Development of sulfonated and aminated poly (ethylene-vinyl alcohol) nanofibrous membrane as a solid phase extraction matrix for trace metal ions preconcentration from dairy wastewater for direct ICP-OES analyses

Abstract

A robust nanofiber-based adsorbent was developed as a potential solid phase extraction matrix for adsorption and preconcentration of Al3+, Ni2+, Cu2+ and Cd2+ ions. This adsorbent was developed by amination and sulfonation of eletrospun poly (ethylene-vinyl alcohol) nanofibrous membranes (SF-EVOH NFM). Possessing porous structure, abundant active amine and sulfonate groups, the SF-EVOH NFM showed static maximum adsorption capacities of 350, 180, 140 and 125 mg.g−1 for Al3+, Cu2+, Ni2+, and Cd2+, respectively. The varied metal affinities toward the NFM are determined by the structural features of the metal ions and the NFM. More significantly, the NFM showed a dynamic column adsorption ratio of 99% with a 97% recovery of metal ions, revealing the features of efficient adsorption and release of metal ions by the unique structures of the SF-EVOH NFM. Furthermore, the SF-EVOH NFM demonstrated excellent stability and recyclability for up to 10 cycles. The NFM was applied as a solid phase extraction (SPE) filter to preconcentrate metal ions from wastewater samples collected from dairy farms in Central Valley California, USA. The preconcentrated solution released from the SF-EVOH NFM filter adsorbents could be directly tested by an ion-coupled plasma optical emission spectroscopy (ICP-OES) with a limit of detection (LOD) of 0.025 mg.L−1 and a relative standard deviation (RSD) < 5% for Al3+, highlighting the excellent performance of the NFM for enhanced instrumental monitoring applications of wastewater samples.