Oxygen Scavenging Hybrid Nanostructure: Localization of Different Iron Nanoparticles on Montmorillonite Clays Host

Abstract

According to the great potential of zero-valent iron nanoparticle applications in the environmental, medical, chemical, packaging and many other industries, there is still a need to tailor their production methods. This study reports the production of a hybrid nanostructure based on iron nanoparticles (INPs) produced in/on montmorillonite (MMT) nanoclays as an oxygen scavenger and barrier additive in polymeric packaging materials of oxygen-sensitive products. INPs and MMT were demonstrated to have effective mutual interactions in which the MMT host played a chemophysical trapping role for iron particles, causing smaller particles around 10 nm with 6.2 g/m 2 higher specific surface area by limiting particle growth and agglomeration. In return, the embedding of primary iron cations in/on clays and growth of these particles during the reduction reaction pushed the clay layers out and helped further clay intercalation–exfoliation. Effective study of solvent and primary cation (Fe 2+ /Fe 3+ ) types showed different preferences in interacting with natural and alkylammonium-modified MMT, resulting in the different site selection. Fe 2+ cations preferred to migrate to the interlayer space, whereas Fe 3+ cations tended to bond to the clay surface. The obtained results in this study suggest tailoring the ultimate oxygen scavenging capacity, shelf life, and migration properties of a hybrid nanoparticle according to the application requirements.

Understanding Nanoscale Interactions between Minerals and Microbes: Opportunities for Green Remediation of Contaminated Sites

“…A well-designed microbe−mineral interface greatly boosts the efficacy of microbial remediation, by enhancing the growth and metabolisms, tolerance to environmental stresses, directed migration, and selectivity and electrontransfer capabilities of the microorganisms (Figure 2). Coating microorganisms with mineral nanoparticles (e.g., pH buffers such as carbonates, 72 and O 2 scavengers such as mesoporous silica nanospheres 73 and iron nanoparticles 74 ) can protect them from environmental stresses, helping the microbes better adapt to the local environments, a major technical obstacle of bioremediation, particularly when exogeneous microorganisms are involved. Similarly, tuning the stiffness, 75 porosity, 76 and mass exchange rates 77 of the nanoparticle coating can regulate microbial respiration and gene expression.…”

Iron-Based Oxygen Scavengers on Mesoporous Silica Nanospheres

“…Oxygen scavengers are of significant interest for food packaging applications. − Oxidative degradation is one of the main mechanisms of food spoilage, and it results in undesirable changes in the food, such as the degradation of nutritional content of the food (due to the degradation of essential fatty acids, vitamins, and proteins), the degradation of odor and taste (due to rancidity), and color change (due to pigment degradation) . To reduce spoilage of the food and increase its shelf-life, oxygen scavengers are commonly used in a variety of packaged foods .…”

“…The oxygen scavenging capacity of an iron-based scavenger can be improved if nanoparticles instead of micron-sized particles/conventional iron powder are used. , The nanoparticles also have an advantage of scavenger operation under both wet and dry conditions . Due to the increased surface area, nanosized iron particles enable fast scavenger response and increased adsorption capacity. , To suppress unwanted aggregation of nanoparticles, their preparation on supports such as montmorillonite clay − and kaolinite has also been explored, and integration of zero-valent iron nanoparticles with clay is of significant interest for preparation of improved oxygen barrier materials. − In addition, mesoporous silica nanospheres (MSN) have been explored for oxygen scavenging applications in our previous work …”

“… 4 Due to the increased surface area, nanosized iron particles enable fast scavenger response and increased adsorption capacity. 4 , 5 To suppress unwanted aggregation of nanoparticles, their preparation on supports such as montmorillonite clay 6 − 9 and kaolinite 10 has also been explored, and integration of zero-valent iron nanoparticles with clay is of significant interest for preparation of improved oxygen barrier materials. 6 − 10 In addition, mesoporous silica nanospheres (MSN) have been explored for oxygen scavenging applications in our previous work.…”