The Removal Of Two Kinds Of Emerging Compounds In Aqueous Solution By Permanganate

Emerging compounds have gained increasing attention as a serious aquatic environment problem with the widespread use of endocrine disrupting chemicals (EDCs) and pharmaceuticals & personal care products (PPCPs). The chemical oxidation process is more feasible in drinking water process than adsorption and biological degradation because of its merits such as completely removal and easily handling. Permanganate shows great potential in removaling EDCs/PPCPs in aqueous solution as a green oxidant. Fisrtly, it has been widly used in water plants in China because of its broad source and economic advantage. Secondly, compared with ozone and chlorine compounds, no harmful byproducts such as halogenated organics and bromated would be produced during the oxidation by permanganate. In this study, the removal efficiency and kinetics of the oxidation of two typical emerging compounds bisphenol A and triclosan by two permanganate agents were investigated, with a focus on studying the effect of oxidant concentration, temperature, pH on removal efficiency and reaction kinetics. Comparative analysis of the oxidation of bisphenol A and triclosan by potassium agent B was conducted.Triclosan can be removed efficiently by permanganate agent A and agent B. While the reaction time is 100s, the removal efficiency is larger than 70% at pH7. The optimal pH for removal of triclosan by agent A and agent B is 7, 8 separately. When the reaction temperature exceed 28℃,the removal efficiency of triclosan dose not increase with the increasement of the temperature. The reactions between agent A/ agent B and triclosan fit second-order kinetics overall, and pseudo-first-order with respect to both triclosan and agent A/ agent B. The second-order rate constants were determined to be 344.7M^-1s^-1,477.4 M^-1s^-1 separately at pH7. The adjuvant ingredient in agent B significantly promoted the removal of triclosan. Both agents reacted slowly with triclosan at weak acid and alkaline conditions, but reacted rapidly in neutral and weak alkaline environment. Arrhenius temperature dependence was observed with apparent activation energies Ea=29.93 kJ2mol^-1, 26.412 kJ2mol^-1 for agent A and agent B separately. Thermodynamic parameters, such as enthalpy (ΔH*) and entropy (ΔS*) were evaluated by Eyring equation. The triclosan removal efficiency in Songhua River is better than in tap water for both agents.While the reaction time is 120s, the removal efficiency of bisphenol A is 74.88%, 65.55% for agent A and agent B, separately. On acid condition, the removal efficiency is low for both agent A and agent B. The lowest removal efficiency was obtained at pH5. When pH>7, the removal efficiency increase with the increasement of pH, therefore the alkaline environment is benefit for bisphenol A removal. The influence of temperature on bisphenol A is similar to triclosan. Both reactions between bisphenol A and agents fit second-order overall and pseudo-first-order with respect to both bisphenol A and agents. The second-order rate constant was 109.88 M^-1s^-1, 91.44 M^-1s^-1, separately. The adjuvant ingredient in agent B promoted the removal of bisphenol A. Both agents reacted slowly with bisphenol A at weak acid conditions, but reacted rapidly in alkaline environment. Arrhenius temperature dependence was observed with apparent activation energies Ea=25.96 kJ2mol^-1, 27.32kJ2mol^-1 for agent A and agent B separately. Thermodynamic parameters, such as enthalpy (ΔH*) and entropy (ΔS*) were evaluated by van't Hoff equation. The bisphenol removal efficiency in Songhua River is better than in tap water for both agents.Compared with BPA, triclosan was removed more easily by agent B when pH>8,and the removal tendency are similar under different concentrations of agent B and temperatures. While pH<7, the influence of pH on triclosan and bisphenol A removal show the same trend. When pH is larger than7, the removal efficiency of triclosan decreased dramatically with the increasement of pH while the removal efficiency of BPA soared. On acid conditions, triclosan and bisphenol A have the similar second-order rate constant. The largest second-order constant of the reaction beween triclosan and agent B is 539.8M^-1s^-1 at pH 8, then decrease dramatically. When pH > 8, the second-order rate constant between BPA and agent B increase with the increasement of pH, and reached 913.2M^-1s^-1 at pH 10. The difference of second- order rate constant between BPA and triclosan increase with the increasement of the temperature.Both permanganate agent A and agent B can remove triclosan and BPArapidly and efficiently. In this study the concentration of agent B is half of agent A, however, agent B showed similar removal efficiency between tricosan and BPA. The green oxidants permanganate agent A and agent B have a promoting future in control of EDCs/PPCPs in aquatic environment.