Abstract
Metal oxide nanoparticles (MONPs) such as TiO2 and ZnO have been engineered for various industrial manufacturing processes. Among MONPs, environmental exposure to ZnO nanoparticles may cause health concerns about their significant toxicity. This leads to a desire of efficient methods for their removal in the aqueous environment with facile detection. In this work, 3-aminopropyltriethoxysilane (APTES) was chosen to treat aqueous suspensions containing ZnO and other metal oxide nanoparticles. APTES first formed a thin surface layer on ZnO nanoparticles and continued in branching polymerization to link up with adjacent APTES-ZnO nanoparticles. Eventually, a web-like sediment settled down onto the bottom and was confirmed to be APTES-ZnO conjugation by FT-IR. A high removal efficiency over 99 % w of ZnO nanoparticles in aqueous suspension was attained using 2.0 % by volume of APTES. The sedimentation was selective towards ZnO nanoparticles due to electrostatic interaction with ZnO to form a sturdy condensation coagulate. Other MONPs (Al2O3, CaO, CeO2, CuO and TiO2) did not form any web-like sediment with APTES but could co-precipitate with the ZnO nanoparticles. Meso-tetra(carboxyphenyl)porphyrin (TCPP) could be added as an indicator to co-precipitate with the sediment, with its color changing from red purple to bright green during the formation of APTES-TCPP-ZnO sediment. A filter paper or membrane placed at the bottom greatly facilitated the disposal of all sediments at a low cost.
Highlights
Numerous advances of nanoscience and nanotechnology have been reported in recent years on the use of metal oxide nanoparticles (MONPs) in enzymatic biosensors 1and enzyme-linked immunosorbent assay 1
Meso-tetra(carboxyphenyl)porphyrin (TCPP) could be added as an indicator to coprecipitate with the sediment, with its color changing from red purple to bright green during the formation of APTES-TCPP-ZnO sediment
Addition of APTES by itself to the aqueous samples containing Metal oxide nanoparticles (MONPs) will experience a hydrolysis first on the epoxy group and result an increase of pH from 7 to 10 at the surface of ZnO nanoparticles 17. This pH range exerts a maximum prohibition to the possible release of free metal ions for MONPs
Summary
Numerous advances of nanoscience and nanotechnology have been reported in recent years on the use of metal oxide nanoparticles (MONPs) in enzymatic biosensors 1and enzyme-linked immunosorbent assay 1. The massive production of MONPs for industrial manufacturing of consumer products leads to the inadvertent release of MONPs to the natural aquatic environment 2 This scenario raises great concerns because ZnO, TiO2 and CeO2 all exhibit toxicity towards microorganisms even though their bulk materials are generally considered to be non-toxic 3. Ivask et al identified the most toxic MONPs to be ZnO and CuO with average IC50 values of around 20 μg/mL against three mammalian cell lines (human alveolar epithelial cells A549, human epithelial colorectal cells Caco[2], and murine fibroblast cell line Balb/c 3T3) at 24 h 5. Jain et al reported in-vitro genotoxicity and cell death (on Chinese hamster lung fibroblast cells V-79) after exposure to 1–20 μg/mL ZnO nanoparticles for 6 hours 6
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
