The Migration And Preparation Of TiO₂Nanoparticles From Food Contact Coating Materials

In this paper, we reviewed the development trends and safety researches offood contact nano-materials. Research methods of nano-materials and food contactmaterials were combined to investigate migration of nano-materials, and westudied the migration of TiO₂nanoparticles from food contact coating materials.Commercially available nano-TiO₂powders were chosen as the original powders,the microwave digestion oven （CEM MARS, Matthews, NC, USA） was used in thepretreatment and the ICP-AES was used to detect the amount of migrationnano-TiO₂.TEM analysis was constructed to confirm the presence and morphologyof nano-TiO₂in the migration substance from simulating solution. The resultshowed that nano-TiO₂added in the coating migrated into the simulating solutionand the amount of migration nano-TiO₂was different with the change of the size ofnano-TiO₂powder. The effect of migration time and temperature was evaluated andit demonstrated that the amount of nano-TiO₂as increasing with soaking time andtemperature and the migrated particles preferred to bo aggregate.Firstly, nano-TiO₂was prepared by means of sol-gel method and we get thesize of15nm TiO₂particles after condensation, drying, calcination and X raydiffraction measurement.Secondly, prepared nano-TiO₂coating and proceeded the migration.Microwave digestion oven （CEM MARS, Matthews, NC, USA） was used tomake the TiO₂to Ti ions by means of supply a high-temperature andhigh-pressure environment and ICP-AES （IRIS Advantage, Thermo ElectronCorporation, USA, RF power:1150w; assistor flow rate:0.5L/min; atomizerpressure:27.00psi; pumping speed:100rpm; purge time:90s; flush time:30s）was used to quantify the total amount of Ti ions in the migration solutions. Fourstudies were investigated in this paper:（1） the migration in four kinds of food-simulating solutions. Four food simulating solutions including water, acids,alcohol and oil were employed to study the migration;（2） the migration in thesame noumenon （matrix） of varisized nanomaterials. Four sizes of TiO₂werechosen as the original powders including5nm,10nm,15nm,100nm;（3） themigration in the different noumenon （matrix） including water-based coating,alkyd resin varnish, nitrocellulose varnish and PU polyester primer;（4） themigration in the same noumenon （matrix） of different simulating temperature andtime. Results of ICP-AES tests showed that nano-TiO₂particles can migrate fromfood contact materials to food simulating solution during soaking and themigration amounts are different according to different particle sizes, foodsimulations and soaking condition. It is recognized that ultrapure water giveshigher migration amount compared with other food-simulating solutions; theminimum value was found in5nm while the minimum is10nm and the migrationamount of TiO₂increased with the size of the nano-TiO₂mixed into the coatingswhen the size is more than10nm.; at the same time, the migrate amount ofnano-TiO₂in different media and the amount was observed as increasing withstorage time and temperature.TEM （Transmission electron microscopy, JEM-1011, JEOL, JAPAN,Accelerating potential:100KV） was used to observe the presence and themorphology of nano-TiO₂in the migration solutions. XRD with CuKα radiation（O/MAX-Rc Japan, Target40KV,100mA） was employed to measure the size ofTiO₂origin powders. According to the TEM images of migration substance, themigration size of nano particles prefer to form agglomeration with a range from30nm to50nm in diameter size, which is10times than original size.Finally，I processed the antimicrobial property of nano-TiO₂test and itshowed that the coatings had some antibacterial effects.This was the first research nationwide and around the world about themigration of nano-TiO₂from food contact coating materials includes the amountof migration, the changes of size and the influence of the changes on soakingconditions to observe and study whether it can modify food components when nano-TiO₂was used as antimicrobial.