Synthesis Of Monometallic (Ni) And Bimetallic (Mn–Ni) Nanoparticles Using Vigna Unguiculata Extract for The Adsorption of Congo Red Dye

10.24271/psr.2026.561807.2601
Abstract
The green synthesis process for Ni and Mn–Ni bimetallic nanoparticles by using Vigna unguiculata seed extract have been investigated for the Congo Red dye adsorption. The aim of the study is to prepare these nanoparticles in more eco-friendly conditions and examine their performance for dye removal from aqueous medium.The plant Vigna unguiculata was selected due to its already proved richness with natural reducing as well as stabilizing agents, especially it is containing of phenolic compounds, flavonoids, and some other bioactive metabolites. These substances have been mentioned in several previous studies for their helping role in formation of nanoparticles, mainly through redox reactions and providing surface passivations. The synthesis was resulted in formation of good-crystallized nanoparticles, with average size about 30 nm for Ni and 22 nm for Mn–Ni particles. The prepared bimetallic Mn–Ni nanoparticles was achieved 83% of dye removal efficiency, which is comparing with 57% for only Ni, giving about 26% enhancement in adsorption activity. The optimum condition was found at 25°C, dye concentration 8 mg·L⁻¹, catalyst amount 0.005 g, neutral pH 7, and contact time of 60 minutes. These findings indicate that the bimetallic nanoparticles is having higher adsorption capacity under suitable experimental conditions.Whereas equilibrium data fits the Freundlich isotherm, kinetic analysis verified pseudo-second-order behavior. With (ΔH, ΔS, and ΔG) all negative thermodynamic parameters, the adsorption process was spontaneous and exothermic. While Ni nanoparticles showed greatly decreased reusability, with only 13% efficiency in the third cycle, Mn–Ni nanoparticles retained 51% of their adsorption efficiency after the third reuse cycle. Mn-Ni nanoparticles have a mean zeta potential of -33.8 mV, indicating strong negative surface charge and colloidal stability. These results support the feasibility of Vigna unguiculata-mediated synthesis as an environmentally friendly and reasonably priced technique for manufacturing recyclable adsorbents in wastewater treatment.
Keywords
Mono metallic Ni nanoparticles
Bimetallic Mn-Ni Nanoparticles
Vigna Unguiculata seed Extract
Congo Red Dye
Green Synthesis
Crossmark
Passer Journal of Basic and Applied Sciences
Volume 8, Special Issue
Proceedings of the 5th International Conference on Advanced science & Engineering ICOASE 2026, University of Zakho and Duhok Polytechnique University, 00th – 00th September 2026
August 2026
Pages 1-17