Fe₃O₄ nanoparticles have attracted extensive attention for solving Cr(VI) pollution because they can effectively reduce Cr(VI) to the less toxic and less soluble Cr(III)-containing species. However, these magnetic nano-adsorbents suffer from very low adsorption capacity and low stability. To solve these drawbacks, we developed a pomegranate-like hybrid nanosphere (PHN) with a polydopamine (PDA) peel and Fe₃O₄ nanocrystals as seeds, which were applied as the nano-adsorbent for removing Cr(VI) ions. The adsorption performance of the resultant PHN nano-adsorbent towards toxic Cr(VI) ions was evaluated systematically with respect to the solution pH, competing ions, and temperature. The adsorption of Cr(VI) ions onto the PHN nano-adsorbent was found to be highly pH dependent with the optimal pH ranging from 2 to 4 and the PHN nano-adsorbent exhibited a remarkable sorption selectivity in complex wastewater. The nano-adsorbent has a fast adsorption rate for Cr(VI) ions that can reach adsorption equilibrium in about 10 min and the maximum adsorption capacity of the PHN nano-adsorbent was as high as 454.55 mg g⁻¹ at 338 K. In addition, the developed PHN nano-adsorbent has good recyclability. After 5 cycles of regeneration and adsorption, it could still maintain a high removal efficiency of up to 92.5% for Cr(VI) ions.

中文翻译：

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聚多巴胺和Fe3O4纳米颗粒的石榴状磁性杂化纳米吸附剂高效去除废水中的Cr（VI）离子

Fe ₃ O ₄纳米颗粒由于能够有效地将Cr（VI）还原为毒性较小，溶解性较弱的Cr（III）物种，因此在解决Cr（VI）污染方面引起了广泛关注。然而，这些磁性纳米吸附剂具有非常低的吸附能力和低稳定性。为了解决这些缺点，我们开发了一种石榴状的杂化纳米球（PHN），其具有聚多巴胺（PDA）皮和Fe ₃ O ₄纳米晶体作为种子，被用作纳米吸附剂以去除Cr（VI）离子。所得PHN纳米吸附剂对有毒Cr（VI）的吸附性能对溶液的pH值，竞争离子和温度进行系统评估。发现Cr（VI）离子在PHN纳米吸附剂上的吸附高度依赖于pH，最佳pH在2-4范围内，并且PHN纳米吸附剂在复杂废水中表现出显着的吸附选择性。纳米吸附剂对Cr（VI）离子具有快速吸附速率，可在约10分钟内达到吸附平衡，PHN纳米吸附剂在338 K时的最大吸附容量高达454.55 mg g ^-1。 ，开发的PHN纳米吸附剂具有良好的可回收性。再生和吸附的5个循环之后，它仍能保持向上的高去除效率，对Cr 92.5％（VI）离子。