Adsorption And Fluorescence Sensing Of Malachite Green By Nickel Or Zinc Coordination Polymer

Malachite green(MG)is a type of triphenylmethane dye.Because of its low cost and high efficiency,it is widely used to control fungi and parasites in fish and its spawns.However,large amount of dyes in water,not only reduces the quality of water,but also affects the photosynthesis of aquatic plants and animals,thereby affecting ecosystem.In addition,MG will affect the human immune system and reproductive system.Therefore,it is of great significance to develop a material with high adsorption capacity and highly sensitive fluorescence detection for MG.Herein,we designed and synthesized three coordination microporous polymers(CMPs).Based on the molecular characteristics of MG,the three types of CMPs synthesized contain H4BTT ligands with a large number of hydrophilic carboxylic acid groups.H4BTT can provide rich active sites and improve the dispersibility of the three materials in water.The results of Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy proved that the three materials were successfully synthesized.The morphology,thermal stability,specific surface area,and pore size distribution of the three materials were analyzed by means of scanning electron microscope,thermogravimetric analysis,and nitrogen adsorption/desorption.The adsorption isotherm indicates that CMP-2 has a high adsorption capacity for MG,and the maximum adsorption capacity is 6000 mg-1 g.The adsorption of CMP-2 to MG is well suitable with Langmuir isotherm model.,which shows that the adsorption of MG by CMP-2 is a single-layer chemical adsorption on the surface.The experimental results of adsorption kinetics show that the the three materials can reach equilibrium within 230 min.In actual sample adsorption experiments,the removal rates of the three materials for MG in lake water reached 94.4%,93.75%and 96.02%,respectively.In addition,using an excitation wavelength of 272 nm,the three materials exhibited the strongest fluorescence emission at 420 nm.By optimizing the detection conditions,after incubating the three materials for 50 minand 80 min,respectively,the fluorescence intensity difference reached the maximum.There is a good linearity between the fluorescence intensity and the negative logarithm of malachite green concentration.The comparison found that the limit of detection for MG could reach a minimum of 3.77×10-6 ?m.Due to the high adsorption capacity of the three materials for MG,the concentration of the three materials below the limit of detection(2.5 × 10-3ng L-1(CMP-1),7.5 × 10-4ng L-1(CMP-2)and 5.0×10-5ng L-1(CMP-3)),respectively.By enrichment experiments,we found that CMP-2 and CMP-3 had obvious enrichment effects.The results indicate that the three materials are a material with a large adsorption capacity,high-sensitivity fluorescence detection and enrichment detection for MG,it is expected to be widely applied for the quantitative detection of MG in complex samples.