Ultrasonic aided synthesis of a novel mesoporous cobalt-based metal-organic framework and its application in Cr(III) ion determination in centrum multivitamin and real water samples

Abstract

A novel Co-based metal organic framework (Co-MOF) was applied as an electroactive material in carbon paste electrode for determination of Cr(III) ion with high selectivity and sensitivity. This Co-MOF was established by transforming the monoclinic structure of the Schiff base as a linker into a 3-D Co-MOF tetragonal system using the cobalt ion as a node under a 1.5:1 M ratio between the Schiff base and cobalt ion by using sonochemical synthesis under optimal conditions. Many characteristic tools were used to test the newly synthesized Co-MOF. The Co-MOF would have a nanometric, mesoporous character (average particle size 45–73 nm and pore diameter 5.0467 nm), 270.201 m2g−1 surface area, and hydrophobicity (average contact angle = 143.23°). Because of its large surface area, porous structure, and electrocatalytic behavior, metal organic framework is a fascinating material to use as an ionophore. This newly synthesized Co-MOF ionophore has been used to determine Cr(III) ions in a variety of samples with high accuracy and precision (RSD % = 0.75–2.55) and the data illustrated a concord with those acquired by atomic absorption spectroscopy (AAS). The proposed carbon paste electrode showed a Nernstian slope of 19.96 ± 0.53 mV decade-1 with a detection limit of 4.3 × 10-9 mol L-1, covering a linear range of 5.0 × 10-9 – 1.0 × 10-2 mol L-1 and fast response time of (<10 s) with long-time stability of 2 months over pH range of 3.0 – 6.2. The proposed sensor was highly selective for Cr(III) ions, and the values of selectivity coefficients assessed using the fixed interference method (FIM) and the separate solution method (SSM) which were long recognized.