Abstract: Modified charcoal (MCC) was made from corn cobs pretreated by NH₃·H₂O and impregnated with  MgCl₂·6H₂O.The morphology and functional groups of MCC was characterized,and its impact on phosphate phosphorus adsorption was investigated.The results showed that MCC had a more porous structure,with a BET surface area of 2.04 times that of pristine biochar.Additionally,MCC had more carbonyl functional groups,and a higher capacity for phosphorus adsorption.When the initial phosphorus concentration was 40 mg/L, the phosphorous adsorption by MCC reached 16.59 mg/g.In simulated adsorption,the ideal adsorption conditions were found to be at pH 6 and 25 °C.When the initial phosphorus concentration is between 0 and 60 mg/L,the adsorption capacity of MCC increases with the increase in phosphorus content.The adsorption process followed the pseudo-secondary kinetic model and the Langmuir and Freundlich models,with both single molecular layer chemical adsorption and multi molecular layer physical adsorption.The theoretical saturation adsorption capacity of 32.60 mg/g demonstrated the potential for phosphorus removal from wastewater.

Key words: biochar, modification, adsorption, phosphorus