Black carbon(BC)is a promising sediment amendment,as proven by its considerable adsorp-tion capacity for hydrophobic organic pollutants and accessibility,but its reliability when used for the removal of pollutants in natural sediments still needs to be evaluated.For ex-ample,the ageing process,resulting in changing of surface physicochemical properties of BC,will decrease the adsorption capacity and performance of BC when applied to sediment pollution control.In this study,how the ageing process and BC proportion affect the ad-sorption capacity of BC-sediment systems was modelled and quantitatively investigated to predict their adsorption capacity under different ageing times and BC additions.The results showed that the ageing process decreased the adsorption capacity of both BC-sediment sys-tems,due to the blockage of the non-linear adsorption sites of BC.The adsorption capacity of rice straw black carbon(RC)-sediment systems was higher than that of fly ash black car-bon(FC)-sediment systems,indicating that RC is more efficient than FC for nonylphenol(NP)pollution control in sediment.The newly established model for the prediction of adsorption capacity fits the experimental data appropriately and yields acceptable predictions,espe-cially when based on parameters from the Freundlich model.However,to fully reflect the influence of the ageing process on BC-sediment systems and make more precise predic-tions,it is recommended that future work considering more factors and conditions,such as modelling of the correlation between the adsorption capacity and the pore volume or specific surface area of BC,be applied to build an accurate and sound model.