Preparation Of Bamboo Charcoal Solid-Phase Extraction Adsorbent And Their Separation And Enrichment Performances For Typical Environmental Pollutants

Due to the complexity of environmental sample matrix and the low concentration of analytes, pretreatment of samples and preconcentration of analytes are usually involved prior to instrument analysis for accurate measurement. The solid-phase extraction (SPE) is widely used in sample pretreatment field owing to the high enrichment efficiency, low dosage of organic solvent and easy automation. The choice of adsorbent is one of most important influence factors. Bamboo charcoal is a new environmental protection material with large specific surface area, advanced pore structure and excellent adsorption property to the pollutants in wastewater. Hense, bamboo charcoal is selected as the research object and the thesis focused on its application potential in SPE technique. A series of bamboo charcoals with different performance were prepared. Using bamboo charcoal as SPE adsorbent, the analysis methods of typical pollutants in environmental samples were developed. The main results are as follows:The SPE cartridges using bamboo charcoal as stationary phase were prepared to separation and enrichment of brominated flame retardants hexabromocyclododecane diastereomers (HBCDs). The conditions affecting the extraction efficiencies were investigated and optimized in detail, and the method for simultaneous preconcentration and sensitive determination of HBCDs in environmental water samples has been developed. It was based on SPE and rapid resolution liquid chromatography-electrospray tandem mass spectrometry (RRLC-ESI-MS/MS). Under the optimum conditions, experimental data exhibited excellent linear relationships between peak area and concentrations over the range of0.1-10μg·L-1. The limits of detection and precision were in the range of0.005-0.015μg·L-1and4.59-7.47%, respectively. The proposed method has been successfully applied for the trace analysis of HBCDs in real-world environmental water samples, the recoveries of standard addition obtained were in the range of88.5-98.3%.Bamboo charcoal was used as SPE adsorbent in this work as well as the analytical method based on SPE combined with high-performance liquid chromatography-ultraviolet detector (HPLC-UV) was established for simultaneous preconcentration and sensitive determination of estrogens hexestrol, diethylstilbestrol and dienestrol in environmental water samples. Important parameters affecting extraction efficiencies, including eluant and its volume, flow rate, sample pH and volume were investigated and optimized in detail. It indicated that the highest enrichment efficiency was obtained when8mL acetone was selected as eluent, the sample flow rate, pH and volume were4mL-min-1,3and500mL, respectively. Under the optimum conditions, analytical performance parameters of the proposed method were determined. Experimental results showed that the linear ranges were1-100μg·L-1, the limits of detection and precision were in the range of0.03-0.06μg·L-1and4.46-8.65%, respectively. The proposed method has been successfully applied for the trace analysis of these estrogens in real-world environmental water samples with satisfactory results, the the recoveries of standard addition were85.0-97.0%.Three bamboo charcoal samples were prepared by carbonization of Moso bamboo at different temperatures (500,700,900℃). The as-prepared samples were characterized by scanning electron microscopy, nitrogen adsorption-desorption and element analysis. It is found that a large number of micro-/mesoporous in bamboo charcoal surface as well as high surface area. The carbonization temperature has a significant impact on micro structure and composition of bamboo charcoal:with the carbonization temperature increases, BET specific surface areas and pore volume increased significantly as well as the carbon content. Adsorption of Cr(VI) onto the as-prepared bamboo charcoal sample from aqueous was investigated and discussed. The bamboo charcoal samples exhibit excellent adsorption property towards Cr(VI) ions in aqueous solutions and about120min to reach adsorption equilibrium. The adsorption data can better described by Langmuir model and pseudo-second-order equation with maximum monolayer adsorption capacity of38.91mg·g-1. The bamboo charcoal samples are found to be effective adsorbents for the removal of Cr(VI) pollutant from wastewater as a result of its unique porous structure and high specific surface areas. Bamboo charcoal materials are expected to be useful in adsorption and separation areas for removal of pollutants from the wastewater.