Averrhoa carambola: A Renewable Source of Oxalic Acid for the Facile and Green Synthesis of Divalent Metal (Fe, Co, Ni, Zn, and Cu) Oxalates and Oxide Nanoparticles

Table 1

Summary of sample codes, synthesis time, and colour of precipitates.

Sample (code)	Synthesis time (min)	Colour of precipitate formed
Fe^2+ (P1)	45	Yellow
Co^2+ (P2)	30	Pink
Ni^2+ (P3)	60	Light green
Cu^2+ (P5)	60	Light blue
Zn^2+ (P4)	60	White