特异性吸附黄曲霉素B1的有序磁性介孔二氧化硅设计及吸附机制研究

Processed foods often contain excessive carcinogen aflatoxins(Afs) which contaminate the staple grain species in China because ordinary processing temperature cannot destroy them. In order to solve the problem caused by using of conventional adsorbents and take the adventage of the richness of amorphous silica in rice husk, by taking the adsorption of aflatoxin B1 as an example, we conceive to synthesize a novel functionalized adsorbent named ordered magnetic mesoporous silica (OMMS) which has a specific adsorption effect to aflatoxin B1(AFB1) and can be easily separated from food materials during manufacturing procedure. Its adsorption behavior and adsorption mechanism will also be investigated. The main research contents are as follows: (1) the design and synthesis of OMMS which has a high adsorption potential to AFB1 and its adsorption behavior and adsorption characterization; (2) the method and mechanism of surface post-grafted/coupling modification to the as-synthesized OMMS by using specific adsorption capacity to AFB1 as a index; (3) the desorption behaviour of AFB1 from as-synthesized OMMS or modified OMMS and the reusability of the regenerated adsorbents, and then the decomposition behavior of AFB1 by ozone and the safety of degradation product. Through the systematical investigation of design and synthesis of specific modified OMMS and the adsorption-desorption-regenerate-decomposition mechanism and the exploration of the specific adsoption theory and method of the novel specific adsorbents, a technical prototype and novel material can be provided to remove Afs from food materials during food manufacturing.

因一般加工温度不能破坏我国大宗谷物品种中污染率较高的致癌物黄曲霉毒素(AFs)，加工成品常出现AFs超标现象。针对常用吸附材料缺陷，利用可再生的稻米加工主要副产品稻壳富含无定形二氧化硅的特点，以黄曲霉毒素B1(AFB1)为例，研究具有特异性吸附且在食品加工过程中易分离功能的新型吸附材料（有序磁性介孔二氧化硅，OMMS）及其吸附行为和机理。开展以下研究内容：(1)设计高载量吸附AFB1的OMMS及其吸附行为和吸附特性；(2)以吸附AFB1的特异性为指标，研究接枝耦联改性OMMS的方法及机理；(3)OMMS和改性OMMS的脱附和再生及AFB1臭氧降解行为和降解安全性。通过以上OMMS设计制备及吸附-脱附-再生-降解等机理的系统研究，探索新型吸附材料特异性吸附的理论和方法，为食品加工过程中脱除黄曲霉毒素提供技术原型与材料。

传统AFB1吸附剂具有吸附选择性弱、难分离、降低产品品质、无法重复利用等缺陷，使其难以应用于食品加工体系。本项目以稻壳为原料制备出有序磁性介孔二氧化硅（OMMS）；筛选、优化了改性工艺后获得了对AFB1具有特异性吸附性能的氨丙基改性OMMS材料（N-OMMS）；研究了N-OMMS在水相和花生油中对AFB1的吸附行为和吸附机制，并考察了重复利用效果；最后探索了臭氧降解AFB1的行为和安全性。. 本项目重要成果如下：（1）以脱除率为指标，筛选出对AFB1具有良好吸附能力的N-OMMS材料并优化了改性工艺，并发现AFB1吸附量随着氨丙基接枝率的上升而提高。（2）吸附体系为酸性时，N-OMMS对AFB1的脱除效果不理想，而为中性或弱碱性时，脱除率可达80%以上。（3）N-OMMS对水相中AFB1的吸附量随着温度的上升而增加，升温同时还能提高吸附速率和吸附亲和力。表明升温有利于吸附过程的进行。吸附热力学参数显示吸附是自发进行的吸热过程，二者间主要通过氢键、偶极矩、疏水作用和范德华力发生相互作用。（4）N-OMMS的吸附选择性系数α1/2值高于NovaSil和Ca-MONT，这说明在较复杂的体系中N-OMMS的吸附选择性和特异性要优于其余二者。（5）N-OMMS在花生油中对AFB1的吸附性能同样良好，AFB1的初始浓度为150 ng/mL时脱除率可达88.43±3.34%；当吸附温度从298 K升至318 K时，N-OMMS对AFB1的吸附量增长了6.92%；而温度进一步增加到333 K时，吸附量则急剧下降。（6）甲醇溶液可将几乎所有被吸附的AFB1分子洗脱，在解吸三轮后，N-OMMS对AFB1的脱除率为67.12%，较第一次吸附时下降了9.78%。（7）通过Q-TOF MS推测出臭氧/臭氧水降解AFB1的十种产物分子式和化学结构，并推测出AFB1降解产物的生成途径。（8）AFB1污染的玉米经臭氧处理后，细胞毒性与未添加AFB1的阴性对照组相比，没有显著性差异，AFB1污染的玉米经臭氧处理后细胞毒性显著降低；对昆明鼠的肝脏和肾脏的毒害作用也显著降低。. 通过以上设计、制备、改性、吸附-脱附-再生-降解等机理的系统研究，探索新型吸附材料特异性吸附的理论和方法，为食品加工过程中脱除黄曲霉毒素提供技术原型与材料。