Lanthanum carbonate @ anion exchange resin (LC@AER) has shown promise in adsorption processes due to its high maximum adsorption capacity and excellent stability in comparison with other lanthanum-based adsorbents. Nevertheless, there is a lack of significant investigation in evaluating the collective effect of the most influential parameters and determining the molecular complexes between the adsorbent and phosphate. This work aims to comprehensively evaluate and optimize the phosphate adsorption performance in fixed-bed columns and to determine the most favourable molecular configurations. Firstly, a response surface model (RSM) was developed to describe the phosphate adsorption performance in fixed-bed columns under the collective effect of selected independent variables, including influent pH, co-existing sulfate concentration, and empty bed contact time (EBCT). The RSM analysis reveals the significant effects of influent pH and co-existing sulfate concentration on phosphate adsorption. Moreover, the model achieves a correlation coefficient of >0.9, demonstrating its suitability for describing the experimental data. Secondly, various phosphate-lanthanum carbonate configurations were formulated, and the respective adsorption energies were compared using density functional theory (DFT) calculations. Subsequently, bidentate mononuclear complexes are determined as the most favourable configurations. The successful matching of the simulated peak locations with the experimental deconvoluted spectra further confirms the presence of such complexes in the system. Overall, this work provides an improved foundation and underlayer theory for potential future scale-up work on phosphate adsorption over LC@AER.

中文翻译：

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采用固定床柱的碳酸镧 @ 阴离子交换树脂选择性去除磷酸盐：用于工艺优化的 RSM 和用于机理研究的 DFT

与其他镧基吸附剂相比，碳酸镧@阴离子交换树脂（LC@AER）由于其较高的最大吸附容量和优异的稳定性而在吸附过程中显示出应用前景。然而，在评估最有影响力的参数的集体效应以及确定吸附剂和磷酸盐之间的分子复合物方面缺乏重要的研究。本工作旨在全面评估和优化固定床柱的磷酸盐吸附性能，并确定最有利的分子构型。首先，开发了响应面模型（RSM）来描述固定床柱在选定自变量（包括进水pH、共存硫酸盐浓度和空床接触时间（EBCT））的集体影响下的磷酸盐吸附性能。 RSM 分析揭示了进水 pH 值和共存硫酸盐浓度对磷酸盐吸附的显着影响。此外，该模型的相关系数>0.9，证明其适合描述实验数据。其次，制定了各种磷酸盐-碳酸镧构型，并使用密度泛函理论（DFT）计算比较了各自的吸附能。随后，双齿单核配合物被确定为最有利的构型。模拟峰位置与实验解卷积光谱的成功匹配进一步证实了系统中此类复合物的存在。总体而言，这项工作为未来潜在的 LC@AER 磷酸盐吸附放大工作提供了改进的基础和底层理论。