Removal of cadmium from aqueous solution using mesoporous PVA/TEOS/APTES composite nanofiber prepared by sol–gel/electrospinning

The novel poly (vinyl alcohol)/tetraethylorthosilicate/aminopropyl triethoxysilane (PVA/TEOS/APTES) composite nanofiber was prepared by the sol–gel/electrospinning method and its application for the removal of cadmium from aqueous solution was investigated. The parameters of electrospinning process such as flow rate of spinning solution, applied voltage and tip–collector distance (TCD) were optimized for fabrication of homogeneous and fine fibers. As results, the fibers with the smallest average diameter of about 196.70 nm were obtained at the flow rate of 0.3 mL h−1, applied voltage of 17.5 kV and TCD of 12.5 cm. Fourier Transform Infrared (FTIR) revealed the presence of amine groups in the structure of PVA/TEOS/APTES composite nanofiber. The result of pore volume calculation by BJH model showed that the structure of PVA/TEOS/APTES nanofiber was mesoporous. Experimental parameters affecting cadmium sorption onto the PVA/TEOS/APTES nanofiber such as pH, contact time, initial concentration and temperature were studied. The kinetic data were analyzed by the pseudo-first-order, pseudo-second-order and double-exponential kinetic models. The Langmuir, Freundlich and Redlich–Peterson isotherm models were applied to describe the equilibrium data of cadmium sorption onto the composite nanofiber. Thermodynamic parameters indicated that the cadmium adsorption onto the composite nanofiber was endothermic and spontaneous process. The reusability of the composite nanofiber was also determined after eight sorption–desorption cycles.

► The synthesized membranes were characterized by FTIR, SEM and BET analyses.
► The structure of PVA/TEOS/APTES composite nanofiber was mesoporous.
► The maximum adsorption capacity of cadmium adsorption was 327.3 mg g−1.
► The mechanism of cadmium sorption onto the nanofiber is chemisorption.
► The cadmium sorption onto the composite nanofiber did not change after 8 cycles.