烟秆生物炭吸附去除水中吡虫啉的研究

Study on adsorptive removal of imidacloprid in water by tobacco stalk biochar

以农业废弃烟秆为原料,通过热解法制备生物炭,研究其对水中典型新烟碱类杀虫剂——吡虫啉(IMI)的吸附去除。结果表明,烟秆生物炭对IMI的吸附效能随烧结温度的升高而增大。900℃烧结2 h的生物炭(BC900)表面含有多种含氧官能团,具有较大的比表面积、丰富的孔隙结构、弱的亲水性和极性,对IMI有最佳的吸附效果,最大理论吸附量为124.87 mg/g;增大BC900投加量以及酸性条件均有利于IMI的吸附,而水中常见阴离子的存在对吸附有抑制作用并遵循以下规律:HCO_(3)^(-)>SO_(4)^(2-)> NO_(3)^(-)> Cl^(-)。BC900对IMI的吸附符合准二级动力学方程,等温吸附曲线符合Freundlich模型。吸附机理包括表面吸附、孔隙填充作用、π-π电子受供体相互作用和氢键作用。

Adsorptive removal of imidacloprid(IMI),a typical neonicotinoid insecticide in water,by biochar 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 temperatures.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 polarity,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 adsorption of IMI,while the existence of the common anions in water inhibited IMI adsorption and abided by the follow rules:HCO_(3)^(-)>SO_(4)^(2-)> NO_(3)^(-)> 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-πelectron donor-acceptor and hydrogen bonding.