Good boron removal and isotopic separation behavior was observed on magnetic magnetite nanoparticles (MMNs) in a previous study, but the mechanism of boron adsorption and isotopic separation remains unclear. Here, experimental studies accompanied by quantum chemistry calculations were implemented for the first time to reveal the nature of boron adsorption and isotopic separation on MMN. First, the fitted peaks of Fe2p of MMN by X-ray photoelectron spectrometry (XPS) before and after adsorption showed decrease in Fe(II)/Fe(III) ratio, which validated the formation of Fe–O–B interaction. Fe–O–B bond was also observed through fitted peaks of O1s and dihydroxy complexation where MMNs prefer to adsorb [B(OH)4]−(H3BO3) at pH < = pHzpc (pH > pHzpc) identified by the ratio of integrated peaks. ATR-FTIR revealed the hydroxyl moiety as the main adsorptive group. The selectivity of MMN toward [B(OH)4]− at pH < = pHzpc and toward H3BO3 at pH > pHzpc was figured out by calculating the ratio between the integrated areas of B–O bands at different pH values. As a result, the trend of adsorption capacity as well as the isotopic separation factor with pH was well illustrated. The concluded adsorption mechanism from the experiment was further verified with the simulated adsorption energies (ΔE) and isotopic separation factors (S) calculated by DFT quantum simulation.

中文翻译：

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磁性磁铁矿纳米粒子吸附硼与同位素分离的机理研究

在先前的研究中，在磁性磁铁矿纳米粒子 (MMN) 上观察到良好的硼去除和同位素分离行为，但硼吸附和同位素分离的机制仍不清楚。在这里，首次实施了伴随量子化学计算的实验研究，以揭示 MMN 上硼吸附和同位素分离的性质。首先，吸附前后 X 射线光电子能谱 (XPS) 拟合 MMN 的 Fe2p 峰显示 Fe(II)/Fe(III) 比值降低，这证实了 Fe-O-B 相互作用的形成。通过 O1s 和二羟基络合的拟合峰也观察到 Fe-O-B 键，其中 MMNs 更喜欢吸附 [B(OH)4]-(H3BO3) 在 pH < = pHzpc (pH > pHzpc) 下由积分峰的比率确定. ATR-FTIR 显示羟基部分是主要的吸附基团。MMN 在 pH < = pHzpc 时对 [B(OH)4]- 和在 pH > pHzpc 时对 H3BO3 的选择性是通过计算不同 pH 值下 B-O 带积分面积之间的比率来计算的。因此，吸附容量的趋势以及同位素分离因子与 pH 值的关系得到了很好的说明。通过 DFT 量子模拟计算的模拟吸附能 (ΔE) 和同位素分离因子 (S) 进一步验证了实验得出的吸附机制。吸附容量的趋势以及同位素分离因子与 pH 值的关系得到了很好的说明。通过 DFT 量子模拟计算的模拟吸附能 (ΔE) 和同位素分离因子 (S) 进一步验证了实验得出的吸附机制。吸附容量的趋势以及同位素分离因子与 pH 值的关系得到了很好的说明。通过 DFT 量子模拟计算的模拟吸附能 (ΔE) 和同位素分离因子 (S) 进一步验证了实验得出的吸附机制。