Degradation Of Dyes Based On CTAB And Iodine Supported Carbon Fibers To Activate PMS

With the rapid development of industry,water pollution is becoming more and more serious.Dyeing wastewater has become a major and difficult point of water pollution control due to its complex composition,deep colour and high toxicity.Advanced oxidation processes?AOPs?have received much concern,due to their high efficiency,mild reaction conditions and wide application.Among them,advanced oxidation based on peroxymonosulfate?PMS?is a new type of water treatment technology.The reactive oxygen species based on the activation of PMS could decompose and even mineralize organic pollutants into harmless CO2 and H2O.The traditional PMS activation method is light activation,heat activation,and transition metals activation.However,high energy input is required in light activation and heat activation,and the metal toxicity and risks of the secondary pollution constrain the further industrial application of transition metals activation.Therefore,it is very important to develop efficient and green catalysts to activate PMS.In this study,metal-free surfactant Cetyltrimethylammonium bromide?CTAB?was first applied to PMS activation from the perspective of metal-free catalyst.It's found that it can effectively activate PMS to remove RR M-3BE and other organic dyes,which not only offers new insights for the application of surfactant in catalysis,but also helps to promote the research of PMS activated by metal-free catalyst in the field of wastewater treatment.Homogeneous catalytic system can effectively activate PMS,while the catalyst in homogeneous system is difficult to be recycled,which limited the further the pratical appllication.Compared to the homogeneous catalyst,the heterogeneous catalyst is convenient for recycling and has more application prospects.Our group has been engaged in the study of catalytic functional fibers,and has a profound understanding of the fiber materials.Carbon fiber?CFs?was selected as the support of the harmless iodine to design a heterogeneous catalytic fibers.The prepared catalytic fibers possessed good properties of high efficiency,easy recycling and no secondary pollution.Using PMS as the oxidant,dyes as the probe compounds,we investigated the catalytic performance of the catalytic fibers.The performance for degradating the pollutants and the reaction mechanism were also investigated.The main research contents are as follows:Using a common metal-free cationic surfactant cetyltrimethylammonium bromide?CTAB?as catalyst,PMS as the oxidant,dyes of reactive brilliant red RR M-3BE as the probe compounds,the catalytic activity of CTAB for PMS activation were investigated.Importantly,we focused on the mechanism investigation by electron paramagnetic resonance?EPR?combined with the radical scavengers.The experimental results showed that the CTAB/PMS system can effectively remove organic pollutants and remove92.87%of RR M-3BE within 15 min.In addition to RR M-3BE,PMS can be effectively activated to remove other dyes including reactive brilliant red X-3B?RR X-3B?,acid orange 7?AO7?,acid red 1?AR1?,methylene blue?MB?.At the critical micelle concentration?CMC?of CTAB?0.92m M?,the oxidation efficiency of the CTAB/PMS system was optimal due to the strong electrostatic attraction between the CTA+micelle and reactive anions?HSO₅^-and Br^-?,concentrating HSO₅^-and Br^-at micellar surface,which accelerated the catalytic oxidation reaction between Br^-and PMS,generating a mass of highly active reactive species?·OH?.Hyroxyl radicals?·OH?were responsible for the dyes degradation.In order to develop a efficient and green catalytic oxidation process.The harmless iodine was chosen to be supported on the carbon fiber?CFs?to obtain the catalytic fibers?I-CFs?,characterized by X-ray photoelectron spectroscopy.With acid red 1?AR1?as the target compound,we investigated the catalytic performance of I-CFs for PMS activation.A hybrid method that combined electron paramagnetic resonance?EPR?technology with different scavengers such as ascorbic acid,methanol,L-histidine and p-benzoquinone was employed for the investigation of active species during the catalytic reaction.The results indicated that I-CFs could effectively activate PMS to degrade 97.5%of AR1 in 8min,while I-CFs showed good sustained catalytic performance.the removal rate in the I-CFs/PMS system was much higher than 97%at pH 3-10 conditions,indicating I-CFs have excellent p H adaptability.In addition,the increase of the temperature,the dosage of catalyst and the oxidant could promote the removal of AR1 in the I-CFs/PMS system.Both hyroxyl and sulfate radicals(·OH,SO₄^·-)were not responsible for the dyes removal,while the singlet oxygen?¹O2?were the dominant active oxygen species.