Oxidation Of Three Kinds Of Chlorophenols By Colloidal MnO₂

Chlorophenols(CPs) are a kind of organic pollutants extensively used in industrial and agricultural production. It leads to the frequent detection of them in lakes, rivers, reservoirs and underground waters. Due to their biological toxicity,bioaccumulation, environmental persistence and difficult to natural degradation, CPs has a serious threat to the health of human and other organisms. Therefore, it will has great importance in studying the control technology of CPs in water environment.Colloidal Mn O2 was used as an oxidant agent to degrade 4-chlorophenol(4-CP),2,4-dichlorophenol(2,4-DCP) and 2,4,6-trichlorophenol(2,4,6-TCP) in the present study. The main results are listed as follows:(1) Colloidal Mn O2 has a good control effect on CPs. In addition, colloidal Mn O2 has excellent oxidative stability. The reactions between colloidal Mn O2 and three kinds of CPs can conformed to a retarded first-order kinetic mode.(2) The degradation rates of three kinds of CPs increased with the increase of colloidal Mn O2 doses or the reaction temperature. The rates of three CPs are decreased greatly with the increase of p H. The rates of three kinds CPs follow the sequence of 4-CP > 2,4,6-TCP > 2,4-DCP under acidic conditions. However, the gap of the CPs removal rates is gradually decreased with p H increasing under alkaline conditions.(3) The coexisting components have certain effect on the degradation of CPs by colloidal Mn O2. Na+, K+, Cl-, EDTA have no significant influence to the reactions.Whereas, the reactions are inhibited by the presence of some cations(such as Ca2+,Mg2+, Mn2+, Fe3+, Al3+, etc.), inorganic anions(such as PO43-, HCO3-, CO32-, etc.)and HA. Moreover, the inhibitory effect is affected by p H. The effect is weakened under strong acidic or alkaline conditions, while it is obviously strengthened under weak acidic, neutral and weak alkaline conditions. It was also found that the removal efficiency of three CPs in deionized water system is obviously higher than in real water.(4) Concentrations of colloidal Mn O2 and [Mn2+] was detected by means ofspectrum scan and AAS technology. It found that their trends were just the opposite.[Mn2+] was first deceased, then increased sharply. It might be due to the absorption of Mn2+ by colloidal Mn O2 in the initial stage of the reaction.(5) SPE and GC–MS technology were employed for the determination of the degradation products of 2,4,6-TCP during colloidal Mn O2 oxidation, based on which the degradation paths of 2,4,6-TCP was postulated in the study.