A magnetic nano-biocomposite based on calcined Ni-Fe layered double hydroxide and chitosan as an adsorbent for cadmium(II)

A novel magnetic nano-biocomposite (MNBC) was introduced as an adsorbent for a dispersive magnetic solid-phase extraction procedure. The synthesis of the MNBC is based on the co-precipitation of Ni(II) and Fe(III) ions as their hydroxide forms via a simple hydrothermal method, calcination of the obtained Ni-Fe layered double hydroxide, and hybridation of the resultant NiO-NiFe2O4 MNC with chitosan nanoparticles. After prosperous synthesis and characterization of the MNBC, it was applied as an effectual adsorbent for the extraction and pre-concentration of cadmium ions (Cd(II)) from aqueous solutions followed by flame atomic absorption spectrometry detection. The essential factors affecting the extraction recovery were investigated and optimized. According to the method validation, the method's linear dynamic range was from 0.2 to 30 ng mL(-1) with a determination coefficient of 0.9996, and the limit of detection was calculated to be 0.02 ng mL(-1). The precision of the method in terms of intra-day and inter-day relative standard deviations (n = 6) with a concentration of 20 ng mL(-1) Cd(II) were 1.42% and 2.11%, respectively. The developed method's accuracy was confirmed by analysis of a certified reference sample. The developed method was applied for the determination of Cd(II) in various water and industrial wastewater samples. The satisfactory relative recovery values between 97.6 and 103.9% were achieved for the spiked samples, confirming the ignorable matrix effect and successive applicability of the method.