Degradation Of Mine Chelating Agent ?-nitroso-?-Naphthol By Ultraviolet And Thermal Activated Three Oxidants

The innovation of mining and metallurgical technology has promoted the capability of mining of low-grade ores.Some stable and efficient new mineral floatation reagents,such as?-nitroso-?-naphthol??N?N?,have been put into use in large quantities.The high stability of such organic reagents has increased the difficulty of environmental treatment and became a widespread concern.Among many treatment technologies,advanced oxidation processes based on long-wave-medium-wave ultraviolet?UVA-B,280-400 nm?has the advantages of high degradation efficiency and convenient application.In order to explore the practical effect of this method in the treatment of organic pollutants in mining industry,the following studies were made with?N?N as the target pollutant.The feasibility of quantitative analysis of?N?N by ultraviolet-visible spectrophotometry was explored;hydrogen peroxide?HP?,sodium persulfate?SPS?and potassium monopersulfate?PMS?were activated by UVA-B and thermal respectively to compare the oxidation performance of different systems under the same activation mode;the effects of some key experimental parameters on the degradation performance of?N?N in different systems were evaluated.Combined with the above experimental results,the effects of radical quenching experiment and GC-MS detection on?N?N in UVA-B/SPS,thermal/SPS systems were studied.Reactive substances,degradation products and the possible degradation mechanisms were studied.The results show that?N?N is stable under UVA-B radiation and high temperature.Compared with other reaction systems,when SPS was activated by UVA-B or high temperature,?N?N showed the best degradation performance.In the UVA-B/oxidant system,the degradation of?N?N follows the pseudo-first-order kinetics model.The variation of SO₄^2-and pH have little effect on the degradation of?N?N.With the increase of oxidant concentration,UVA-B power significantly promoted the degradation of?N?N.NO₃^-inhibited the degradation of?N?N and the effect of Cl^-on the degradation of?N?N in UVA-B/HP and UVA-B/SPS is related to its concentration.PMS can be activated by HCO₃^-and Cl^-to improve the removal efficiency of?N?N.In the thermal/oxidant systems,the degradation of?N?N in thermal/HP and thermal/SPS systems conforms to pseudo-first-order kinetics model.The degradation of?N?N in thermal/HP and thermal/SPS systems is affected by the pH change.The degradation of?N?N was promoted by oxidant concentration and temperature.In the thermal/PMS system,SO₄^2-inhibit the degradation of?N?N,while HCO₃^-and Cl^-promote the degradation of?N?N by activating PMS.The degradation of?N?N in UVA-B/SPS and thermal/SPS systems was coordinated by hydroxyl radicals and sulfate radicals,and a total of 9 intermediates were detected by GC-MS.In conclusion,this study prove that advanced oxidation processes based on UVA-B/SPS and thermal/SPS are cost-effective approaches for the degradation of?N?N,which shows a promising application prospect in the treatment of wastewaters released from mining areas comprising high concentration of organic pollutants.