An almost exhaustive overview of the determination and remediation ofp-nitrophenol (p-NP)-contaminated media is herein presented.p-NP is one of the priority pollutants on the U.S. Environmental Protection Agency list. This is becausep-NP is either a precursor or a derivative of a good number of pollutants. It is itself very carcinogenic and tends to persist in water and soil. This has prompted the development of a wide range of analytical tools by researchers for its determination and eventual removal from contaminated sites. These include electrochemical methods with many electrode modifiers and electroanalytical procedures developed for the detection/quantification ofp-NP in contaminated environments. Also, chromatographic andp-NP uptake techniques, particularly adsorption onto various adsorbents (ranging from natural to synthetic), are reviewed. The use of microorganisms for the bioremediation ofp-NP-contaminated samples and sites has equally been largely studied and is herein overviewed, not forgetting advanced oxidative processes.

Amperometric sensors dedicated to the determination of pollutants and other compounds of interest face daily a great challenge: the development of sensitive, reproducible and low-cost devices allowing fast analyses. This review deals with the beneficial role and application of organoclays exploited as sensing materials in various fields of electroanalysis, for the past 15 years (period 2000-2014). After a description of different preparation methods leading to clay minerals chemically modified by organic compounds, the common methods used for their characterization are exposed; then, their application as electrode modifiers is described, covering several approaches that were developed to enhance either the sensitivity or the selectivity of the indexed organoclay-based sensors. Finally, a brief description of voltammetric methods frequently used for electroanalytical purposes is given, followed by an update of recent and salient results achieved for the detection of inorganic and organic electroactive compounds or ions.

Electrochemical determination of acetaminophen (APAP) was successfully performed using a carbon paste electrode (CPE) modified with coffee husks (CH-CPE). Scanning electron microscopy (SEM) and SEM-energy dispersive X-ray spectroscopy (SEM-EDX) were, respectively, used for the morphological and elemental characterization of coffee husks prior to their utilization. The electrochemical oxidation of APAP was investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV), and square wave voltammetry (SWV). SWV technique appeared to be more sensitive since the oxidation current of APAP was twofold higher with the CH-CPE sensor than with the bare CPE, in relation to the increase in the organophilic character of the electrode surface. Furthermore, on CH-CPE, the current response of APAP varied linearly with its concentration in the range of 6.6 μM to 0.5 mM, leading to a detection limit of 0.66 μM (S/N=3). Finally, the proposed CH-CPE sensor was successfully used to determine the amount of APAP in commercialized tablets (Doliprane® 500 and Doliprane 1000), with a recovery rate ranging from 98% to 103%. This novel sensor opens the way for the development of low-cost and reliable devices for the electroanalysis of pharmaceutical formulations in developing countries.

A glassy carbon electrode (GCE) coated with a thin film of organoattapulgite was used for the voltammetric detection and quantification of mangiferin (MG), a bioactive xanthone with several therapeutic properties. The used modified attapulgite was prepared by surface grafting of [3‐(2‐aminoethylamino)propyl]trimethoxysilane. The grafted clay was characterised by SEM, CHN elemental analysis, FTIR spectroscopy and XRD techniques. The electrochemical behaviour of MG was first investigated on bare GCE by cyclic voltammetry which showed a single irreversible oxidation peak at ca 0.770 V (vs Ag/AgCl) in HCl/KCl buffer at pH 1. When the GCE was covered by the organoattapulgite, the electrode response for MG increased significantly due to favourable electrostatic interactions between MG and the protonated organoclay. A sensitive voltammetric method for the determination of MG, based on adsorptive stripping voltammetry was then developed. A linear variation of MG concentration with peak current was obtained in the range from 0.61 to 10.57 μM, with a detection limit of 2.75×10−7 M (S/N=3). Kinetic and chronocoulometric studies were also performed to characterise the diffusion of MG at the organoclay modified electrode. The interfering effect of some compounds likely to affect the stripping signal of MG was also evaluated, followed by the application of the developed method to a real biological sample.

A novel tridentate Schiff base, 1-((E)-(2-mercaptophenylimino) methyl) naphthalen-2-ol (H2L1), was synthesized by the condensation reaction of 2-hydroxy-1-naphthaldehyde with 2-aminothiophenol in absolute ethanol. The resulting ligand was reacted with Co(II), Ni(II), and Cu(II) ions to obtain tetrahedral CoL1, NiL1, and square planar CuL1 complexes. The Schiff base and its metal complexes were characterized using 1H-NMR, microanalysis, FT-IR, UV-visible, and mass spectroscopy (ESI-MS). All the compounds are soluble in DMSO and DMF. Spectroscopic studies show that the ligand coordinates to the metal center through the azomethine nitrogen, naphthoxide oxygen, and thiophenoxide sulfur to form a tridentate chelate system. Conductance measurements show that these compounds are molecular in solution. Cyclic voltammetry studies show Co(III)/Co(II) and Cu(II)/Cu(I) redox systems to be quasi-reversible involving a monoelectronic transfer while Ni(III)/Ni(II) was irreversible. In vitro antibacterial and antifungal activity against five bacterial strains (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Enterococcus faecalis, and Proteus mirabilis) and five fungal strains (Candida albicans, Candida glabrata, Candida tropicalis, Candida krusei, and Candida parapsilosis) showed no antifungal activity but moderate antibacterial activity on E. coli, S. aureus, P. aeruginosa, and P. mirabilis bacterial strains. Antioxidant studies reveal that the ligand and its Cu(II) complex are more potent than Co(II) and Ni(II) complexes to eliminate free radicals.