Heavy metals contamination in the natural waters remains an unresolved environmental challenge pressing for the development of purification technologies. This paper presents the green engineering of a new bio-sponge for heavy metals adsorption composed of alginate bio-polymeric network encapsulated with reduced graphene oxide (rGO) modified with iron oxide nanoparticles and covalently attached multithiol (pentaerythritol tetrakis-mercaptopropionate) molecules using photoinitiated thiol-ene click chemistry. The multithiol functionalized graphene bio-sponge (SH-Graphene bio-sponge) is designed to enhance adsorption performances of heavy metals including structural approach combined with oxygen functionalities and high density of sulfur-containing groups (10.2 at % S, confirmed by X-ray Photoelectron Spectroscopy, XPS) with high binding affinity towards specific heavy metals (Cd and Pb). It was shown that the level of thiol functionalization on the graphene structure within the bio-sponge can be controlled by tuning the Ultraviolet (UV) irradiation time without adjusting the concentration of the precursors. SH-functionalized graphene bio-sponge showed outstanding adsorption capacity for Pb (II): 101.01 mg/g and Cd (II): 102.99 mg/g, outperformed commercial and literature reported adsorbents in highly competitive selectivity studies using co-existing heavy metal ions (Cu, Co, Pb and Cd) spiked- sea water. The multithiol modified bio-sponge also showcased an excellent stability and reusability feature with only 0.015 mg/L Pb (II) detected, conforming the strict United States Environmental Protection Agency (US EPA) maximum contaminant level (MCL) for lead, after five recurring cycles using mixed heavy metal ions solution and acidic eluent. The outcomes from this work present valuable and promising contribution towards the development of a scalable and sustainable adsorbents for efficient remediation of heavy metals from waters.

天然水体中的重金属污染仍然是尚未解决的环境挑战，迫切需要开发纯化技术。本文介绍了一种新型的重金属吸附生物海绵的绿色工程，该藻海绵由藻酸盐生物聚合物网络组成，该藻类生物聚合物网络被氧化铁纳米粒子修饰的还原氧化石墨烯（rGO）封装，并使用光引发的硫醇共价连接多硫醇（季戊四醇四巯基丙酸酯） -ene单击化学。多硫醇官能化石墨烯生物海绵（SH-Graphene bio-sponge）旨在增强重金属的吸附性能，包括与氧官能团结合的结构方法和高密度的含硫基团（10.2 at％S，通过X射线证实）光电子能谱 XPS）对特定重金属（Cd和Pb）具有高结合亲和力。结果表明，可以通过调节紫外线（UV）照射时间来控制生物海绵中石墨烯结构上硫醇官能化的程度，而无需调节前体的浓度。SH官能化的石墨烯生物海绵对Pb（II）：101.01 mg / g和Cd（II）：102.99 mg / g表现出出色的吸附能力，在使用竞争性重金属离子共存的高竞争选择性研究中表现优于商业和文献报道的吸附剂（铜，钴，铅和镉）加标海水。多硫醇修饰的生物海绵还具有出色的稳定性和可重复使用性，仅检测到0.015 mg / L的Pb（II），符合严格的美国环境保护局（US EPA）铅最大污染水平（MCL），使用混合的重金属离子溶液和酸性洗脱液重复五个循环后。这项工作的成果为开发可扩展和可持续的吸附剂以有效修复水中的重金属提供了宝贵而有希望的贡献。