Template-free synthesis of hybrid silica nanoparticle with functionalized mesostructure for efficient methylene blue removal

Dambarudhar Parida,Khalifah A Salmeia,Amin Sadeghpour,Shanyu Zhao,Anjani K Maurya,Khaleel I Assaf,Eva Moreau,Robin Pauer,Sandro Lehner,Milijana Jovic,Hirsch Cordula,Sabyasachi Gaan

doi:10.1016/j.matdes.2021.109494

Abstract

A simple one-pot synthesis process for functionalized mesostructured silica nanoparticles (MSNP) is reported. The novel process demonstrated the possibility to achieve MSNP with a surface area up to 501 m2.g−1 using a phosphonate based nonsilane precursor such as N, N´-bis[4,6-bis(diethylphosphono)-1,3,5-triazin-yl]-1,2-diaminoethane (ED). MSNP obtained by using 20 mol% of ED achieved a surface area of 80 m2.g−1 and increasing the ED content to 30 mol% resulted in a surface area of 501 m2.g−1. Zeta potential of novel MSNPs (−65.5 and 70.0 mV) were much higher than the nanoparticle (NP) prepared from only TEOS (−49 mV), indicating the presence of a large number of –SiOH and phosphonic acid surface functional groups, as confirmed by Fourier-transform infrared spectroscopy (FT-IR) and Nuclear magnetic resonance (NMR) analysis. The functionalized MSNPs were used as an adsorbent for the removal of cationic pollutants like methylene blue (MB). The MSNP with the highest porosity displayed favorable MB adsorption behavior with ~380 mg.g−1 of MB adsorption capacity. Facile regeneration in an acidic medium (~pH 4.5) with easy recyclability (10 cycles) confirmed the practical applicability of this novel functionalized MSNPs.

Highlights

Degradation-resistant dyes present in industrial effluents accumulate in water bodies and have the potential to cause irreversible damage to aquatic ecosystems and pose a serious threat to human health
tetraethyl orthosilicate (TEOS) (99%), NaOH, ethanol (99.8%), diethyl ether (99%), methylene blue (MB), Congo Red (CR), and Brilliant Blue were purchased from Sigma-Aldrich and used as received
mesostructured silica nanoparticles (MSNP) were recovered by centrifugation and washing in ethanolH2O mixture was repeated four times to ensure removal of unreacted precursors

Summary

Introduction

Degradation-resistant dyes present in industrial effluents accumulate in water bodies and have the potential to cause irreversible damage to aquatic ecosystems and pose a serious threat to human health. High doses of accumulated methylene blue (MB) in water can cause anemia, breathing difficulties, and nausea [1]. Removing these pollutants from water by adsorption is a viable and safer option of pollution control, unlike oxidation or degradation methods, where degradation product of these dyes can lead to secondary pollution. The use of functionalized hydrogels [3,4], carbon-based adsorbents [5], and mesoporous silica nanoparticles (MSNs) [6,7,10] are extensively investigated because of their high adsorption capacity. MSNs have attracted a lot of attention, owing to their docile nature, high stability, and potential applications in the field of drug delivery [13,14], bio-molecule delivery [15,16], bioimaging [15], and many more areas [17,18,19,20]

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Discussion

Conclusion