Sequestration of Ni II ions using green synthesized manganese oxide nanoparticles encapsulated in hybrid biopolymeric microspheres

Abstract

newline The present study focuses on synthesizing manganese oxide nanoparticles (MnO2NPs) both by chemical route using sodium thiosulphate reduction and green route using Cenchrus ciliaris L. leaf extract. The green synthesized MnO2NPs were further encapsulated by hybrid biopolymers such as sodium alginate and iota-carrageenan. The removal efficiency of Ni(II) ions from aqueous solution and real water samples using the prepared adsorbents were tested. The leaf extract used for the green synthesis of MnO2NPs was subjected to Gas Chromatography-Mass spectrometry screening for the presence of photo components revealed the presence of eight photo components with reference to the NIST (National Institute of Standards and Technology) database. Synthesis of nanoparticles both by chemical as well as green route showed the appearance of dark brown precipitates confirming the formation of manganese oxide nanoparticles. Microspheres were formed using sodium alginate and iota-carrageenan hybrid biopolymers for encapsulating green synthesized manganese oxide nanoparticles. The synthesized manganese oxide nanoparticles were subjected to characterization techniques such as UV Visible Spectroscopy, Raman Spectroscopy, Particle Size and Zeta Potential Analysis, Fourier Transform Infrared Spectroscopy (FT-IR), Powder X-ray Diffraction Analysis (PXRD), Scanning Electron Microscopy (SEM), Field Emission Scanning Electron Microscopy (FE-SEM), High-resolution Transmission Electron Microscopy (HR-TEM), Selected Area Diffraction Study (SAED), Energy-Dispersive iv X-ray Spectroscopic Analysis (EDX). UV Visible Spectrum showed the maximum absorption at wavelength 360 nm for both MnO2NPs, indicating the formation of manganese oxide nanoparticles. Raman spectrum revealed the presence of peaks between wavelengths 500 cm-1 and 700 cm-1 . The particle size graph showed peaks in the 100 to 1000 nm range. The zeta potential was -29.8 mV and -25.7 mV for green synthesized and chemically synthesized MnO2NPs, respectively. FT-IR spectrum of g