Oxidative Degradation Of 4-chlorophenol Research Articles

A Novel Integration of CWPO Process with Fe3O4@C and Sonication for Oxidative Degradation of 4-Chlorophenol

A Novel Integration of CWPO Process with Fe3O4@C and Sonication for Oxidative Degradation of 4-Chlorophenol

Efficient Fenton-like treatment of high-concentration chlorophenol wastewater catalysed by Cu-Doped SBA-15 mesoporous silica

Effective treatment for industrial wastewater that contains high concentration of chlorophenols is urgent and indispensable for environmental governance and human health due to their nonbiodegradable, carcinogenic and cytotoxic properties. Four kinds of Cu-containing mesoporous silica materials were utilized to catalyse Fenton-like treatment of high-concentration chlorophenols wastewater (1.0 g L−1). All of chlorophenols in various water matrices could be oxidatively decomposed in 35 min with the catalysis of Cu-doped SBA-15. Cu-doped SBA-15 with a Cu/Si molar ratio of 0.133 had the best catalytic activity in the oxidative degradation of 4-chlorophenol with an apparent reaction rate constant of 0.170 min−1 which was 1.3–3.6 times higher than those with other Cu-containing catalysts. After 300 min reaction, total organic carbon content of 4-chlorophenol solution declined continuously to 23.8% with an advisable utilization efficiency of H2O2 of 26.5%–68.4%. Electron spin resonance tests and quenching experiments demonstrated that Cu-doped SBA-15 had a selective catalytic activity in the decomposition of H2O2 into hydroxyl radicals which dominated the degradation of chlorophenols in wastewater. The redox of Cu(II)/Cu(I) in Cu-doped SBA-15 occurred efficiently, which could be attributed to chemical adsorption and electron transformation of organic molecular fragments onto Lewis acidic sites formed by the incorporation of Cu2+ ions in SBA-15. The biological toxicity of the treated 4-CP wastewater declined significantly in comparison with that of the original wastewater. Our work provided an effective way of the heterogeneous treatment of high-concentration chlorophenol wastewater.

Dechlorination and oxidative degradation of 4-chlorophenol with nanostructured iron-silver alginate beads

In this work, bimetallic zerovalent iron-silver nanoparticles (NZVI-Ag) immobilized in calcium alginate beads were prepared and characterized. This material was tested as catalyst in the dechlorination and oxidation of 4-chlorophenol (CP-4). The bimetallic nanoparticles showed average size and BET surface area around 80nm and 22m2g−1, respectively, with morphology and crystallinity typical of nanometric metallic iron. 4-CP dechlorination was more efficient at pH 3 than at pH 5 and at the former was completed in 30min. Further addition of H2O2 allowed high TOC reduction, quite similar to the obtained with the bare metallic nanoparticles but with lower metal leaching.

Elimination of 4-chlorophenol in aqueous solution by the bimetallic Al–Fe/O2 at normal temperature and pressure

Oxidative degradation of 4-chlorophenol in aqueous solution at normal temperature and pressure by the bimetallic Al–Fe/O2 was investigated. The proposed main mechanism, verified by the addition of methanol and benzoic acid as OH scavenger and the detection of para-hydroxybenzoic acid, involves the in situ generation of H2O2 by the electron transfer from ZVAl to O2, and the Fenton reaction occurring within ZVI and H2O2. The effects of initial pH, concentration of 4-chlorophenol and ethylenediaminetetraacetic acid, Fe0 content and Al–Fe loading were investigated. The results showed that the bimetallic Al–Fe/O2 process exhibited higher reactivity than ZVAl/O2 and ZVI/O2 process and the 50mgL−1 of 4-CP could be completely degraded in 2h with the 100:1 mass ratio of Al and Fe. EDTA significantly enhanced the degradation of 4-CP with the optimized 1:1 mass ratio of Al and Fe while its appropriate initial concentration needed to be optimized. The degradation pathway of 4-CP in Al–Fe/O2 may only follow 4-chlorocatechol pathway, while it may contain hydroquinone pathway in Al–Fe/O2+EDTA.

