Enhanced adsorptive removal of selected pharmaceutical antibiotics from aqueous solution by activated graphene
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Activated graphene adsorbents (G-KOH) were synthesized by a one-step alkali-activated method, with a high specific surface area (SSA) and a large number of micropores. As a result, the SSA of the final product greatly increases to ∼512.6 m2/g from ∼138.20 m2/g. The resulting G-KOH was used firstly as an adsorbent for the removal of ciprofloxacin (CIP) in aqueous solutions. Experimental results indicated that G-KOH has excellent adsorption capacity (∼194.6 mg/g). The alkali-activation treatment introduced oxygen-containing functional groups on the surface of G-KOH, which would be beneficial to improving the adsorption affinity of G-KOH for the removal of CIP. Kinetic regression results showed that the adsorption kinetic was more accurately represented by a pseudo-second-order model. The overall adsorption process was jointly controlled by external mass transfer and intra-particle diffusion, and intra-particle diffusion played a dominant role. A Langmuir isotherm model showed a better fit with adsorption data than a Freundlich isotherm model for the adsorption of CIP on G-KOH. The remarkable adsorption capacity of CIP onto G-KOH can be attributed to the multiple adsorption interaction mechanisms (hydrogen bonding, π–π electron donor–acceptor interactions, and electrostatic interactions). Results of this work are of great significance for environmental applications of activated graphene with higher SSA as a promising adsorbent for organic pollutants from aqueous solutions.
KeywordsActivated graphene Adsorption Ciprofloxacin
This research was supported by the National Natural Science Foundation of China (No. 21207100 and No. 51408362), Specialized Research Fund for the Doctoral Program of Higher Education (20120072120058), the Shanghai Institute of Technology Scientific Research Foundation for Introduced Talent, China (No. YJ2014-30), the Key Research Projects of the Science and Technology Commission of Shanghai Municipality (12231201702), and the Central Finance Special Fund to Support the Development of Local Colleges and Universities (City Safety Engineering). We are also thankful to anonymous reviewers for their valuable comments to improve this manuscript.
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