efficacy of surface modified mnfe 2 o 4 nanoadsorbents for removal of cr vi from aqueous solution

Abstract

Manganese ferrite (MnFe2O4) nanoparticles were prepared using the chemical coprecipitation newlinemethod and were further functionalized using five different modifiers namely, newline(N-dodecyl-N,N-dimethylammonio) butyrate (DDMAB), Poly (methyl methacrylate)PMMA, newlinePolyethylene glycol (PEG), PMMA-PEG, DDMAB-PMMA-PEG. The as-synthesized newlinenanoparticles were characterized using various analytical techniques such as: Particle Size newlineAnalysis (PSA), Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), newlineEnergy Dispersive X-ray (EDX), Fourier Transform Infrared Spectroscopy (FT-IR), newlineScanning Electron Microscopy (SEM), Thermal Gravimetric Analysis (TGA) and Vibrating newlineSample Magnetometry (VSM). The as-synthesized PEG modified nanoparticles (PEG-MF newlineNPs) showed an excellent uptake capacity (38.46 mg/g) for Cr(VI) at optimum levels of pH newline8, contact time 120 min, adsorbent dosage 0.2 g/L and initial metal ion concentration 1 ppm. newlineThe isotherm data best fitted with Langmuir isotherm (R2 newline= 0.988). The kinetics of Cr(VI) newlineadsorption on the PEG-MF NPs followed the pseudo-second-order model. The isotherm newlinestudies confirmed that Cr(VI) chemically adsorbed on the PEG-MF NPs in monolayer newlinefashion, consistent with the electrostatic interaction between the positively charged Cr(VI) newlinecation and the surface of the nanoadsorbent which was negatively charge beyond its pHpzc newlinevalue of 6. The process of Cr(VI) adsorption was found to be thermodynamically newlinespontaneous and endothermic. The results of the study showed that the PEG modified newlineMnFe2O4 NPs were found to be cost effective and easily separable magnetic nanoadsorbent newlinefor efficient removal of Cr(VI) from aqueous solution. The highest desorption percentage newline(83%) was achieved in NaOH as a eluent. newlineKeywords: Manganese ferrite, functionalization, PEG, magnetic nanoparticles, Cr(VI) newlineremoval newline