Kinetic investigations of quinoline oxidation by ferrate(VI)

Abstract

Quinoline is considered as one of the most toxic and carcinogenic compounds and is commonly found in industrial wastewaters, which require treatment before being discharged. Removal of quinoline by the use of an environmentally friendly oxidant, potassium ferrate(VI) (K2FeO4), was assessed by studying the kinetics of the oxidation of quinoline by ferrate(VI) (Fe(VI)) as a function of pH (8.53-10.53) and temperature (21-36°C) in this work. The reaction of quinoline with Fe(VI) was found to be first order in Fe(VI), half order in quinoline, and 1.5 order overall. The observed rate constant at 28°C decreased non-linearly from 0.5334 to 0.2365 M(-0.5) min(-1) with an increase in pH from 8.53 to 10.03. Considering the equilibria of Fe(VI) and quinoline, the reaction between quinoline and Fe(VI) contained two parallel reactions under the given pH conditions. The individual rate constants of these two reactions were determined. The results indicate that the protonated species of Fe(VI) reacts more quickly with quinoline than the deprotonated form of Fe(VI). The reaction activation energy Ea was obtained to be 51.44 kJ·mol(-1), and it was slightly lower than that of conventional chemical reaction. It reveals that the oxidation of quinoline by Fe(VI) is feasible in the routine water treatment.

A study on the mechanism of oxidized quinoline removal from acid solutions based on persulfate–iron systems

“…14 Luo et al studied the kinetic of Qu oxidation by ferrate(VI), and the results indicated that Qu species was the major part at neutral and alkaline pH, and it possesses a positive charge under acidic conditions. 38 Sulfate radical with negative charge is much easier to get close to Qu with a positive charge in an acidic solution. The reaction results can be represented in Fig.…”

Towards Use of Persulfate Electrogenerated at Boron Doped Diamond Electrodes as Ex-Situ Oxidation Approach: Storage and Service-Life Solution Parameters

“…3, kinetic studies were carried out under pseudo-order conditions. [25][26][27][28] Under the experimental circumstances, the concentration of SO 4 2− in solution was kept in excess respect to the oxidants in solution (…”

“…It is generally considered that the reaction rate is fast if E a less than 40 kJ mol −1 , while the reaction is too hard to proceed if Ea > 400 kJ mol −1 . 27 Then, E a indicates that the decomposition reactions for the solution are feasible, but it is slower for the solution electrosynthetized at 60 mA cm −2 , giving novel information about the stability of the sulfate-based oxidant species.…”