| Hexavalent chromium and divalent mercury ions in water are two common heavy metal ions,which are easy to accumulate in the human body and cause diseases such as nervous system damage,hereditary gene defects and cancer.Therefore,it is of great significance to realize the detection and removal of heavy metal ions.At present,the commonly used detection methods mainly include ultraviolet spectrophotometry,inductively coupled plasma detection method,electrochemical method and fluorescent probe detection method.Among them,fluorescent probe detection has attracted much attention due to its advantages of good selectivity,simple operation,and wide response range.As a new type of fluorescent nanomaterials,fluorescent carbon dots have become a research hotspot of fluorescent probes due to their advantages of good stability,simple synthesis,cheap and easy availability of raw materials,and low cytotoxicity.In my country,a large number of textile scraps and waste clothes are discarded,resulting in a lot of waste of resources and environmental pollution.The fluorescent probes based on carbon dots are directly prepared from waste fabrics,which provides high-value utilization of waste textiles.new ideas.On the other hand,the removal of heavy metal ions is mainly based on adsorption,and most of the current research is only limited to single-function detection or adsorption,and it is difficult to realize the integration of adsorption and detection.Based on the above problems,this paper designed several carbon dot fluorescent probes to achieve the selective detection of hexavalent chromium and mercury ions,and composite chitosan non-woven fabrics to realize the detection and adsorption of hexavalent chromium ions.change.The specific research contents are as follows:1.A new type of polyester carbon dots was successfully synthesized by a one-step solvothermal method using waste polyester containing red 167 dye as the carbon source,and it was modified on chitosan non-woven fabrics to obtain a bifunctional material that can detect and efficiently remove hexavalent chromium ions.Compared with pure polyester carbon dots,the bifunctional material exhibited higher selectivity and lower detection limit for hexavalent chromium,with a detection limit of 0.15 mg/L.In addition,the material exhibited fast and efficient removal of hexavalent chromium.The adsorption equilibrium was reached in only 8 min,the maximum adsorption amount was 203 mg/g,and a high relative removal rate（above 90%）was maintained after 5 cycles.The fluorescence detection mechanism of the material for hexavalent chromium was mainly attributed to the fluorescence inner filter effect（IFE）,and the efficient adsorption mechanism was derived from the amino and hydroxyl groups in chitosan.Notably,this bifunctional material has been successfully applied for semi-quantitative detection on a smartphone-integrated device and effectively removes hexavalent chromium from real samples.2.Waste ramie fabric with cellulose as the main component was designed as carbon source,and blue-emitting ramie carbon dots were synthesized by one-step hydrothermal method,realizing the high sensitivity and high selectivity detection of mercury ions.The structure and properties of the carbon dots were analyzed by transmission electron microscopy,infrared and X-ray diffraction tests.The carbon dots have good fluorescence stability and the lowest detection limit for mercury ions is 47.2 n M.In addition,the fluorescent carbon dots prepared from waste cotton fabrics with cellulose as the main component were compared,and the two carbon dots showed similar fluorescence properties and detection performance,but the detection limit of carbon dots prepared by cotton fabric was 61.5 n M,which is higher than the carbon dots prepared from ramie.Importantly,the ramie carbon dots were successfully used for the detection of mercury ions in actual water samples,with recoveries ranging from 98.6% to 103.3%,showing good practicability. |
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