A natural polyphenol as a green M chelating agent in environmental and industrial matrices

Gallic acid (GA) is a natural polyphenolic compound abundantly present in citrus fruit wastes, green and black tea leaves, grapes, honey, and nuts, and it exhibits several beneficial properties [1]. This contribution reports the results of a study focused on the on GA interaction towards Ca , Mg , Zn , Cu , Cd and Pb , with the aim of assessing its potential as a green and sustainable anti-scalant, water-softening, or sequestering agent for mitigation and remediation applications in real contaminated matrices. Indeed, pollutants speciation studies are essential to gain insight into contaminant mobility, transport, toxicity, environmental impact, and fate [1]. Experiments were carried out using potentiometric and UV–Vis spectrophotometric techniques at T = 298.15 K and 0.10 ≤ I/mol dm ≤ 1.00, in NaCl ionic medium, one of the main inorganic 2+ 2+ 2+ 2+ 2+ 2+ -3 constituents of many environmentally [2] and industrially [3] relevant systems. The pL0.5 [4] and pM [5] parameters were calculated to evaluate the sequestering ability and affinity of GA towards the selected M under various pH and ionic strength conditions, representative of natural waters 2+ [2], industrial waters [6], hard waters [7], and wastewaters [8]. Lastly, speciation diagrams describing the behaviour of gallic acid towards these metal cations were drawn in the presence of both natural components and pollutants typical of the considered matrices, highlighting promising performance for future practical applications. References 1. R.M. Cigala et al., J. Env. Chem. Eng., vol. 12, p. 114620, 2024. 2. F.J. Millero, Physical Chemistry of Natural Waters, John Wiley & Sons, New York, 2001. 3. S.S. Kaushal et al., Nat. Rev. Earth Environ., vol. 4, p. 770, 2023. 4. F. Crea et al., Curr. Med. Chem., vol. 21, p. 3819, 2014. 5. K.N. Raymond and C.J. Carrano, Acc. Chem. Res. vol. 12, p. 183, 1979. 6. N. Manivasakam, Industrial Water Analysis Handbook, Chemical Publishing, 2011. 7. M.K. Ahn et al., Water, vol.10, p. 54, 2018. 8. G. Tchobanoglous et al., Wastewater Engineering: Treatment and Resource Recovery (5 ed.), New York: McGraw-Hill Education, 2014.