活性白土是一种常见的无机吸附材料,由膨润土经过酸改性获得。本文采用硫酸作为改性剂,活化改性膨润土制备高吸附活性的活性白土。通过单因素试验确定了活化温度A、活化时间B、酸用量C、液固比D的取值范围,并采用Box-Behnken 响应曲面法设计优化白土制备工艺参数,以大豆油中β-胡萝卜素的吸附率为响应值,分析4种工艺参数对吸附率的影响规律,并预测了最佳的工艺条件。结果表明,建立的吸附率响应曲面模型可靠,可用于活性白土吸附能力优化。活化时间和酸用量对吸附率的影响最大,在所选液固比范围内,液固比对吸附率影响不明显。预测的最佳吸附能力制备条件为: 活化温度92.5 ℃、活化时间5.5 h、酸用量40%(质量分数)、液固比4∶1。该条件下活性白土对β-胡萝卜素的吸附率为97.71%。

Activated bentonite is a kind of inorganic adsorbent material, which is usually prepared by acid modification of bentonite. In this paper, natural bentonite was modified by sulfuric acid to acquire activated bentonite with high adsorption capacity. According to the results of single-factor experiment, the range of values of activation temperature A, activation time B, acid dosage C and liquid-solid ratio D were obtained. The removal rate of β-carotene in soybean oil was considered as the response value, and the Box-Behnken response surface method was used to optimize the adsorption performance of activated bentonite by analyzing the effects of four factors on the removal rate. The results show that the established response surface model is reliable enough to be used for the optimization of the adsorption capacity of activated bentonite. Besides, activation time and acid dosage have the greatest effect on the removal rate. However, liquid-solid ratio has no significant effect on the adsorption rate within the selected range. Finally, the predicted parameters of the optimal adsorption capacity are as follow: activation temperature 92.5 ℃, activation time 5.5 h, acid dosage 40% (mass fraction), liquid-solid ratio 4∶1, and the best adsorption rate of β-carotene can reach 97.71%.