Sonophotocatalytic degradation of 4-chlorophenol using Bi 2O 3/TiZrO 4 as a visible light responsive photocatalyst

The oxidative degradation of 4-chlorophenol (4-CP) by sonolytic, photocatalytic and sonophotocatalytic processes was studied in aqueous solutions using Bi 2O 3/TiZrO 4 as a visible light driven photocatalyst and with 20 kHz ultrasound. The results reveal that Bi 2O 3/TiZrO 4 is an efficient photocatalyst capable of degrading 4-CP by both photocatalytic and sonophotocatalytic processes. During the sonolysis of 4-CP solutions, HPLC results showed the formation of a number of intermediate products, whereas, no such intermediates were formed during the sonophotocatalytic degradation of 4-CP. TOC results showed rapid mineralization of 4-CP during the sonophotocatalytic degradation process, relative to that observed with sonolysis alone. The results reveal a clear advantage in using a coupled method for the oxidation of 4-CP and a cumulative effect was observed. Further, the solution pH had no specific influence on the sonophotocatalytic degradation of 4-CP, unlike the situation for sonolysis alone where the degradation rate decreased as the pH was raised from acidic to basic conditions. The combined sonophotocatalytic degradation process was found to be simple to apply and has the potential to be a powerful method for the remediation of organic contaminants present in water and wastewater.

The Influence of the Inorganic Species on Oxidative Degradation of 4-chlorophenol by Photo-Fenton Type Process

An experimental study on 4-chlorophenol (4-CP) degradation in aqueous solutions by advanced oxidation process photo-Fenton type is presented. The efficiency of the oxidation process is determined by the very high oxidative potential of the OH. radicals generated by catalytic and photo-catalytic processes. The presence of the inorganic species inside the reaction medium influences the rate of the oxidation process as function of their nature and concentration. The inorganic anionic species reduce drastically the 4-CP oxidation efficiency by Fe2+/3+ complexing processes, HO. radicals scavenging effect or iron precipitate forming. The decrease of the 4-CP oxidation degree is correlated with the nature of the anions as following: Cl- ] PO43- ] SO42- ]] NO3-. The presence of the insoluble inorganic species (bentonite) modifies the oxidation efficiency by additional 4-CP and UV sorption processes, especially at high solution turbidity values.

Oxidative Degradation of 4-chlorophenol in Aqueous Induced by Plasma with Submersed Glow Discharge Electrolysis

The oxidative degradation of 4-chlorophenol (4-CP) in aqueous solution induced by plasma with submersed glow discharge has been investigated. The concentration of 4-CP and the reaction intermediates were determined by high performance liquid chromatography (HPLC). Various influencing factors such as the initial pH, the concentration of 4-CP and the catalytic action of Fe2+ were examined. The results indicate that 4-CP is eventually degraded into inorganic ion, dioxide carbon and water. The attack of hydroxyl radicals on the benzene rings of 4-CP in the initial stage of oxidative reactions is presumed to be a key step. They also suggest that the reaction is of a pseudo-first order kinetic reaction and the proposed method is an efficient way for the 4-CP degradation.

Degradation of 4-Chlorophenol, 3,4-Dichloroaniline, and 2,4,6-Trinitrotoluene in an Electrohydraulic Discharge Reactor

An electrohydraulic discharge (EHD) process for the treatment of hazardous chemical wastes in water has been developed. The liquid waste in a 4-L EHD reactor is directly exposed to high-energy pulsed electrical discharges between two submerged electrodes. The high-temperature (>14 000 K) plasma channel created by an EHD emits ultraviolet radiation and produces an intense shockwave as it expands against the surrounding water. The oxidative degradation of 4-chlorophenol (4-CP), 3,4-dichloroaniline (3,4-DCA), and 2,4,6-trinitrotoluene (TNT) in an EHD reactor was explored. The initial rates of degradation for the three substrates are described by dC/dN = −k1Ci − k0, where dC/dN is the change in concentration per discharge; Ci is the initial substrate concentration; k0 is the zero-order term that accounts for direct photolysis; and k1 is the first-order term that accounts for oxidation in the plasma channel region. For 4-CP in the 4-L reactor, the values of these two rate constants are k0 = 0.73 ± 0.08 μM disc...