Preparation of MWCNT/CoMn2O4 nanocomposite for effectual degradation of picric acid via peroxymonosulfate activation

In recent years, using nanomaterials based on multi-wall carbon nanotubes (MWCNT) through the activation of peroxymonosulfate (PMS) has attracted more attention to the degradation of organic pollutants. This research presented a new route for the synthesis of MWCNT/CoMn2O4 nanocomposite for the degradation of picric acid using advanced oxidation processes (AOPs). Firstly, CoMn2O4 nanoparticles were prepared and then loaded on MWCNT using ultrasonic waves. The results of various analyzes confirmed the successful loading of nanoparticles on carbon nanotubes. As the degradation process proceeds through oxidation processes, the high electronic conductivity of MWCNT and the active sites of Mn and Co in the nanocomposite play an essential role in activating PMS to generate reactive oxygen species (ROS). An investigation of the reaction mechanism in different conditions showed that the highest speed of picric acid decomposition in the presence of nanocomposite (98%) was in 47 min. However, the scavenger test showed that HO· and SO4·- radicals are more important in the degradation process. Meanwhile, the results showed that removing picric acid using MWCNT/CoMn2O4 was more effective than CoMn2O4 alone and confirmed the interaction effect of MWCNT nanotubes with AB2O4 nanocatalyst.

o-Toluidine in electrochemistry – an overview

The substituted aromatic amine o-toluidine (2-methylaniline, 1-amino-2-methylbenzene) is frequently encountered in electrochemical research as a soluble corrosion inhibitor dissolved in aqueous media used e.g., in cooling systems, as a homomonomer for formation of intrinsically conducting poly-o-toluidine and as a comonomer in formation of respective copolymers and their composites. The obtained polymers are suggested as corrosion protection coatings, as active materials in devices for electrochemical energy storage, but more frequently, they are examined as active components in electrochemical sensors.

The significant and pronounced carcinogenicity of o-toluidine has hardly been addressed; presumably, most researchers are not even aware of this property. After a brief summary of the health risks and effects, the following overview presents typical examples of said studies and applications. If possible, substitutes with lower health risks are proposed, at least further studies enabling such replacement are suggested.

Development of nano-immunosensor with magnetic separation and electrical detection of Escherichia coli using antibody conjugated Fe3O4@Ppy

Detection of bacterial pathogens is the need of the hour due to the increase in antibiotic resistance and the infusion of multi-drug-resistant parasites. The conventional strategies such as ELISA, PCR, and MNP based tests for the detection are efficient but they are cost, time, lab, and manpower intensive. Thus, warranting a simple and effective technique for rapid detection of bacterial pathogens. Magnetic nanoparticles (NPs) have proved to be better alternatives for separation of bacterial pathogens from a variety of sample sources. However, the use of magnetic NPs has not been successful in the detection of these parasites. The current work involves the coating of magnetic NPs (Fe₃O₄) with a conducting polymer (polypyrrole; Ppy) to facilitate simultaneous separation and detection. Electrical (conductivity) measurement was the mode of choice due to the sensitivity, accuracy, and ease it offers. To enhance the conductivity, carboxylic groups were expressed on the Fe₃O₄@Ppy complex and to ensure specificity, E. coli specific antibodies were conjugated. The resulting complex at various process parameters was characterized using FTIR, VSM, and SEM. SEM images were recorded to ensure bacterial separation at optimal process parameters. The impedance analysis and conductivity measurements were carried out for the sample volume of 15 μl. The bacterial suspension from 10¹-10⁶ CFU ml^-1 was successfully detected with a limit of detection of 10 CFU ml^-1 within 10 min using a simplistic detection method.

Potentiometric extractive sensing of lead ions over a nickel oxide intercalated chitosan-grafted-polyaniline composite

The present research paper reports the extractive potentiometric sensing of lead ions over a chemically functionalized ternary nanocomposite of nickel oxide intercalated chitosan grafted polyaniline (NiO-in-CHIT-g-PANI) prepared by the in situ chemical polymerization and composite formation technique under optimized conditions. The structural, morphological, and physical properties of the composite material were investigated by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and other suitable ASTM methods. The obtained analytical result suggests the formation of a porous hybrid composite matrix with better electrical conductivity ∼ 5.25 × 10^-3 S cm^-1, free interactive carbonyl sites, and evolved aligned crystallinity. Furthermore, a film of the synthesized composite was cast on ITO coated glass by the spin coating technique for potentiometric sensing and the recovery of adsorbed Pb²⁺ ions from natural and artificial water solutions. Under optimum conditions of ∼pH = 7.0 and a temperature of 25 °C, the electrode exhibited potential responses for Pb²⁺ ions in concentrations ranging from 1.0 × 10^-6 M to 1 × 10^-3 M along with a sensitivity of 0.2379 mV μM^-1 cm^-2, response time of 40 s, recovery time of 10 s, and stability for 64 days. The adsorbed Pb²⁺ ions were recovered at a rate of 84% after applying an optimized reverse voltage on the above-used electrodes. The adsorption and desorption mechanism has been explained based on the induced potential due to the electrochemical surface interaction between Pb²⁺ and the NiO-in-CHIT-g-PANI based electrode. The analytical application of the fabricated electrode in the real sample was also explored for the sensing and recovery of the respective metal ions in wastewater samples along with the possibility of optimization of the required metal concentrations.

Highly selective heteroaromatic sulfur containing polyamides for Hg+2 environmental remediation

Environmental remediation concerns about pollution and contamination removal from environmental media, such as soil, air, or surface water. Enormous efforts have been applied in metal removal from surface water. In this study, four novel heteroaromatic sulfur-containing polyamides 6a-d carry both types of aliphatic and aromatic species in their polymer backbones as selective adsorbents for Hg+2 metal ion from aqueous solution have been synthesized in considerable amounts. The polycondensation method at low temperature is used as a simple and low coast polymerization technique. This occurred by the interaction of the thiophene-based monomer 5 with different diacid chlorides of both types. Beforehand the polymerization, the structures of monomer 5 were confirmed by spectral and elemental analyses. Also, the structures of the new polymers were investigated by both spectral and elemental analysis; besides their solubility, GPC data, XRD diffraction patterns, thermal analysis, and FE-SEM micrographs. The synthesized polymers were freely soluble in polar protic solvents due to the presence of heteroaromatic sulfur functional groups. Furthermore, the analytical competition of the new polymers has been tested using inductively coupled plasma-optical emission spectrometry (ICP-OES) for its selective extraction across different metal ions. Polymer 6c was the most selective toward Hg+2 and considered as a highly selective adsorbent for Hg+2 environmental remediation among all derivatives and its adsorption detection and efficiency were also investigated. Polymer 6c showed the most effective adsorption quantity on its surface at pH = 1. Moreover, the calculated adsorption isotherm showed a typical isotherm to the Langmuir adsorption type. This showed that the adsorption capacity of polymer 6c for Hg+2 was 47.95 mg g-1. These novel polymers are serving as simple and inexpensive heavy metal ions adsorbent materials from drinking water and wastewater.