Mechanism of and relation between the sorption and desorption of nonylphenol on black carbon-inclusive sediment

• Modified two-domain model fits kinetic data of NP desorbed from BC-sediment well.
• NP of partition domain can desorb, but NP of adsorption domain resists desorbing.
• Pore of BC is responsible for the nonlinear adsorption of NP in sediment.
• The release risk of NP from BC-sediment could be predicted by sorption data.
• The study perfects theory of relation between sorption domain and desorption site.

Correlation between the sorption and desorption of nonylphenol (NP) and binary linear regression were conducted to reveal the underlying mechanism of and relation between sorption domains and desorption sites in black carbon (BC)-amended sediment. The sorption and desorption data could be fitted well using dual-mode (R2 = 0.971–0.996) and modified two-domain model (R2 = 0.986–0.995), respectively, and there were good correlations between these two parts of parameters (R2 = 0.884–0.939, P < 0.01). The NP percentage in desorbable fraction was almost equal to that of the partition fraction, suggesting the desorbed NP came from linear partition domain, whereas the resistant desorption NP was segregated in nonlinear adsorption sites, which were dominated by pores in BC-amended sediment. Our investigation refined theory about the relation between sorption domains and desorption sites in sediment and could be used to predict the release risk of NP using sorption data when BC is used for NP pollution control.

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