Removal of Chromium from Synthetic Wastewater Using Modified Maghemite Nanoparticles

Shishir Kumar Behera,Aditi Rai,Eldon R Rene,Srijan Sahni,Biswanath Mahanty,Gunjan Tiwari,Ayi Vinati,Arivalagan Pugazhendhi

doi:10.3390/app10093181

Abstract

The main aim of this study was to ascertain the removal of chromium ions from synthetic wastewater using modified maghemite nanoparticles (MNPs). Commercially available maghemite nanoparticles (NPs) (< 50 nm) were modified using sodium dodecyl sulfate (SDS). The MNPs were characterized using a powder X-ray diffractometer (XRD) and Fourier transform infrared spectrophotometer (FTIR). Statistically designed batch experiments were carried out to evaluate the effects of various parameters, namely the pH of the solution, initial chromium concentration, and adsorbent dose, on the chromium removal efficiency (RE). The results from this study showed that the adsorbent dose had a synergistic effect on chromium RE, while pH and initial chromium concentration had antagonistic effects on the RE. An optimal chromium RE of 95.8% was obtained at pH = 2.6, adsorbent dose = 5 g/L, and initial chromium concentration = 20 mg/L. The analysis of variance (ANOVA) results showed that the model was significant, with high F value (F = 80.07) and low P value (P = < 0.001). Based on the results obtained from the experiments, the MNPs could be exploited as an efficient adsorbent for chromium removal from wastewater.

Highlights

The three most common forms of chromium that exist in our environment are metallic (Cr0 ), trivalent (Cr+3 ), and hexavalent (Cr+6 )
Fourier transform infrared spectrophotometer (FTIR) analysis determined the specific functionality of the NPs (Figure 1a) and maghemite nanoparticles (MNPs) (Figure 1b)
The results of X-ray diffractometer (XRD) analysis of NPs and MNPs given in Figure 2a,b reveals that all diffraction peaks are consistent with the standard structure of maghemite

Summary

Introduction

The three most common forms of chromium that exist in our environment are metallic (Cr0 ), trivalent (Cr+3 ), and hexavalent (Cr+6 ). Metallic chromium does not occur naturally in elemental form. Cr (III), is found in trace amounts in humans and is an essential nutrient for insulin, sugar, and lipid metabolism. Hexavalent chromium species (Cr+6 ) are highly toxic agents that act as carcinogens, mutagens, and teratogens in different biological systems [1]. Hexavalent chromium is included in the World Health Organization’s (WHO) list of 10 chemicals of major public health concern and the maximum level of total chromium in drinking water has been set as 0.05 mg/L [2]. The United States Environmental Protection Agency (USEPA) prescribes that the levels of chromium in water should be reduced to 0.1 mg/L using appropriate technologies [3]

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