阳离子对Bt蛋白在矿物表面吸附动力学的影响

Effects of cations on the adsorption kinetics of Bt protein on mineral surfaces

为了探讨金属阳离子对Bt蛋白在矿物表面吸附动力学的影响,选取蒙脱石、高岭石、凹凸棒石和碳酸钙四种不同类型的矿物,在Na^+、K^+、Mg^(2+)、Ca^(2+)添加浓度均为1 mmol·L-1的条件下,采用静态吸附法研究Bt蛋白的吸附动力学特征,并采用一级动力学、二级动力学、内扩散和Elovich四种模型对动力学数据进行拟合,依据相关系数和拟合吸附量对模型优劣进行评价。结果表明,Na^+、K^+、Mg^(2+)、Ca^(2+)均对Bt蛋白的吸附有促进作用,其作用强弱依次为Ca^(2+)>Mg^(2+)>K^+>Na^+。模型分析结果表明:二级动力学模型R2>0.995 1,由拟合模型计算得出的平衡吸附量与实测值吻合,因此适合描述Bt蛋白的吸附动力学特征;Elovich模型R2在0.914 1~0.982 9之间,也能够较好描述矿物对Bt蛋白的吸附特性;一级动力学模型R2在0.710 8~0.987 6之间,相关系数分布范围过宽,且由模型计算得出的平衡吸附量与实测值差异较大,故不适合用于动力学特征描述;内扩散模型相关系数低(R2>0.619 4),不建议在Bt蛋白吸附动力学中使用。

In order to better understand the influence of metal cations on the adsorption kinetics of Bacillus thuringiensis（Bt） protein on mineral surfaces, four types of minerals（montmorillonite, kaolinite, attapulgite, and calcium carbonate）were studied. The concentration of Na^＋, K^＋, Mg^2＋, and Ca^2＋was adjusted to 1 mmol·L^-1, and the adsorption kinetics of Bt protein on the mineral surfaces were investigated using a static adsorption method. The kinetic data were analyzed and fitted to four models（first-order kinetics, second-order kinetics, internal diffusion, and Elovich）, and the models were evaluated using the correlation coefficient and the fitted adsorption capacity. The adsorption of Bt protein was enhanced by Na^＋, K^＋, Mg^2＋, and Ca^2＋, in the following order：Ca2＋Mg2＋K＋Na＋. The second-order kinetic model showed a high correlation coefficient（R20.995 1）, and the quantity of equilibrium adsorption calculated using the model was concordant with measured values. This model was chosen to describe the kinetic characteristics. The R2 value of the Elovich model ranged from 0.914 1 to 0.982 9, indicating that the Elovich model can be used to describe the adsorption kinetics. The R2 value of the first-order kinetic model ranged from0.710 8 to 0.987 6, making it unsuitable to describe the adsorption kinetics, due to the wide distribution of R2 and the large discrepancy between modeled and measured values for adsorption quantities. The internal diffusion model was not recommended to describe the adsorption kinetics of Bt protein due to the low correlation coefficient（R20.619 4）.