Preparation And Research Of Carbon Based Nanomaterials And Its Application In Food Safety And Environmental Monitoring Analysis

Carbon based nanomaterials are one of the most widely researched and applied synthetic nanomaterials.Besides having different electronic,magnetic and optical properties,they possess some key merits including chemical versatility,biocompatibility,ease of modification,and chemical inertness.Therefore,the researchers have sustained interest in the application of carbon based nanomaterials.Carbon based nanomaterials showed huge structural diversity,existing in allotropic forms,such as graphene,diamond,amorphous carbon,C60,and single-walled carbon nanotubes.They can be classified into zero-dimension,one-dimension and two-dimension layer materials by the number of dimensions.In this paper,we focused on the study of two-dimensional layer graphene and zero-dimensional carbon dots,particularly,including the synthesis,characterization and sensing of micro-trace amount of small molecules.The two carbon based nanomaterials,graphene and carbon dots,are used for the detection of multiple synthetic colorants in beverages and Cu2+in water systems,respectively.Section 1.Selective separation and determination of the synthetic colorants in beverages by MSPDE based on Fe3O4/rGO nanocomposite followed by HPLC.Synthetic food colorants have long been used to substitute natural ones for their high stability under processing conditions,relatively lower cost and better performance in optimizing food color,and flavor.Tartrazine,allura red,amaranth,and new coccine are typical synthetic aromatic azo colorants,widely used in food such as beverages,sugar-based and gelatin-based confectioneries.Some of these substances have potential risks to human health including high genotoxicity,cytostaticity,and cytotoxicity,especially when consumed excessively.Therefore,a facile and environmentally friendly pretreatment method is highly required for the separation and enrichment of colorants with high selectivity and sufficient adsorption capacity,since multiple colorants always coexist in complex food matrix.The details of this section are categorized as following:Fe3O4/rGO was synthesized by a one-step in situ process,in which Fe3O4 and rGO were formed simultaneously,and then Fe3O4 was doped into the rGO sheet.The magnetism and adsorbance of Fe3O4/rGO could be easily controlled by adjusting the ratio of Fe3O4 and rGO.Several methods were employed in the characterization of Fe3O4/rGO and GO.The adsorption and desorption characteristics of Fe3O4/rGO towards aromatic compounds were studied.The detection system showed good selectivity,stability and repeatability.Good linearity was achieved in the range of 0.05-10 ?g mL-1,LODs were 10.02,11.90,10.41,15.91 ng mL-1 for tartrazine,allure red,amaranth,and new coccine,respectively(S/N=3).The developed method was used to detect the colorants in beverages,and the recoveries were in the range of 89.0-95.9%with the RSD ?2.7%.Section 2.One-step facile synthesis of novelb-amino alcohol functionalized carbon dots for the fabrication of a selective copper ion sensing interface based on the biuret reaction.Copper ions,the third most abundant transition metal ions except zinc and iron ion in human body,play a critical role not only in electron transfer processes of many biological reactions,but also in the areas of environmental,and chemical systems.Many brain diseases,such as Alzheimer's,Parkinson's disease,are related to Cu2+Due to its non-biodegradability and accumulation in the environment,Cu2+can be toxic at elevated concentrations,although it is an essential micronutrient to aquatic organisms.In recent years,several studies have shown that the level of Cu2+in water is related to oxidative stress in marine cnidarians.What's more,Cu2+is listed as priority pollutant by the U.S.Environmental Protection Agency(EPA)and the limit of it in drinking water set by EPA is 1.3 ppm(-20 ?MOL L-1).Therefore,there is a great demand for a simple,green,reliable and sensitive strategy to qualify and quantify the level of Cu2+presented in the environment and the ecosystem.The details of this section are categorized as following:A facile and one-step hydrothermal carbonization approach has been developed for the first time to synthesize ?-amino alcohol functionalized fluorescent carbon dots(CDs)with L-phenylaninol as the sole precursor source.The added copper ions,not only lead to the specific cross-linked formation of the violet complex with the two ?-amino alcohol unites on the surface of CDs,but also in turn lead to the aggregation of the functionalized CDs and induce fluorescence quenching.Such fluorescence responses can be used for well monitoring copper ions in the range of 0.01-100.05 ?mol L-1 under basic conditions with the LOD as low as 6.15 nmol L-1(S=3?/k).Moreover,the proposed fluorescent sensor can resist the interferences from other metal ions and can be employed for the detection of copper ions in water samples,and the recoveries were in the range of 91.3-101.8%with the RSD<6.0%.