Preparation of a coated Ti anode for producing acidic electrolyzed oxidizing water

Degradation of Dibutyl Phthalate Plasticizer in Water by High-Performance Iro2-Ta2O5/Ti Electrocatalytic Electrode

Dibutyl phthalate (DBP) in the presence of a wastewater system is harmful to the environment and interferes with the human’s endocrine system. For wastewater treatment, DBP is very difficult to be decomposed by biotechniques and many catalytic processes have been developed. Among them, the electrocatalytic oxidation (EO) technique has been proven to possess high degradation efficiency of various organic compounds in wastewater. In this study, an electrocatalytic electrode of iridium-tantalum/titanium (IrO2-Ta2O5/Ti) was employed as the anode and graphite as the cathode to decompose DBP substances in the water. According to experimental results, the high removal efficiency of DBP and total organic carbon (TOC) of 90% and 56%, respectively, could be obtained under a voltage gradient of 10 V/cm for 60 min. Compared with other photocatalysis degradation, the IrO2-Ta2O5/Ti electrode could shorten about half the treatment time and electric power based on the same removal efficiency of DBP (i.e., photocatalysis requires 0.225~0.99 KWh). Results also indicated that the production of hydroxyl radical (•OH) in the electrocatalytic electrode played a key role for decomposing the DBP. Moreover, the pH and conductivity of water containing DBP were slightly changed and eventually remained in a stable state during the EO treatment. In addition, the removal efficiency of DBP could still remain about 90% after using the IrO2-Ta2O5/Ti electrode three times and the surface structure of the IrO2-Ta2O5/Ti electrode was stable.

Electrochemical oxidation of aniline using Ti/RuO2-SnO2 and Ti/RuO2-IrO2 as anode

Electrocatalytic properties of anode and the electrolyte composition are important parameters influence the degradation efficiency for aniline wastewater. Ti/RuO₂-SnO₂ and Ti/RuO₂-IrO₂ have been fabricated using thermal decomposition method and experiments in electrolyte containing 0.05 M Na₂SO₄, 0.05 M NaCl and 0.05 M Na₂SO₄+0.005 M FeSO₄ at different current density were conducted to study the influence on aniline degradation. Linear sweep voltammetry (LSV) showed that Ti/RuO₂-SnO₂ had higher oxygen evolution potential and degrade aniline through electrochemical transformation and electrochemical combustion while Ti/RuO₂-IrO₂ degrade aniline mainly through electrochemical transformation. The study showed that Ti/RuO₂-SnO₂ had higher electrocatalytic activity towards the degradation of aniline than Ti/RuO₂-IrO₂ anode in 0.05 M Na₂SO₄ and in 0.05 M NaCl electrolyte. The maximum TOC removal efficiency for Ti/RuO₂-SnO₂ was 64.2% at 40 mA cm^-2 in Na₂SO₄ electrolyte while the average MCE was 1.6% and the average EC_TOC was 1.51 kWh (g TOC)^-1. On the contrary, the maximum TOC removal efficiency for Ti/RuO₂-IrO₂ was 63.1% at 40 mA cm^-2 in NaCl electrolyte while the average MCE was 1.6% and the average EC_TOC was 1.95 kWh (g TOC)^-1. The presence of Fe²⁺ in Na₂SO₄ electrolyte would decrease the TOC removal efficiency except at low current density (20 mA cm^-2) for Ti/RuO₂-SnO₂. These results indicated that Ti/RuO₂-SnO₂ and Ti/RuO₂-IrO₂ anode were suitable in Na₂SO₄ and NaCl electrolyte, respectively, while the presence of Fe²⁺ would inhibit aniline degradation.

