Facile Use of Silver Nanoparticles-Loaded Alumina/Silica in Nanofluid Formulations for Enhanced Catalytic Performance toward 4-Nitrophenol Reduction.

Rashmi Mannu,Wha-Jung Kim,Venkatramanan Kannan,Prashant Sonar,Vellaisamy A L Roy,Gopalan Saianand,Dong-Eun Lee,Vaithinathan Karthikeyan,Murugendrappa Malalkere Veerappa,Anantha-Iyengar Gopalan,Binrui Xu,Kwang-Pill Lee

doi:10.3390/ijerph18062994

Abstract

The introduction of toxic chemicals into the environment can result in water pollution leading to the degradation of biodiversity as well as human health. This study presents a new approach of using metal oxides (Al2O3 and SiO2) modified with a plasmonic metal (silver, Ag) nanoparticles (NPs)-based nanofluid (NF) formulation for environmental remediation purposes. Firstly, we prepared the Al2O3 and SiO2 NFs of different concentrations (0.2 to 2.0 weight %) by ultrasonic-assisted dispersion of Al2O3 and SiO2 NPs with water as the base fluid. The thermo-physical (viscosity, activation energy, and thermal conductivity), electrical (AC conductivity and dielectric constant) and physical (ultrasonic velocity, density, refractive index) and stability characteristics were comparatively evaluated. The Al2O3 and SiO2 NPs were then catalytically activated by loading silver NPs to obtain Al2O3/SiO2@Ag composite NPs. The catalytic reduction of 4-nitrophenol (4-NP) with Al2O3/SiO2@Ag based NFs was followed. The catalytic efficiency of Al2O3@Ag NF and SiO2@Ag NF, for the 4-NP catalysis, is compared. Based on the catalytic rate constant evaluation, the catalytic reduction efficiency for 4-NP is found to be superior for 2% weight Al2O3@Ag NF (92.9 × 10−3 s−1) as compared to the SiO2@Ag NF (29.3 × 10−3 s−1). Importantly, the enhanced catalytic efficiency of 2% weight Al2O3@Ag NF for 4-NP removal is much higher than other metal NPs based catalysts reported in the literature, signifying the importance of NF formulation-based catalysis.

Highlights

In recent years, there is a high demand for a high standard of living conditions with minimized or negligible impact from environmental pollution, which necessitates the development of novel materials or methodologies for treating contaminated media and for environmental remediation [1]
The measurements of physicochemical, physical of Al2 O3 /SiO2 NFs with varying contents of metal oxide NPs in the base fluid can provide, in particular, the information of the molecular interactions existing between the dispersed NPs, which will form the basis to understand the application prospects
The characteristics as obtained from XRD, Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and EDX are presented in Appendix A (Figures A1–A6) and discussed below

Summary

Introduction

There is a high demand for a high standard of living conditions with minimized or negligible impact from environmental pollution, which necessitates the development of novel materials or methodologies for treating contaminated media and for environmental remediation [1]. The use of metal/metal oxide nanoparticles (NPs) offers several advantages in water treatment and contaminant removal due to their inherent characteristics such as a high surface area to volume ratio, smaller size, availability of a large number of reactive sites and high capacity for regeneration [2,3,4]. The clear advantage of NF has been documented from the 300 times increase in thermal conductivity of the copper particles dispersed water medium over the base fluid [6]. This triggered research studies on the preparation of metal dispersed NF and applied it in numerous heat transfer applications. Further extension of research activities has been projected on metal oxide-based NFs

Methods

Results

Conclusion