Removal of boron and silicon by a modified resin and their competitive adsorption mechanisms

To prevent the negative effects of both elements in water utilization process, a new diol type T-resin was prepared by a grafting method and investigated the application properties. This resin exhibited good adsorption properties for both boron and silicon in a wide pH range. The adsorption capacity of boron was 21.25 mg/g (1.97 mM/g), which was much higher than those for other modified resins with polyol functional groups. The adsorption capacity of silicon was only 8.36 mg/g (0.30 mM/g), which was lower than boron, suggesting that the adsorption of one molecule of silicic acid required more adsorption sites than the adsorption of one molecule of boric acid. Boron and silicon were competitively adsorbed on T-resin, and the silicic acid molecule replaced boron adsorbed on the resin, indicating a more stable adsorption of silicon compared to that of boron. Different complex types were observed in the complexation reaction involving the adsorption of boron and silicon on resin. While boron was adsorbed via triangular and tetrahedral complexes, silicon was only adsorbed via an octahedral complex. T-resin could be reused after regeneration, and showed a good performance for boron or silicon removal after multiple regeneration cycles.

为规避水体利用过程中硼与硅两种组分带来的负面影响，本研究通过接枝法制备了一种新型二醇类T-树脂，并对其应用性能开展了系统研究。该树脂在宽pH范围内对硼和硅均展现出良好的吸附性能。其对硼的吸附容量可达21.25 mg/g（1.97 mM/g），远高于其他带有多元醇官能团的改性树脂。对硅的吸附容量仅为8.36 mg/g（0.30 mM/g），低于硼的吸附容量，这表明吸附1分子硅酸所需的吸附位点多于吸附1分子硼酸所需的位点。硼与硅在T-树脂上存在竞争吸附行为，硅酸分子可置换吸附于树脂表面的硼，说明硅在树脂上的吸附稳定性优于硼。在硼、硅与树脂的吸附络合反应中，观测到了不同的络合类型：硼通过三角络合物与四面体络合物两种形式实现吸附，而硅仅通过八面体络合物完成吸附。T-树脂经再生处理后可重复使用，且在多次再生循环后仍保持良好的除硼或除硅性能。