Preparation Of Transition Metal Sulfides Catalysts And The Application For The Degradation Of Organic Pollutant

With the rapid development of industrialization,urbanization and commercialization,a large number of untreated or partially treated industrial wastewater emissions lead to serious water pollution,.At present,chemical waste-water treatment mainly relies on chemical oxidation,biological treatment,electrochemical degradation,photocatalysis etc.conventional wastewater treatment technologies.However,the conventional treatment method is inefficient,leading to the discovery of some unacceptable contaminants in the treated wastewater.This requires a new method of depth treatment to degrade the organic matter in the wastewater.In recent years,progress has been made in the treatment of wastewater by the advanced oxidation process.Applied free radicals?SO₄·^-,·OH?with strong oxidation properties to removal non-biodegradable,difficult-to-degrade and toxic organic pollutants under environmental conditions is the focus of research at present.In order to overcome the obstacles in the practical use of traditional homogeneous AOPs and reduce the demand for its chemical and energy input,multiphase catalyst is a good choice.Recent studies have shown that sulfur elements in Fenton or Fenton-like there are many positive effects in the process of on reaction.In addition,sulfur minerals are abundant in nature.Therefore,as an efficient,green and economical environmental catalyst,it has a wide application prospect.In this paper,highly efficient recyclable micrometer cobalt sulphide and other transition metal sulfides were designed and prepared to catalyze the degradation of organic pollutants by activated persulfate?PMS?or hydrogen peroxide?H₂O₂?.The specific research work is as follows:?1?A one-step solvothermal reaction was used to prepare spherical cobalt sulphide with micro-nano-structure formed by lamellar self-assembly.The obtained samples have high crystallinity,single composition and no other impurities.It was found that the prepared CoS could effectively catalyze the rapid degradation of bisphenol A?BPA?,by activating PMS,and the effect of sulfur in CoS on the activation and degradation of bisphenol A?BPA?by PMS was also systematically studied.The results show that when the temperature is 25?,the concentration of CoS and PMS is 0.05gL^-1 and 0.3mmolL^-1 respectively,the degradation rate of 20 mg L^-11 BPA in 10 min is about 90%and the reaction rate constant is 0.49 min^-1,which is1.8 times that of the commonly used cobalt-based material Co₃O₄ nanoparticles in the catalytic degradation of BPA.In addition,it was found that the removal rate of BPA increased with the increase of the initial pH value of the reaction solution,and the initial pH range of the reaction solution was 3.2-10.6.By means of electron paramagnetic resonance?EPR?analysis and quenching experiment,it is observed that when the initial pH of reaction solution is increased from 3.2 to 10.6,the conversion of free radicals from SO₄·^-to·OH.In addition,the degradation intermediates were analyzed according to the results of LC-MS,and the possible degradation pathway of BPA in CoS/PMS system was put forward.Finally,according to the XPS spectra,the evolution of the surface valence state of CoS during the reaction was observed,and the evolution of the surface valence state was proposed.The possible mechanism of PMS activation by CoS.?2?Synthesis or purchase of a series of other transition metal sulfides,ferrous sulfide?FeS?,copper sulfide?CuS?,zinc sulfide?ZnS?,nickel pyrite?NiS?,nickel,manganese sulfide?MnS?,etc.The catalytic activities of various transition metal sulfides activated persulfate or hydrogen peroxide were further studied with 20?M Rhodamine B?RhB?as the target pollutant.The results showed that under the same reaction conditions,0.2gL^-1 catalyst and 2mM oxidant H₂O₂,FeS can effectively activate H₂O₂ at room temperature.It has good catalytic activity and good stability,while CuS?ZnS?PbS?MnS and CoS had no obvious activation effect.For the activation of PMS,the catalyst was still 0.2gL^-1 at room temperature,the concentration of oxidizer PMS was 0.5mm,and the oxidation activity was CoS>FeS>CuS>NiS>MnS=ZnS.Based on the above experimental results,in order to provide a certain theoretical basis for the application of sulfides in practical wastewater treatment,a new idea of whether sulfides can be used in the degradation of organic pollutants in mobile systems is put forward.Considering the activity of the catalyst and its economic accessibility,a circulating process device for continuous flow reaction was designed,in which the packed column of Mackinawite?FeS?was used as a reactor.The reactor can be used to process continuous flow reaction.In general,FeS exhibits good catalytic activity and stability in continuous flow reaction,which provides a feasible basis for the application of practical wastewater treatment.