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3 pages, 189 KiB

Open AccessEditor’s ChoiceEditorial

Environment-Friendly Electrochemical Processes

by Carlos A. Martínez-Huitle

Materials 2021, 14(6), 1548; https://doi.org/10.3390/ma14061548 - 22 Mar 2021

Cited by 6 | Viewed by 1758

Abstract

The present water crisis is probable to grow worse in the coming decades, and this has motivated the scientific community to identify innovative, safe, and robust water treatment technologies at a lower cost and with less energy, diminishing the use of chemicals and [...] Read more.

The present water crisis is probable to grow worse in the coming decades, and this has motivated the scientific community to identify innovative, safe, and robust water treatment technologies at a lower cost and with less energy, diminishing the use of chemicals and impact on the environment [...] Full article

(This article belongs to the Special Issue Environment-Friendly Electrochemical Processes)

Research

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17 pages, 3815 KiB

Open AccessEditor’s ChoiceArticle

Applicability of Cork as Novel Modifiers to Develop Electrochemical Sensor for Caffeine Determination

by Mayra K. S. Monteiro, Djalma R. Da Silva, Marco A. Quiroz, Vítor J. P. Vilar, Carlos A. Martínez-Huitle and Elisama V. Dos Santos

Materials 2021, 14(1), 37; https://doi.org/10.3390/ma14010037 - 24 Dec 2020

Cited by 20 | Viewed by 2684

Abstract

This study aims to investigate the applicability of a hybrid electrochemical sensor composed of cork and graphite (Gr) for detecting caffeine in aqueous solutions. Raw cork (RAC) and regranulated cork (RGC, obtained by thermal treatment of RAC with steam at 380 °C) were [...] Read more.

This study aims to investigate the applicability of a hybrid electrochemical sensor composed of cork and graphite (Gr) for detecting caffeine in aqueous solutions. Raw cork (RAC) and regranulated cork (RGC, obtained by thermal treatment of RAC with steam at 380 °C) were tested as modifiers. The results clearly showed that the cork-graphite sensors, GrRAC and GrRGC, exhibited a linear response over a wide range of caffeine concentration (5–1000 µM), with R² of 0.99 and 0.98, respectively. The limits of detection (LOD), estimated at 2.9 and 6.1 µM for GrRAC and GrRGC, suggest greater sensitivity and reproducibility than the unmodified conventional graphite sensor. The low-cost cork-graphite sensors were successfully applied in the determination of caffeine in soft drinks and pharmaceutical formulations, presenting well-defined current signals when analyzing real samples. When comparing electrochemical determinations and high performance liquid chromatography measurements, no significant differences were observed (mean accuracy 3.0%), highlighting the potential use of these sensors to determine caffeine in different samples. Full article

(This article belongs to the Special Issue Environment-Friendly Electrochemical Processes)

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22 pages, 6848 KiB

Open AccessArticle

A New Cr³⁺ Electrochemical Sensor Based on ATNA/Nafion/Glassy Carbon Electrode

by Reda M. El-Shishtawy, Mohammed M. Rahman, Tahir Ali Sheikh, Muhammad Nadeem Arshad, Fatimah A. M. Al-Zahrani and Abdullah M. Asiri

Materials 2020, 13(12), 2695; https://doi.org/10.3390/ma13122695 - 12 Jun 2020

Cited by 13 | Viewed by 3083

Abstract

A new electrochemical sensor of metal cation in an aqueous solution based on homobifunctional tridentate disulfide Schiff base and named 1,1′-(-((disulfanediylbis(2,1-phenylene))bis(azaneylylidene))bis(methaneylylidene))bis(naphthalene-2-ol) (ATNA) was easily obtained quantitatively from the condensation reaction of 2-hydroxy-1-naphthaldehyde and 2-aminothiophenol, and then fully characterized by spectroscopic techniques for [...] Read more.

