Electrochemical identification of hazardous phenols and their complex mixtures in real samples using unmodified screen-printed electrodes

Synthesis of MRGO@ZIF-7-Based Molecular Imprinted Polymer by Surface Polymerization for the Fast and Selective Removal of Phenolic Endocrine-Disrupting Chemicals from Aqueous Environments

In this study, Zn(NO3)2·6H2O was selected as the metal source, and ZIF-7-modified magnetic graphene-based matrix materials (MRGO@ZIF-7) were prepared by in situ growth. ZIF-7 modified magnetic graphene-based molecular imprinting complexes (MRGO@ZIF7-MIP) were successfully synthesized by a surface molecular imprinting technique using bisphenol A (BPA) as the template molecule. The obtained experimental materials were characterized by X-ray diffraction (XRD), Brunner–Emmet–Teller (BET) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), and X-ray photoelectron spectroscopy (XPS). The proper adsorption and selective recognition ability of the MRGO@ZIF7-MIP were studied by an equilibrium adsorption method. The obtained MRGO@ZIF7-MIP showed significant molecular recognition of bisphenol A (BPA) and good selectivity and reproducibility for BPA in different aqueous environments such as drinking water, river water, and lake water. These properties make this material potentially applicable for the efficient removal of phenolic endocrine disruptors in real water environments.

A high-performance electrochemical sensor based on a mesoporous silica/titania material and cobalt(II) phthalocyanine for sensitive pentachlorophenol determination

The synthesis and characterization of a novel titania/silica hybrid xerogel subsequently modified with 4-methylpyridine (4-Pic), named TiSi4Pic⁺Cl^- is reported. The physicochemical, structural and thermal properties of TiSi4Pic⁺Cl^- were characterized using several techniques. Anchoring cobalt(II) phthalocyanine (CoTsPc) in TiSi4Pic⁺Cl^- showed greater electroanalytical sensitivity over other sensors built with these materials. A novel electroanalytical method was developed to quantify the noxious biocide pentachlorophenol (PCP) for environmental monitoring. The peak current intensity increased linearly with the analyte concentration in the range between 0.99 and 4.21 μmol L^-1, based on the oxidation process (at + 0.81 V, vs. Ag/AgCl) of differential pulse voltammetry (DPV). The estimated limit of detection (LOD) was 29 nmol L^-1. Recovery tests in environmental samples showed a PCP concentration of 2.05 ± 0.03 μmol L^-1 (n = 3). The method was statistically validated by comparing the PCP concentrations with those obtained by molecular absorption spectrometry and high-performance liquid chromatography-diode array detection (HPLC-DAD). At a 95% confidence level, no difference between the results was found, therefore confirming the excellent accuracy of the proposed method.