Effect of platinum electrode materials and electrolysis processes on the preparation of acidic electrolyzed oxidizing water and slightly acidic electrolyzed water

Electrolyzed oxidizing water (EOW) can be divided into acidic electrolyzed oxidizing water (AEOW) and slightly acidic electrolyzed water (SAEW). AEOW has the characteristics of low pH (pH < 2.7) and high oxidation-reduction potential (ORP > 1100 mV). SAEW is slightly acidic (pH = 5-6) and has an ORP of 700-900 mV. AEOW and SAEW both have a certain amount of active chlorine content (ACC), so they have the characteristics of broad spectrum, rapidity and high efficiency of sterilization. At present, there is little systematic research on AEOW and SAEW preparation. However, it is very important to study the preparation process, including electrode material and electrolytic process. First, the effects of Pt electrodes with different thermal decomposition temperatures on AEOW's pH, ORP and ACC values were investigated in detail. Next, for the SAEW preparation, the process is based on the preparation of AEOW by ion-exchange membrane electrolysis, reasonably mixing the electrolyzed cathode and anode solution. The effects of technological conditions such as electrolysis time, current density and electrolyte concentration have been systematically studied, and it is expected to get SAEW with a pH value slightly less than 7, a higher ORP value and a certain amount of ACC.

Effectiveness of Sensors Contact Metallization (Ti, Au, and Ru) and Biofunctionalization for Escherichia coli Detection

In designing a bacteria biosensor, various issues must be addressed: the specificity of bacteria recognition, the immobilization of biomolecules that act as the bacteria receptor, and the selectivity of sensor surface. The aim of this paper was to examine how the biofunctionalized surface of Ti, Au, and Ru metals reacts in contact with strains of Escherichia coli (E. coli). The focus on metal surfaces results from their future use as electrodes in high frequency biosensors, e.g., resonant circuits or transmission-line sections. First, the surfaces of different metals were chemically functionalized with 3-aminopropyltriethoxysilane (APTES) and glutaraldehyde or with 3-glycidylooxypropyltrimethoxysilane (GPTMS) followed by N-(5-amino-1-carboxypentyl) iminodiacetic acid (AB-NTA) and NiCl₂. Secondly, the lipopolysaccharide binding protein (LBP), polyclonal anti-Escherichia coli antibody and bacteriophage protein gp37 were tested as bacteria receptors. The selectivity and specificity have been confirmed by the Enzyme-Linked Immunosorbent Assay (ELISA) and visualized by scanning electron microscopy at low landing energies. We noticed that LBP, polyclonal antibody, and gp37 were successfully immobilized on all studied metals and recognized the E. coli bacteria selectively. However, for the antibody, the highest reactivity was observed when Ti surface was modified, whereas the bacteria binding was comparable between LBP and gp37 on the functionalized Ru surfaces, independent from modification. Thus, all surfaces were biocompatible within the scope of biosensor functionality, with titanium functionalization showing the best performance.

Development of Portable Flow-Through Electrochemical Sanitizing Unit to Generate Near Neutral Electrolyzed Water

We developed a portable flow-through, electrochemical sanitizing unit to produce near neutral pH electrolyzed water (producing NEW). Two methods of redirecting cathode yields back to the anode chamber and redirecting anode yields the cathode chamber were used. The NEW yields were evaluated, including: free available chlorine (FAC), oxidation-reduction potential (ORP), and pH. The performances of 2 electrodes (RuO₂ -IrO₂ /TiO₂ and IrO₂ -Ta₂ O₅ /TiO₂ ) were investigated. The unit produced NEW at pH 6.46 to 7.17, an ORP of 805.5 to 895.8 mV, and FAC of 3.7 to 82.0 mg/L. The NEW produced by redirecting cathode yields had stronger bactericidal effects than the NEW produced by redirecting anode yields or NEW produced by mixing the commercial unit's anode and cathode product (P < 0.05). Electron spin resonance results showed hydroxyl free radicals and superoxide anion free radicals were present in the NEW produced by developed unit. The NEW generator is a promising sanitizing unit for consumers and the food industry to control foodborne pathogens.

PRACTICAL APPLICATION

Current commercial NEW-producing units are quite large and are not convenient for family using. The developed portable flow-through, NEW-producing unit has great potential in a wide range of applications, such as organic farm, households, and small food industries. The examined sanitizing treatments showed effective control of Escherichia coli O157:H7 and Listeria monocytogenes.

Effect of electrode material and electrolysis process on the preparation of electrolyzed oxidizing water

The efficient preparation of EO water can be controlled by different electrode materials and electrolysis processes.

Preparation of electrolyzed oxidizing water with a platinum electrode prepared by magnetron sputtering technique

EO water has the maximum value of available chlorine content when prepared by the Pt-MS electrode due to its good selectivity for CER.