Controllable growth of flower-like hierarchical CoNiO2 nanoflakes anchored on Nitinol fiber substrate with good selectivity for highly efficient solid-phase microextraction of polycyclic aromatic hydrocarbons in water

Abstract

The flower-like hierarchical cobalt nickel oxide nanoflakes (CoNiO2NFs) with a porous structure were fabricated on Nitinol (NiTi) fiber substrate by a hydrothermal reaction and subsequent annealing treatment. The morphology affected by the molar ratios of Ni to Co and counter ions in starting precursors as well as hydrothermal reaction temperature and time was investigated in detail. The obtained CoNiO2NFs coating exhibited outstanding performance for the selective extraction of PAHs. After optimizing the main parameters that affected extraction through orthogonal experiments, the developed method showed good linearity in the ranges of 0.05 μg L−1 - 200 μg L−1 with the determination coefficient >0.999. LODs were between 0.006 μg L−1 and 0.114 μg L−1, LOQs were in the ranges of 0.020–0.376 μg L−1 and RSDs were below 5.19% and 5.71% for intra-day and inter-day analyses, respectively. The developed method was successfully applied to selective enrichment and determination of target PAHs in real water samples. Moreover, the fabricated fiber exhibited high chemical and mechanical stability, and could withstand more than 260 extraction-desorption cycles without loss of its extraction efficiency.