Capture and chemical fixation of carbon dioxide by chitosan grafted multi-walled carbon nanotubes

Abstract

Since last few years, climate change has been a serious concern all over the world. The concentrations of carbon dioxide (CO2) in the atmosphere have been increasing at an alarming rate and this has been a key contributor to global warming and associated climate change. Hence, there is a global demand to reduce atmospheric CO2 for balancing our climatic condition. Herein, we have synthesized cost-effective and environment-friendly chitosan grafted multi-walled carbon nanotubes (CSMWCNTs) based solid adsorbents for the capture of carbon dioxide as well as an efficient catalyst for its chemical fixation. Physical characterization of CSMWCNTs was done by fourier transformation infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscope (SEM) analysis, Brunauer-Emmett-Teller (BET) isotherm and thermogravimetric analysis (TGA). The CO2 uptake capacity of CSMWCNTs was found to be significantly higher (1.92 ccg−1) than that of pure chitosan but lower than functionalized multi-walled carbon nanotubes (10.20 ccg−1). Moreover, it has been found that CSMWCNTs shows significant catalytic activity towards the chemical fixation of CO2 with epoxides (propylene oxide and styrene oxide) and leading to the formation of corresponding cyclic carbonates. Cycloaddition of CO2 with epoxides is one of the greenest approach to form high value added organic chemicals which have several applications as synthons in fine chemicals, petrochemicals, valuable intermediates, antifoam additives, engineering plastics and pharmaceuticals. Hence, to the best of our knowledge, for the first time capture and chemical fixation of CO2 (at atmospheric pressure) by CSMWCNTs is being reported herein and which may help to reduce CO2 gas from the atmosphere.