Preparation Of Silver-loaded Zeolite And Its Migration In Kraft Paper

Kraft paper, one of paper packaging materials with superior burststrength, good water resistance and rustic appearance, is widely used infood packaging industry. However, the shelf life of kraft paper packagingis often shortened by the contamination of microorganism. Therefore,silver-loaded zeolite antibacterial kraft paper with great antibacterial andantifungal properties was studied in the paper to reduce the deteriorationof food caused by microorganisms. Meanwhile, migration of silver-loadedzeolite from antibacterial kraft paper into distilled water,4%(v/v) aceticacid,65%ethanol, hexane and olive oil were investigated to assure thesafety of antibacterial kraft paper. Main research contents are as follows:(1) Preparation of silver-loaded zeolite antibacterial agent byion-exchanged method. The optimization processes for preparation ofsilver-loaded zeolite are: silver nitrate concentration0.1mol/L, pH value6~8, temperature70℃, time3h and agitating speed300r/min. Theinhibition zone of silver-loaded zeolite to E.coli is21.5mm; MIC reaches0.5mg/mL and antibacterial rate up to100%. Moreover, high levels of Ag+are exchanged into zeolite and the structure of zeolite remains the same bythe characterization of FT-IR, SEM, ED, AAS and TG.(2) Preparation of silver-loaded zeolite antibacterial karft paper bysurface sizing. The antibacterial and antifungal effects of antibacterialkraft papers with different additions of silver-loaded zeolite are analyzed,and the impacts of silver-loaded zeolite with different addition on physicaland mechanical properties, printability of kraft paper, white cardboard andcoated paper are comparatively studied. Kraft papers with goodantibacterial and antifungal effect are obtained and the impacts ofantibacterial agent on the performance of kraft paper, white cardboard andcoated paper are not obvious when the addition of silver-loaded zeolite is0.5g.(3) Analysis on migration of silver-loaded zeolite in antibacterialkraft paper. The migration of antibacterial agent from antibacterial kraftpaper into different food simulants in2h,24h,96h,240h,480h,720h and960h under40℃are detected by AAS, when the addition of silver-loaded zeolite in kraft paper is0.5g. Migration concentration of silver-loadedzeolite is increased with time, and the orders of migrants’ concentrationare:65%ethanol>4%(v/v) acetic acid> distilled water, but silver-loadedzeolite is not found in hexane and olive oil.(4) Establishment of the model on migration of silver-loaded zeolitefrom antibacterial kraft paper. Migration model with finitepackaging-infinite food is established based on the Fick’s law, and theeffective diffusion coefficient and partition coefficient are determined toanalyze the migration of silver-loaded zeolite from antibacterial kraftpaper into distilled water,4%(v/v) acetic acid and65%ethanol effectively.Results show that the migration of silver-loaded zeolite from antibacterialkraft paper can be investigated after240h by the mathematical model.Moreover, migration of silver-loaded zeolite under different effectivediffusion coefficient, paper thickness and time can be predictedimmediately.