Study On Magnetic Molybdenum Disulfide Composite For Analysis Of Benzotriazole Ultraviolet Absorbers In Environmental Water

Objectives Benzotriazole ultraviolet absorbers（BZTs）are widely used in industrial products and personal care products to absorb ultraviolet irradiation from sunlight.The wide application of these compounds may result in the hazardous risk of ecosystem and human health,thereby it is of crucial significance to monitor the exposure level of BZTs in environment water.In this work,a magnetic nanocomposite（MoS₂/Co Fe₂O₄）was synthesized and applied as an adsorbent for the magnetic solid phase extraction.Combined with high performance liquid chromatography-variable wavelength detector,the proposed method was developed for convenient,rapid and effective determination of BZTs in environment water.Methods1 MoS₂/Co Fe₂O₄was fabricated by hydrothermal reaction using Na₂Mo O₄·2H₂O as molybdenum source,C₂H₅NS as sulfur source,and Fe Cl₃·6H₂O and Co Cl₂·6H₂O as magnetic source.The prepared MoS₂/Co Fe₂O₄was characterized by X-ray diffractometry（XRD）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）and vibrating sample magnetometer（VSM）.2 MoS₂/Co Fe₂O₄was applied as adsorbent for MSPE of BZTs in environmental water.The key parameters such as the sorbent amount（10,20,30,40 and 50 mg）,adsorption time（2,4,6,8 and 10 min）,p H value（2.0-12.0）,ionic strength(0,50,100,150 and 200 mmol.L^-1Na Cl),eluting solvent（methanol,acetonitrile,acetone and ethyl acetate）and eluting volume（0.5,1,2 and3 m L）were examined in detail.Moreover,the adsorption kinetics,isotherms and thermodynamics of MoS₂/Co Fe₂O₄were investigated.The analytical figures of merit of the proposed method,including the linear range,limit of detection,limit of quantification,accuracy and precisions were calculated.Results 1 The XRD results confirmed that the diffraction peaks of MoS₂/Co Fe₂O₄were attributed to the MoS₂and Co Fe₂O₄,which indicated the successful combination of MoS₂/Co Fe₂O₄.SEM and TEM images revealed the distinctive flower-like morphology of MoS₂and the presence of well-distributed nanoparticles on the surface of MoS₂.The saturation magnetization value of MoS₂/Co Fe₂O₄was 29.3 emu.g^-1,which indicated the prepared MoS₂/Co Fe₂O₄possessed sufficient magnetic property.2 The prepared MoS₂/Co Fe₂O₄was developed for MSPE of BZTs from environmental water.The adsorption of BZTs was accomplished within 8 min using 40 mg of adsorbent,and 2 m L of ethyl acetate was chosen as elution solvent.MoS₂/Co Fe₂O₄gave the maximum adsorption capacity of 11.4-30.7 mg.g^-1for BZTs.The adsorption process followed the pseudo-second-order kinetics model（R²≥0.958）and Langmuir adsorption models（R²≥0.994）.Furthermore,thermodynamics calculations revealed that adsorption was an endothermic process.Under optimal conditions,the method of MoS₂/Co Fe₂O₄-based MSPE achieved wide linear ranges of 0.08-100 ng.m L^-1with the correlation coefficients higher than 0.9992.The limits of detection（S/N=3）and limits of quantification（S/N=10）ranged 0.023-0.030ng.m L^-1and 0.08-0.10 ng.m L^-1for the analytes,respectively.The recovery of three spiked levels ranged from 80.5%-107%,and the intra-day and inter-day precisions were in the range of 1.1%-6.9%and 2.4%-10.3%,respectively.MSPE of 20 m L sample solution with MoS₂/Co Fe₂O₄gave the enhancement factors of 163.6-193.0.In addition,MoS₂/Co Fe₂O₄could be reused 10 times with the relative standard deviation of recoveries≤11.3%.Conclusions MoS₂/Co Fe₂O₄adsorbent was constructed via hydrothermal reaction and coupled with HPLC-VWD for the analysis of BZTs in environmental water.The established method was accomplished within only 8 min using 40 mg of sorbent.Meanwhile,the enrichment factors of three BZTs were in the range of 163.6-193.0 when20 m L of environmental water sample were loaded.The developed method gave the advantages of convenience and effectiveness,and it not only brought a new dawn for the application of MoS₂/Co Fe₂O₄in the field of the sample pretreatment,but also offered the new ideas for analysis of pollutants in environmental water.Figure 19;Table 10;Reference 143...