Oxidation of Chlorophenols in Aqueous Solution by Excess Potassium Permanganate

Abstract

A simple spectrophotometric method was developed to quantify chlorophenol (CP) concentrations after reaction with potassium permanganate and quenching with sodium sulfite. Other quenching agents (peroxide, sodium thiosulfate and hydroxylamine hydrochloride) were found to create absorbance in the spectral range required for CP quantification. Analysis at pH 12 gave greater absorption and sensitivity for the method compared with pH 5.6. The calibration curves of the proposed methods were linear in the concentration ranges 0.0061-0.61 and 0.0078-0.78 mM with detection limit of 0.0006 and 0.0008 mM for dichlorophenols and monochlorophenols, respectively. The oxidation kinetics of five chlorophenols in aqueous solution with excess potassium permanganate were evaluated using the analytical method. The pseudo-first-order reaction rates were found to be relatively rapid 1.42× 10 −3 to 0.024 s −1 and followed the sequence 2-chlorophenol (2-CP) > 2,6-dichlorophenol (2,6-DCP)> 4-chlorophenol (4-CP) > 2,4-dichlorophenol (2, 4-DCP)>3-chlorophenol (3-CP). The apparent second-order rate constant was calculated from the measured pseudo-first-order rate constant with respect to CP with initial KMnO 4 concentration (1.5 mM) and follows the same sequence of pseudofirst-order rate constant. This shows that chlorine atoms in the structure of chlorophenol had a significant influence on the oxidation of chlorophenols by potassium permanganate. Permanganate can be used for the treatment of chlorophenolcontaminated soil and groundwater.

Kinetics study on the oxidation of chlorophenols by permanganate

“…4 also reveal that the reaction rates of the CPs present different sequences under different pH conditions. The sequence of 2,4,6-TCP > 2,4-DCP > 4-MCP (p < 0.05) is always valid under acidic conditions, which is different to that of 2-MCP > 2,6-DCP > 4-MCP > 2,4-DCP > 3-MCP at pH 5.3-6.2 as reported by Hossain and McLaughlan [20]. The rate order is 2,4-DCP > 2,4,6-TCP > 4-MCP at pH 7.0 in the present study, which is also different to those of 4-MCP > 2,4-DCP > 2,6-DCP at pH 7.2 and 2.6-DCP > 2,4,6-TCP > 2,4-DCP > 2-MCP > 4-MCP at pH 7.0 achieved by Zhang et al [21] and by He et al [19], respectively.…”

“…2, the k 2 value at 25˚C of 2.53, 5.14, and 20.23 M −1 s −1 can be calculated for 4-MCP, 2,4-DCP, and 2,4,6-TCP, respectively. [20].…”

“…However, the reported reaction kinetics for oxidation of them is inconsistent. For example, pseudo-first-order reaction rates were reported as 2,6-DCP > 2,4,6-trichlorophenol (TCP) > 2,4-DCP > 2-MCP > 4-MCP by He et al [19], while others found the following order of 2-MCP > 2,6-DCP > 4-MCP > 2,4-DCP > 3-MCP [20]. Actually, pH has an important effect on permanganate oxidation of phenolic compounds and therefore on their reaction rates.…”

Oxidation of Chlorophenols by MnO&lt;sub&gt;2&lt;/sub&gt; Supported on Kaolinite

“…These commonly used oxidants are ozone, Fenton, potassium permanganate, manganese dioxide, etc. [6,7,8]. Previous studies showed that MnO 2 have an excellent performance in the removal of bisphenol A (BPA), bromophenols, Pb(Ⅱ) and Cd(Ⅱ), fluoride, etc.…”

Oxidation of cefazolin by potassium permanganate: Transformation products and plausible pathways

“…There have been reports that Mn(VII) could oxidize a wide range of emerging environmental micropollutants, such as chlorophenol, ciprofloxacin, lincomycin, triclosan, estradiol, bisphenol A and sulfamethoxazole (Gao et al, 2014;Liu et al, 2009;Hossain and McLaughlan, 2012;Hu et al, 2011;Zhang et al, 2013;Jiang et al, 2012). On the other hand, researchers have reported the degradation of cephalosporins by UV photocatalysis, ozonation and chlorination (Dodd et al, 2010;Pugazhenthiran et al, 2013;Biçer et al, 2013;Li et al, 2013).…”