Multifunctional graphene oxide/biopolymer composite aerogels for microcontaminants removal from drinking water

Abstract

Due to water depletion and increasing level of pollution from standard and emerging contaminants, the development of more efficient purification materials and technology for drinking water treatment is a crucial challenge to be addressed in the near future. Graphene oxide (GO) has been pointed as one of the most promising materials to build structure and devices for new adsorbents and filtration systems. Here, we analyzed two types of GO doped 3D chitosan-gelatin aerogels with GO sheets embedded in the bulk or deposited on the surface. Through combined structural characterization and adsorption tests on selected proxies of drinking water micropollutants, we compared both GO-embedded and GO-coated materials and established the best architecture for achieving enhanced removal efficiency toward contaminants in water. To evaluate the best configuration, we studied the adsorption capacity of both systems on two organic molecules (i.e., fluoroquinolonic antibiotics ofloxacin and ciprofloxacin) and a heavy metal (lead Pb 2+) of great environmental relevance and with already proved high affinity for GO. The Pb monolayer maximum adsorption capacity q max was 11.1 mg/g for embedded GO aerogels and 1.5 mg/g in coated GO-ones. Only minor differences were found for organic contaminants between coating and embedding approaches with an adsorption capacity of 5-8 mg/g and no adsorption was found for chitosan-gelatin control aerogels without GO. Finally, potential antimicrobial effects were found particularly for the GO-coated aerogels materials, thus corroborating the multifunctionality of the newly developed porous structures.

Porous Aerogels and Adsorption of Pollutants from Water and Air: A Review

“…On the other hand, graphene aerogels are largely and almost exclusively proposed to remove a wide variety of pollutants from wastewater, including dyes [ 128 , 129 ], drugs [ 8 , 20 ], heavy metals [ 121 , 130 ], radioactive elements [ 28 , 29 ], bacteria [ 124 , 131 ], organic solvents [ 131 , 132 ], and oils [ 26 , 125 ]. GO-based aerogels have exhibited great potential for wastewater treatment and the purification of natural waters, such as removing mercury [ 133 ] and microcontaminants from drinking water [ 134 ].…”

“…The removal of Cr(VI) from water using GO-based aerogels was the focus of various studies, such as those of Li et al [ 80 ], Liang et al [ 130 ], and Wei et al [ 135 ], who managed to eliminate up to about 95%, 99%, and 89% of Cr(VI) ions, respectively. In the last few years, GO-based aerogels have been proven to be excellent absorbent matrices for the removal of other heavy metal ions with genotoxic, mutagenic, and carcinogenic effects on humans and aquatic living organisms, including Pb(II) [ 121 , 134 ], Cu(II) [ 118 ], and Fe(III) ions [ 5 ]. In addition, the effective elimination of radioactive elements—known as radionuclides—was also proven in the studies of Huo et al [ 28 ] and Lee et al [ 29 ], specifically in the removal of Sr(II) and Cs + , employing polyvinyl alcohol (PVA)/GO and polyvinylpyrrolidone (PVP)/GO aerogels, respectively.…”

Recent Developments in Chitosan-Based Adsorbents for the Removal of Pollutants from Aqueous Environments

“…Moreover, other biopolymers have been combined with chitosan to form blends which are then combined with GO to give high performing adsorbents. These comprise CS/GO/gelatin [ 227 ], CS/GO/alginate [ 228 ], CS/GO/heparin [ 229 ] and CS/GO/cellulose blends [ 230 ].…”

Graphene-Based Materials Immobilized within Chitosan: Applications as Adsorbents for the Removal of Aquatic Pollutants

“…For example, a polylactic acid (PLA) 3D scaffold was printed and then immersed in a GO/CS mixture, followed by freeze-drying to give a 3D sponge [201], while aerogel microspheres were prepared by combining electrospraying and freeze-casting [202]. Likewise, Kovtun et al [203] used aerogels comprising 3D chitosan-gelatin. These were then modified with GO by either embedding the GO sheets within the aerogel or by coating the surface of the aerogel with GO sheets.…”