Production of green nano zero-valent iron (G-nZVI) particles using polyphenol extracts of Tawa-tawa ( Euphorbia hirta linn ) leaves and green tea ( Camelia sinensis ) leaves

Abstract

Green synthesis of nano zero-valent iron (nZVI) can be used for environmental remediation. In this study, nZVI was produced from the extracts of Tawa-tawa ( Euphorbia hirta ) and Green tea ( Camelia sinensis ) leaves using Fe 2+ and Fe 3+ precursors. Solid-liquid extraction was used to obtain the extract of oven-dried Tawa-tawa and Green tea leaves with 60% v/v ethanol at a fixed solid-liquid ratio (1:20) and varying time (30, 60, 90, 120, and 150 min). Total phenolic content (TPC) of the extracts was determined by Follin Ciocalteu method. The extraction time of 60 min yielded the highest average TPC values of 7.26 xx0.01 mg GAE/ g of Tawa-tawa dried sample and 5.23 //0.13 mg GAE/g of Green tea dried sample. To produce 0.1 gram of nZVI, 12 mL and 6 mL tawa-tawa extract were needed for Fe 2+ and Fe 3+ , respectively. For green tea, 24 mL and 20 mL extracts were needed for Fe 2+ and Fe 3+ to obtain the same amount of particles. G-nZVI has a particle diameter ranging from 50 nm to 130 nm, and mainly composed of iron and oxygen. Synthesized nZVIs from Tawa-tawa and Green tea reduced the nitrates (as nitrogen) concentration from 99.35 mg-L-1 to 42.32 mg-L-1 and 48.77 mg-L-1, respectively.