# Deep eutectic solvent-impregnated cellulose triacetate matrix as a dual- function platform for selective preconcentration and colorimetric detection of Ni(II) ions

“Deep eutectic solvent-impregnated cellulose triacetate matrix as a dual- function platform for selective preconcentration and colorimetric detection of Ni(II) ions” (2026), by Nisha Yadav et al. Chemistry research paper. Original abstract below, unchanged. A free PDF is available.

- Authors: Nisha Yadav, Kalyan Yakkala, Ashok K. Pandey
- Published: October 27, 2026
- Field: Chemistry
- DOI: https://doi.org/10.21203/rs.3.rs-11280337/v1
- Free PDF: https://www.researchsquare.com/article/rs-11280337/latest.pdf

## Abstract

Monitoring of Ni(II) in environmental waters is essential given its toxicity and widespread occurrence, yet conventional analytical techniques are equipment-intensive, time-consuming and poorly suited to routine monitoring. This study reports a colorimetric membrane optode for Ni(II). The optode was fabricated by immobilizing a deep eutectic solvent (DES), prepared from tetrabutylammonium chloride and decanoic acid (1:1 mole ratio), together with 1-(2-pyridylazo)-2-naphthol (PAN) in a cellulose triacetate (CTA) matrix. The DES acted as both extractant and plasticizer, so no separate additives were needed. At the optimized pH of 6, the membrane changed from yellow to magenta within 30 min, with maximum absorbance at 568 nm. The optode exhibited a linear response over 0.05–2.5 µg/mL Ni(II), with a detection limit of 0.03 µg/mL, and showed good selectivity over competing ions. FTIR, DSC, TGA, FESEM-EDX and AFM confirmed hydrogen bonding within the DES, the thermal stability of the membrane and the uptake of Ni(II) in the optode matrix. Results for river water, industrial wastewater, electroplating wastewater and open-drain water agreed with ICP-MS, with deviations of 1.25–9.72% for spiked samples. The DES–CTA optode therefore offers a simple, selective platform for the simultaneous preconcentration and optical detection of Ni(II) in water samples.

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