A new electrochemical sensor of metal cation in an aqueous solution based on homobifunctional tridentate disulfide Schiff base and named 1,1′-(-((disulfanediylbis(2,1-phenylene))bis(azaneylylidene))bis(methaneylylidene))bis(naphthalene-2-ol) (ATNA) was easily obtained quantitatively from the condensation reaction of 2-hydroxy-1-naphthaldehyde and 2-aminothiophenol, and then fully characterized by spectroscopic techniques for structure elucidation. The molecular structure of ATNA was also confirmed by a single-crystal X-ray diffraction study to reveal a new conformation in which the molecule was stabilized by the O–H…N type intramolecular hydrogen bonding interactions in both moieties. The ATNA was used as a selective electrochemical sensor for the detection of chromium ion (Cr³⁺). A thin film of ATNA was coated on to the flat surface of glassy carbon electrode (GCE) followed by 5 % ethanolic Nafion in order to make the modified GCE (ATNA/Nafion/GCE) as an efficient and sensitive electrochemical sensor. It was found to be very effective and selective against Cr³⁺ cations in the company of other intrusive heavy metal cations such as Al³⁺, Ce³⁺, Co²⁺, Cu²⁺, Ga³⁺, Hg²⁺, Mn²⁺, Pb²⁺, and Y³⁺. The detection limit at 3 S/N was found to be 0.013 nM for Cr³⁺ ions within the linear dynamic range (LDR) (0.1 nM–10.0 mM) of Cr³⁺ ions with r² = 0.9579. Moreover; this work instigates a new methodology for developing the sensitive as well as selective electrochemical toxic cationic sensors in the field of environmental and health care. Full article

(This article belongs to the Special Issue Environment-Friendly Electrochemical Processes)

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8 pages, 3080 KiB

Open AccessCommunication

A Novel Electrochemical Process for Desulfurization in the CaO-SiO₂-Al₂O₃ System

by Sang Hoon Lee and Dong Joon Min

Materials 2020, 13(11), 2478; https://doi.org/10.3390/ma13112478 - 29 May 2020

Cited by 11 | Viewed by 1971

Abstract

The effect of electric potential on the sulfide capacity of the CaO-SiO₂-Al₂O₃ system was evaluated by applying voltages in the range of −1.5 to 1.5 V at 1823 K in a C/CO gas equilibrium. When the cathodic potential [...] Read more.

The effect of electric potential on the sulfide capacity of the CaO-SiO₂-Al₂O₃ system was evaluated by applying voltages in the range of −1.5 to 1.5 V at 1823 K in a C/CO gas equilibrium. When the cathodic potential (−1.5 to 0 V) was applied, it was confirmed that the sulfur partition ratio increased based on the electrochemical reaction of sulfur (S + 2e⁻ = S²⁻). However, the reversibility of the electrochemical resulfurization reaction (S²⁻ = S + 2e⁻) in slag was not established in the reverse (anodic) potential region (0–1.5 V), yet the sulfur partition ratio increased. In particular, sulfur evaporation was observed in the anodic potential region. Therefore, in the present study, potential anodic electro-desulfurization mechanisms based on sulfur evaporation are proposed. To verify these mechanisms, sulfur evaporation is discussed in detail as a function of the thermodynamic stability of sulfur in the slag. Full article

(This article belongs to the Special Issue Environment-Friendly Electrochemical Processes)

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17 pages, 3628 KiB

Open AccessArticle

Electro-Oxidation–Plasma Treatment for Azo Dye Carmoisine (Acid Red 14) in an Aqueous Solution

by Héctor Barrera, Julián Cruz-Olivares, Bernardo A. Frontana-Uribe, Aarón Gómez-Díaz, Pedro G. Reyes-Romero and Carlos E. Barrera-Diaz

Materials 2020, 13(6), 1463; https://doi.org/10.3390/ma13061463 - 23 Mar 2020

Cited by 20 | Viewed by 3208

Abstract

Currently, azo dye Carmoisine is an additive that is widely used in the food processing industry sector. However, limited biodegradability in the environment has become a major concern regarding the removal of azo dye. In this study, the degradation of azo dye Carmoisine [...] Read more.

