马家柚柚皮果胶的提取及其吸附Pb(Ⅱ)性能研究

Studies on Preparation of Pectin from Majiayou Pomelo Peel and Its Adsorption Properties on Pb(Ⅱ)

以江西特色马家柚柚皮为原料,采用水提法、盐酸法和柠檬酸法分别提取马家柚柚皮中的果胶,分析果胶的理化性质,并探究不同果胶对Pb(Ⅱ)的吸附性能及吸附机理,明确初始pH值、初始离子浓度、吸附时间等因素对Pb(Ⅱ)吸附率的影响。结果显示,柠檬酸法提果胶(CEP)的提取率最高为28.62%,其次是盐酸法(HEP,12.68%)和水提法(WEP,12.13%)。此外,CEP的酯化度(58.20%)和分子质量(598.40 ku)显著低于WEP和HEP(P<0.05),表明CEP具有较多的羧基和较高的溶解性。3种提取方法得到的果胶吸附Pb(Ⅱ)的最佳pH值为5.0,并在吸附120 min后达到平衡。此外,CEP对Pb(Ⅱ)的吸附率显著高于WEP和HEP。3种提取方法得到的果胶吸附等温线均符合Langmuir单层吸附模型,其吸附动力学均符合拟一级动力学模型,对Pb(Ⅱ)的吸附是物理和化学吸附共同作用的结果。结论:果胶的理化特性及其对Pb(Ⅱ)的吸附能力与提取方法密切相关,其中CEP对Pb(Ⅱ)具有较高的吸附率,可作为低成本、高效、天然环保型的Pb(Ⅱ)吸附剂。

This study aimed to extract pectin from local Majiayou pomelo(Citrus grandis(L.)Osbeck)peel in Jiangxi province with distilled water,hydrochloric acid and citric acid,respectively,and analyze the physicochemical components of pectin and its adsorption properties on Pb(Ⅱ),and explicit the effect of adsorption parameters(initial pH value,initial ion concentration,adsorption time)on Pb(Ⅱ)and its adsorption mechanism by adsorption isotherms and adsorption kinetics.The results showed that the yield of pectin by citric acid extraction(CEP)was highest(28.62%),followed by hydrochloric acid extraction(HEP)and distilled water extraction(WEP).In addition,the esterification degree(58.20%)and molecular weight(598.40 ku)of CEP were significantly lower than those of WEP and HEP(P<0.05),indicating that CEP had more carboxyl and higher solubility.The three pectins showed optimal adsorption of Pb(Ⅱ)at initial pH 5.0,and reached equilibrium after 120 min adsorption.In addition,the adsorption capacity of CEP on Pb(Ⅱ)was significantly higher than that by WEP and HEP.The adsorption isotherms of the three pectins were in accordance with Langmuir monolayer adsorption model,and the adsorption kinetics of the three pectins was consistent with pseudo first-order kinetics model.The adsorptions of three pectins on Pb(Ⅱ)were the result of physical and chemical adsorption.Conclusion:The physicochemical properties of pectin and its adsorption capacity on Pb(Ⅱ)were closely related to the extraction method,and CEP has a high adsorption capacity on Pb(Ⅱ),which could be used as a low-cost,efficient,natural and environmental friendly adsorbent for removal of Pb(Ⅱ).