Solid phase extraction of Fe3+ from the aqueous system via eggshell with sensing applications

The conversion of biological waste into high-value commodities is crucial for environmental conservation and sustainable economic development. Eggshells, a naturally occurring organic-inorganic biomaterial with a distinctive hierarchically porous structure, have been extensively studied in catalysis, adsorption, and energy sectors. The eggshell was found to be a unique candidate for the removal of Fe3+. K+ facilitated the removal efficiency selectively, and the formation of K+ sensor was made possible (Limit of quantification 1.7 × 10− 5 M, linear detection range 10− 4 M-10− 6 M). No other metal ion could facilitate such Fe3+ removal process (unlike K+). The adsorption (solid phase extraction) of Fe was Langmuir in nature with monolayer homogeneous adsorption. Potassium ferrocyanide was employed to monitor the removal efficiency very efficiently. A recyclable and inexpensive tactic of water purification is helpful for prototype applications.