苎麻麻骨水溶物的溶出影响因素及其组成

Influencing Factors and Composition of Water Soluble Substances from Ramie Stalks

为探讨生物质材料吸附重金属过程中溶出物的溶出规律及成分,以苎麻麻骨为材料,在实验室模拟其吸附Cd^(2+)废水条件下,考察溶出时间、温度、pH、苎麻麻骨粒径及ρ(Cd^(2+))对苎麻麻骨水溶物DOC溶出量的影响,通过气相色谱-质谱法对溶出物成分进行鉴定,并利用扫描电子显微镜(SEM)、红外光谱(FTIR)、热重分析(TGA)等技术对溶出物溶出前后苎麻麻骨表面物化性质进行了表征.结果表明:在弱酸性(pH为5)条件下,苎麻麻骨DOC溶出量高于65.90 mg/L.各因素对DOC溶出量的影响程度不同,以粒径及温度的影响最大,随着粒径由1 mm增至20 mm,DOC溶出量由78.37 mg/L迅速降至60.14 mg/L,降低了18.23mg/L;升温可促进苎麻麻骨DOC溶出量的增加,随着温度由5℃升至55℃,DOC溶出量增加了13.63 mg/L.提取液pH、溶出时间、ρ(Cd^(2+))对DOC溶出量的增加量分别为5.08、4.60、3.11 mg/L.溶出物溶出前后苎麻麻骨表面无显著变化,但溶出后的苎麻麻骨表面易溶于水的官能团数量显著减少.溶出物中鉴定出9类物质(共19种化合物),以酮类和酯类居多,表明苎麻麻骨表面不带电.

Recycling agricultural waste for environmental heavy metal removal has the advantage of low cost in operation, but its simultaneous leaching of organic content could be an issue of concern. In order to investigate the rules of leaching from ramie stalks during the adsorption process and the composition, a simulated laboratory experiment for adsorbing Cd^2＋ using ramie stalk from aqueous solution was designed. The influences of dissolution time, temperature, pH value, particle sizes of ramie stalk and the concentration of ions on the leaching of organic content were investigated and identified using GC-MS. The surface physical and chemical properties of ramie stalk before and after dissolution were characterized with scanning electron microscopy （SEM）, infrared spectroscopy （FTIR） and thermogravimetric analysis （TGA）. thermo-gravimetric and simultaneous differential thermal analysis （TGA/SDTA）. The results showed that leaching of organic content would be not greater than 65.90 mg/L at the conduction of pH=5.The particle size of ramie stalk and temperature were the two dominant factors controlling the leaching of organic content. The leaching of organic content decreased from 78.37 mg/L to 60.14 mg/L when the particle size increased from 1 mm to 20 mm, while it was promoted as temperature rose, with a total of 13.63 mg/L organic leaching content increasing as temperature increased from 5 ℃ to 55 ℃. The facilitate DOC leaching of other factors such as pH, contacting time, and ρ（Cd^2＋） were 5.08,4.60 and 3.11 mg/L, respectively. FTIR and SEM showed that there was no obvious change on the surface of the ramie stalk, but the content of functional groups on the surface of the ramie stalk was significantly reduced. Nine categories with a total of 19 compounds were analyzed in the dissolutions; most of them were ketones and esters, indicating a neutral charged surface of ramie stalk.