scholarly journals Application of Hierarchical Nanostructured WO3 and Fe2O3 Composites for Photodegradation of Surfactants in Water Samples

Catalysts ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1039 ◽  
Author(s):  
Ewa Biaduń ◽  
Sylwia Gajewska ◽  
Krzysztof Miecznikowski ◽  
Beata Krasnodębska-Ostręga
Keyword(s):  
Water Samples ◽  
Anodic Stripping Voltammetry ◽  
Sodium Dodecyl ◽  
Stripping Voltammetry ◽  
Xrd Analysis ◽  
Surface Films ◽  
Layer By Layer ◽  
Layer System ◽  
Water Contact ◽  
Mercury Electrodes

This study describes the utilization of hierarchical photoactive surface films for the decomposition of surfactants in water samples (with different pH). Photoactive films, containing tungsten (VI) oxide and iron (III) oxide (hematite), were deposited in a systematic and controlled manner using a layer-by-layer method. Physicochemical properties of the photoactive materials were developed and characterized using XRD analysis, Raman spectroscopy, water contact angle, voltammetry, and microscopic (SEM) techniques. The resulting multilayer films showed attractive performances in the photodegradation of the anionic surfactant sodium dodecyl sulfate (SDS) and the nonionic surfactant (1,1,3,3-tetramethylbutyl)phenyl-polyethylene glycol (Triton™ X-144) under solar light irradiation. The efficiency of the surfactants’ photodegradation was evaluated with a “test” based on a method, which is extremely sensitive to surfactants’ interference, with trace analysis of Pb using anodic stripping voltammetry on mercury electrodes (recovery study). The usefulness of hierarchical photoactive systems in the photodegradation of both surfactants is demonstrated in the presence and absence of the applied bias voltage. The maximum decomposition times were 2–3 h and 30 min, respectively. Furthermore, a properly designed layer system may be proposed, matching the pH of the water sample (depending on the treatment on the sampling side).

scholarly journals Nafion-Protected Sputtered-Bismuth Screen-Printed Electrode for On-site Voltammetric Measurements of Cd(II) and Pb(II) in Natural Water Samples

Sensors ◽  
2019 ◽  
Vol 19 (2) ◽  
pp. 279 ◽  
Author(s):  
Samuel Frutos-Puerto ◽  
Conrado Miró ◽  
Eduardo Pinilla-Gil
Keyword(s):  
Natural Water ◽  
Water Samples ◽  
Inductively Coupled Plasma ◽  
Surface Characterization ◽  
Anodic Stripping Voltammetry ◽  
Detection Limits ◽  
Reference Method ◽  
Stripping Voltammetry ◽  
Natural Water Samples ◽  
Screen Printed

In this work, we explore the protection with Nafion of commercial sputtered-bismuth screen-printed electrodes (BiSPSPEs), to improve its ability for on-site determination of Cd(II) and Pb(II) ions in ambient water samples. The modified screen-printed platform was coupled with a miniaturized cell, in combination with a battery-operated stirring system and a portable potentiostat operated by a laptop for decentralized electrochemical measurements using Square-Wave Anodic Stripping Voltammetry (SWASV). We also describe a detailed electrode surface characterization by microscopy and surface analysis techniques, before and after the modification with Nafion, to get insight about modification effect on signal size and stability. Optimization of the chemical composition of the medium including the optimization of pH, and instrumental parameters, resulted in a method with detection limits in the low ng/mL range (3.62 and 3.83 ng·mL−1 for Cd and Pb respectively). Our results show an improvement of the sensitivity and stability for Nafion-protected BiSPSPEs in pH = 4.4 medium, and similar or lower detection limits than comparable methods on commercial BiSPSPEs. The values obtained for Pb(II) and Cd(II) in natural water samples agreed well with those obtained by the much more costly Inductively Coupled Plasma Mass Spectrometry, ICP-MS, technique as a reference method (recoveries from 75% to 111%).

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