Preparation Multiple Color Carbon Dots Fluorescence Probe From Medicine Residues With Abundant Impurity Elements Applied In Environmental Sensing

Utilization of biomass is one of the important approaches to achieve the the carbon peaking and carbon neutrality goal.And converting waste biomass into high added value carbon materials has been attention,which alleviates the shortage of carbon based energy and reduces environmental pollution.It is a feasible approach to develop and select suitable waste biomass into carbon dots(CDs)and its multifunctional composites.In view of the problems of rich production,complex recycling operation and low economic added value of medicine residues,as well as the characterization of low environmental toxicity,abundant impurity elements and rich functional group,CDs was prepared by solvothermal method or hydrothermal method from medicine residues in this study.The prepared CDs and its multifunctional materials were used to sensitively and selectively detect metal ions and organic molecules in aqueous solution by fluorescence response.The main works includes:1.N,Cl doped CDs with multi-fluorescence was prepared by solvothermal method from Ligusticum wallichii and Corydalis residues.In the preparation process,the preparation parameters were optimized including solvent species,reaction temperature,holding time,the mass of o-phenylenediamine and solution pH.The prepared CDs showed blue,yellow and red fluorescence under different excitation wavelength.The triple emission channels of prepared CDs behaved fluorescence response by the mechanism of dynamic quenching for Cr(VI),with linear range of 5-350 μM,250-600 μM and 300-850 μM,respectively.The multi-channels detection expanded the detection range and enhanced the reliability of the sensing results.To visualization,CDs was encapsulated into ZIF-8 and PVA film to form composites,with limit of detection of 0.83 μM and 0.89 μM,respectively.The established detection method was applied into tap water and sludge for sensing Cr(VI),and the recovery was in the range of 93-110%.2.N,S,B doped CDs from Clematis Chinensis Osbeck residues and orange-red CDs were encapsulated into molecularly imprinted polymers forming ratiometric fluorescent probe by sol-gel method.And in the preparation process of N,S,B doped CDs,reaction temperature,reaction time and solute quality were optimized taken relative quantum yield as index.The N,S,B doped CDs was characterized and the successful doping of impurity elements was verified by TEM,FT-IR and XPS.The distribution of pharmacologically active substances and impurity elements in N,S,B doped CDs were analyzed by TOF-SIMS spectra.The detection process was dominated by static quenching and inner filter effect explored by UV-Vis spectra,fluorescence spectrum and fluorescence lifetime.Ratiometric fluorescence probe could sense furazolidone in the range of 5-400 mg/L with limited of detection of 1.98 mg/L.And the selectivity test suggested that the probe had good optical stability and specific recognition sites for structural stability.The composite material was applied to high sensitively and selectively sense furazolidone in common food samples,and the recovery was in 90-109%range.3.Biochar and nitrogen doped CDs were prepared from fermentation residues by simple and green hydrothermal carbonization method to realize the full comprehensive utilization of waste biomass.The obtained biochar had the good absorption capacity,and the maximum iodine value reached to 693.22 mg/g.The relative quantum yield of prepared CDs could reach to 36.17%because the raw material contained many nitrogen elements which was favorable for self-passivation.Considering the outer surface area and permeable pore structure of two dimensional leaf-like ZIF-L,the nitrogen doped CDs was encapsulated into ZIF-L to form a novel fluorescent composite.In addition,this composite material,as an effective probe,was effectively quenched by static quenching and inner filter effect in the presence of tetracycline,doxycycline and chlortetracycline.This fluorescence probe was used to detect tetracyclines in honey and milk,and had satisfied recovery and accuracy suggesting the great application potential in the field of environmental detection and food safety.In this study,CDs was prepared from medicine residues,which avoids the waste of medicine residues,realizes the high value-added utilization of medicine residues,reduces the pollution to environment and decreases the possible harm to body health and animals.This study provides a novel idea for the green,economic and efficient utilization of waste biomass.