Study On Fenton-like Catalytic Oxidation Of Lignin Model Compound-guaiacol By Using Vermiculite

Papermaking industry is one of the most water-consumpting industry in national economy,of which the wastewater is with high color,toxic and also with large amount of lignin.And the totally degradation the lignin in papermaking industry with complicated structure is the most hardest.However,traditional methods used in treating papermaking wastewater can not meet the demand of more complex papermaking processes and stricter standards than ever before.Therefore,advanced treatment is necessary.Being as an advanced oxidation process?AOPs?,Fenton reaction technique is efficiently utilized in wastewater treatment process for the removal of organic chemicals from wastewater.However,in Fenton reaction process it is necessary to adjust the pH value in the range of 3-5 and to deal with the iron sludge.Therefore,in order to increase and widen the applicability of Fenton reaction technique for wastewater treatment,developing novel and environment-friendly heterogeneous Fenton catalyst has attracted great attention recently.In present study,the degradation of the Guaiacol lignin by Fenton-like oxidation catalyzed by vermiculite was studied.The characterization of ground and unground vermiculite was conducted by EDS,SEM and Scattering laser particle analyzer.EDS analysis showed that the mass content of iron in vermiculite is about 13.6-20.5%,SEM images showed that there are more micro pores in lamellar structure of vermiculite,and the size test showed that after being ground,the particle size of vermiculite decreased while specific area increased.And a series of experiments had been conducted to elucidate the influence of parameters on the oxidation system,such as vermiculite dosage,H₂O₂ concentration,initial pH of reaction system and the initial concentration of GL solution.The removal rate of GL could almost be 100%within 180min at pH=3 when the initial concentration of H₂O₂ and vermiculite dosage were 1.3mmol/L and 2.0g/L,respectively.The ground vermiculite was used as the support to fabcrite a novel catalyst magnetic modified vermiculite,and its catalytic performance for Fenton-like oxidation of Guaiacol lignin was studied.The prepared catalyst was characterized by EDS,SEM and Scattering laser particle analyzer,which suggesting that the active component iron oxide particles successfully embedded in pores of vermiculite and presented in the form of Fe3O4 and dispersed uniformly.The catalytic performance of the catalyst was evaluated by degradation of Guaiacol,and the results showed that the oxidation of Guaiacol catalyzed by magnetic modified vermiculite was found to be much more effective than catalyzed by vermiculite.In the specific conditions,the removal rate of GL could almost be 100%within 120min at pH=3 when the initial concentration of H₂O₂ and vermiculite dosage were 1.3mmol/L and 1.0g/L,respectively,also with a higher TOC removal.The Fenton-like mechanism and degradation pathway was also discussed.In Fenton-like system catalyzed by vermiculite,the large amount of structural ions such as Fe,Mn,Ti and Cu exposed on the surface of vermiculite after grinding and act as active sites for catalyzing H₂O₂ to generating · OH for oxidation of guaiacol while in Fenton-like system catalyzed by magnetic vermiculite,octahedral iron ions in nano magnetic Fe3O4 loaded in vermiculite microporous internal and surface significantly enhanced the catalytic ability.And TOC,HPLC and UV-visible spectrophotometer were used to study the degradation process.Also by referring to some literatures,a possible degradation of guaiacol was suggested,the hydroxyl and methoxy on the benzene ring of guaiacol was firstly attacked by ·OH generating benzene and phenol,and other substances,and this kind of material is then oxidized to form small molecule intermediates eventually mineralized to CO₂ and H₂O.