Modified Biochar Adsorption Of Sulfonamide Antibiotics In Water

In recent years,as the classic bacteriostatic and bactericidal drugs,the molecular structure design,preparation technology research and development of antibiotics have been rapidly developed.However,the abuse of these drugs can easily lead to the emergence of super bacteria and harm the health of humans and animals.At present,certain concentrations of antibiotic residues have been detected in many different water bodies.Therefore,the research and development of antibiotic pollution remediation technology in water has important practical significance.Biochar materials have attracted much attention because of their wide range of sources.However,from the structural analysis,the surface functional groups and pore structure of a single biochar material are limited,and its adsorption capacity is difficult to meet the actual requirements.In order to improve the adsorption efficiency of biochar,different ways are usually used to improve the structure of biochar.In this paper,NBC-100,p BC-400 and p BC_(1.0)-400 were prepared by nitric acid oxidation method,H₃PO₄activation method and H₃PO₄-CuCl₂ co-pyrolysis method,respectively.The morphology and structure of the prepared materials were characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),infrared spectroscopy(FTIR)and N2 adsorption desorption curve(BET).Taking sulfonamides antibiotics as the target pollutants,the adsorption properties of the prepared materials to pollutants were studied,the kinetics and thermodynamics of the adsorption process were revealed and the adsorption mechanism was described.The main contents of this paper are as follows:(1)Walnut shell biochar BC was synthesized by pyrolysis method.Carboxylated biochar NBC-X was prepared by solvothermal method with nitric acid as activator,and its structure was characterized.The adsorbents were used for the adsorption of sulfadimethyrimidine(SDZ),sulfadimethyrimidine(SMZ)and sulfachlorpyridazine(SCP).The effects of external conditions on the adsorption process,such as the synthesis temperature,p H value and ionic strength,were investigated.NBC-100material shows the high adsorption performance,and the removal efficiency of SDZ,SMZ and SCP at 20 mg·L^-1 are 64%,92%and 80%,respectively.The kinetics of the adsorption process is consistent with the Elovich model,and the isotherm is consistent with the Freundlich multilayer adsorption.(2)Porous biochar PBC-X was prepared by phosphoric acid pre-activation co-pyrolysis method.The morphology and structure of p BC-X were characterized and they were applied to the adsorption of sulfametacaryl(SAP),sulfamethyldimethyrimidine(SMZ)and sulfamethylchlorpyridazine(SCP).The effects of co-pyrolysis temperature and system p H on the adsorption process were investigated.p BC-400 shows the high adsorption efficiency.For the SAP,SM and SCP at the concentration of 100 mg·L^-1,the adsorption equilibrium was reached in 30 min,and the removal efficiency were 54.82%,91.55%and 96.18%,respectively.The adsorption kinetics was in line with pseudo-secondary chemisorption,SMZ and SCP isotherms were in line with Freundlich model,and SAP was in line with Langmuir model.(3)The porous biochar pBC_(x)-400 was prepared through the H₃PO₄-CuCl₂composite activator.The structure was characterized and then used for adsorption of SAP,SMZ and SCP.The effects of various external conditions on the adsorption process were investigated,and the p BC_(1.0)-400 had the high adsorption efficiency.For100 mg·L^-1 SAP,150 mg·L^-1 SMZ and SCP,the removal efficiency was 65.15%,93.07%and 96.89%,respectively.Adsorption kinetics was in line with pseudo-second-order kinetics,SMZ and SCP adsorption isotherms were in line with Freundlich model,and SAP adsorption isotherms were in line with both Langmuir and Freundlich models.