Study On Mesoporous Graphitic Carbon Nitride-based Material For Analysis Of Bisphenols From Environmental Water

Objectives Bisphenols,such as bisphenol A and bisphenol F,are main chemicals mainly used in the production of macromolecular materials.The production,application and disposal of bisphenols-containing products lead to the release of bisphenols into environmental water.Considering the endocrine disrupting effect of bisphenols,it is of great significance to clarify the exposure level of bisphenols in environmental water for environmental sanitation and human health.In this study,magnetic mesoporous graphitic carbon nitride（MCN/Co Fe₂O₄）sorbent was firstly synthesized via one-pot facile hydrothermal method and developed for efficient,convenient and rapid analysis of bisphenols in environmental water samples coupled with high perforamce liquid chromatography-variable wavelength detector（HPLC-VWD）.Methods 1 Mesoporous graphitic carbon nitride（MCN）was prepared using hexamethylenetetramine as precursor and SBA-15 as silica template through a hard templating method.Co Cl₂and Fe Cl₃were introduced as the magnetic source to fabricate MCN/Co Fe₂O₄.The obtained MCN/Co Fe₂O₄was characterized by Fourier transform infrared spectrometer,X-ray diffractometer,scanning electron microscopy,field emission electron microscope,N₂adsorption-desorption experiments,and vibrating sample magnetometer.2 MCN/Co Fe₂O₄based magnetic solid-phase extraction coupled with HPLC-VWD was developed for analysis of bisphenols in environmental water samples.Firstly,the amount of mesoporous graphitic carbon nitride（45,60,75 and 90 mg）was investigated.The extraction parameters,including adsorbent amount（10,15,20 and 25mg）,adsorption time（5,10,15 and 20 min）,p H（3,4,5,6,7,8 and 9）and ionic strength(0,25,50,75 and 100 mmol.L^-1Na Cl)of sample solution,elution solvent（acetone,acetonitrile,ethyl acetate and methanol）and elution volume（1 m L×1,1 m L×2,1 m L×3and 1 m L×4）were optimized in detail.Moreover,the adsorption kinetics,isotherms and thermodynamic analysis were also explored to evaluate the adsorption behaviors of MCN/Co Fe₂O₄towards bisphenols.3 To evaluate the analytical performance of the established method for determintaion of bisphenols in environmental water samples,figures of merit in terms of linear range,regression equation,limit of detection,limit of quantification,accuracy,and precisions were evaluated under the optimized experimental conditions.Results 1 The results of Fourier transform infrared spectrometer,X-ray diffractometer proved that the observed representative bands of MCN/Co Fe₂O₄were attributed to the typical signals of MCN and Co Fe₂O₄,indicating the successful fabrication of MCN/Co Fe₂O₄.Scanning electron microscopy and field emission electron microscope images confirmed that MCN/Co Fe₂O₄possessed the mesoporous structure,and Co Fe₂O₄nanoparticles were uniformly formed on the surface of MCN.The surface area of MCN/Co Fe₂O₄was calculated to be 202.5 m².g^-1and the saturation magnetization value was 55.5 emu.g^-1.2 75 mg of MCN was selected as the optimum condition to prepare MCN/Co Fe₂O₄when the molar ratio of the magnetic source was fixed.The synthesized MCN/Co Fe₂O₄was employed as an adsorbent for magnetic solid-phase extraction of bisphenols in environmental water samples.The proposed method was accomplished within only 15 min using 20 mg of adsorbent,and 1 m L×3 of Me OH was used as the optimum elution conditions.Besides,the adsorption of bisphenols on MCN/Co Fe₂O₄followed the pseudo-second-order kinetics（R²0.997-0.999）,the Freundlich model（R²0.990-0.992）,and the adsorption process was spontaneous and exothermic.3 Under the optimized conditions,the method provided good linear ranges of 0.5-300 ng.m L^-1（r≥0.9996）,low limit of detection(0.15-0.2 ng.m L^-1)and limit of quantification(0.5-0.8ng.m L^-1)in lake water samples.The recoveries of the spiked lake water samples varied from 89.3%to 104%,with intra-and inter-day precisions≤9.5%.The corresponding values were 0.6-360 ng.m L^-1（r≥0.9996）,0.2-0.25 ng.m L^-1and 0.6-0.9 ng.m L^-1in tap water samples,respectively.The recoveries of the spiked tap water samples varied 80.5%-95.3%,with intra-and inter-day precisions≤8.0%.Furthermore,the enrichment factors were 120-156 when 15 m L of environmental water sample was loaded.The adsorbent could be reused at least 16 cycles,with the recoveries above 84.5%.Conclusions MCN/Co Fe₂O₄with ordered mesoporous structure was synthesized by one-pot facile hydrothermal method and successfully applied for determination of bisphenols in environmental water samples combined with HPLC-VWD.The adsorption was achieved within only 15 min using 20 mg of adsorbent.The proposed method provided high enrichment factors of 120-156 for bisphenols with the consumption of 15 m L of environmental water samples.The sorbent could be reused at least 16 cycles.The developed strategy exhibited the advantages of convenience and cost-effectiveness,confirming the great potential for analysis of organic pollutants in complicated environmental water.Figure 20;Table 9;Reference 115...