Highly porous foams based on graphene oxide functionalized with polyethylenimine are generated and used with unprecedented efficiency for adsorbing heavy metal ions. A multiscale analysis of the GO–BPEI nanocomposite provided evidence for the covalent grafting of BPEI on GO and the formation of low crystalline porous foams. The uptake experiments revealed that the GO–BPEI's adsorption of toxic cations is strongly dependent on the pH in range from 2 to 10, as a result of the different interactions at the supramolecular level between the metal ions and the GO–BPEI foam. The maximum uptake capacities for Cu(II), Cd(II) and Pb(II) are achieved at pH = 5 and exhibit values as high as 1096, 2051 and 3390 mg g⁻¹, respectively, being ca. over 20 times greater than standard sorbents like activated carbon. The GO–BPEI composite can be easily regenerated as proven by performing adsorption cycles. Also, the thermodynamic parameters including standard Gibbs free energy (ΔG^o), the enthalpy change (ΔH^o) and entropy change (ΔS^o) revealed the exothermic and spontaneous nature of the adsorption process.

中文翻译：

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氧化石墨烯支化的聚乙烯亚胺泡沫可有效去除水中的有毒阳离子†

产生并利用以聚乙烯亚胺官能化的氧化石墨烯的高度多孔的泡沫，并以前所未有的效率吸附重金属离子。GO-BPEI纳米复合材料的多尺度分析为BPEI在GO上的共价接枝和低结晶性多孔泡沫的形成提供了证据。吸收实验表明，由于金属离子和GO-BPEI泡沫在超分子水平上的不同相互作用，GO-BPEI对有毒阳离子的吸附强烈取决于pH值（从2到10）。在pH = 5时，Cu（II），Cd（II）和Pb（II）的最大吸收能力达到，分别显示出高达1096、2051和3390 mg g ^-1的值。约。比标准吸附剂（例如活性炭）大20倍以上。通过执行吸附循环可以证明，GO-BPEI复合材料易于再生。此外，包括标准吉布斯自由能（ΔG ^o），焓变（ΔH ^o）和熵变（ΔS ^o）在内的热力学参数显示了吸附过程的放热和自发性质。