| The rapid development of industrial and agricultural production has resulted in increasingly severe organic and antibiotic pollution in the surrounding environment.The development of new adsorption materials that can quickly and efficiently remove various pollutants is of great significance for repairing environmental pollution and protecting human health.In this study,biochar（C）was used as the substrate,and Fe3O4-loaded magnetized biochar（MC）was prepared by co-precipitation,and then dodecyl dimethyl betaine（BS-12）was used to secondly modify MC for preparing amphoteric-magnetized biochar（BS-MC）.We determined the basic physical and chemical properties of amphoteric-magnetized biochar and analyzed its characteristics such as FTIR,TG,VSM and SEM;studied the isothermal adsorption and thermodynamic characteristics of tetracycline and phenanthrene by MC and BS-MC materials;discussed the effects of pH,ionic strength and temperature on adsorption;revealed the structure-effect relationship between the surface characteristics and adsorption mechanism of amphoteric-magnetized biochar.In order to improve the applicability and pollutant removal ability of BS-MC,Alternanthera philoxeroides was used to prepare biochar（Ap-C）and magnetized biochar（MAp-C）,and bentonite（B）and amphoteric bentonite（BS-B）were loaded on its surface,then the characterization and adsorption performance of the new material amphoteric-magnetized carbon-based clay（BS-MAp-C/B）were discussed,for providing a theoretical basis for the study of adsorption materials to remove organic and antibiotic pollution.The main results were as follows:（1）With the increasing the modification ratio of BS-12,the pH value,CEC and specific surface area of each test material gradually decreased of the BS-MC materials prepared by the co-precipitation method and the wet method.FTIR results confirmed that Fe3O4and BS-12 have been modified to the C surface,and BS-MC had good magnetic separation performance.With the increase of BS-12modification ratio,the thermal combustion weight loss rate of BS-MC material gradually increased.SEM characteristics showed that BS-MC had lower surface roughness,higher particle density and stronger smoothness.（2）The adsorption of tetracycline by C,MC and BS-MC was in line with the Langmuir model,and the order of adsorption capacity was 100%BS-MC>50%BS-MC>25%BS-MC>MC>150%BS-MC>200%BS-MC>C.After C was magnetized and amphiphilically modified,its ability to adsorb tetracycline gradually increased.The adsorption of tetracycline by C,MC and BS-MC all increased with the increase of pH.The increase in temperature was conducive to the adsorption of tetracycline by the material,and the largest adsorption amount of tetracycline for each test material was at 0.1 mol·L-1Na Cl.The adsorption of tetracycline by each test material was a spontaneous endothermic and entropy increasing reaction.The adsorption isotherm of phenanthrene by each test material was suitable to be described by Henry model.The adsorption capacity of each test material on phenanthrene was 25%BS-MC>50%BS-MC>100%BS-MC>C>150%BS-MC>200%BS-MC>MC,the adsorption capacity of phenanthrene decreased with the increasing modification ratio of BS-12.The adsorption of phenanthrene by the test materials had a negative temperature effect,and mainly caused by physical adsorption.The change of pH had no significant effect on its adsorption of phenanthrene.With the increase of ionic strength,the adsorption amount of phenanthrene by each test carbon material first decreased and then increased.The adsorption of phenanthrene by the test materials was a spontaneous exothermic entropy increase physical adsorption process.（3）The Ap-C material prepared at a pyrolysis temperature of 400℃has a smooth surface and a regular pore structure.The surface becomes rough after the material is loaded with Fe3O4.As the modification ratio of BS-12 increased,the smoothness of the surface of BS-MAp-C/B material increased.FTIR results showed that both BS-12 and Fe3O4had been modified to the surface of BS-MAp-C/B,and the magnetized carbon-based clay（MAp-C/B）and BS-MAp-C/B had good magnetic separation performance.（4）The adsorption isotherm of tetracycline on each tested material was suitable to be described by the Langmuir model.The adsorption capacity of each tested material on tetracycline showed 50%BS-MAp-C/B>MAp-C/B>100%BS-MAp-C/B>MAp-C>50%BS-Ap-C/B>Ap-C/B>100%BS-Ap-C/B>Ap-C.The adsorption isotherm of each test material to phenanthrene was suitable to be described by Henry model,and the adsorption capacity of each test material to phenanthrene was shown as 50%BS-MAp-C/B>100%BS-Ap-C/B>100%BS-MAp-C/B>50%BS-Ap-C/B>MAp-C/B>Ap-C/B>Ap-C>MAp-C.The adsorption amount of tetracycline for each tested material decreased with the increase of pH value,and the adsorption of phenanthrene firstly decreased and then increased with the increase of pH value.With the increase of ionic strength,the adsorption amount of tetracycline by the different materials firstly increased and then decreased,whereas the adsorption amount of phenanthrene showed a decreasing trend.The increase of temperature was conducive to the increase of tetracycline adsorption capacity and the decrease of phenanthrene adsorption capacity.The adsorption of tetracycline was a spontaneous,endothermic and entropy-increasing process,and the phenanthrene adsorptoin was a spontaneous,exothermic and entropy-increasing process. |
