Scalable synthesis and purification of functionalized graphene nanosheets for water remediation

Abstract

Microwave (MW) accelerated synthesis combined to microfiltration (MF) on commercial hollow fiber modules enable fast and easy upscale of highly pure modified graphene oxide nanosheets. The MW-MF procedure is demonstrated...

Facile high-yield synthesis and purification of lysine-modified graphene oxide for enhanced drinking water purification

“…This microfiltration protocol allowed us to speed up the filtration by working at a higher flow rate (100 mL min −1 ), with respect to the previously reported dead-end in-out microfiltration procedure, which works at a maximum of 20 mL min −1 . 2 In addition, by working in the loop modality, we did not observe clogging of the pores of the membranes, as instead observed in the dead-end closed modality. 2 The overall procedure resulted in (i) less water/time consumption than centrifugation, (ii) less energy demand, and (iii) less mechanical detriment for the modules than those of the previously reported microfiltration procedure.…”

“…Graphene oxide nanosheets (GO) have been widely investigated in the last few years as sorbents for several organic molecules and heavy metal ions in water. [1][2][3] The abundant surface chemical groups, combined with the large surface area available for adsorption, have resulted in faster adsorption kinetics and efficiency toward several classes of pollutants, including emerging concern contaminants, in comparison to other carbon-based nanomaterials such as active carbon, the standard industrial sorbent. 4 These contaminants are a matter of great concern because of their persistence, mobility in water bodies and health and environmental toxicity.…”

“…5–7 The carboxylic and carbonyl groups of GO nanosheets play an important role in the adsorption efficiency of organic molecules, since they enable H-bonds and metal ion complexation. 2,3 In addition, chemical modification of such surface groups can be exploited for promoting selective adsorption capability. For instance, polyethyleneimine (PEI) modification has been reported as a successful strategy to adsorb metal cations, 8 organic molecules and arsenic anions 2 from tap water thanks to the synergy of π-stacking, complexation and electrostatic interactions enabled by GO and PEI structures.…”

“…2,3 In addition, chemical modification of such surface groups can be exploited for promoting selective adsorption capability. For instance, polyethyleneimine (PEI) modification has been reported as a successful strategy to adsorb metal cations, 8 organic molecules and arsenic anions 2 from tap water thanks to the synergy of π-stacking, complexation and electrostatic interactions enabled by GO and PEI structures. On this line, here we report the synthesis of a lysine-modified GO (GO-Lys) and the study of its potential for water remediation.…”

“…The dead end in-out procedure ( i.e. inlet by point 1 and out by point 3, 2/4 exits were closed), previously reported, 2 was here improved by working in the loop-dead end modality, as shown in Scheme 1b and c. The crude suspension was flowed through the inner fiber lumen (inlet by point 1, out by points 3 and 4, and recirculation by point 4) and recirculated, while small molecules of size below the fiber pores pass by the fiber section (exit 3). Clean water was progressively added to the crude to purify the modified GO until a neutral pH was measured for the collected GO-Lys solution.…”