Polyacrylamide hybrid nanocomposites hydrogels for efficient water treatment

Spherical polyacrylamide nanoparticles (PAM-NPs) were prepared by inverse emulsion polymerization technique. Polyacrylamide/functionalized-multiwalled carbon nanotubes (PAM/f-MWCNTs) and polyacrylamide/TiO2 (PAM/TiO2) nanocomposites were successfully prepared by in situ emulsion polymerization and solution mixing methods to investigate their efficiencies in removal of organic dyes. The super-hydrogel behavior of the prepared nanocomposites proved water absorbance of 3664% and 2996% for PAM/1% f-MWCNT and PAM/10% TiO2 nanocomposites; respectively. A maximum photodegradation efficiency of 35% was achieved upon using PAM/10% TiO2 nanocomposite for CR dye removal, while in case of MG dye it reached 76% after 240 min irradiation time. Dye removal efficiency increased as f-MWCNT loading increased and reached maximum values of 49% and 80% for CR and MG dyes, respectively, using PAM/1% f-MWCNT nanocomposite after 240 min irradiation time. Pseudo-second-order kinetic model best fitted the adsorption kinetics behavior which reached maximum rates of 0.0615 and 0.463 for CR and MG dyes, respectively, using PAM/1% f-MWCNT nanocomposite. However, in the case of PAM/10% TiO2 nanocomposite it was found that adsorption reached maximum rates of 0.552 and 0.571 for CR and MG dyes, respectively. On the other hand, pseudo-first-order kinetic model best described the photodegradation behavior of the prepared nanocomposites with higher degradation rate of 0.0018 and 0.0075 for CR and MG dyes, respectively, using PAM/10% TiO2 nanocomposite. In this work, the combination of PAM-NPs, prepared by inverse emulsion polymerization, TiO2 NPs with photocatalytic activity and CNTs with high adsorption activity combined the photocatalytic and absorption activities of these nanoparticles in conjunction with reducing their amounts and diminishing the risk of fine catalyst dispersion in the treated water.