Prepartion Of Mesoporous SiO₂-Based Materials And Their Applications In Sample Pretreatment

Mesoporous silica materials have potential applications in the fields of adsorption,catalysis,and biomedical applications due to their unique characteristics of large surface area,tunable pore structure,good biocompatibility,modifiable surface property,good stability and chemical stability.In this paper,monodisperse mesoporous silica nanomaterials?MSNs?,amino-modified mesoporous silica?MSNs-NH₂?,and composites of mesoporous silica and metal-organic framework?MSNs@MIL-101?were prepared and used as dispersive solid phase extraction adsorbent?dSPE?for dyes in environmental water,adsorption of synthetic dyes in foods and plant hormones.The main contents of this thesis are as follows:1.In this work,a highly efficient and rapid method for simultaneously removing cationic dyes from aqueous solution was developed by using monodispersed mesoporous silica nanoparticles?MSNs?as the adsorbents.The MSNs were prepared by a facile one-pot method.The prepared materials showed excellent adsorption performance and the maximum adsorption capacities for the above mentioned cationic dyes in the range of 14.70 to 34.32 mg/g,which could be achieved within 2 to 6 min.The probable adsorption mechanism of MSNs for adsorption of cationic dyes was proposed.It could be considered that the adsorption is mainly controlled by the electrostatic interactions and hydrogen bonding between the cationic dyes and MSNs.As an economical,environmentally friendly,low-cost material,MSNs have a potential application in the wastewater treatment for removing some cationic environmental contaminants.2.In this work,the MSNs materials modified with different groups were prepared,and the adsorption properties of different materials on synthetic dyes were researched.Finally,MSN-NH₂ were selected as the adsorbent of dispersive solid phase extraction?dSPE?for extraction and preconcentration of synthetic dyes from foodstuffs.To achieve optimized extraction efficiency,several factors including amount of MSN-NH₂,sample pH,adsorption and desorption time,adsorption temperature and desorption solvents,were systematically investigated.Then,under the optimized conditions,the enrichment factors were higher than 120.The limits of detection were found to be 0.10-0.30 ng/mL.The method showed excellent linearity in the range of 0.45-1000.0 ng/mL with correlation coefficients?R²??0.9951.The intra-day and inter-day precision?n=5?were 1.72-3.64%and 1.45-4.52%.The recoveries at three concentration levels ranged from 82.7 to 116.3%.The developed method demonstrated a simple,low-cost,high efficiency,and sensitive properties for the analysis of synthetic dyes in different foodstuffs,which provided alternative way for small institutes and factories.3.In this work,a method based on MSN@MIL-101?Fe?composite as adsorbent of dSPE combined with HPLC for the analysis of five plant hormones in plants was established.To achieve optimized extraction efficiency,several factors including sample volume,amount of adsorbent,adsorption time,desorption time and desorption solvents were systematically investigated.Under the optimized conditions,the limits of detection were found to be 0.08-0.45 ng/mL.The method showed excellent linearity in the range of 0.75-200.0 ng/mL with correlation coefficients?R²??0.9968.The intra-day and inter-day precision?n=5?were 1.59%-4.38%and 4.79%-7.27%.Compared with that without MSN@MIL-101?Fe?enrichment,the sensitivity of the develop method can be increase by 144-207 times.The method realize the trace analysis of plant hormones in plants.