盐酸改性西瓜皮不溶性膳食纤维对亚硝酸盐的吸附作用

Adsorption of Nitrite by Hydrochloric Acid Modified Insoluble Dietary Fiber in Watermelon Peel

以西瓜皮为原料提取不溶性膳食纤维(IDF),并通过HCl改性,对比HCl改性西瓜皮不溶性膳食纤维(HCl-IDF)和未改性IDF对亚硝酸盐的吸附作用,探讨pH值、振荡温度、HCl-IDF添加量、吸附时间、NO-2初始质量浓度对HCl-IDF吸附NO-2的影响。结果表明,经HCl改性后,西瓜皮IDF对NO-2的吸附量提升为原来的2倍;当HCl-IDF添加量为12.5g/L时,去除率为64.6%,并趋于吸附平衡;NO-2初始质量浓度达到40mg/L时,吸附量接近饱和;升高温度、降低pH值、延长吸附时间有利于HCl-IDF对NO-2的吸附,在pH值1.5、温度328K、吸附时间70min时可达吸附平衡;HCl-IDF对NO-2的吸附平衡可以通过Langmuir等温方程拟合,吸附动力学行为符合Langergren准二级动力学模型,该吸附过程以化学吸附为主;HCl-IDF对NO-2的吸附是一个吸热自发反应。

Insoluble dietary fiber(IDF)was extracted from watermelon peel and modified by hydrochloric acid.The adsorptions of nitrite by hydrochloric acid modified insoluble dietary fiber(HCl-IDF)and IDF were evaluated.The effects of pH value,oscillating temperature,HCl-IDF dosage,adsorption time,NO-2 initial concentration on NO-2 adsorption of HCl-IDF were tested.The results showed that the adsorption capacity of NO-2 was doubled after modification.When the addition amount of HCl-IDF was 12.5 g/L,the removal rate was 64.6%and tended to adsorption equilibrium.When the initial concentration of NO-2 was 40 mg/L,the adsorption was close to saturation.Increasing temperature,lowering pH and prolonging adsorption time were beneficial to the adsorption of NO-2 by HCl-IDF,and the adsorption equilibrium was reached at pH 1.5,328 K and 70 min.The adsorption equilibrium of HCl-IDF for NO-2 could be fitted by Langmuir isotherm equation,and the adsorption kinetics conformed to Langergren quasi-second-order kinetic model,which was mainly chemical adsorption.Thermodynamic studies showed that the adsorption of NO-2 by HCl-IDF was an endothermic spontaneous reaction.