Oxidation of Phenol in Acidic Aqueous Suspensions of Manganese Oxides

Abstract

Abstract--Phenol (benzenol) oxidation by three synthetic manganese oxides (buserite, manganite, and feitknechtite) has been studied in aerated, aqueous, acidified suspensions. The rate of reaction was pH dependent. Oxidation was greatly enhanced below pH 4, when diphenoquinone and p-benzoquinone were identified as the first products. Initial reaction rate was correlated with standard reduction potential (E ~ of the oxides following the order: feitknechtite > manganite > buserite. A more gradual process of phenol oxidation after the initial reaction was influenced by electrochemical properties of the solution. High soluble manganese activity and increase in pH adversely affected reaction rates. Thus, the reactivity of the oxides was related to their stability and possibly the ability to readsorb Mn(II), following the order: buserite > manganite > feitknechtite. The results indicate that thermodynamic and electrochemical data for oxides and phenols are useful in predicting under which conditions phenols can be oxidized by a given system.

Removal of phenol from aqueous phase by using neutralized red mud

“…The supernatant solution was analyzed for residual concentration of phenol at λ max = 500 nm using spectrophotometry by the 4-aminoantipyrene method [25] as follows; 0.5 mL of 4-aminoantipyrene was added into supernatant solution. After mixing the solution, 0.5 mL of K 3 Fe(CN) 6 was added into the solution and mixed again. After 15 min, spectrophotometric determination was carried out.…”

“…Dutta et al [3] classified the treatment processes for phenolic wastewater into two principal categories: destructive process such as destructive oxidation with ozone [4], hydrogen peroxide [5], or manganese oxides [6], and recuperative processes such as adsorption [7] and membrane separation [8].…”

The removal of phenol from aqueous solutions by adsorption using surfactant-modified bentonite and kaolinite

“…Different water treatment technologies are used to remove phenolic pollutants: destructive process such as destructive oxidation with ozone [4], hydrogen peroxide [5], or manganese oxides [6] and recuperative process such as adsorption into porous solids [7,8], membrane separation [9] and solvent extraction [10].…”

Photoelectrochemical performance of birnessite films and photoelectrocatalytic activity toward oxidation of phenol

“…Without external potential, no obvious degradation was detected. It has been reported that phenol oxidation by manganese oxide usually occurs at pH < 4 (Ukrainczyk, 1992). In our experiment, initial pH was fixed at 6.0, and direct oxidation of phenol was negligible.…”

“…In the course of the reaction, the phenol absorbance band became weak and finally disappeared after 8 hr. An absorption peak at 245 nm, typical for p-benzoquinone (Ukrainczyk, 1992;Drozd et al, 2014), appeared from 2 to 6 hr and finally the p-benzoquinone band became indistinguishable after 8 hr, indicating that p-benzoquinone might be an intermediate degradation. Besides, the TOC values of samples before and after PEC oxidation were calculated to be 10.20 and 4.54 mg/L, respectively, corresponding to a TOC removal of about 55.5%.…”