The synergistic effect of CoFe2O4 on the capacity of bio-silica extracted from rice husk for the removal of methylene blue (MB) was investigated. The novel composite of cobalt ferrite/nano bio-silica was prepared by dispersing cobalt and iron salt in ratio 1:2 in a solution containing biosilica, calcined at 700 oC and characterized. The adsorption capacity of the composite (253.6 mg g-1) was higher than that of bio-silica (52.6 mg g-1), and the process was exothermic and spontaneous. Langmuir and Freundlich models were applicable to explain the adsorption isotherm, while pseudo-second order and Elovich are best applicable for the kinetics mechanism. Amount of methylene blue that was removed, increased with an increase in ionic strength due to dimerization of MB. Regeneration and reusability of the adsorbents showed that they are economically viable. EFTEM (Energy-filtered TEM) and FTIR analysis of MB-loaded adsorbent confirmed the adsorption of MB.

中文翻译：

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尖晶石铁氧体对纳米生物二氧化硅去除亚甲基蓝吸附能力的协同作用

研究了 CoFe2O4 对从稻壳中提取的生物二氧化硅去除亚甲基蓝 (MB) 能力的协同作用。通过将钴和铁盐以 1:2 的比例分散在含有生物二氧化硅的溶液中，在 700 oC 下煅烧并进行表征，制备了新型铁酸钴/纳米生物二氧化硅复合材料。复合材料的吸附容量（253.6 mg g-1）高于生物二氧化硅（52.6 mg g-1），并且该过程是放热和自发的。Langmuir 和 Freundlich 模型适用于解释吸附等温线，而伪二级和 Elovich 模型最适用于动力学机制。由于 MB 的二聚化，被去除的亚甲蓝的量随着离子强度的增加而增加。吸附剂的再生和可重复使用性表明它们在经济上是可行的。载有 MB 的吸附剂的 EFTEM（能量过滤 TEM）和 FTIR 分析证实了 MB 的吸附。