All‐in‐One Bioinspired Multifunctional Graphene Biopolymer Foam for Simultaneous Removal of Multiple Water Pollutants

Abstract

Polluted waters are complex systems with many different co‐existing contaminants that make their simultaneous removal a very challenging task. To address this problem, all‐in‐one ad/ab‐sorbent with unique combination of interfacial properties and multiple surface chemistry is developed to simultaneously and efficiently remove several pollutants including heavy metals, dyes, oils, and organic solvents. By mimicking the wetting micro‐topology of a darkling beetle with a combined hydrophilic‐hydrophobic surface, a new bioinspired adsorbent, graphene biopolymer foam (Alg‐Fe3O4‐rGO‐4S) for removal of multiple water pollutants is engineered by combining alginate (Alg) and reduced graphene oxide (rGO) functionalized with tetrathiol that is also decorated with iron oxide nanoparticles (Fe3O4). This concept is first proved by single pollutant removal, showing adsorption capacity of 789.7 ± 36 mg/g for methylene blue (MB), 107.0 ± 2.1 mg/g for Hg (II), 73.5 ± 0.7 mg/g for Cu (II), and rapid oil‐water separation with high sorption capacity (11–18 g/g). A remarkable performance for simultaneous removal of their mixtures in milli‐Q, river, and sea water is demonstrated with efficiency for MB (≈90%), Cu (II) (>99.99%) and Hg (II) (100%) and rapid (≈30 s) uptake of organic solvents and oils. The obtained results indicate a valuable potential of proposed concept for simultaneous removal of co‐existing water pollutants.

Graphene‐Based Sorbents for Multipollutants Removal in Water: A Review of Recent Progress

“…The poor performance of rhodamine B was due to the reduced positive charge density of rhodamine B molecule in the presence of the zwitterions (N + and COO − ) at pH >3 that decreased its interaction with the negatively charged functionalized sorbent. [ 42 ]…”

“…It was astounding that this functionalized biopolymer foam conformed to the maximum contaminant level for copper and mercury after the simultaneous sorption experiments. [ 42 ] Similarly, chitosan/sulfydryl‐functionalized GO composite (CS/GO‐SH), another functionalized graphene sorbent with mixed functional groups, was studied for a single pollutant system consisting of multi‐metal ions (Cu 2+ , Cd 2+ , and Pb 2+ ions). High maximum sorption capacities, 447, 425, and 177 mg g ‐1 , were accomplished for the studied metal ions, Pb 2+ , Cu 2+ and Cd 2+ ions, respectively.…”

“…Based on the reviewed graphene sorbents presented in previous sections, a comprehensive doped/functional groups–sorption performance relationship ( Figure ) is established to correlate sorption performance toward different types of water pollutant using a single advanced graphene material modified by heteroatoms and functionalized groups. [ 29–35,39–42,50–52,54–66 ] On average, sorption capacity achieved for multipollutants include heavy metal ions, organic dyes, oils, and organic solvents are within 1000 mg g ‐1 for organic dyes and heavy metal ions. While, less than 100 g g ‐1 recorded for organic solvents and oils using the advanced graphene sorbents.…”

“…With limited data available on the chemical composition of advanced graphene sorbents, a few examples (Figure 12) were identified to establish a correlation between the common atomic ratios of advanced graphene sorbents with the maximum adsorption capacities of the pollutants investigated, which has previously never been reported. [ 31–33,35,42,52,58,60,66b,71 ]…”

“…It is therefore paramount to correlate the pore size of advanced graphene sorbents with their corresponding maximum sorption capacities as depicted in Figure . [ 34,39,40,42,50,51,57–59,c,62–63,66b,68,71a,75 ] Taking 3D nitrogen and boron codoped graphene aerogel (B/N‐GA) as an example, enhanced textural properties including the specific surface area and pore volume were observed in B/N‐GA after the doping process. With pore width ranging from 2.5 to 11 nm, mesoporous B/N‐GA exhibited a larger surface area (169.9 m 2 g ‐1 ) and higher total pore volume (2.21 cm 3 g ‐1 ) compared to its undoped material (graphene aerogel, GA), 52.3 m 2 g ‐1 and 0.94 cm 3 g ‐1 , respectively.…”