Removal of methylene blue from aqueous solution by graphene oxide

Abstract

Graphene oxide (GO) is a highly effective absorbent of methylene blue (MB) and can be used to remove MB from aqueous solution. A huge absorption capacity of 714 mg/g is observed. At initial MB concentrations lower than 250 mg/L, the removal efficiency is higher than 99% and the solution can be decolorized to nearly colorless. The removal process is fast and more efficient at lower temperatures and higher pH values. The increase of ionic strength and the presence of dissolved organic matter would further enhance the removal process when MB concentration is high. The results indicate that GO can be applied in treating industrial effluent and contaminated natural water. The implications to graphene-based environmental technologies are discussed.

Graphene oxide adsorption enhanced by in situ reduction with sodium hydrosulfite to remove acridine orange from aqueous solution

“…Thus, GO definitely has proved to have great potential as an adsorbent. In addition, SRGO performed much better than teak wood bark and activated carbon [29]. It is worth noting that a longer pre-reduction period lessened the adsorption capacity, implying that only a suitable reduction degree would maximize the capacity.…”

“…Previous work found that methylene blue had a capacity of up to 714 mg g -1 [29]. Thus, GO definitely has proved to have great potential as an adsorbent.…”

“…As seen, the equilibrium concentration 14 (C e , g L -1 ) and equilibrium adsorption capacity values (q e , mg g -1 ) were fitted by their linearized expressions [29][30][31][32][42][43][44]. Accordingly, the maximum adsorption capacity for GO and SRGO were calculated by the Langmuir equation, as follows:…”

“…GO showed a high affinity for positively charged molecules/ions because of oxygen atoms [29][30][31][32]45]. AO is positively charged in nature; accordingly, the electrostatic interaction is the primary binding strength [29].…”

“…Previous work has indicated its application for contaminant removal as a GO/composite. Yang et al demonstrated methylene blue removal by GO with a large adsorption capacity, as high as 714 mg g -1 (better than activated carbon, yet less comparable to teak wood bark, with its capacity of 914.6 mg g -1 ) [29]. Yang et al applied the Cu 2+ -inducing GO folding/aggregation for ion elimination from aqueous solution, demonstrating an adsorption capacity about 10 times better than that for activated carbon [30].…”