The Study On Removal Of Sulfathiazole From Water By Spirulina Residue Biomass Graphene Oxide Activated Persulfate

Spirulina contains rich nutrients,among which C-phycocyanin is widely used in the food field due to its anti-oxidation,anti-inflammatory and immune-enhancing properties,and also has potential medicinal value.However,the algal residue after phycocyanin extraction in industry is rich in inorganic salts,leading to the difficulty of the subsequent treatment.Therefore,it is an effective method for solid waste recycling to convert it into an economically viable and environmentally friendly biomass graphene oxide for wastewater treatment.A large number of refractory sulfonamide antibiotics are being discharged,which posing a potential threat to the ecological environment and human health.In this study,Spirulina residue biomass graphene oxide（SBGO）was manufactured from C-phycocyanin extracted Spirulina residue.And SBGO was used as an activator of peroxymonosulfate（PMS）to catalyze the degradation of sulfathiazole（STZ）by PMS.Combining density functional theory（DFT）calculations to in-depth study the degradation path of STZ,aiming to develop a green and efficient STZ removal method.The characterization methods,such as elemental analysis,specific surface area analysis,Transmission electron microscope（TEM）,X-ray diffraction（XRD）,Raman spectroscopy（Raman）,Fourier transform infrared spectroscopy（FTIR）and X-ray photoelectron spectroscopy（XPS）,have demonstrated the successful preparation of SBGO.Oxygen-containing functional groups,such as C-OH,C-O and C=O,were successfully inserted into SBGO.The higher the content of inorganic salt in C-phycocyanin extraction solvent,the less oxygen-containing functional groups were inserted into SBGO,and the smaller the defect degree of SBGO.Oxidative degradation experiments showed that SBGO could be used as an activator of PMS,and Spirulina residue biomass graphene oxide-high salty（SBGO-HS）had the best activation effect.20mg/L STZ could be completely degraded by 1 g/L SBGO-HS within 10 min.The effects of SBGO concentration,initial p H and inorganic anions in the SBGO/PMS system were investigated.The results showed that the higher the SBGO concentration,the faster the degradation of STZ,and the SBGO/PMS system was almost unaffected by the initial p H and inorganic anions.The quenching experiment showed that the reaction system of SBGO/PMS degradation of STZ did not involve the action of free radicals,and the nonradical pathway was the dominant pathway of the reaction.Both ¹O₂and electron transfer were involved in the degradation of STZ.The ESR experiment confirmed that the reaction did not involve free radicals,and SBGO enhanced the ¹O₂ pathway.The C=O in SBGO promoted the decomposition of PMS to generate more ¹O₂,while the graphitized structure of SBGO promoted the electron transfer process.DFT calculations predict the reactive sites on the STZ molecule.Liquid chromatography-tandem mass spectrometer（LC-MS/MS）detection found degradation products with molecular weights of 285,269,274,218,216,174,122,100,142,and 60.Combined with the predicted reactive sites,the chemical structure of the degradation products was inferred.It is clear that STZ is mainly degraded by attacking the N and S atoms connected to the benzene ring and the thiazole ring.