Removal of 4-chlorophenol from wastewater using a pilot-scale advanced oxidation process

Revista de Chimie, 2008

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.

Journal of Hazardous Materials, 2006

This study reports the photodegradation of 4-chlorophenol (4-CP) in aqueous solution by the photo-Fenton process using solar irradiation. The influence of solution path length, and Fe(NO3)3 and H2O2 concentrations on the degradation of 4-CP is evaluated by response surface methodology. The degradation process was monitored by the removal of total organic carbon (TOC) and the release of chloride ion. The results showed a very important role of iron concentration either for TOC removal or dechlorination. On the other hand, a negative effect of increasing solution path length on mineralization was observed, which can be compensated by increasing the iron concentration. This permits an adjustment of the iron concentration according to the irradiation exposure area and path length (depth of a tank reactor). Under optimum conditions of 1.5 mM Fe(NO3)3, 20.0 mM H2O2 and 4.5 cm solution path length, 17 min irradiation under solar light were sufficient to reduce a 72 mg C L−1 solution of 4-CP by 91%.

Journal of Engineering

The degradation and mineralization of 4-chlorophenol (4-CP) by advanced oxidation processes (AOPs) was investigated in this work, using both of UV/H2O2 and photo-Fenton UV/H2O2/Fe+3 systems.The reaction was influenced by the input concentration of H2O2, the amount of the iron catalyst, the type of iron salt, the pH and the concentration of 4-CP. A colored solution of benzoquinon can be observed through the first 5 minutes of irradiation time for UV/H2O2 system when low concentration (0.01mol/L) of H2O2 was used. The colored solution of benzoquinon could also be observed through the first 5 minutes for the UV/H2O2/Fe+3 system at high concentration (100ppm) of 4-CP. The results have shown that adding Fe+3 to the UV/H2O2 system enhanced the rate of 4-CP oxidation at a molar ratio of H2O2/Fe+3/4-CP equals to 13/0.4/1 by a factor of 7. This reduced the consumption of H2O2 by a factor of 6 and the irradiation time required for complete degradation was reduced by a factor of 6. The experim...

2009

The removal efficiency of 4-chlorophenol with different advanced oxidation processes have been studied. Oxidation experiments were carried out using two 4-chlorophenol concentrations: 100 mg L-1 and 250 mg L-1 and UV generated from a KrCl excilamp with (molar ratio H2O2: 4-chlorophenol = 25:1) and without H2O2, and, with Fenton process (molar ratio H2O2:4- chlorophenol of 25:1 and Fe2+ concentration of 5 mg L-1). The results show that there is no significant difference in the 4- chlorophenol conversion when using one of the three assayed methods. However, significant concentrations of the photoproductos still remained in the media when the chosen treatment involves UV without hydrogen peroxide. Fenton process removed all the intermediate photoproducts except for the hydroquinone and the 1,2,4-trihydroxybenzene. In the case of UV and hydrogen peroxide all the intermediate photoproducts are removed. Microbial bioassays were carried out utilising the naturally luminescent bacterium Vib...

Background: This research studied the effect of UV light on pentachlorophenol (PCP) removal in the electro-Fenton (EF) process. Methods: PCP was used as the pollutant in this study. The effects of Fenton's reagent, i.e. hydrogen peroxide concentration, solution pH, and treatment time by EF (EF) and photoelectro-Fenton (PEF) processes, were studied to determine rates of PCP removal. The results showed that a better performance and a high removal efficiency were achieved by coupling UV radiation and the EF process. Results: EF processes required more time to remove PCP, while after a reaction time of 10 minutes, the PEF achieved a removal efficiency of 90.4%; this value is higher than the maximum efficiency of the EF process (83.44% after 40 minutes). The kinetic mechanisms of both processes were examined and compared. The rate constants at optimum conditions were 0.0455 and 0.0579 min −1 for EF and PEF processes, respectively. Conclusion: Removal efficiency was obtained in the order of PEF > EF.

2003

The study explores the utility of the electro-Fenton process for the degradation of o-chlorophenol (o-CP) from aqueous solution. The extent of degradation of o-CP is found to be a function of applied current, electrolysis time, concentration of o-CP and concentration of ferrous ions. Under optimized conditions it is possible to achieve efficiencies higher than 70%. Accelerating the regeneration of Fe2+ ions in the electrolyte determines the efficiency of the process.

