Acid And Cellulase Modification Of Waste Biomass And Its Adsorption Mechanism Of Antibiotics In Micro Polluted Water

On the basis of conclusion in related research at home and abroad,this paper takes a typical antibiotic in micro-polluted water as the research object,and straw which is the abundant and renewable waste biomass during agricultural producing,as adsorbent with non-carbonization modification to study the absorptive removal of typical antibiotic contamination(tylosin)in micro-polluted water.Since straw is mainly composed of cellulose,hemicellulose and lignin,it was modified with strong acid and cellulase according to the modification experience of other papers.In this paper,Fourier infrared spectrometer,transmission scanning electron microscopy were used to characterize the modified straw,and the adsorption effect of tylosin was calculated by high performance liquid chromatography.It was found that the surface structure of the straw was changed after the modification of strong acid,the folds increased,and the functional groups did not change significantly.The adsorption capacity of the modified maize straw(C-MS)in the water was 2201mg/kg,which was 1.5 times of the adsorption amount of unmodified maize straw.The adsorption capacity of the straw with different acids modified followed the order of C-MS(hydrochloric acid)>N-MS(nitric acid)>S-MS(sulfuric acids).More folds and pores were added on the surface of straw after cellulase modification,the functional groups increased,and more active adsorption sites were exposed which was more conducive to adsorption.After 24 h of cellulase modification on corn straw(T-MS),the saturated adsorption amount of tylosin on T-MS is 2109 mg/kg,which was 1.4 times that of MS.The adsorption capacity of T-MS is better than that of cellulase modified rice straw(T-RS,whose adsorption capacity is 1949 mg/kg).The adsorption mechanism was analyzed by adsorption kinetics,adsorption thermodynamics,adsorption isotherm and the effect of pH and ion intensity on adsorption.The adsorption kinetics of the modified straw was well fitted with the Lagrange second-order kinetics model,and the adsorption isotherm was close to the Freundlich model.The adsorption of tylosin on the modified straw was influenced by initial pH and ion intensity,the adsorption decreased with the increase of pH or ion intensity.Since the TYL sorption was an exothermic process according to the adsorption thermodynamics,it's good for the adsorption to improve the solution temperature.It was calculated by thermodynamics that the adsorption of TYL on modified straw was main about chemical sorption such as electrostatic interaction,hydrogen bonding,hydrophobicity and surface complexation,etc.