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Effects of particle size and mineral crystallinity on formation of Zn Al layered double hydroxides (LDH) on aluminum (oxyhydr)oxides
Applied Clay Science ( IF 5.6 ) Pub Date : 2021-02-01 , DOI: 10.1016/j.clay.2020.105933
Biao Wan , Xinran Liang , Zhen Hu , Yupeng Yan , Wenfeng Tan , Xionghan Feng

Abstract The widespread usage of zinc oxide nanoparticles (ZnO NPs) inevitably leads to its release in nature and interaction with environmental minerals. To reveal ZnO NP retention by natural aluminum (Al) minerals as layered double hydroxide (LDH) in the environments, the effects of Al (oxyhydr)oxide particle size and crystallinity on Zn Al LDH formation were investigated during ZnO NP interaction with seven different Al (oxyhydr)oxides at neutral and alkaline pHs. Dissolution kinetics displayed a decrease of dissolved Zn2+ and Al(OH)4− concentrations in a dual-solid system (ZnO and Al minerals) relative to a single-solid one (ZnO or Al minerals), suggesting a potential transformation of mixture solids. Diffraction, spectroscopic, and microscopic analyses indicated that Al (oxyhydr)oxide particle size and crystallinity had obviously impacted on Zn Al LDH formation. The composition percentage of Zn Al LDH in solid products followed the order of amorphous Al hydroxides (89.90% and 86.41% Zn species as Zn Al LDH at pH 7 and 10, respectively) > 5 nm γ-Al2O3 (41.62% and 49.62%) > 35 nm γ-Al2O3 (14.77% and 19.03%) > large size Al (oxyhydr)oxides (below 13.00%), including 70 nm γ-Al2O3, corundum, boehmite, and gibbsite. Zn Al LDH formation was regulated mainly by Al (oxyhyro)oxide crystallinity and particle size via changing Al oxide dissolution at pH 10 and Zn2+ adsorption at pH 7, whereas solution pH controlled the crystallinity of the formed Zn Al LDH. A dissolution-interaction-coprecipitation pathway was proposed to elucidate the mechanism of Zn Al LDH formation. The findings highlight the importance of substrate mineral size and crystallinity for Zn Al LDH formation in environmental settings.

中文翻译:

粒度和矿物结晶度对铝(羟基)氧化物上形成 Zn Al 层状双氢氧化物 (LDH) 的影响

摘要 氧化锌纳米颗粒(ZnO NPs)的广泛使用不可避免地导致其在自然界中的释放以及与环境矿物的相互作用。为了揭示天然铝 (Al) 矿物作为层状双氢氧化物 (LDH) 在环境中对 ZnO NP 的保留,在 ZnO NP 与七种不同的 Al 相互作用期间研究了 Al(羟基)氧化物粒径和结晶度对 Zn Al LDH 形成的影响(羟基)氧化物在中性和碱性 pH 值下。溶解动力学显示双固体系统(ZnO 和 Al 矿物)中溶解的 Zn2+ 和 Al(OH)4− 浓度相对于单固体系统(ZnO 或 Al 矿物)降低,表明混合物固体可能发生转变。衍射、光谱、微观分析表明,Al(羟基)氧化物的粒径和结晶度对Zn Al LDH的形成有明显影响。固体产物中 Zn Al LDH 的组成百分比遵循无定形氢氧化物的顺序(分别为 89.90% 和 86.41% Zn 物质,作为 Zn Al LDH 在 pH 7 和 10)> 5 nm γ-Al2O3(41.62% 和 49.62%) > 35 nm γ-Al2O3(14.77% 和 19.03%) > 大尺寸 Al(羟基)氧化物(低于 13.00%),包括 70 nm γ-Al2O3、刚玉、勃姆石和三水铝石。Zn Al LDH 的形成主要受 Al (oxyhyro)oxide 结晶度和粒径的调节,通过改变 pH 10 时的 Al 氧化物溶解和 pH 7 时的 Zn2+ 吸附,而溶液 pH 控制所形成的 Zn Al LDH 的结晶度。提出了溶解-相互作用-共沉淀途径来阐明Zn Al LDH形成的机制。
更新日期:2021-02-01
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