| In this work,cobalt-gadolinium-modified biochar（Co-Gd-BC）obtained from raw camellia oleifera shells（YC）was prepared via slow pyrolysis in a nitrogen-filled tube furnace.The optimal preparation process of Co-Gd-BC was through by single-factor experiments and response surface experiments,and the characteristics of Co-Gd-BC were analysed with a variety of instruments.Then,the influencing factors,optimal conditions and adsorption mechanism for antibiotic adsorption were investigated.The desorption conditions and regeneration performance were also studied.In addition,Co-Gd-BC was applied to the treatment of aquaculture wastewater.The results are as follows:（1）The optimal conditions for the preparation of Co-Gd-BC were as follows:YC:Co:Gd is 100:5.10:19.65,883℃,5 h,and 10℃/min.When 0.05 g biochar was applied to treat 100 m L simulated wastewater,the CIP removal efficiency was 77.43%.（2）During the preparation process,on the one hand,cobalt nitrate and gadolinium nitrate were doped into biochar in the form of metal oxides,while on the other hand,as pore-forming agents,they promoted the formation of pores in the biochar.The biochar modified with these two modifiers exhibited an interconnected spongy pore structure,which greatly increased the specific surface area and pore volume of Co-Gd-BC,and both parameters were more than twice as large as those of the unmodified biochar prepared under the same conditions.In addition,the-OH group in Co-Gd-BC playd an important role in the CIP and TC adsorption process.（3）CIP and TC adsorption by Co-Gd-BC involved chemisorption.The CIP adsorption rate onto Co-Gd-BC was higher than for TC,so the CIP adsorption process reached the adsorption equilibrium state faster.By comparing the adsorption of these two antibiotics between single-and binary-solute systems,it was found that due to the occurrence of competitive adsorption,the adsorption rate of Co-Gd-BC for the antibiotics in the single system was higher.Moreover,the adsorption capacity of Co-Gd-BC was relatively higher in single-solute system.（4）The CIP adsorption process onto Co-Gd-BC involved homogeneous monolayer adsorption.The adsorption of TC occurred on the heterogeneous surfaces of the adsorbents,and the adsorption process was a multilayer process.The adsorption process of these two antibiotics onto Co-Gd-BC was spontaneous and endothermic.An increase in temperature could increase the adsorption capacity of Co-Gd-BC for these two antibiotics,and the adsorption process was irreversible.（5）The optimal p H value of CIP and TC wastewater treated with Co-Gd-BC was 9.The type and concentration of antibiotics in wastewater affected the optimal adsorption time,Co-Gd-BC dosage and other factors.The effect of inorganic salts on the adsorption of antibiotics was complex.The adsorption capacity of Co-Gd-BC for the antibiotics could be promoted or inhibited by inorganic salts.（6）The optimal desorption temperature and time of Co-Gd-BC after the adsorption of CIP and TC were 629℃and 30 min,respectively.Under these conditions,Co-Gd-BC was desorbed and could be reused.When Co-Gd-BC was recycled for the fifth time,the adsorption capacity of the reused Co-Gd-BC was still higher than 90%of the initial adsorption.（7）The optimal treatment conditions of aquaculture wastewater were as follows:p H is 8,Co-Gd-BC dosage is 12 g/L,and contact time is 5 h.Under these optimal treatment conditions,the removal efficiency of all kinds of antibiotics in wastewater reached 97%,COD and NH4+-N removal efficiency were 81.25%and92.48%,respectively. |
