Sorption mechanisms of diethyl phthalate by nutshell biochar derived at different pyrolysis temperature

The sorption properties of diethyl phthalate (DEP) by four series of biochar samples produced from apricot shell, coconut shell, peanut shell and walnut shell at 300-800 degrees C were investigated. The morphology, physical structure and chemical composition of biochar were characterized by SEM, N-2 and CO2 adsorption-desorption isotherms, elemental analysis, C-13 NMR, FTIR and TGA, showing that with the increase of pyrolysis temperature, the yield and polarity of biochar decreased, while the aromaticity increased. All the sorption isotherms were fitted by Freundlich model and exhibited highly nonlinear with n ranging from 0.16 to 0.55. Compared with higher-temperature biochar (HBCs, 500-700 degrees C), the lower-temperature biochar (LBCs, <= 400 degrees C) had stronger sorption intensity in each series due to specific interaction (e.g. hydrogen bonding) between the polar functional groups in LBCs (ASBs, WSBs and PSBs) and DEP molecules. Differently, the sorption interactions between HBCs and DEP were mainly driven by the surface adsorption at the energy sites and the 800 degrees C-derived biochars with high specific surface area (415.13-454.17 m(2)/g) were the strongest in the same series. Peanut shell derived-biochar with higher K-oc (C-e=0.1S(w)) values of 358-3670 L/kg had excellent sorption performance, suggesting its promising potential for remediation of DEP in the environment. Capsule: The underlying sorption mechanisms of diethyl phthalate (DEP) by four series of nutshell biochar derived at different pyrolysis temperature (300-800 degrees C) were investigated.

Automated summary

The sorption properties of diethyl phthalate (DEP) by biochar samples derived from different nutshell sources at different pyrolysis temperatures were investigated. The results showed that lower temperature biochar exhibited stronger sorption intensity due to specific interactions between polar functional groups and DEP molecules, while higher temperature biochar had stronger sorption driven by surface adsorption. Peanut shell derived-biochar showed promising potential for remediation of DEP in the environment.