Preparation of biologically reduced graphene oxide-based aerogel and its application in dye adsorption

Graphene-based materials have attracted great attention in wastewater treatment due to their excellent adsorbability for refractory pollutants. However, the high cost, environmental pollution during preparation and the separation after adsorption are issues that restricted its widespread application. In this study, biologically reduced graphene oxide was prepared via bacterium Shewanella sp. CF8-6 in 12 h, and a 3D poly(vinyl alcohol)/BRGO aerogel (PVA-GA) was further synthesized using PVA as cross-linker. Results showed that BRGO had smooth surface, low I_D/I_G value (1.26) and smaller layer spacing (0.38 nm), indicating that the reaction process had little damage to GO structure. The prepared PVA-GA had strong mechanical strength and porous network structure, and its BET specific surface area was 59.02 m²/g. Benefit from the excellent structure of PVA-GA, it had good adsorption performance for methylene blue (MB) and Congo red (CR) (with removal rate of 94.62%, 93.97% and adsorption capacity of 135.17 mg/g, 134.24 mg/g at an initial dye concentration of 50 mg/L), and could maintain more than 75% removal rate after 5 cycles. This study developed a relatively mild and green way of graphene-based material synthesis and demonstrated the great potential of PVA-GA as an efficient and safe adsorbent for dye removal from wastewater.