米糠不溶性膳食纤维的提取及吸附铅离子探究

为促进米糠资源的综合利用,对米糠不溶性膳食纤维的提取方法及吸附Pb2+特性进行研究。采用酶-化学方法提取脱脂米糠中的不溶性膳食纤维。通过单因素和正交试验对高温淀粉酶添加量、NaOH质量分数、碱解时间和碱解温度对产物提取率和纯度的影响进行研究,确定制备米糠不溶性膳食纤维的较优参数条件。结果显示,在高温淀粉酶添加量0.3%,NaOH质量分数3%,75℃碱解75 min时,所得产物纯度85.74%,得率37.40%。吸附试验结果:提取物在20 mg/L Pb2+水溶液中振荡反应180 min时达到吸附平衡,此时吸附率为96.67%。动力学符合准二级动力学方程,能较好地描述米糠不溶性膳食纤维与Cd2+的结合行为,说明吸附过程存在化学吸附。热力学探究表明:25℃有利于吸附的进行,这一过程是熵驱动、自发进行的,同时吸附Pb2+强度较弱,推测作用力主要是物理吸附。米糠不溶性膳食纤维具有较好的吸附Pb2+能力。本试验为米糠膳食纤维材料的提取条件及其吸附Pb2+特性提供了理论依据。

Studies on the Insoluble Dietary Fiber from Rice Bran Extraction and Adsorption of Lead Ion

In order to promote the comprehensive utilization of rice bran resources, the extraction method and adsorption characteristics of Pb2+of rice bran insoluble dietary fiber were studied. In this paper, enzyme-chemical method was used to extract insoluble dietary fiber from defatted rice bran. The single factor and orthogonal experiments were used to study the effects of high-temperature amylase addition, NaOH mass fraction, alkaline hydrolysis time, and alkaline hydrolysis temperature on the extraction rate and purity of the product, and the optimal preparation parameter of rice bran insoluble dietary fiber was determined. The results showed that when the high-temperature amylase was added at 0.3%, with the 3% NaOH mass fraction and the alkaline hydrolysis at 75 ℃ for 75 min. The purity and yield of the obtained product was 85.74% and 37.40% respectively. Furthermore, adsorption experiments revealed that when the extract was shaken in a 20 mg/L Pb2+aqueous solution for 180 minutes, and the adsorption rate was 96.67%. The kinetics was in line with the pseudo-second-order kinetic equation. It could better describe the binding behavior between rice bran insoluble dietary fiber and Cd2+, and there existed chemical adsorption during the adsorption process. The rmodynamic investigations had found that: 25 ℃ was more conducive to the adsorption process. This process was entropy-driven and spontaneous. At the same time, the adsorption ability of Pb2+was weak, predicting that the applied force was mainly physical adsorption. Therefore, rice bran insoluble dietary fiber had a better ability to adsorb Pb2+. This test provides a theoretical basis for the extraction conditions of rice bran dietary fiber material and its Pb2+adsorption characteristics.