Papers by Keyword: Advanced Oxidation Process (AOP)

Abstract: Reactive Blue (RB 19), also known as Remazol brilliant blue, is a widely-used colorant in various textile applications. RB 19 is very resistant to chemical oxidation due to its aromatic anthraquinone structure highly stabilized by resonance. Its relatively low fixation efficiency (75-80%) attributed to the competition between the formation of the reactive form (vinyl sulfone) and the hydrolysis reaction, results in its prevalence in textile wastewater discharges. In this study, electro-Fenton (EF) process, a popular advanced oxidation process (AOP) was used to treat RB 19 dye-containing simulated wastewater. The electrochemical reactor (0.5 L) used in all experiments had parallel plate/mesh electrodes coated with metal oxides. Synthetic textile wastewater was prepared by dissolving RB 19 dye (300 ppm) in distilled water. The effects of pH, initial [Fe²⁺], initial [H₂O₂] and current on RB 19 decolorization efficiency were investigated. Removal of 100 percent RB 19 was achieved at pH 2, 0.71 mM initial [Fe²⁺], 5 mM initial [H₂O₂] and 1.86 A in 20 minutes. High decolorization efficiencies and absence of sludge during the treatment process render the electro-Fenton process a viable treatment option for dye wastewaters.

Abstract: This study evaluated and optimized the UV/ chlorine process for natural organic matters (NOMs) removal using response surface methodology (RSM). The effects of both the primary and secondary interactions of the reaction variables, including initial chlorine concentration (X₁), UV radiation time (X₂) and pH value (X₃), were examined. A satisfactory prediction response model (R²=0.999) was obtained, indicating the reliability of the methodology. The optimum condition obtained by CCD were 4.5 mg·L^-1 initial chlorine concentration, 7 min UV radiation time and pH 6.7. Under the optical condition, the maximum TOC removal was 48% and TOC concentration was only 2.6 mg·L^-1. The UV/ chlorine process as a novel AOP has many advantages for drinking water treatment, in terms of less chemical consumption, shorter reaction time and simpler technology.

Abstract: The efficacy of the UV-H₂O₂ treatment to degrade the antibiotic chloramphenicol (CHL) was investigated at 20 °C using a low-pressure mercury lamp as UV source. A two-level factorial design was used to study the effects of initial CHL (c₀ = 4080 mg L¹) and H₂O₂ (h₀ = 2050 mM) concentrations, reaction time (t = 3070 min) and irradiance level (I = 400800 μW cm²) on CHL degradation. Under the best conditions (c₀ = 40 mg L¹, h₀ = 20 mM, t = 70 min, I = 800 μW cm²), almost 96% of the antibiotic was degraded. No residual antibiotic activity was detected in the treated solution, thereby confirming the efficacy of the UV-H₂O₂ process.

Abstract: Oxidative degradation of ethylenediaminetetraacetic acid (EDTA) in aqueous solution at room temperature and pressure by the bimetallic Al-Fe/O₂ process, which was verified by the addition of benzoic acid as ·OH scavenger and the detection of para-hydroxybenzoic acid, was investigated. The results showed that the removal efficiency of EDTA, TOC and TN could be about 98%, 77.5% and 43% respectively after 3h reaction when the initial pH was 5. The effects of initial pH, concentration of EDTA, mass ratio of Al⁰ and Fe⁰ and Al-Fe loading were also investigated. Significantly, the bimetallic Al-Fe process exhibited higher reactivity than monometallic Fe⁰/Al⁰ process for the degradation of EDTA when the mass ratio of Al⁰ and Fe⁰ ranged from 0.11 to 2.97.

Abstract: Oxidative degradation of ethylenediaminetetraacetic acid in aqueous solution at normal temperature and pressure by the bimetallic Fe-Cu, which was verified by ESR spectroscopy, was investigated. The results showed that the removal efficiency of EDTA, TOC and TN could be about 99%, 60% and 39% respectively after 3h reaction. The degradation products were iminodiacetate, formate and acetate. The effects of initial pH, concentration of EDTA, Cu content and Fe-Cu loading were also investigated. Significantly, the bimetallic Fe-Cu process exhibited higher reactivity than monometallic Fe⁰ process for the degradation of EDTA and it would not cause new heavy metal pollution in effluent.

