Abstract
This study focuses on synthesizing pyrolyzed hydrochar from corn stover to adsorb MCLR from aqueous solutions. The underlying hypothesis of this study is that both porosity and surface functional groups play a role in MCLR adsorption. To test the hypothesis, wet waste corn stover was first hydrothermally carbonized (HTC) at 260 ℃ for 30 min to enhance the surface functionality and hydrophobicity. Hydrochars, which are solid products of HTC, were then pyrolyzed at 400, 600, and 800 ℃ for 60 min which enhanced the BET surface area (SBET) from 1.97 ± 0.92 m2/g up to 277.53 ± 7.6 m2/g. Oxygen containing functional groups increase from 833.54 µmol/g up to 1604.24 µmol/g at pyrolysis temperature 400 °C then decrease as low as 211.74 µmol/g with increase in pyrolysis temperatures. Higher SBET (CS-P800) facilitated high uptake of MCLR compared to the other pyrolyzed hydrochars suggesting pore-filling interactions as a possible adsorption mechanism. Adsorption isotherms studies indicated that MCLR follows Freundlich-type adsorption. Fully atomistic simulations showed that MCLR molecules have a propensity to aggregate, which supports the Freundlich adsorption isotherm. Furthermore, atomistic simulations provided insight on MCLR behavior with graphene sheet proving high affinity for adsorption as the molecule conforms to stable configuration in the adsorbed state.
Published Version
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