Synthesis and Characterization of Activated Carbon Co-Mixed Electrospun Titanium Oxide Nanofibers as Flow Electrode in Capacitive Deionization

Flow capacitive deionization is a water desalination technique that uses liquid carbon-based electrodes to recover fresh water from brackish or seawater. This is a potential second-generation water desalination process, however it is limited by parameters such as feed electrode conductivity, interfacial resistance, viscosity, and so on. In this study, titanium oxide nanofibers (TiO2NF) were manufactured using an electrospinning process and then blended with commercial activated carbon (AC) to create a well distributed flow electrode in this study. Field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and energy dispersive X-ray (EDX) were used to characterize the morphology, crystal structure, and chemical moieties of the as-synthesized composites. Notably, the flow electrode containing 1 wt.% TiO2NF (ACTiO2NF 1 wt.%) had the highest capacitance and the best salt removal rate (0.033 mg/min·cm2) of all the composites. The improvement in cell performance at this ratio indicates that the nanofibers are uniformly distributed over the electrode’s surface, preventing electrode passivation, and nanofiber agglomeration, which could impede ion flow to the electrode’s pores. This research suggests that the physical mixture could be used as a flow electrode in capacitive deionization.

Development of Carbon Paste Electrode Chemically Modified with Schiff Base Complexes for Forensic Analysis of Cocaine

In this article we have studied the electrochemical behavior of cocaine hydrochloride on the surface of a carbon paste electrode chemically modified with a Schiff base complex, namely [FeIII(salen)], [ZrOII(salen)], or [NiII(salen)], during voltametric analyses. Among the tested complexes, [NiII(salen)] provided amperometric and thermal stability and it was only degraded at temperatures above 400 ºC. To prepare the cocaine hydrochloride was used hydrochloric acid (HCl 1 mol L-1) after we tested the electrode, the HCl did not cause electrode passivation. In this study we can see that the voltammetric analyses revealed a satisfactory result, that the peak current obtained between 0.1 and 0.2 V (vs. Ag/AgCl) varied linearly with cocaine hydrochloride concentration and the average amperometric sensitivity, the LOD, and the LOQ were 5.5 μmol L-1, 0.945 μmol L-1, and 3.16 μmol L-1, respectively.

Application of Electrocoagulation with a New Steel-Swarf-Based Electrode for the Removal of Heavy Metals and Total Coliforms from Sanitary Landfill Leachate

Sanitary landfill leachate (LL) composition varies according to climate variables variation, solid waste characteristics and composition, and landfill age. Leachate treatment is essentially carried out trough biological and physicochemical processes, which have showed variability in efficiency and appear a costly solution for the management authorities. Electrocoagulation (EC) seems a suitable solution for leachate treatment taking into account the characteristics of the liquor. One of the problems of EC is the electrode passivation, which affects the longevity of the process. One solution to this problem could be the replacement of the electrode by one made of recyclable material, which would make it possible to change it frequently and at a lower cost. The objective of the present work was to evaluate the removal of heavy metals (As, Ba, Cd, Cr, Cu, Fe, Pb, Mn, Ni, Se and Zn) and coliforms from a LL by EC using electrodes made from steel swarf (SfE) up to 8 h. Removal efficiencies of detected heavy metals were 51%(Cr), 59%(As), 71%(Cd), 72%(Zn), 92%(Ba), 95%(Ni) and >99%(Pb). The microbial load of coliforms in leachate was reduced from 10.76 × 104 CFU/mL (raw leachate) to less than 1 CFU/mL (after treatment with SfE) (i.e., approximately 100% reduction). The use of SfE in EC of LL is very effective in removing heavy metals and coliforms and can be used as alternative treatment solution for such effluents.

How to Improve the Performance of Electrochemical Sensors via Minimization of Electrode Passivation

It follows from critical evaluation of possibilities and limitations of modern voltammetric/amperometric methods that one of the biggest obstacles in their practical applications in real sample analysis is connected with electrode passivation/fouling by electrode reaction products and/or matrix components. This review summarizes possibilities how to minimise these problems in the field of detection of small organic molecules and critically compares their potential and acceptability in practical laboratories. Attention is focused on simple and fast electrode surface renewal, the use of disposable electrodes just for one and/or few measurements, surface modification minimising electrode fouling, measuring in flowing systems, application of rotating disc electrode, the use of novel separation methods preventing access of passivating particles to electrode surface and the novel electrode materials more resistant toward passivation. An attempt is made to predict further development in this field and to stress the need for more systematic and less random research resulting in new measuring protocols less amenable to complications connected with electrode passivation.

High-efficiency and energy-saving alternating pulse current electrocoagulation to remove polyvinyl alcohol in wastewater

Compared with DC-EC, the application of APC-EC can reduce electrode passivation and production of sludge and operating costs, and improve electrode stability and PVA removal efficiency.

Simultaneous photoadhesion and photopatterning technique for passivation of flexible neural electrodes based on fluoropolymers

Herein, we introduce a method to simultaneously photoadhere a photocrosslinkable polymer to a plasma-treated fluoropolymer while photopatterning the photocrosslinkable polymer via a single-photo-exposure as a new electrode passivation technique. Photoadhesion was determined to result from plasma-generated radicals of the plasma-treated fluoropolymer. Crystallinity of the fluoropolymer was analysed to determine the photoadhesion strength through its effects on both the formation of radicals and the etching of fluoropolymers. Passivation feasibility of simultaneous photoadhesion and photopatterning (P&P) technique were demonstrated by fabricating an Au electrocorticography electrode array and modifying the electrode with electro-deposited metallic nanoparticles. Adhesion of sputter-deposited Au to the fluoropolymer was dependent on mechanical interlocking, indicated by the formation of Au clusters which are typically influenced by the surface temperature during the sputter-deposition and the glass transition temperature of the fluoropolymer. The adhesion of Au to the fluoropolymer without an additional adhesion promotor and the proposed P&P passivation technique would help prevent detachment of the electrode and the delamination of the passivation layer in fluoropolymer-based neural electrode.