Currently, azo dye Carmoisine is an additive that is widely used in the food processing industry sector. However, limited biodegradability in the environment has become a major concern regarding the removal of azo dye. In this study, the degradation of azo dye Carmoisine (acid red 14) in an aqueous solution was studied by using a sequenced process of electro-oxidation–plasma at atmospheric pressure (EO–PAP). Both the efficiency and effectiveness of the process were compared individually. To ascertain the behavior of azo dye Carmoisine over the degradation process, the variations in its physical characteristics were analyzed with a voltage–current relationship, optical emission spectra (OES) and temperature. On the other hand, chemical variables were analyzed by finding out pH, electrical conductivity, absorbance (UV/VIS Spectrophotometry), chemical oxygen demand (COD), cyclic voltammetry (CV), energy consumption and cost. The sequenced process (EO–PAP) increased degradation efficiency, reaching 100% for azo dye Carmoisine (acid red 14) in 60 min. It was observed that the introduction of small quantities of iron metal ions (Fe²⁺/Fe³⁺) as catalysts into the plasma process and the hydrogen peroxide formed in plasma electrical discharge led to the formation of larger amounts of hydroxyl radicals, thus promoting a better performance in the degradation of azo dye. This sequenced process increased the decolorization process. Full article

(This article belongs to the Special Issue Environment-Friendly Electrochemical Processes)

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12 pages, 5800 KiB

Open AccessArticle

Effect of Ultrasonic Parameters on Electrochemical Chloride Removal and Rebar Repassivation of Reinforced Concrete

by Qingyang Liu, Zijian Song, Huanchun Cai, Aiping Zhou, Wanyi Wang, Linhua Jiang, Yongqi Liu, Yingjie Zhang and Na Xu

Materials 2019, 12(17), 2774; https://doi.org/10.3390/ma12172774 - 29 Aug 2019

Cited by 5 | Viewed by 2316

Abstract

Electrochemical chloride removal (ECR) from reinforced concrete can be considered as an environment-friendly technique since it can reduce the environmental issues arising from demolition and reconstruction. In this study, we used ultrasonic waves to promote the ECR efficiency without increasing the current density [...] Read more.

Electrochemical chloride removal (ECR) from reinforced concrete can be considered as an environment-friendly technique since it can reduce the environmental issues arising from demolition and reconstruction. In this study, we used ultrasonic waves to promote the ECR efficiency without increasing the current density so as to shorten the overall power-on time, lowering the power consumption and electricity-induced material damage. Rebar-embedded cement mortar specimens were prepared and a set of ultrasonic-assisted ECR test devices was designed. For obtaining the optimal parameters, different ultrasonic frequencies and powers were adopted to conduct the ECR test. After that, the discharged and residual chloride ion amounts were detected to characterize the ECR efficiency. The corrosion behavior of rebar was characterized by electrochemical method. It was found that ultrasonic waves can not only promote the discharge of chloride ions, but also promote the passivation process of steel bar. For this investigation, the ultrasonic waves with a frequency of 40 Hz and a power of 60 W had the best auxiliary effect and could reduce the work time by 64%. It is considered that the ultrasound-assisted method has potential to promote the application possibilities of the ECR technique. Full article

(This article belongs to the Special Issue Environment-Friendly Electrochemical Processes)

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16 pages, 2805 KiB

Open AccessArticle

Electrochemical Oxidation/Disinfection of Urine Wastewaters with Different Anode Materials

by Sondos Dbira, Nasr Bensalah, Mohammad I. Ahmad and Ahmed Bedoui

Materials 2019, 12(8), 1254; https://doi.org/10.3390/ma12081254 - 16 Apr 2019

Cited by 48 | Viewed by 4500

Abstract

In the present work, electrochemical technology was used simultaneously for the deactivation of microorganisms and the destruction of micro-pollutants contained in synthetic urine wastewaters. Microorganisms (E. coli) were added to synthetic urine wastewaters to mimic secondary treated sewage wastewaters. Different anode [...] Read more.

