Green Nanoarchitectonics Using Cleistocalyx Operculatus Leaf Extract in the Preparation of Multifunctional Graphene Oxide/Fe 3 O 4 /Ag Nanomaterials for Water Decontamination and Disinfection

The demand for clean water has been increasing around the world. In this study, graphene oxide/Fe 3 O 4 /Ag nanomaterials with different graphene oxide:Fe 3 O 4 ratios were prepared and determined the best formulations for water treatment. Ag nanoparticles were incorporated into the materials by a green reduction method using Cleistocalyx Operculatus leaf extract for the first time. The synthesized materials were characterized by FTIR, Raman, XRD, FESEM, EDX and VSM methods. The characterizations confirm that the materials have been prepared successfully with various element compositions and can be separated by outer magnetic fields. The results show that the GF31A sample with graphene oxide:Fe 3 O 4 ratio of 3:1 and about 5 wt.% Ag in the composition exhibits the highest efficiency for chemical oxygen demand (COD), total nitrogen (TN) and PO 4 3− removals. This material also induces good antibacterial and antifungal activity on harmful gram (+), gram (−), and fungi microorganisms such as Staphylococcus aureus , Salmonella enterica , Candida albicans with small IC 50 values (from 1.5 to 11.1 mg/L). More than 70% of COD, TN, PO 4 3− and 100% of E. coli have been removed from two real water samples treated with GF31A (0.1 g/100 mL). The results reveal that GF31A is a potential agent for water treatment application. Besides the newly using of Cleistocalyx Operculatus in the synthesis, this is also the first time various graphene oxide/Fe 3 O 4 /Ag materials have been systematically investigated for both water decontamination and disinfection with the ease of magnetically separation. Graphical Abstract