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Synthesis, characterization and batch assessment of groundwater fluoride removal capacity of trimetal Mg/Ce/Mn oxide-modified diatomaceous earth
Arabian Journal of Chemistry ( IF 5.3 ) Pub Date : 2020-01-01 , DOI: 10.1016/j.arabjc.2017.01.002
Wilson M. Gitari , Anthony A. Izuagie , Jabulani R. Gumbo

Abstract In this study, trimetal Mg/Ce/Mn oxide-modified diatomaceous earth (DE) was synthesized at optimal conditions. Comparison of the SEM images and the results of EDX analyses of the raw and the modified DE confirmed the surface modification of the raw DE with the trimetal oxide. Groundwater fluoride removal capacity of the sorbent was evaluated by batch method at various defluoridation conditions. At a sorbent dosage of 0.6 g/100 mL (contact time: 60 min, mixing speed of 200 rpm and temperature: 297 K), the fluoride removal was >93% for solutions containing initial fluoride concentration of 10–60 mg/L. Sorbent’s optimum fluoride uptake capacity was 12.63 mg/g at the initial fluoride concentration of 100 mg/L. Fluoride removal was >91% for solutions with initial pH range of ∼4–11 (initial fluoride concentration: 9 mg/L, sorbent dosage: 0.6 g/100 mL). Appraisal of the effect of co-existing anions on fluoride removal showed that CO 3 2− would reduce the amount of fluoride removed from solution, while other anions such as PO 4 3− , NO 3 − and SO 4 2− had no observable effect. K 2 SO 4 solution was found to be most suitable for regeneration of spent Mg/Ce/Mn oxide-modified DE compared to Na 2 CO 3 and NaOH. The mechanism of fluoride removal at pH > 5.45 (pHpzc = 5.45) occurred by exchange of hydroxyl groups on surface of sorbent with fluoride ions from solution. Sorption data fitted better to Langmuir isotherm and pseudo-second-order model. External diffusion was observed to be the sorption rate limiting factor.

中文翻译:

三金属Mg/Ce/Mn氧化物改性硅藻土对地下水除氟能力的合成、表征及批量评价

摘要 本研究在最佳条件下合成了三金属 Mg/Ce/Mn 氧化物改性硅藻土 (DE)。SEM 图像和原始和改性 DE 的 EDX 分析结果的比较证实了原始 DE 与三金属氧化物的表面改性。吸附剂的地下水除氟能力在各种脱氟条件下通过间歇法进行评估。在吸附剂剂量为 0.6 g/100 mL(接触时间:60 分钟,混合速度为 200 rpm 和温度:297 K)时,对于含有 10–60 mg/L 初始氟化物浓度的溶液,氟化物去除率 >93%。在 100 毫克/升的初始氟化物浓度下,吸附剂的最佳氟化物吸收能力为 12.63 毫克/克。对于初始 pH 值范围约为 4-11(初始氟化物浓度:9 毫克/升,吸附剂剂量:0.6 克/100 毫升)。共存阴离子对除氟效果的评价表明,CO 3 2- 会减少溶液中除氟量,而其他阴离子如PO 4 3- 、NO 3 - 和SO 4 2- 则没有明显的影响. 发现与 Na 2 CO 3 和 NaOH 相比,K 2 SO 4 溶液最适合用于废 Mg/Ce/Mn 氧化物改性 DE 的再生。pH > 5.45 (pHpzc = 5.45) 的除氟机制是通过吸附剂表面的羟基与溶液中的氟离子交换而发生的。吸附数据更符合朗缪尔等温线和伪二阶模型。观察到外部扩散是吸附速率限制因素。而其他阴离子如PO 4 3- 、NO 3 - 和SO 4 2- 则没有明显的影响。发现与 Na 2 CO 3 和 NaOH 相比,K 2 SO 4 溶液最适合用于废 Mg/Ce/Mn 氧化物改性 DE 的再生。pH > 5.45 (pHpzc = 5.45) 的除氟机制是通过吸附剂表面的羟基与溶液中的氟离子交换而发生的。吸附数据更符合朗缪尔等温线和伪二阶模型。观察到外部扩散是吸附速率限制因素。而其他阴离子如PO 4 3- 、NO 3 - 和SO 4 2- 则没有明显的影响。发现与 Na 2 CO 3 和 NaOH 相比,K 2 SO 4 溶液最适合用于废 Mg/Ce/Mn 氧化物改性 DE 的再生。pH > 5.45 (pHpzc = 5.45) 的除氟机制是通过吸附剂表面的羟基与溶液中的氟离子交换而发生的。吸附数据更符合朗缪尔等温线和伪二阶模型。观察到外部扩散是吸附速率限制因素。45) 通过吸附剂表面的羟基与溶液中的氟离子交换而发生。吸附数据更符合朗缪尔等温线和伪二阶模型。观察到外部扩散是吸附速率限制因素。45) 通过吸附剂表面的羟基与溶液中的氟离子交换而发生。吸附数据更符合朗缪尔等温线和伪二阶模型。观察到外部扩散是吸附速率限制因素。
更新日期:2020-01-01
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