超声波对粉煤灰提硅的强化效果研究

Enhancement effects of ultrasound on the extraction efficiency of silicon from coal fly ash

针对粉煤灰含有大量硅元素的特点,采用水热-碱溶法进行物质提取,并研究超声技术对粉煤灰提硅效果的影响.在无超声条件下,反应温度由70℃提高到110℃,水热反应90min后粉煤灰提硅效率增加了41.7%.而在110℃下,反应时间由10min增加到90min,提硅效率升高了20.0%.高温下(>100℃),在水热反应前进行超声预处理可以缩短水热反应时间.在45.0%的提硅效率下,超声预处理10min,水热反应时间可由60min缩短到20min.低温下(<100℃),在水热反应过程中同时进行超声处理可以提高提硅效率.在70℃下反应10min,辅助600W超声处理可以使提硅效率由1.9%提高至20.0%.提硅后,脱硅灰比表面积与孔体积明显增大,具有作为廉价吸附材料的潜能.

Silicon is the most abundant element in coal fly ash(CFA).In this study,silicon was extracted from CFA by hydrothermal-alkaline technique and the enhancement effects of ultrasonic techniques was also discussed.Raising temperature from70℃to110℃,the extraction efficiency was increased by41.7%after90min reaction,while at110℃the extraction efficiency was elevated by20.0%after reaction time was extended from10min to90min.Under the condition of90min reaction at110℃,the extraction efficiency reached49.5%.At high temperature(>100℃),ultrasound pre-treatment could shorten the reaction time.When the extraction efficiency was higher than45.0%,the hydrothermal reaction time was shortened from60min to20min by10min pretreatment of ultrasound.At lower temperatures(<100℃),the silicon extraction efficiency was upregulated with simultaneous hydrothermal and ultrasonic treatment.When the ultrasonic treatment power was raised from0to600W,the extraction efficiency was increased from1.9%to20.0%after10min reaction at70℃.The surface area and pore volume of coal fly ash were markedly increased after silicon extraction,which would be benefit for its potential utilization as cheap adsorbents.