【作者】 刘杨；

【导师】 王双飞；

【作者基本信息】 广西大学 ， 制浆造纸， 2007， 硕士

【摘要】 在食品包装纸的生产过程中，需要加入各种各样的化学品，以改善食品包装纸的包装性能。研究发现，这些化学品会残留在纸张中，进而迁移到食品中，引起食品的污染，影响食品的卫生安全。本文的研究目的是研究食品包装纸中潜在的残留有机物传质到空气中的迁移行为，以预测化学残留物向食品迁移的能力。本文主要研究食品包装纸中的有机物，选用二甲苯作为有机模拟物。另外，选择了7种食品包装纸作为研究纸样。研究内容主要包括两部分：一是分析、测定二甲苯从食品包装纸传质到空气中的分配系数(K_P&B/air)和吸附等温线，即热力学的研究；二是研究二甲苯从食品包装纸传质到空气中的迁移行为，即动力学的研究。为了研究食品包装纸中有机物的迁移行为，本文介绍了一种利用间接顶空气相色谱（HS-GC）技术测定气、固平衡（VSE）分配系数的新方法，分析并测定了二甲苯的VSE分配系数和吸附等温线，完成热力学的研究部分。本文采用多次顶空萃取气相色谱法（MHS-GC）中依时间顺序的多次萃取法，对二甲苯从食品包装纸传质到空气中迁移行为进行动力学研究。研究成果包括：1．设计测定VSE分配系数的新方法——间接HS-GC方法，并用实验数据证实了方法的准确性。间接HS-GC方法是一种快速、自动、精确测定VSE分配系数的方法，是测定VOC的K_P&B/air的简单、可靠的先进方法。2．分析、测定二甲苯从食品包装纸传质到空气中的VSE分配系数，高K_P&B/air值表示二甲苯在食品包装纸中具有显著吸附水平，且K_P&B/air值随着温度的升高而减小。3．二甲苯在不同温度下，从不同食品包装纸样传质到空气中的吸附等温线都呈现典型的朗缪尔曲线趋势，说明食品包装纸对二甲苯的吸附是单分子层吸附。4．检测、分析得到二甲苯从食品包装纸传质到空气中的动力学曲线。二甲苯的传质反应为一级反应，算出40℃、70℃、100℃条件下，动力学速率常数分别为0.0019、0.0031和0.0045；反应活化能为15.8kJ/mol。更多还原

【Abstract】 During the process of pulp and paper making, different types of additives have been added to improve the performance of packaging materials. The studies have found that the packaging materials were a source of contamination through the migration of substances from the packaging into food. The purpose of this work is to study the migration of the potentially hazardous substances from food paper-packaging to the air.Xylene as the standard surrogate of volatile organic compounds is studied in this paper. Five paper samples are chosen. The study contents include two parts. Firstly, the thermodynamics studies, including determinations and analysis of the partition coefficients of vapor-gas phase equilibrium (VSE) of xylene, and drawing the adsorption isotherms. Secondly, the migration study of xylene from paper-packaging to the air, as kinetics studies.For this purpose, it was necessary to develop a new method of analysis for fiber materials. This study reports on an indirect headspace gas chromatographic method (HS-GC) for the study of VSE. The present method can accurately measure a wide range of VSE partitioning coefficients of solutes. The time sequence of the multiple extractions in multiple headspace gas chromatographic (MHE-GC) technique to automate the study of process kinetics that involves volatile species was developed in this paper.A number of main conclusions can be drawn from the paper:1. The indirect HS-GC was developed to study the partition coefficients of VSE. The method is rapid and automated. Therefore, the present method can accurately measure the partition coefficients of VSE.2. High partition coefficient values were generally measured for xylene indicating significant sorption levels into paper-packaging. The partition coefficients of the xylene decrease with increasing temperature, indicating that the use of paper and board samples as food-packaging materials at high temperatures is more risky.3. The adsorption isotherms of the studied compounds onto paper samples are of Longmuir type.4. Real migration curves of xylene from paper-packaging to the air was gained at different temperature. The migration process can be regard as first-order reaction, the energy of activation is 15.8kJ/mol, the reaction speed constant are 0.0019, 0.0013, 0.0045, at 40℃、70℃、100℃, respectively.更多还原