Abstract Lanthanum hydroxides (La(OH)3) materials play an important role in managing eutrophication. The crystal structure-reactivity relationship of La(OH)3 nanoparticles deserves in-depth investigation. Herein, three La(OH)3 nanomaterials of different crystal structures denoted as LH-1, LH-2 and LH-3 were freshly synthesized. LH-1 and LH-3 were in the form of rod-like crystallite with a dominant exposure of {1 0 0} facets which was occupied by singly La atom coordinated (-LaOH), doubly La atom coordinated (-La2OH) and triply La atom coordinated (-La3OH) hydroxyl groups. LH-2 presented as nano-plates and was majorly enclosed by {1 0 1} facets which was dominated by -La2OH hydroxyl groups. The quantity of -LaOH groups on three materials was positively correlated with the Langmuir constants derived from the adsorption isotherm, which suggested they were the predominant species for enhanced phosphate affinity. In comparison, the contribution of -La2OH to phosphate affinity was weaker, and function of -La3OH was negligible. The high affinity and fast kinetic of LH-3 towards phosphate could be attributed to the abundance of -LaOH groups on its main exposed crystal planes and relatively small grain size. These results provided new insights into the understanding of functions of facets on La(OH)3 crystals which could generate new strategies for engineering novel materials for water treatment.

中文翻译：

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不同晶体结构的氢氧化镧的小平面依赖性磷酸盐吸附反应性：表面羟基的作用

摘要 氢氧化镧 (La(OH)3) 材料在控制富营养化方面发挥着重要作用。La(OH)3 纳米粒子的晶体结构-反应性关系值得深入研究。在此，新合成了三种不同晶体结构的 La(OH)3 纳米材料，分别表示为 LH-1、LH-2 和 LH-3。LH-1 和 LH-3 呈棒状微晶形式，主要暴露{1 0 0} 晶面，其中被单 La 原子配位 (-LaOH)、双 La 原子配位 (-La2OH) 和三重原子占据。 La 原子配位 (-La3OH) 羟基。LH-2 呈现为纳米片，主要被 {1 0 1} 面包围，其中 -La2OH 羟基占主导地位。三种材料上 -LaOH 基团的数量与由吸附等温线导出的朗缪尔常数呈正相关，这表明它们是增强磷酸盐亲和力的主要物种。相比之下，-La2OH 对磷酸盐亲和力的贡献较弱，-La3OH 的作用可以忽略不计。LH-3 对磷酸盐的高亲和力和快速动力学可归因于其主要暴露晶面上的大量 -LaOH 基团和相对较小的晶粒尺寸。这些结果为理解 La(OH)3 晶体上小平面的功能提供了新的见解，这可以为设计用于水处理的新型材料提供新的策略。LH-3 对磷酸盐的高亲和力和快速动力学可归因于其主要暴露晶面上的大量 -LaOH 基团和相对较小的晶粒尺寸。这些结果为理解 La(OH)3 晶体上小平面的功能提供了新的见解，这可以为设计用于水处理的新型材料提供新的策略。LH-3 对磷酸盐的高亲和力和快速动力学可归因于其主要暴露晶面上的大量 -LaOH 基团和相对较小的晶粒尺寸。这些结果为理解 La(OH)3 晶体上小平面的功能提供了新的见解，这可以为设计用于水处理的新型材料提供新的策略。