Abstract It is keenly desired to develop an environmentally benign and highly stable magnetic adsorbent for efficient recovery of Au(III) ion from an acidic solution. In the present study, we investigated the synthesis of magnetic adsorbents that the magnetic particles, which was prepared from natural iron sand, were modified with silica layer on which chitosan was fixed through 3-chloropropyltrymethoxysilane (CPTMS) by a sol-gel process. Since the magnetic particles were almost completely covered with the silica layer and chitosan was tightly fixed on it through CPTMS, the adsorbent was highly stable in an acidic solution with pH 3 or lower. Excess CPTMS significantly lowered the adsorption capacity for Au(III) ion, while lead to little improvement in the stability. Thus, 1 mmol of CPTMS against 4 mmol of chitosan gave the best magnetic adsorbent in terms of stability and adsorption capacity, of which the maximum was 112 mg g−1 for Au(III) ion at pH 5. The adsorbent showed high selectivity of Au(III) adsorption in the solution containing Cu(II) and Zn(II), and was reusable for two times keeping high selectivity without fatal decline in the adsorption performance. The magnetic adsorbent was separable from the solution simply with an external magnet, while the modification caused a slight decrease of the saturated magnetization.

中文翻译：

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用（3-氯丙基）三甲氧基硅烷改性的壳聚糖功能化天然磁性颗粒@二氧化硅作为金（III）离子的高度稳定的磁性吸附剂

摘要 迫切需要开发一种环境友好且高度稳定的磁性吸附剂，以有效地从酸性溶液中回收 Au(III) 离子。在本研究中，我们研究了磁性吸附剂的合成，该磁性颗粒由天然铁砂制备，用二氧化硅层改性，壳聚糖通过溶胶-凝胶工艺通过 3-氯丙基三甲氧基硅烷 (CPTMS) 固定在二氧化硅层上。由于磁性颗粒几乎完全被二氧化硅层覆盖，壳聚糖通过 CPTMS 紧紧固定在其上，因此吸附剂在 pH 3 或更低的酸性溶液中非常稳定。过量的CPTMS显着降低了对Au(III)离子的吸附能力，而稳定性几乎没有提高。因此，就稳定性和吸附容量而言，1 mmol CPTMS 对 4 mmol 壳聚糖提供了最佳的磁性吸附剂，其中在 pH 5 时对 Au(III) 离子的最大吸附量为 112 mg g-1。该吸附剂对 Au( III) 在含有 Cu(II) 和 Zn(II) 的溶液中吸附，可重复使用两次，保持高选择性，吸附性能没有致命的下降。磁性吸附剂可以简单地用外部磁铁从溶液中分离，而改性导致饱和磁化强度略有下降。并且可重复使用两次，保持高选择性，吸附性能没有致命的下降。磁性吸附剂可以简单地用外部磁铁从溶液中分离，而改性导致饱和磁化强度略有下降。并且可重复使用两次，保持高选择性，吸附性能没有致命的下降。磁性吸附剂可以简单地用外部磁铁从溶液中分离，而改性导致饱和磁化强度略有下降。