Application of silica and germanium dioxide nanoparticles/

Abstract

One of the current global issues of increasing environmental-health concern is the ubiquitous occurrence of emerging micropollutants (EMPs) in aquatic environments. Among these EMPs, bisphenol A (BPA), technical 4- nonylphenol (NP), tonalide (AHTN), carbamazepine (CBZ), caffeine (CAF) and galaxolide (HHCB) find their way into aquatic environments as a result of their ever increasing production and consumption coupled with their incomplete removal in conventional water and wastewater treatment plants. This study fabricated silicon dioxide (silica) (SiO2) and germanium dioxide (GeO2) embedded polyethersulfone (PES) blend membranes using phase inversion method for the removal of EMPs from water samples collected from North West Province, South Africa. The EMPs were extracted and enriched by auto-trace solid-phase extraction and analyzed using comprehensive two dimensional gas chromatography coupled to time of flight mass spectrometry (GCxGC-TOFMS). The fabricated membranes' permeation properties were determined by computing the pure water flux and EMPs' rejection. The water flux was observed to increase with increase in transmembrane pressure as well as increase in SiO2 and GeO2 nanoparticle loadings in the polymer matrices. Compared to the pristine PES, the contact angles for the SiO2/PES and GeO2/PES membranes were much lower, showing increased hydrophilicity of the membranes with increase in SiO2 and GeO2 nanoparticle loadings in the matrices. The mean EMPs' concentrations (ng/L) ranges in the feed were found to be: BPA (5.19 ± 0.8 to 53.60 ± 4.25), CAF (6.09 ± 0.00 to 49.96 ± 3.45), CBZ (0.68 ± 0.00 to 3.06 ± 0.74), HHCB (21.31 ± 4.24 to 13.31 ± 14.8), AHTN (8.31 ± 2.23 to 141.82 ± 21.70), and NP (0–174.99 ± 14.5). Even though SiO2/PES membranes showed slightly higher EMPs' removal efficiencies than their GeO2/PES counterparts, both membranes showed the highest and lowest removal efficiencies range of 97.85–99.00% (for HHCB) and 87.42–93.00% (for CAF), respectively. The results showed superiority in capability of the fabricated nanocomposite membranes in removing EMPs from water.