Research On The Construction Of Copper-based Mesoporous Nanomaterials, Enzyme-mimicking Catalytic Performance And Application Of Visual Detection Of Aminophenol Pollutio

With the continuous development of modern industry and the rapid increase of population,environmental issues have come into being one of the hot spots in the world nowadays.As a key kind of organic chemical raw materials and intermediates,isomers are widely applied by the chemical industry.However,aminophenols are high toxic,long half-life,difficult to be degraded,and easy to be accumulated in the food chain,which could cause serious damage to the safety of the environment and the health of human beings.Although a series of efficient methods have been reported for monitoring or removal of phenolic or ammonia in the literatures,most of them require expensive instruments and complex manufacturing techniques,which could not meet the requirement for portable,on-site,real-time monitoring of these organic contaminations.It is quite important for us to develop a series of green,convenient,efficient and visual mornitoring methods for aminophenol isomers.With this in mind,a kind of Cu-based mesoporous nanozymes with controllable structure,large specific surface area,superior enzyme-like catalytic activity and high stability were constructed by homogeneous reduction or microwave-assisted hydrothermal self-assembly methods.It was expected that the proposed Cu-based mesoporous nanozymes could be applied for"naked eye"visual detection of aminophenol isomers in practice.The main research contents of this paper are summarized as follows:1.Cu-Zn bimetal oxide mesoporous nanozyme,peroxidase-like activity and catalytic recognition of o-aminophenol:Bimetallic Cu-Zn oxide mesoporous nanospheres(Cu_2/3Zn_1/3O PNPs)were synthesized by one-pot microwave-assisted hydrothermal self-assembly methods using polyvinylpyrrolidone（PVP）as template,Cu（NO₃）₂·3H₂O and Zn（NO₃）₂·6H₂O as raw materials.By virtue of its high specific surface area(34.89 m²·g^-1),uniformly distributed mesoporous structure（6.07 nm）and enough catalytic active sites,Cu_2/3Zn_1/3O PNPs expressed excellent peroxidase activity with synergistic enhancement effect.Under the optimal enzyme-like conditions（p H=3.5,280μL1.5m M TMB,250μL 1.0M H₂O₂,25 ℃）,Cu_2/3Zn_1/3O PNPs could effectively accelerate the oxidation of colorless 3,3’,5,5’-tetramethylbenzidine（TMB）to blue ox TMB.The K_m/V_max for catalyzing the oxidation of TMB is 0.104m M/3.79×10^-8 mol/L·s^-1.Especially,trace o-aminophenol（o-AP）could deteriorate the UV-vis spectrum at 653 nm with obvious hypochromic effect from blue to colorless.When applied for colorimetric detection of o-AP in practice,the linear range was between 0.33～25.0μmol·L^-1with recovery of 96.1～107.2%.The mechanism for improved peroxidase-like activity of Cu_2/3Zn_1/3O PNPs and the one for the recognition of o-AP were investigated in detail.2.Cu-Ru bimetallic alloy mesoporous nanozyme,bifunctional enzyme-like activity and multi-channel monitoring of aminophenol isomers:Cu-Ru bimetallic mesoporous nanoenzyme（Cu-Ru MPNZ）,with specific surface area of 91.22 m²·g^-1and aperture of 4.17 nm,was prepared by homogeneous reduction self-assembly methods,using cationic cetyltrimethylammonium bromide（CTAB）as template.Based on the synergistic effect between mesoporous Cu and Ru,Cu-Ru MPNZ possesses excellent bifunctional enzyme-like activity,i.e.,oxidase mimics and peroxidase mimics.In air atmosphere,Cu-Ru MPNZ could accelerate the oxidation of colorless TMB into blue ox TMB with K_m/V_max of 0.0072 m M/6.33×10^-8 mol/L·s^–1.o-AP could further make blue Cu-Ru MPNZ-TMB into colorless,expressing clear hypochromic effect.When applied for visual detection of o-AP,the LOD was 1.60×10^-8 mol/L（S/N=3）.While in the presence of H₂O₂,Cu-Ru MPNZ can catalyze the oxidation of colorless ABTS to turquoise ox ABTS.The K_m/V_max for its catalyzing the redow of ABTS and H₂O₂ are 0.017 m M/6.47×10^-8mol/L·s^–1 and 3.809 m M/8.23×10^-8 mol/L·s^–1 respectively.Especially,m-aminophenol（m-AP）could exclusively make Cu-Ru MPNZ-ABTS-H₂O₂ changed from blue to green-blue and further to purple-pink,exhibiting strong visibility.When applied for visiual detection of m-AP,the LOD was 3.25×10^-8 mol/L（S/N=3）with recovery of 96.6～102.3%.Cu-Ru MPNZ will act as an efficient sensor for simultaneous monitoring of several analytes.The mechanism for synergistic bifunctional enzyme-like activity of Cu-Ru MPNZ and the ones for selective monitoring of o-AP and m-AP were investigated carefully.3.Cu-Fe bimetal oxide nanozyme,peroxidase-like activity and catalytic recognition of toxic o-AP and bioactive GSH:To further improve the enzyme-like catalytic activity of mesoporous nanomaterials,Cu-Fe bimetal oxide mesoporous nanomaterials（Cu-Fe NPs）were prepared under microwave-assisted conditions at 140 ℃,using polyvinylpyrrolidone（PVP）as template,Cu（NO₃）₂·3H₂O and Fe SO₄·7H₂O as raw materials.Cu-Fe NPs possess large specific surface area of 197.52 m²·g^-1 and mesoporous size of 3.91 nm,which endows Cu-Fe NPs with strong enzyme-like catalytic activity(K_m/V_max=0.011 m M/3.01×10^-8 mol/L·s^-1)and high stability between 20～60 ℃.Importantly,toxic o-AP and bioactive GSH could exclusive make the characteristic UV-vis spectrum deteriorated,accompanying with a color change from blue to colorless.Under the optimal experimental conditions（p H=3.5,0.07 m M TMB,83.33 m M H₂O₂）,Cu-Fe NPs-TMB-H₂O₂ was successfully applied for visual detection of toxic o-AP and bioactive GSH by virtue of the enzyme-like catalytic signal amplification.LODs for toxic o-AP and bioactive GSH were 1.57×10^-8 mol/L（S/N=3）and 3.35×10^-8 mol/L（S/N=3）with recovery of96.8～101.4%and 95.7～105.8%respectively.The mechanism for synergistic enzyme-like activity of Cu-Fe NPs and the ones for selective monitoring of o-AP and m-AP were investigatedin detail.