High Adsorption of Benzoic Acid on Single Walled Carbon Nanotube Bundles

Shifan Li,Xingmao Ma,Robinson Karunanithy,Saikat Talapatra,Aldo Migone,Iskinder Arsano,Mesfin Tsige,Xianfeng Zhang,Milinda Wasala,Thushani De Silva,Dinuka Gallaba,Poopalasingam Sivakumar

doi:10.1038/s41598-020-66871-4

Abstract

Removal of harmful chemicals from water is paramount to environmental cleanliness and safety. As such, need for materials that will serve this purpose is in the forefront of environmental research that pertains to water purification. Here we show that bundles of single walled carbon nanotubes (SWNTs), synthesized by direct thermal decomposition of ferrocene (Fe(C5H5)2), can remove emerging contaminants like benzoic acid from water with high efficiencies. Experimental adsorption isotherm studies indicate that the sorption capacity of benzoic acid on these carbon nanotubes (CNTs) can be as high as 375 mg/g, which is significantly higher (in some cases an order of magnitude) than those reported previously for other adsorbents of benzoic acid such as activated carbon cloth, modified bentonite and commercially available graphitized multiwall carbon nanotubes (MWNTs). Our Molecular Dynamics (MD) simulation studies of experimental scenarios provided major insights related to this process of adsorption. The MD simulations indicate that, high binding energy sites present in SWNT bundles are majorly responsible for their enhanced adsorptive behavior compared to isolated MWNTs. These findings indicate that SWNT materials can be developed as scalable materials for efficient removal of environmental contaminants as well as for other sorption-based applications.

Highlights

Removal of harmful chemicals from water is paramount to environmental cleanliness and safety
We show that adsorption capacity of benzoic acid on single walled carbon nanotube (SWNT) bundles synthesized by direct thermal decomposition of ferrocene (Fe(C5H5)2)19,20 [and abbreviated as Fe-single walled carbon nanotubes (SWNTs) ] is significantly higher than commercially available multiwall carbon nanotubes (MWNTs)
A key insight from the Molecular Dynamics (MD) simulations is that the grooves formed by SWNT bundles can offer high energy binding sites compared to isolated MWNTs and perhaps underlie the higher adsorption capacity of benzoic acids on SWNT as seen in our experiments

Summary

Introduction

Removal of harmful chemicals from water is paramount to environmental cleanliness and safety. Organic compounds represent a very large group of environmental contaminants and their molecular structures range from simple carbon-carbon aliphatics to multi-ringed aromatic structures with varying number of functional attachments Many of these organic compounds are potent carcinogenic chemicals and are highly recalcitrant to biodegradation in the environment. A key insight from the MD simulations is that the grooves formed by SWNT bundles can offer high energy binding sites compared to isolated MWNTs and perhaps underlie the higher adsorption capacity of benzoic acids on SWNT as seen in our experiments. These findings indicate that SWNT materials can be developed for a variety of adsorption-based applications including the removal of environmental contaminants

Methods

Results

Conclusion