Fluorescence Detection of Pb2+ in Environmental Water Using Biomass Carbon Quantum Dots Modified with Acetamide-Glycolic Acid Deep Eutectic Solvent.

In this study, a novel green fluorescent probe material, nitrogen-doped carbon quantum dots (N-CQDs), was prepared by a one-step hydrothermal synthesis method using walnut green skin as a carbon source and acetamide-glycolic acid deep eutectic solvent (AGADES) as a modifier. By covalent coupling, the amide chromophore in AGADES is designed to cover the surface of walnut green skin carbon quantum dots (W-CQDs), forming a fluorescence energy resonance effect and improving the fluorescence performance of the carbon quantum dots. The prepared N-CQDs have a uniform particle size distribution, and the fluorescence quantum efficiency has increased from 12.5% to 32.5%. Within the concentration range of 0.01~1000 µmol/L of Pb2+, the linear detection limit is 1.55 nmol/L, which can meet the trace detection of Pb2+ in the water environment, and the recycling rate reaches 97%. This method has been successfully applied to the fluorescence detection and reuse of Pb2+ in actual water bodies, providing new ideas and methods for the detection of heavy metal ions in environmental water.

Selective detection of ionic liquid fluorescence probes for visual colorimetry of different metal ions.

At present, the fast distinction of different metal ions in pure water media is not only a great challenge, but also drives the protection of water quality in environmental water bodies. In this paper, a novel ionic liquid fluorescent probe Glycolic Acid-L-Arginine (GA-L-Arg) was rationally created and designed through an in-depth study of ionic liquids. It is also used as an innovative multi-ion fluorescent probe for colorimetric detection and separate identification of Fe3+ and Co2+ in aqueous solutions of various metal ions. GA-L-Arg has excellent water solubility due to the strong hydrophilicity of Glycolic Acid and L-Arginine. The probe showed high sensitivity, extremely significant selectivity, and great pH stability for Fe3+ and Co2+ in pure water. The GA-L-Arg structure and the mechanism of Fe3+ and Co2+ detection were analyzed by infrared spectroscopic characterization and quantum chemical calculations. More importantly, the distinct colorimetric partitioning of Fe3+ and Co2+ was performed by the unique extraction of Fe3+ in the presence of the fluorescent probe and buffer solution.

Physical properties of natural deep eutectic solvent and its application in remediation of heavy metal lead in soil.

At present, solvent extraction is an effective method to remove heavy metals from soil, which has certain practical significance. The physical properties such as density, viscosity and conductivity of NADESs with different proportions synthesized based on the double solid components of glycolic acid (GA) and L-proline (L-PRO) and the physical properties of NADESs aqueous solution at the lowest eutectic point (3:1) were studied. The extraction effect of NADESs on soil heavy metal Pb2+ under different conditions was studied. The results showed that under the conditions of atmospheric pressure of 101.33 kPa, the lowest eutectic melting point, DESs concentration of 0.6 mol·L-1, extraction temperature of 313.15 K and extraction time of 4 h, the extraction rate of Pb2+ by NADESs was 95.28%. In addition, the internal structure of DESs was characterized by IR and NMR, which indicated that intermolecular hydrogen bonds were formed. and the interaction between DESs and Pb2+ was analyzed by quantum chemical calculation, which showed that the hydroxyl group of GA was more likely to form coordination bond with Pb2+, and chelation occurred between them. This kind of DESs provides a new idea for the removal of heavy metals in soil.

Preparation of carbon quantum dots from ionic liquid modified biomass for the detection of Fe3+ and Pd2+ in environmental water.

A new type of green carbon quantum dots (ILB-CQDs) was prepared by hydrothermal method using ionic liquid as a modifier and grape skin as carbon source, and was obtained from hydrogen-bonded lattice structure ionic liquid preparation, which makes the CQDs in a ring-like stable structure with a stability period of more than 90 day. There is also the catalytic effect of the ionic liquid on cellulose, which makes the prepared CQDs show good advantages, such as uniform particle size, high quantum yield (26.7%), and very good fluorescence performance. This is a smart material for the selective detection of Fe3+ and Pd2+. It has a detection limit of 0.001 nM for Fe3+ and 0.23 µM for Pd2+ in pure water. It has a detection limit of 3.2 nmol/L for Fe3+ and 0.36 µmol/L for Pd2+ in actual water, both of which meet the requirements of WHO drinking water standards. And there is to achieve more than 90% of water restoration effect.