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Structural modification of aluminum oxides for removing fluoride in water: crystal forms and metal ion doping
Environmental Technology ( IF 2.2 ) Pub Date : 2021-05-04 , DOI: 10.1080/09593330.2021.1921044
Guomin Jiang 1 , Linfeng Jin 1, 2, 3 , Qinglin Pan 1 , Ning Peng 1, 2, 3 , Yun Meng 2, 3 , Lei Huang 2, 3 , Haiying Wang 2, 3
Affiliation  

ABSTRACT

In this paper, the effect of different crystal forms of Al2O3 on fluoride removal was studied. All crystal forms of Al2O3 were based on the same boehmite precursor and were obtained using a hydrothermal and calcination method. γ-Al2O3 had higher fluoride removal performance (52.15 mg/g) compared with θ-Al2O3 and α-Al2O3. Density functional theory (DFT) calculations confirmed that fluoride removal was greatest for γ-Al2O3, followed by θ-Al2O3 and α-Al2O3, and γ-Al2O3 possessed the strongest fluoride binding energy (–3.93 eV). The typical adsorption behaviour was consistent with the Langmuir model and pseudo-second-order model, indicating chemical and monolayer adsorption. Different metal ions were used to modify γ-Al2O3, and lanthanum had the best effect. Lanthanum oxide was shown to play an important role in fluoride removal. The best La/Al doping ratio was 20 At%. The adsorption process of the composite was also consistent with chemical and monolayer adsorption. When the La/Al doping rate was 20%, the adsorption capacity reached 94.64 mg/g. Compared with γ-Al2O3 (1.39 × 10−7 m/s), the adsorption rate of 20La-Al2O3 was 3.93 × 10−7 m/s according to the mass transfer model. Furthermore, DFT was used to provide insight into the adsorption mechanism, which was mainly driven by electrostatic attraction and ion exchange.



中文翻译:

去除水中氟化物的氧化铝的结构改性:晶型和金属离子掺杂

摘要

本文研究了Al 2 O 3不同晶型对除氟效果的影响。Al 2 O 3的所有晶型均基于相同的勃姆石前体,并使用水热法和煅烧法获得。与θ-Al 2 O 3和α-Al 2 O 3相比, γ - Al 2 O 3具有更高的除氟性能(52.15 mg/g)。密度泛函理论 (DFT) 计算证实γ -Al 2 O 3的氟化物去除率最高,其次是 θ-Al 2 O3和α-Al 2 O 3γ - Al 2 O 3具有最强的氟化物结合能(–3.93 eV)。典型的吸附行为与朗缪尔模型和准二级模型一致,表明化学吸附和单层吸附。使用不同的金属离子修饰γ - Al 2 O 3, 镧的效果最好。氧化镧被证明在氟化物去除中起重要作用。最佳的 La/Al 掺杂比为 20 At%。复合材料的吸附过程也与化学和单层吸附一致。当La/Al掺杂率为20%时,吸附量达到94.64 mg/g。 根据传质模型,与γ -Al 2 O 3 (1.39 × 10 -7  m/s)相比,20La-Al 2 O 3的吸附率为3.93 × 10 -7 m/s。此外,DFT 用于深入了解吸附机制,吸附机制主要由静电吸引和离子交换驱动。

更新日期:2021-05-04
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