Chemosphere, 2002

The photo-Fenton process using potassium ferrioxalate as a mediator was investigated for the photodegradation of dichloracetic acid (DCA) and 2,4-dichlorophenol (DCP) in aqueous medium using solar light as source of irradiation. The influence of the solution depth, the light intensity and the effect of stirring the solution during irradiation process were evaluated using DCA as a model compound. A negligible influence of stirring the solution was observed when the concentration of ferrioxalate (FeOx) was 0.8 mM and solution depth was 4.5 or 14 cm. The optimum FeOx concentration determined for solution depths between 4.5 and 14 cm was 0.8 mM considering total organic carbon (TOC) removal during DCA irradiation. The high efficiency of the photo-Fenton process was demonstrated on summer days, when only 10 min of exposition (around noon) were sufficient to completely destroy the organic carbon of a 1.0 mM DCA solution in the presence of 0.8 mM FeOx and 6.0 mM H2O2 using a solution depth of 4.5 cm. It was observed that the photodegradation efficiency increases linearly with the solar light intensity up to values around 15 W m−2 but this linear relationship does not hold above this value showing a square root dependence. The photodegradation of a solution of DCP/FeOx showed a lower TOC removal rate than that observed for DCA/FeOx, achieving ∼90% after 35 min irradiation under 19 W m−2, while under this light intensity, the same TOC removal of DCA/FeOx was achieved in only 10 min irradiation.

Journal of Hazardous Materials, 2011

A central composite rotatable design and response surface methodology (RSM) were used to optimize the experimental variables of the solar photoelectro-Fenton (SPEF) treatment of the herbicide 4-chloro-2-methylphenoxyacetic acid (MCPA). The experiments were made with a flow plant containing a Pt/air-diffusion reactor coupled to a solar compound parabolic collector (CPC) under recirculation of 10 L of 186 mg L −1 MCPA solutions in 0.05 M Na 2 SO 4 at a liquid flow rate of 180 L h −1 with an average UV irradiation intensity of about 32 W m −2 . The optimum variables found for the SPEF process were 5.0 A, 1.0 mM Fe 2+ and pH 3.0 after 120 min of electrolysis. Under these conditions, 75% of mineralization with 71% of current efficiency and 87.7 kWh kg −1 TOC of energy consumption were obtained. MCPA decayed under the attack of generated hydroxyl radicals following a pseudo-first-order kinetics. Hydroxyl radicals also destroyed 4-chloro-2-methylphenol, methylhydroquinone and methyl-p-benzoquinone detected as aromatic by-products. Glycolic, maleic, fumaric, malic, succinic, tartronic, oxalic and formic acids were identified as generated carboxylic acids, which form Fe(III) complexes that are quickly photodecarboxylated by the UV irradiation of sunlight at the CPC photoreactor. A reaction sequence for the SPEF degradation of MCPA was proposed. (E. Brillas).

Korean Journal of Chemical Engineering, 2018

Photocatalytic degradation of 4-chlrophenol (4-CP) using UVA-LED assisted persulfate and hydrogen peroxide activated by the nZVI (Nano Zero Valent Iron) in a batch photocatalytic reactor was investigated. The reaction involved a lab-scale photoreactor irradiated with UVA-LED light emitted at 390 nm. The efficiency of the reaction was evaluted in terms of 4-CP degradation and mineralization degree at different pH of solution, initial concentrations of nZVI, persulfate, hydrogen peroxide and 4-CP. In UVA-LED/H 2 O 2 /nZVI process, complete degradation of 4-CP (>99%) and 75% mineralization was achieved at pH of 3, hydrogen peroxide concentration of 0.75 mM, nZVI dosage of 1 mM and initial 4-CP concentration of 25 mg/L at the reaction time of 30 min. The optimum conditions obtained for the best 4-CP degradation rate were at an initial concentration of 25 mg/l, persulfate concentration of 1.5 mM, nZVI dosage of 1 mM, pH of 3 and reaction time of 120 min for UVA-LED/persulfate/nZVI process. It was also observed that the 4-CP degradation rate is dependent on initial 4-CP concentrations for both processes. The pseudofirst-order kinetic constant at 25 mg/L initial concentration of 4-CP was found to be 1.4×10 -1 and 3.8×10 -2 in UVA-LED/H 2 O 2 /nZVI and UVA-LED/persulfate/nZVI processes, respectively. Briefly, the UVA-LED/H 2 O 2 /nZVI process enhanced the degradation rate of 4-CP by 3.67-times in comparison to UVA-LED/persulfate/nZVI process at 30 min contact time, which serves as a new and feasible approach for the degradation of 4-CP as well as other organic contaminants containing wastewater.

International Journal of Environmental Health Engineering, 2013

In this study, the efficiency of several advanced oxidation processes such as ultrasonic oxidation, heterogeneous Fenton-like oxidation, ultrasound or UV assisted heterogeneous Fenton-like oxidation, heterogeneous sonophotoFenton oxidation and oxidation with ultrasound+UV light combination was tested for COD reduction in effluents of purified terephthalic acid (PTA) production. The highest COD removal was achieved as 18% when UV light assisted heterogeneous Fenton-like oxidation was applied to PTA manufacturing wastewater in the presence of 5 wt% iron containing TiO2 catalyst. This combined advanced oxidation process seems to be a promising one to enhance the COD removal when it is used after biological treatment.