Effect of formation pH, molar ratio and calcination temperature on the synthesis of an anionic clay based adsorbent targeting defluoridation
Effect of formation pH, molar ratio and calcination temperature on the synthesis of an anionic clay based adsorbent targeting defluoridation
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DOI：
10.1016/j.clay.2015.08.026
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发表时间：
2015-11
影响因子：
5.6
通讯作者：
P. Ghosal;A. Gupta;S. Ayoob
中科院分区：
文献类型：
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作者：
P. Ghosal;A. Gupta;S. Ayoob
在不同工艺条件下合成了焙烧钙铝(硝酸钙)LDH阴离子黏土基吸附剂。考察了生成pH、摩尔比、焙烧温度对该吸附剂物化性能的影响。应用响应面方法(RSM)，采用33个因子设计对吸附容量进行了优化。通过X射线衍射仪、红外光谱、能谱分析、扫描电子显微镜和氮气吸附脱附分析对该吸附剂进行了表征。所设计的实验点的吸附容量变化很大(6.4~12.5 mg/g)。X-射线衍射仪结果表明，随着生成pH的增加，LDH材料的结晶度增加。随着pH值和摩尔比的增加，LDH的脱氟能力降低，因为LDH结构中的铝含量与这两个因素呈负相关。在500℃左右的焙烧温度下，LDH对氟的吸附容量最大。通过“记忆效应”从LDH的焙烧产物中重建原始结构可以提高其吸附容量。用朗缪尔等温吸附模型估算的最大吸附容量为108.69 mg/g。
Calcined Ca Al (NO3) LDH, an anionic clay based adsorbent, was synthesized at different process conditions. The influence of formation pH, molar ratio, and calcination temperature on the physicochemical characteristics of this adsorbent was assessed. The response surface methodology (RSM) was applied to optimize the adsorption capacity by employing a 33factorial design. Characterization of the adsorbent was conducted through XRD, FTIR, EDX, SEM and N2adsorption desorption analysis. A significant variation in adsorption capacity (6.4 to 12.5 mg/g) was observed for the experimental points designed. XRD results demonstrated that the increase in formation pH enhances the crystallinity of the LDH material. The defluoridation capacity was observed to decrease with increasing pH or molar ratio, as the aluminum content in LDH structure was found to be inversely correlated with both the factors. The fluoride adsorption capacity was found to attain optima at a calcination temperature of approximately 500°C. The reconstruction of the original structure from the calcined product of LDH through a ‘memory effect’ may enhance its adsorption capacity. The maximum adsorption capacity by the Langmuir isotherm model was estimated to be 108.69 mg/g.