High efficiency of mechanosynthesized Zn-based metal–organic frameworks in photodegradation of congo red under UV and visible light

Abstract

Three zinc(II) metal–organic frameworks, [Zn₂(oba)₂(4-bpdb)] (TMU-4), [Zn(oba)(4-bpdh)_0.5]_n (TMU-5) and [Zn(oba)(4-bpmb)_0.5]_n (TMU-6), (H₂oba = 4,4′-oxybisbenzoic acid, 4-bpdb = 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene, 4-bpdh = 2,5-bis(4-pyridyl)-3,4-diaza-2,4-hexadiene and 4-bpmb = N¹,N⁴-bis((pyridin-4-yl)methylene)benzene-1,4-diamine), containing azine-functionalized pores have successfully been synthesized via mechanosynthesis as a convenient, rapid, solventless and green process. These MOFs were studied for degradation of congo red from aqueous solutions under UV and/or visible light irradiation without auxiliary oxidants such as H₂O₂. TMU-6 could decolorize 100 ppm of congo red readily and quickly within 90 min, exhibiting about 68.4% in COD reduction after 72 h of UV irradiation. These results suggest that TMU-6/UV photocatalysis may be envisaged as a method for treatment of diluted colored waste waters not only for decolorization, but also for detoxification in textile industries.