In the present work, electrochemical technology was used simultaneously for the deactivation of microorganisms and the destruction of micro-pollutants contained in synthetic urine wastewaters. Microorganisms (E. coli) were added to synthetic urine wastewaters to mimic secondary treated sewage wastewaters. Different anode materials were employed including boron-doped diamond (BDD), dimensionally stable anode (DSA: IrO₂ and RuO₂) and platinum (Pt). The results showed that for the different anode materials, a complete deactivation of E. coli microorganisms at low applied electric charge (1.34 Ah dm⁻³) was obtained. The complete deactivation of microorganisms in wastewater seems to be directly related to active chlorine and oxygen species electrochemically produced at the surface of the anode material. Complete depletion of COD and TOC can be attained during electrolyses with BDD anode after the consumption of specific electric charges of 4.0 and 8.0 Ah dm⁻³, respectively. Higher specific electric charges (>25 Ah dm⁻³) were consumed to removal completely COD and about 75% of TOC during electrolyses with DSA anodes (IrO₂ and RuO₂). However, the electrolysis using Pt anode can partially remove and even after the consumption of high specific electric charges (>40 Ah dm⁻³) COD and TOC did not exceed 50 and 25%, respectively. Active chlorine species including hypochlorite ions and chloramines formed during electrolysis contribute not only to deactivate microorganisms but also to degrade organics compounds. High conversion yields of organic nitrogen into nitrates and ammonium were achieved during electrolysis BDD and DSA anodes. The results have confirmed that BDD anode is more efficient than with IrO₂, RuO₂ and Pt electrodes in terms of COD and TOC removals. However, higher amounts of perchlorates were measured at the end of the electrolysis using BDD anode. Full article

(This article belongs to the Special Issue Environment-Friendly Electrochemical Processes)

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Review

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24 pages, 4134 KiB

Open AccessReview

Coupling of Anodic Oxidation and Soil Remediation Processes: A Review

by Maiara Barbosa Ferreira, Aline Maria Sales Solano, Elisama Vieira dos Santos, Carlos A. Martínez-Huitle and Soliu O. Ganiyu

Materials 2020, 13(19), 4309; https://doi.org/10.3390/ma13194309 - 27 Sep 2020

Cited by 19 | Viewed by 3271

Abstract

In recent years, due to industrial modernization and agricultural mechanization, several environmental consequences have been observed, which make sustainable development difficult. Soil, as an important component of ecosystem and a key resource for the survival of human and animals, has been under constant [...] Read more.

In recent years, due to industrial modernization and agricultural mechanization, several environmental consequences have been observed, which make sustainable development difficult. Soil, as an important component of ecosystem and a key resource for the survival of human and animals, has been under constant contamination from different human activities. Contaminated soils and sites require remediation not only because of the hazardous threat it possess to the environment but also due to the shortage of fresh land for both agriculture and urbanization. Combined or coupled remediation technologies are one of the efficient processes for the treatment of contaminated soils. In these technologies, two or more soil remediation techniques are applied simultaneously or sequentially, in which one technique complements the other, making the treatment very efficient. Coupling anodic oxidation (AO) and soil remediation for the treatment of soil contaminated with organics has been studied via two configurations: (i) soil remediation, ex situ AO, where AO is used as a post-treatment stage for the treatment of effluents from soil remediation process and (ii) soil remediation, in situ AO, where both processes are applied simultaneously. The former is the most widely investigated configuration of the combined processes, while the latter is less common due to the greater diffusion dependency of AO as an electrode process. In this review, the concept of soil washing (SW)/soil flushing (SF) and electrokinetic as soil remediation techniques are briefly explained followed by a discussion of different configurations of combined AO and soil remediation. Full article

(This article belongs to the Special Issue Environment-Friendly Electrochemical Processes)

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