Fly ash grafted poly(acrylic acid-co-acrylamide) composite hydrogel as the carbon dioxide adsorbent.

The unique tuneable properties of hydrogel have served many purposes in various application. In this study, crosslinked poly(acrylic acid-co-acrylamide)(AAc/AAm) composite hydrogels was incorporated with coal fly ash (FA) was synthesised, characterized and analysed as adsorbent for carbon dioxide capture. The high alumina and silica content in the FA make it exploitable as the inorganic filler in the composite hydrogel. N,N'-methylenebis(acrylamide)(MBA) was used as crosslinker and ammonium peroxodisulphate (APS) as the initiator. Neat AAc/AAm hydrogel and FA-AAc/AAm hydrogels with 0.5, 1.0 and 2.0 wt% FA loading were synthesis using solution polymerization. Then, the hydrogels samples infused using monoethanolamine (MEA). The disappearance bands 1100 and 936 cm−1 in 0.5FA-AAc/AAm FTIR spectra indicates the FA as grafted into the AAc/AAm hydrogel matrices. The morphology of 0.5FA-AAc/AAm shows increment in pore volume after the addition of of FA. The TGA curves of 0.5FA-AAc/AAm displays the desorption and evaporation of carbon dioxide (CO2) and MEA occurred at 160°C and 220°C, respectively. The MEA uptake rate was also studied to understand the effect of FA on the absorption rate of MEA. The 2.0FA-AAc/AAm composite hydrogel showed 100% improvement in CO2 adsorption capacity compared to neat AAc/AAm. Due to the presence of FA and amine, it allowed more carbon dioxide gas molecule to absorbed into the hydrogel. The FA-AAc/AAm composite hydrogel has showed considerable potency as the CO2 adsorbent. [ABSTRACT FROM AUTHOR]