Study On The Degradation Of Orange ? By Peroxymonosulfate Activated With CoFe₂O₄ Nanomaterials

With the rapid development of the industrial economy in recent years,the numbers of organic pollutants discharged from industries,such as oil refineries,petrochemical plants,dyestuffs,paper making,textile printing and dyeing,pharmaceutical and other industries,have gradually increased.It poses a great threat to the survival and health of humans and other organisms.The treatment of organics in water has garnered increased attention.At present,the main treatment methods of organics in wastewater mainly include physical,chemical and biological methods,or their combined technology.The advanced oxidation technology based on sulfate radicals is a new treatment method of organics developed in recent years.It is a process in which the organic macromolecule is attacked by the active radical generated by the reaction of the catalyst and the persulfate,to become an organic small molecule until it is completely mineralized into wa ter and CO2.The method is simple to operate,and compared with the conventional advanced oxidation technology based on·OH,SO₄^·-has a longer survival life and better selectivity,and the organics can be degraded effectively.In this thesis,the degradation of 250 mL 35 mg/L Orange ? by common oxidants?such as persulfate,persulfate and hydrogen peroxide?activated with CoFe2O4nanomaterials which were prepared by different methods was studied.The factors which influence the degradation of Orange ? in CoFe2O4 nanosheet-PMS and CoFe2O4 nanofiber-PMS system were tested.The active species in the experiment s were further revealed by using ethanol and tert-butanol as quenchers.The main contents were shown in the following parts:?1?CoFe2O4 nanomaterials was prepared according to the related reports in the literature.It was found that the commercially available CoFe 2O4 was a spherulite type with a particle size of about 40 nm.The other one have a lamellar structure,and the surface was rough and porous.The CoFe2O4 synthesized by hydrothermal method had nanofibrillar structure,and its surface grain size was finer.?2?The degradation of Orange ? by 0.98 mol/L oxidants activated with CoFe2O4nanosheets was studied.It was found that when the oxidant was PDS or H2O2,the concentration of Orange ? almost unchanged.In the case of PMS,the degradation effect was significant.The experimental variables in the CoFe 2O4 nanosheet-PMS system by using PMS as the oxidant was investigated.The study found that when the dosage of CoFe2O4 nanosheets increased from 0.05 g/L to 0.2 g/L,the degradation rate of Orange ? increased from 52.41%to 96.78%after 120 min.When the dosage was further increased to 0.3 g/L,the degradation time can be shortened to 90 min.The PMS concentration was tested by using 0.3 g/LCoFe2O4 nanosheets.It was found that when the concentration of PMS increased from 0.16 to 0.98 mmol/L,the degradation rate of Orange ? gradually increased.The Ea calculated by the pseudo-first-order kinetic equation for the experimental data at different temperatures?15^oC,25^oC and35^oC?was much higher than the Ea which was controlled by the diffusion process.Combined with the free-radical queching experiment,we know that the main roles which affecting the process of degradation of Orange ? was·OH and SO₄^·-.?3?When CoFe2O4 with a dosage of 0.2 g/L were used to degrade the orange orange ?,the effect of the materials was CoFe2O4 nanofiber>CoFe2O4 nanosheet>commercially available CoFe2O4.The CoFe2O4 nanofiber was used as catalysts to investigate the influencing factors of the specific experiments in CoFe 2O4nanofiber-PMS system.When the amount of CoFe2O4 nanofibers was 0.2 g/L,250 mL35 mg/L of orange ? could be fully degraded within 35 min,so we selected 0.2 g/L as the optimal concentration of PMS.The existence of·OH and SO₄^·-was revealed by the free-radical quenching experiments.In summary,three kinds of CoFe2O4 materials were prepared to used as catalysts in the degradation process of orange ?.The effects of catalyst dosage,PMS concentration,temperature and the active radical species on the degradation of Orange ? were investigated.