摘要
采用Boehm滴定法量化了低温焚烧稻壳灰表面官能团,考察了溶液初始pH值和温度对吸附效能的影响,借助动力学方程和吸附等温线,研究了稻壳灰对Cr（Ⅵ）的吸附性能,利用红外图谱、扫描电镜表征了稻壳灰的表面形貌和吸附机理。结果表明：在pH值为5时,稻壳灰对Cr（Ⅵ）取得最优去除效果,吸附前后溶液pH值变化很小。稻壳灰对Cr（Ⅵ）有较强的去除能力,对于20 mg.L-1的Cr（Ⅵ）溶液,最高去除率能达到95%左右,达到《污水综合排放标准GB8978—1996》1~2级标准。吸附过程能更好地符合准二级反应动力学方程和Langmuir等温线方程,饱和吸附容量可达3.277 6 mg.g-1。红外光谱表明酰胺Ⅱ带、Si—O—Si、O—Si—O等在Cr（Ⅵ）吸附过程中可能有重要贡献。扫描电镜图片表明吸附Cr（Ⅵ）后,稻壳灰表面分布有众多的光亮沉积物,有条带状或不规则点斑出现,推测无机微沉淀和氧化还原机理在吸附过程中起重要作用。稻壳灰是一种价格低廉、有应用潜力的高效吸附剂,可以用于水体重金属污染的治理修复。
Boehm titration method was used to analyze functional groups on cell surface of rice husk ash burned at low temperature in the present paper.Effects of initial pH value and temperature on Cr（Ⅵ） adsorption were studied,adsorption capacity was tested with the help of kinetic models and adsorption isotherms,instruments of Fourier transform infrared spectroscopy（FTIR） and scanning electron microscope（SEM） were used to check characteristics and adsorption mechanism of Cr（Ⅵ）.The results indicated that optimal removing rate was achieved at initial pH value 5,and pH values of aqueous solution changed little before and after adsorption process.The adsorbent of rice husk ash could remove Cr（Ⅵ） effectively, and the maximum removing rate could be 95% with Cr（Ⅵ） concentration 20 mg·L-1 and achieve 1-2 level of state standard（GB8978—1996）.The adsorption process fits pseudo-second-order kinetic model and Langmuir isotherm better,the maximum adsorption capacity of Cr（Ⅵ） was 3.277 6 mg·g-1.Results of FTIR showed that amide Ⅱ band,Si—O—Si,O—Si—O were important for Cr（Ⅵ） removal.SEM micrographs revealed that series of needle-shaped precipitation appeared on cell surface,and inorganic precipitation mechanism and redox mechanism might work in the test.As a kind of low cost adsorbent,rice husk ash can be applied to remove heavy metals in environment with great potential.
出处
《光谱学与光谱分析》
SCIE
EI
CAS
CSCD
北大核心
2010年第9期2345-2349,共5页
Spectroscopy and Spectral Analysis
基金
黑龙江省科技厅中国-以色列国际合作项目重大专项(WB07N01)
黑龙江省自然科学基金项目(E2007-16)
国家科技支撑计划课题(2009BADC2B00)资助
