Poly(Acrylic acid)/SiO 2 composite nanofiber functionalized with mercapto groups for the removal of humic acid from aqueous solution

Abstract

Functionalized poly(acrylic acid)/SiO 2 (PAA/SiO 2 ) composite nanofiber with mercapto groups have been prepared through an electro spinning process. The characterization of the composite nanofiber was performed using FTIR, optical microscopy, SEM, TEM and Brunauer-Emmett-Teller (BET) analysis. Finally, the prepared nanofiber was used for the adsorption of humic acid (HA) from an aqueous solution using a batch adsorption technique. The effects of pH, contact time, initial concentration, dosages and temperature on adsorption capacities were studied in a batch mode. The experimental data was well described by the Langmuir isotherm model with an adsorption capacity of 427.62 mg/g. It was found that the kinetic data follow the pseudo-second-order models. The data of thermodynamic parameters indicated that the HA adsorption process was non-spontaneous and endothermic under the experimental conditions with the values of Gibbs free energy (ΔG°) being in the range of 3.235 to 5.914 kJ mol –1 ; as well as the values of enthalpy (ΔH°) and entropy (ΔS°) that were found to be 22.41 kJ mol –1 and 55.59 J mol –1 . K –1 , respectively. The functionalized composite nanofiber exhibited as a high potential adsorbent for the adsorption of HA from an aqueous solution.