Preparation And Application Of Cellulose And Nano-Silver Composites

Cellulose is the most widely distributed and abundant natural polymer on the earth,and is the main source of renewable materials in the form of plant fibers.Cellulose is widely used because of its non-toxic,non-polluting,biodegradable,good biocompatibility,easy modification and renewable.Nano-silver is a kind of metallic silver with nanometer particle size,which shows excellent performance in catalysis,biological labeling,cell imaging,antibacterial and other fields.Composites composed of cellulose materials and silver nanoparticles can be used in food packaging,sewage treatment,reaction catalysis,molecular recognition and other fields.In this paper,nano-silver / cellulose composites were constructed based on cellulose pulp and nano-cellulose through new composite strategies,and their applications in antibacterial,molecular recognition and reaction catalysis were explored.The research work is mainly divided into two parts :In the first part,the construction method of silver nanoparticles loaded functional paper was explored,and its antibacterial properties were studied.Firstly,cellulose was modified by graft copolymerization,and poly(methacrylic acid)with stable silver nanoparticles was introduced on its surface.Then,the conditions of silver nanoclusters loaded on grafted cellulose were optimized.Finally,the ratio of cellulose pulp and coniferous wood pulp loaded with silver nanoclusters was optimized,and the influence of papermaking conditions on the silver nanoclusters loaded on the final paper was investigated to study the antibacterial properties of the final paper.The results show that the prepared functional paper loaded with silver nanoclusters has good whiteness.When the pulp content of loaded silver nanoclusters increases from 0 to 40%,the whiteness of the paper decreases from 81.5% to 74.4%,although the whiteness decreases somewhat,At this time,the whiteness of the paper loaded with silver nanoclusters is still good.The tensile index of the paper loaded with silver nanoclusters with a pulp content of 10% reached the maximum value of 39.3 N·m/g.The antibacterial experiments show that the obtained paper has good antibacterial properties,and the diameter of the antibacterial circle of the paper loaded with silver nanocluster pulp with 10% content is 14 mm.In the second part,the method of constructing silver nanoparticles / cellulose nanocrystals(Ag-CNC)composite was explored,and its application in the detection of cysteine and wastewater treatment containing p-nitrophenol was studied.Firstly,cellulose nanocrystals(CNC)were modified by functional groups,and the conditions of loading silver nanoparticles on the surface of CNC were optimized.The ideal composite material of silver nanoparticles and cellulose nanocrystals was obtained,and the material was used to explore the influence of external conditions such as ionic strength on the recognition of cysteine.Explore the selective detection of cysteine.In addition,4-nitrophenol was used as the target pollutant to study the catalytic reduction performance of the synthesized silver nanoparticles and cellulose nanocrystals composite for this pollutant.The results showed that the prepared silver nanoparticles / cellulose nanocrystals(Ag-CNC)composite could be used for colorimetric detection of p-cysteine(Cys),The CNC-Ag-NPs composite can detect cysteine sensitively and selectively within 5 min under the optimal ionic strength provided by NaCl(600 mM).CNC-Ag-NPs have high reducing activity to 4-nitrophenol,and can basically reduce 4-nitrophenol to 4-aminophenol within 12 min,which had great potential in wastewater catalytic treatment.