Abstract: NiTi is alloy that has unique properties include shape memory dan superelasticity. However, it has disadvantages which cause allergic and toxicity to the body from the Ni release. In order to reduce Ni release and increase corrosion resistance an Electropolishing Pretreatment-Photoelectrocatalytic Oxidation (EP-PEO) and Advanced Oxidation Process (AOP) coating were synthesized in order to produce TiO₂. Scanning Electron Microscope (SEM) was depicted various morphologies of NiTi orthodontic wire surface. Ni release experiment in various saliva by using Inductively Coupled Plasma (ICP) was shown reducing Ni release significantly both in saliva pH 3 dan pH 6.25 in AOP coating for 2 months monitoring. This results confirmed that the Ni release was evidently decreased and the corrosion resistance significantly improved after coated with AOP.

Abstract: The synthetic dyes are a refractory and poisonous material. Most of industrial textile today used the synthetic dyes that can be dangerous to the environment because of the colored wastewater produced from their processes. This study concentrates on the application of Advanced Oxidation Processes (AOPs) for synthetic dyes wastewater treatment. Photocatalysis process as one of AOPs was applied for the degradation of organic content of synthetic dyes wastewater. The reactive dye, C.I. Reactive Red 2 (RR 2) was used as the organic pollutant model at the concentration of 100 mg/l. The TiO₂ concentration of 0.05-0.4 g/ml was used as the photocatalyst. The bulk and nanosize of TiO₂ were coating on the PET plastic and the degradation of organic content was examined in the term of color and COD within 0-12 hrs under solar irradiation. By using 0.4 g/ml of bulk TiO₂, the color degradation of 88% and COD removal of 46% was achieved. Furthermore, by using 0.4 g/ml of nanosize TiO₂, the enhancement of color degradation and COD removal was observed, that is 98% and 56%, respectively.

Abstract: Phosphorus is one of the main pollutants in glyphosate wastewater. In order to remove the phosphorus in the effluent, two units including CaO precipitation and advanced oxidation processes (AOPs) were used to degrade inorganic phosphate and organic phosphorus in the wastewater. It is found that in the precipitation process the removal rate of TP is 79% when 1g CaO is added to 100ml glyphosate wastewater, while the removal rate of TP is almost 99% when advanced oxidation processes are implemented after the second disposal unit.

Abstract: Oxidative degradation of ethylenediaminetetraacetic acid(EDTA) in aqueous solution at normal temperature and pressure by the novel bimetallic Al-Fe was investigated. The results showed that the removal efficiency of EDTA, TOC and TN could be about 98%, 75% and 47% respectively after 3h reaction. The effects of initial pH, concentration of EDTA, mass ratio of Al⁰ and Fe⁰ and Al-Fe loading were also investigated. Significantly, the bimetallic Al-Fe process exhibited higher reactivity than monometallic Fe⁰/Al⁰ process for the degradation of EDTA.

Abstract: In the present scenario, the problem of water pollution is remarkable. The need to maintain clean water for both flora and fauna has become a major, even a critical concern. A large number of organic substances are introduced into the natural water system from various sources such as industrial effluents, agricultural runoff and chemical spills. Textiles industries specifically pollute the water sources due to the random use and discharge of various types of dyes. It may significantly affect photosynthetic activity in aquatic life and their presence in drinking water constitutes a potential human health hazard. It is therefore essential either to remove the dyes from water or to treat them in such a way so as to minimize their effects on the environment and also to decolorize the water. Various research works on different processes are reviewed and discussed in the present article. It has been observed that the advanced oxidation processes are used widely to degrade the organic compounds in water. Photocatalytic systems are effective for the degradation of many unwanted complex organic compounds through the use of efficient nanophotocatalysts activated under ultra-violet (UV) irradiation.