Source
Sultan Qaboos University Journal for Science, v. 29, no. 3, p. 59-78.
English abstract
The role of oxygen-based functional groups in the photoluminescence
of dehydrated carbon dots (DCs) and the adsorption mechanism of dye molecules onto
the surface of DC is investigated. DC were prepared from orange peel for the first time
via the chemical dehydration effect of sulfuric and phosphoric acid at 180 oC. We
compared the emission spectra of DCs in different solvents in great detail. The
solvatochromism of DC in different solvents is discussed. The role of oxygen-based
functional groups in the light emission process is examined. Adsorption of methylene
blue (MB) on the surface of DC was studied at different contact times, pH,
concentrations, and temperatures. In this work, we used Langmuir and Freundlich
adsorption models for the analysis. Sorption kinetic data were found to fit well with
the pseudo-second-order model. Our results also showed increased MB adsorption
capability with temperature. The results are essential for the application of CQDs, such
as in wastewater treatment.
