Photodegradation of microcystin-LR using graphene-TiO2/sodium alginate aerogels

Abstract

In this study, sustainable graphene oxide-TiO₂/sodium alginate and reduced graphene oxide-TiO₂/sodium alginate aerogels were synthesized and the potential of these aerogels was investigated for microcystin-LR degradation in aqueous solution. Along with the role of alginate in the synthesis of aerogels, effects of different concentrations of photocatalyst, photolysis, pH, and combination of TiO₂ (anatase)/Degussa P25 with graphene were investigated in lieu of microcystin-LR photodegradation.The complete degradation of microcystin-LR was attained in case of reduced graphene oxide-TiO₂/sodium alginate aerogel-not in graphene oxide-TiO₂/sodium alginate aerogel case-by the synergistic effect of adsorption and photodegradation. The recyclability study of reduced graphene oxide-TiO₂/sodium alginate aerogel demonstrated high stability and photoactivity and the degradation efficiency was not much hampered during six consecutive cycles of degradation reaction. The possible fragmentation pathways were also proposed based on identified intermediate products. High adsorption and degradation synergy and ease of separation/recycling of reduced graphene oxide-TiO₂/sodium alginate aerogel can make it a suitable option for removing microcystin-LR from water systems.

Keywords: Graphene oxide; Microcystin-LR; Photodegradation; Sodium alginate; Titanium dioxide.