Fabrication Of Titania Nanostructures And Composite Coating On Titanium Fiber Substrate For Solid-phase Microextraction

Solid-phase microextraction(SPME)technology overcomes the defects of traditional sample pretreatment technology.It is an environment-friendly sample pretreatment technology,and has been widely used in many fields due to its characteristics of high efficiency,portable,solvent-free and automation.Extracted fiber with metal substrate has good mechanical strength,chemical stability and thermal stability,and the rapid and convenient coating preparation method has a great advantage over the traditional fused quartz fiber,so it has aroused great interest of many researchers.In this paper,the preparation of two kinds of titanium(Ti)fibers with different coating morphology and titanium/carbon composite coating fibers were studied.At the same time,the preconcentration,separation and determination of different pollutants in actual water samples by the prepared fibers were evaluated.In chapter 1:The background,principle,operating device and preparation method of fiber coating of SPME technology were introduced.Its application field and combined equipment were discussed.The future development of SPME technology was prospected,and the research ideas and experimental assumptions of this paper were introduced.In chapter 2:The electrochemical anodization of titanium wire in the ammonium fluoride glycol solution and the adjustment of the anodization parameters optimize the morphology of the fiber surface,and finally generate oriented titanium dioxide nanostrips(Ti@TiO₂NSs)morphology.The fiber was characterized by scanning electron microscopy(SEM)and energy dispersive X-ray spectroscopy(EDX).The prepared fiber was combined with high performance liquid chromatography-ultraviolet absorption detector(HPLC-UV)to analyze four typical aromatic compounds.The measurement results showed that the aligned titanium dioxide nanostrips(Ti@TiO₂NSs)exhibited adsorption to polycyclic aromatic hydrocarbons(PAHs)and ultraviolet filters(UVFs),but the adsorption efficiency of PAHs was better.Under optimized conditions,the proposed detection method showed a linear in the range of 0.1-200 g·L^-1,and the correlation coefficients(r)were all greater than 0.999.The limit of detection(LODs)of fiber was between 0.027 g·L^-1 and 0.133 g·L^-1,and the limit of quantification(LOQs)was between 0.090 g·L^-1 and 0.433 g·L^-1.The relative standard deviations(RSDs)of single fiber intraday and interday analysis were between 1.33%-3.74%and 2.39%-4.64%,respectively.The RSDs of 5 fibers prepared in batches were between 2.13%and 4.83%.The recoveries obtained by detecting PAHs in real water samples was between 81.20%and 109.7%.After 230 times of extraction and desorption cycles,the extraction efficiency of the prepared fibers was not significantly reduced and the service life of the fibers was good.In chapter 3:The influence of electrolyte composition on the morphology of fibers prepared by anodization was investigated,Ti wires were immersed in the electrolyte composed of ammonium fluoride solution and methanol for reaction.By optimizing the parameters,the in-situ TiO₂ nano octahedrons(Ti@TiO₂NOs)fiber coating was obtained.The extraction efficiency of the prepared fibers was optimized by using four kinds of aromatic analytes as models to be measured.The results showed that Ti@TiO₂NOs fibers could efficiently enrich and detect target PAHs in real water samples.Under optimized conditions,and 7 kinds of PAHs in the linear range of 0.05-200?g·L^-1.The correlation coefficient(r)was between 0.9990 and 0.9998;The recoveries ranged from 93.71%to110.6%.LODs were 0.015 to 0.077?g·L^-1(S/N=3),LOQs were 0.050 to 0.258?g·L^-1(S/N=10).RSDs were below 2.98%and 4.12%for intra-day and inter-day analyses of PAHs at the spiking level of 50?g·L^-1 with the single fiber,respectively.Furthermore,RSDs for 5 fibers prepared in different batches were between 2.17%and 4.08%.The recoveries of real water samples ranged from 90.20%to 109.9%.The service life of the fibers did not change significantly after 230 cycles of extraction and desorption.In chapter 4:The surface of Ti@TiO₂NSs fiber grown in situ orientation,a new type of carbonaceous nanostrips(Ti@TiO₂@CNS)structure was prepared by hydrothermally depositing polyglucose nanoparticles and heat treatment under inert gas protection conditions.After optimizing the conditions,it was prepared into a high-efficiency SPME fiber,using PAHs and UVFs as the detection analytes,and comparing with Ti@TiO₂NSs fiber in the level of extraction efficiency,it is found that Ti@TiO₂@CNS fiber has excellent extraction efficiency.After comparing the extraction efficiency of commercial fiber polydimethylsiloxane(PDMS)and polyacrylate(PA),it was concluded that it showed good extraction performance when measured PAHs.The linearity of the established method under optimized conditions was 0.02-200?g·L^-1,the correlation coefficient was between 0.9995 and 0.9998,LODs were 0.005?g·L^-1 to 0.056?g·L^-1,and LOQs were 0.017?g·L^-1 to 0.185?g·L^-1.The intra-day and inter-day RSDs of the single fiber were 2.06%-3.99%and 2.85%-5.17%,respectively.When produced 5 fibers in the same batch,the RSDs of the fiber-to-fiber reproducibility of the proposed method were2.86%-5.21%.The recoveries of the real water sample were between 83.82%and 117.8%.After a complete extraction performance optimization and actual water sample detection,the extraction efficiency of the fiber does not decrease significantly,and it has a good service life.