2024

Dwivedi, Amarendra Dhar; Lahtinen, Manu; Dubey, Shashi Prabha; Varma, Rajender S.

Momordica dioica (Spiny Gourd; popularly known as Kantola) find limited applications except in foodomics. Aqueous peeled liquid extract (PLE), obtained from Spiny Gourd leftovers, offers advantages in terms of simplicity in operation, non-toxicity, and ability to transform ~ 99% of human carcinogen, hexavalent chromium Cr(VI) into non-toxic Cr(III), a vital trace nutrient. Aging impact assessment revealed that reversible transformation did not occur in samples aged 1 day to 18 months, and there was no redox transition of Cr(III) to Cr(VI) under the uncontrolled pH conditions (5.96 ± 0.2). Solid-supported matrix effect was eliminated without leftover chemicals, thus avoiding the possibility of secondary pollution compared to other clean-up strategies. Zerovalent silver (35 nm) was harvested from PLE without the use of a template, and the deployment of PLE/Ag matrix resulted in 99% catalytic reduction of the nitrophenols (o-, m-, and p-isomers) when assessed in various types of water samples. Collectively, the FTIR, PXRD, SEM, EDX and TEM data affirmed the characteristics of the blend matrix. A rate-limiting kinetic pseudo-first order Cr(VI) reduction was observed (R2 0.9806), while the nitrophenols decontamination was triggered through electron transfers. Reductive extraction by PLE electron donors became the principal mechanism governing the fate of dissolved contaminants. PLE remained active over a wide temperature gradient (278–318 K) through an endothermic process with minimal interference from varying ionic strengths (10–500 mM) or hardness (0.5–10 mM) and when mixed with contaminated waters containing As(V) (1000 µg/L) or Fe(III), Pb(II) and Cd(II) at 10 mg/L. Surface and groundwater samples (Cr(VI) levels ranging from 8.3 to 9.7 mg/L) were tested to validate the laboratory results for practical applications in natural water sources. Intriguing merit of waste-derived green chemicals enables an edge for expeditious, specific, and sustainable utility in the aquatic environment.