Abstract
In the present research, new carbon nanosorbents were developed for removal of salicylic acid (SA) in aqueous media. The starting materials were graphene flakes with thicknesses of 12 nm (C12) and 60 nm (C60) subjected to covalent functionalisation in a reflux reactor using different chemical reagents (HNO3,H2SO4, NaOH and KOH) at 353 K for 4 h. Characterisation work revealed that the specific surface areas of C12 and C60 were 68.74 and 9.76 m2/g, respectively. The capability of the prepared nanosorbents in SA sequestration was examined using batch adsorption system. The results suggested that C12 treated withH2SO4 (C12-H2SO4) exhibited the highest percentage removal of SA (55 %). FTIR analysis showed the presence of various functional groups viz. hydroxyl, alkyne, amine, carboxylic acid, carbonyl, alcohol and alkyl halide on C12-H2SO4 which might have interacted with SA. The adsorption equilibrium was evaluated by varying the initial SA concentration. Experimental data were analysed by Langmuir, Temkin and Dubinin-Radushkevich (D-R) and Freundlich models. The goodness-of-fit of the models was determined by Marquardt’s percent standard deviation, chi-square, average relative error and sum of absolute error with model parameter optimisation evaluated by sum of normalised errors (SNE). It was found that D-R model was the best fit model with the lowest SNE. The primary results showed that chemical functionalisation has been successfully used for attaching specific functional groups onto C12. In addition, the new graphene- based nanosorbent viz. C12-H2SO4 has a great potential application for SA removal.
