Adsorption Removal Of Antibiotics By Biochar-DOMs Complex And Its Mechanism

In this study,bagasse and cassava residue wastes were chosen as the raw materials to pyrolysis biochars at different temperatures.The effect of oxytetracycline and sulfamerazine removal efficiency in biochar was explored with adding various dissolved organic matter(DOMs).Chose exogenous gallic acid and humic acid loading,representative of low and high molecular organic matter acid,separately,and endogenous dissolved black carbon extracted from cassava residue biochar for simulating natural situation.In addition,elemental analysis,scanning electron microscopy,pore volume and aperture analysis,Fourier infrared spectroscopy,UV-visible spectrophotometer were used to characterize the structural properties of dissolved organic matter and biochars before and after loaded to clarify the influence mechanism of dissolved organic matter on the adsorption performance of biochar.The purpose of this study is to master the effect and mechanism of different types of dissolved organics in regulating the removal of antibiotic performance of biochar,providing theoretical support and reference for the natural treatment of antibiotics.This paper mainly draws the following conclusions:(1)With the increase of the pyrolysis temperature,both of the ash and alkaline content of bagasse derived biochar increases,more micropore structures and larger specific surface area are developed,the polarity and aromaticity of biomass carbon decreased after carbonization,indicating the enhanced adsorption affinity of bagasse derived biochar to pollutants.Dissolved organic matter changed the micropore structure and surface chemical properties of biomass carbon,and at the same time,it had a great influence on its specific surface area and pore size structure.Loaded macromolecular dissolved organic matter increases the specific surface area of biochar because of the "pore blocking",gallic acid enter the micropore region of biochar and decrease its specific surface area.(2)With the increase of pyrolysis temperature,the total number of functional groups and the intensity of the corresponding infrared absorption peak of the dissolved black carbon showed a decreasing trend;the absorption of ultraviolet light by the dissolved black carbon extracted from cassava residue at different temperatures had high and low absorption band.(3)The adsorption of oxytetracycline by biochar before and after loading of dissolved organic matter includes three stages: rapid adsorption,slow adsorption and equilibrium adsorption.The adsorption of oxytetracycline by biochar performs better with temperature increasing.The kinetic data were fitted to pseudo-second-order kinetic equation.Freundlich and Langmuir models can fit the experimental data well.(4)The adsorption kinetics showed that the adsorption rate of sulfamethazine by biochar was switched before and after adding dissolved black carbon,which reached equilibrium at 24 h.Pseudo-second-order kinetic model and Elovich kinetic model can better describe the adsorption process.(5)The influence of dissolved organic matter on the adsorption performance of biochar wasrestricted by many factors,including the variety,concentration of dissolved black carbon and antibiotic concentration.When the low concentration of sulfamethazine,on the one hand,the adsorption of sulfamethazine by biochar is reduced because of the high hydrophilic energy of dissolved organic matter from carbon source,on the other hand,competitive adsorption with antibiotics was formed;when its concentration is at a high level,the addition of dissolved black carbon improves the adsorption capacity of biochar to sulfamethazine due to co-adsorption.