Synthesis of allophane from rice husk ash and its use as a phosphate adsorbent: A novel approach
Synthesis of allophane from rice husk ash and its use as a phosphate adsorbent: A novel approach
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DOI：
10.1016/j.jece.2022.108634
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发表时间：
2022-09
影响因子：
7.7
通讯作者：
Saki Ohta;Kazuma Yoshida;T. Hongo
中科院分区：
文献类型：
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作者：
Saki Ohta;Kazuma Yoshida;T. Hongo
由于以稻壳为原料的发电厂产生大量稻壳灰，因此有必要开发稻壳灰的回收方法。本研究对缅甸一家稻壳发电厂排放的RHA进行了评价。结果表明，RHA的二氧化硅含量为91.65质量%，在80℃条件下，用1.0 mol/L NaOH溶液可提取92.7%的二氧化硅。通过调整Si萃取液的pH值，成功合成了I型和II型allophanes。ⅰ型和ⅱ型allophanes的BET比表面积分别为334.2和150.2 m2/g。两者在微观和中微观范围内均具有双峰型孔隙结构，其中ⅰ型硅烷在微观区域的孔隙体积要大得多。ⅰ型磷光烷对磷酸盐的吸附速率和吸附容量均高于ⅱ型磷光烷。Langmuir吸附等温线显示，ⅰ型和ⅱ型氧原子的最大吸附量分别为35.1和4.3 mg/g。
There is a need to develop a recycling method for rice husk ash (RHA), as large amount of RHA is generated in rice husk-based power plants. Present study evaluated the RHA discharged from a rice husk-based power plant in Myanmar. It was found that RHA contained 91.65 mass % silica, of which 92.7 % Si could be extracted with 1.0 mol/L NaOH solution at 80 °C. Type I and II allophanes were successfully synthesized by adjusting the pH of the Si extract. The BET specific surface areas of type I and II allophanes were 334.2 and 150.2 m2/g, respectively. Both have bimodal pore structures in the micro- and meso-micro ranges, with the pore volume in the micro region being much larger for type I allophane. Both the adsorption rate and adsorption capacity for phosphate was higher for type I allophane than for type II. Langmuir adsorption isotherms revealed that the maximum adsorption capacities of the type I and type II allophanes were 35.1 and 4.3 mg/g, respectively.