward trend.M0.05,M0.1,M0.2 and M0.5 all showed a certain adsorption capacity for florfenicol.And the more graphene added,the stronger the adsorption capacity.Comprehensive the pure water flux and the adsorption capacity,M0.2 was the best.The p H had little effect on the adsorption of florfenicol by the hybrid membrane under acidic and neutral conditions.The adsorption kinetics showed that the first 5 min was a fast adsorption stage,followed by a slow adsorption,and finally reached the adsorption equilibrium at about 20 min.The pseudo-first-order kinetic model and the Langmuir model were more in line with the adsorption process,and the calculated theoretical maximum adsorption capacity was 1.72 mg/g.The adsorption hybrid membrane had better regeneration ability.After five regenerations,the total regeneration rate reached68%,which was 13%higher than that of graphene.The continuous ultrafiltration experiment of low-concentration florfenicol was carried out by using the adsorption hybrid membrane.When the feed concentration was 10μg/L,the operating pressure was 0.1 MPa,and the maximum pollution level was 5μg/L,the processing capacity of M0.2 was about 127.39 L/m².