IMMOBILIZATION OF NANOSTRUCTURES IN PAPER MATRICES: SYNTHESIS & APPLICATIONS

Abstract

The emergence of antibiotic resistant microbes commonly known as “superbugs” is most threatening in recent times. They can be controlled by treatment in transmission medium using various metal and metal oxides nanostructures. Although, the fungi are not as threatening as the bacteria but few of them are pathogenic to the human. However, they are more pathogenic towards plant. The another major problem, the current generation facing is global warming and related after effects owing to the unprecedented rise in the concentration of greenhouse gases such as CO2. The use of CO2 to synthesize products of industrial importance has taken the center stage in the CO2 utilization research. With the evolution in nanotechnology, metals and metal oxides are being used for both antimicrobial and catalytic activity. One of the major drawbacks of using the nanostructures for the antimicrobial activity is the recovery or separation of the active materials from the waterbodies. The drawbacks of using the ultra-small nanostructures from the reaction mixture is the challenge to separate the nanocatalysts from the reaction medium. In order to overcome these issues, nanostructures could be incorporated or immobilized in various substrates such as glass, ceramic, and paper etc. making nanocomposites that could be removed rather easily from the water bodies after the deactivation. Paper, being a natural biopolymer, bio degradable, cheap, abundant is a very good alternative. In the current research work, hydrothermal method is used for the immobilization of multicomponent system (doped metal oxides) in the paper matrices, i.e., Ag/Ag+ ZnO nanowires and nitrogen doped titania in the paper matrices. Furthermore, a new methodology has been developed that requires very little time as small as only five min for immobilization process that uses the microwave radiation. This ultrafast method of immobilization could save energy and hence is environmental friendly. This ultrafast microwave assisted method has been used for the immobilization of CuO nanoflakes on the paper matrices. Ag/Ag+ ZnO nanowires immobilized paper matrices have shown fantastic antimicrobial activity completely inhibiting the E. coli growth within 2 h of visible light exposure with the initial CFU count of the order of 108 and antifungal activity by desisting the growth of cellulose eating fungus G. trabeum for 7 days. The CuO paper have shown extraordinary antifungal activity by desisting the G. trabeum infection for 28 days. Moreover, CuO paper has shown remarkable activity as a heterogeneous catalyst in conversion of epoxides and CO2 into cyclic carbonates, where synergy has been observed in CuO and hydroxyl group of paper matrices. Here paper not only acted as a substrate, but also as a co-catalyst.