Multifunctional system based on hybrid nanostructured rod formation, for sensoremoval applications of Pb2+ as a model toxic metal

Abstract

A new and simple multifunctional system based on hybrid calcite–poly(ethyleneimine) (PEI) nanostructured rod (NR) formation, which shows as a proof-of-concept the sensing and removal (sensoremoval concept) of Pb²⁺ as a model toxic metal for environmental applications, has been developed. The addition of Na₂CaEDTA and Na₂CO₃ solutions to Pb²⁺ contaminated water leads to the crystallization of calcite–PEI NRs. These NRs are composed of self-assembled hexagonal plate-like shapes of around 450 nm. The formed calcite–PEI NRs in suspension permit Pb²⁺ detection, through a simple turbidimetric measurement, and at the same time act as a Pb²⁺ remover. This sensing and removal system is able to detect up to 1 ppm Pb²⁺ (1–1000 ppm linear range) and reaches an adsorption capacity of 240 mg Pb²⁺ per g of NRs, as evaluated using a 342 ppm initial Pb²⁺ concentration at pH 4 after 30 min incubation time. The maximum Pb²⁺ removal capacity reported here is higher than other capacities reported previously, using materials that are not as cheap and biodegradable as calcite. The Pb²⁺ detection range found for this system is suitable to evaluate levels of metal contamination from industrial wastewater of around 1–100 ppm. This system based on an advanced biodegradable material constitutes a useful tool as a proof-of-concept in the design of future multifunctional platforms for the development of integrated environmental technologies with sensing and remediation functions.