Study on adsorptive removal of imidacloprid in water by tobacco stalk biochar
Adsorptive removal of imidacloprid(IMI),a typical neonicotinoid insecticide in water,by bio-char prepared from agriculturally wasted tobacco stalks by pyrolysis was studied.The results showed that the adsorption efficiency of IMI on tobacco stalk biochar increased with the increase of sintering tempera-tures.The biochar(BC900)sintered at 900 ℃ for 2 h owned a variety of oxygen-containing functional groups on its surface,more large specific surface area,rich pore structure,weak hydrophilicity and polari-ty,which had the best adsorption capacity for IMI.Its maximum theoretical adsorption amount was 124.87 mg/g.Moreover,increasing the dosage of BC900 and acidic conditions were benefit to the adsorp-tion of IMI,while the existence of the common anions in water inhibited IMI adsorption and abided by the follow rules:HCO3-＞SO42-＞NO3-＞Cl-.The pseudo-second-order kinetic model and the Freundlich model fitted well with the experimental data.The mechanism of IMI adsorption on BC900 included surface adsorption,pore-filling effect,π-π electron donor-acceptor and hydrogen bonding.
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