White Eggshells: A Potential Biowaste Material for Synergetic Adsorption and Naked-Eye Colorimetric Detection of Heavy Metal Ions from Aqueous Solution

Abstract

In the present work, we have utilized a simple, no-cost, unmodified eggshell powder as a naked-eye colorimetric detector, which on simple dispersion in aqueous solution of metal ions exhibited characteristic color change from white to pale green, pale blue, yellow, pale yellow, dark yellow, pale pink, blue, and brown for metal ions V 4+ , Cr 3+ , Cr 6+ , Fe 2+ , Fe 3+ , Co 2+ , Cu 2+ , and Ag + , respectively. The effects of various parameters like concentration of metal ions, pH, temperature, and adsorbent dosage were investigated by batch sorption experiments. Also, Freundlich and Langmuir models were used to describe the adsorption isotherm. The eggshell powder before and after adsorption was characterized qualitatively by the naked-eye and quantitatively by diffuse reflectance spectroscopy-UV, Fourier transform infrared, atomic absorption spectroscopy, powder Xray diffraction, scanning electron microscopy with energy-dispersive X-ray spectroscopy, Brunauer−Emmett−Teller, zeta potential, and X-ray photoelectron spectroscopy techniques. In addition, the competitive adsorption of metal ions in mixtures and the recycle experiments were carried out to prove the sustainability of the material. Further, the red, green, and blue alterations were extracted from the colorimetric array and subjected to hierarchical clustering analysis using the Ward method by calculating the Euclidean distance, which displayed facile discrimination of 10 heavy metal ions at 1 mM level. Thus, the unmodified eggshell powder has been proven to be an impressive value-added sustainable material for synergistic metal adsorption and colorimetric naked-eye detection of a series of metal ions with detection limits of 10 −4 M for Fe 3+ , Fe 2+ , and Cu 2+ ; 10 −3 M for Cr 3+ , Cr 6+ , Ag + , and Co 2+ ; and 5 × 10 −3 M for V 4+ .

Journey of ZnO quantum dots from undoped to rare-earth and transition metal-doped and their applications

“…Many researchers are working in this eld for the development of selective detection of transition and heavy metal ion impurities. From the different available detection methods such as colorimetry, [128][129][130] mass spectrometry, [131][132][133] atomic absorption spectroscopy, 134-136 electrochemical [137][138][139][140] and uorescence 141-145 methods, the uorescence methods are the most reliable and effective because of their high sensitivity, high efficiency, and operative simplicity. Praethong Laopa and Tirayut Vilaivan 40 synthesized cationic polymer-coated ZnO QDs for the selective detection of the Fe(II) ion.…”

One-Step Instantaneous Detection of Multiple Military and Improvised Explosives Facilitated by Colorimetric Reagent Design

“…21 Another interesting attempt shows that eggshell powder could be exploited as a colorimetric detector for the successful detection and discrimination of 10 ions from aqueous solution through physical adsorption. 22 By further analyzing the colorimetric sensing principle, it is promising if one could consider the design of a versatile colorimetric reagent with great sensitivity and accuracy for the detection and identification of multiple military and improvised explosives, no matter whether they are water-soluble or water-insoluble.…”

“…From the colorimetric sensing material design aspect, multicolorimetric sensors, typically based on target molecule-guided etching and the change of the noble metal nanostructure color that could reflect the exact species of the target molecules, have been widely used for visual inspection applications . Another interesting attempt shows that eggshell powder could be exploited as a colorimetric detector for the successful detection and discrimination of 10 ions from aqueous solution through physical adsorption . By further analyzing the colorimetric sensing principle, it is promising if one could consider the design of a versatile colorimetric reagent with great sensitivity and accuracy for the detection and identification of multiple military and improvised explosives, no matter whether they are water-soluble or water-insoluble.…”

Fabrication, Characterization, and Evaluation of Eggshells as a Carrier for Sustainable Slow-Release Multi-Nutrient Fertilizers

“…It was found that the incorporation of nutrients decreased the pore volume due to the blockage of pores by incorporation of nutrient elements. 13 Also, compared to ES, the BET surface area of ES-SMF decreased, which demonstrated that the macro-and micronutrients occupied the pores in ES. The heat of adsorption was found to be less than 50 KJ/mol, which indicates that the interactions are physisorption.…”