In the present study, we synthesized a magnetically separable adsorbent, i.e., composite of magnetite and Zn/Al layered double hydroxide (Fe₃O₄−Zn/Al LDH), for effective removal of humic acid (HA). The composite was synthesized through conventional co-precipitation method using NaOH as precipitating agent. The presence of well-dispersed Fe₃O₄ outside the interlayer space of Zn/Al LDH made the Fe₃O₄−Zn/Al LDH magnetically active and thus the adsorbent was easily separated from aqueous solution by application of an external magnetic field. The adsorption test on HA demonstrated that Fe₃O₄−Zn/Al LDH was optimum in removing HA at pH 4.0 with removal capacity estimated according to the Langmuir isotherm model was 1.21 × 10⁻⁴ mmol g⁻¹ or equivalent to 35.28 mg g⁻¹, while the removal rate constant according to the pseudo-second order kinetic model was 443.6 (mol/g)⁻¹ min⁻¹. The results strongly suggest that the removal of HA on Fe₃O₄–Zn/Al LDH occurs solely through simple adsorption on the outer surface through an electrostatic interaction. In addition, when the material was tested in a real raw water sample from a drinking water treatment agency in Pontianak City, West Kalimantan, Indonesia, the performance was far surpassing commercially available alum.

在本研究中，我们合成了一种磁性可分离的吸附剂，即磁铁矿和Zn / Al层状双氢氧化物（Fe ₃ O ₄ -Zn / Al LDH）的复合物，可有效去除腐殖酸（HA）。通过常规共沉淀法以NaOH为沉淀剂合成了复合材料。Zn / Al LDH的层间空间外存在良好分散的Fe ₃ O ₄使得Fe ₃ O ₄ -Zn / Al LDH具有磁性，因此通过施加外部磁场很容易从水溶液中分离出吸附剂。在HA上的吸附测试表明Fe ₃ O ₄-Zn / Al LDH最适合在pH 4.0的条件下去除HA，根据Langmuir等温模型估算的去除容量为1.21×10 ^-4 mmol g ^-1或相当于35.28 mg g ^-1，而根据拟二阶动力学模型为443.6（mol / g）^-1 min ^-1。结果强烈表明去除Fe ₃ O ₄上的HA–Zn / Al LDH仅通过静电相互作用简单地吸附在外表面上而发生。此外，当从印度尼西亚西加里曼丹省坤甸市的一家饮用水处理公司的真实原水样品中测试该材料时，其性能远远超过了市售的明矾。