| Industry wastewater,which usually contains aromatic compounds,is hard to deal with due to organic contaminants’ chemical stability.Electro-oxidation for aromatic wastewater treatment receives a lot of concentration.However,its practical application in water treatment is limited due to anode materials.DSA(Dimensionally Stable Anode)is widely used in electro-catalysis oxidation and Sb/SnO2/Ti anode is one of the very popular DSA.This article prepared MOFs/PS(polystyrene)/graphite modified Ti anode and MOFs/Sb/SnO2 modified Ti anode and chose two typical benzene compounds(aniline and phenol)as target contaminants,aimed at the application and mechanism of MOFs(Metal Organic Frameworks)in electro-catalysis.MIL-101(Cr)was selected as the anode modification due to its polyporous structure and high specific surface area.Effects of pH,current density and electrolyte concentration on the catalysis speed were systematically studied;Furthermore,MIL-101(Cr)combined Sb/SnO2/Ti anode was applied and compared with traditional Sb/SnO2/Ti anode.In addition,the mechanism in aromatic compound electro-catalysis was investigated.(1)MIL-101(Cr)was firstly used to modify the surface of Ti anode with PS as a binder and graphite as a conductive agent.Then,investigation was conducted on the effects of pH,current density and electrolyte concentration on catalysis speed.It turned out that when pH was 9,eurrent:density was 20mA·cm-2 and electrolyte concentration was 0.1mol/L,the modified anode showed best electro-catalysis ability.The removal of aniline and phenol reached 95%and 94%in 6 h when modified anode was applied.Comparatively,unmodified anode only achieved 75%and 66%removal of aniline and phenol during the same time.Moreover,the COD removal experiments also showed differences.The removal of COD is 90%and 88%for aniline and phenol respectively in 6h when modified anode was applied.The unmodified anode achieved 70%and 63%of COD removal of aniline and phenol.All the experiments showed after MIL-101(Cr)was modified,the Ti anode showed better catalysis ability.Through free radical scavenger experiments,it was confirmed that the main species,which played the dominant role in electro-catalysis,was hydroxide radical.The reason why MIL-101(Cr)modification could help electro-catalysis was that there were quantities of h+in the structure of MOFs.As known,h+can process hydroxide radicals.At the same time,the electrons gained in h+would pass away through current under the effect of electric field.In this way,h+could continuously process hydroxide radicals,thus accelerating electro-catalysis.At last,we inferred that the possible ways that how benzene compounds transforms in electro-catalysis.(2)We modified MOFs on the surface of Ti/Sb/SnO2.The results of effects of pH,current density and electrolyte concentration were close to the previous research.The best condition of electro-catalysis was that pH was 9,current density was 20mA cm-2 and electrolyte concentration was 0.1mol/L.The removal of aniline and phenol was beyond 90%in 4h when MOFs modified Ti/Sb/SnO2 anode was applied.Comparatively,unmodified Ti/Sb/SnO2 anode only achieved around 70%removal of both aniline and phenol.Also COD removal was investigated.The COD removal of both aniline and phenol reached over 85%in 4h when MIL-101(Cr)modified Sb/Sn02/Ti anode was applied.Comparatively,normal Sb/SnO2/Ti anode only achieved less than 65%COD removal for both aniline and phenol during the same time.In conclusion,two different kinds of MIL-101(Cr)modified anodes were prepared through two different ways.After investigating the effects of different parameters on electro-catalysis,the best condition for elecro-catalysis was filtered.The electro-catalysis was conducted under the best condition.Compared with unmodified anodes,the catalysis ability of MIL-101(Cr)modified anodes was promoted obviously.The research also provides theoretical basis for application in real wastewater treatment. |
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