The alginate/reduced graphene oxide composite hydrogels with hierarchical network structures were synthesized through the hydrothermal treatment of graphene oxide and alginate in an aqueous solution followed by ionically cross-linking of metal ions. The network of reduced graphene oxide was prepared via self-assembly of graphene nanosheets in the presence of alginate during the hydrothermal process; then, the polymer network of alginate was obtained by ionically cross-linking, forming the composite hydrogel. The effect of metal ions on the physical properties of the composite hydrogels was investigated. The prepared alginate/reduced graphene oxide composite hydrogel cross-linked by Fe3+ ions showed higher compression strength and lower swelling ratio. Moreover, due to the synergetic interaction between graphene and alginate, the composite hydrogels exhibited the improved dye adsorption performance, especially for cationic dyes. Even after ten adsorption/desorption cycles, the composite hydrogels can retain more than 90% dye adsorption capacity. The results indicated that the composite hydrogel with good stability, adsorption and regeneration ability could be a promising candidate for dye removal from waste aqueous solutions.

中文翻译：

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具有增强染料吸附性能的强藻酸盐/还原氧化石墨烯复合水凝胶

通过在水溶液中对氧化石墨烯和藻酸盐进行水热处理，然后金属离子进行离子交联，合成了具有分级网络结构的藻酸盐/还原氧化石墨烯复合水凝胶。还原氧化石墨烯网络是在水热过程中，在藻酸盐存在下，通过石墨烯纳米片的自组装制备的；然后，通过离子交联得到藻酸盐的聚合物网络，形成复合水凝胶。研究了金属离子对复合水凝胶物理性能的影响。Fe3+离子交联的海藻酸盐/还原氧化石墨烯复合水凝胶表现出更高的抗压强度和更低的溶胀率。此外，由于石墨烯和藻酸盐之间的协同作用，复合水凝胶表现出改善的染料吸附性能，尤其是对阳离子染料。即使经过十次吸附/解吸循环，复合水凝胶仍能保留超过 90% 的染料吸附能力。结果表明，该复合水凝胶具有良好的稳定性、吸附性和再生能力，是去除废水溶液中染料的有前景的候选者。