Microwave-assisted photocatalytic degradation of dimethyl phthalate using a microwave discharged electrodeless lamp

Abstract

O processo de fotodegradação catalítica assistido por radiação microondas do dimetilftalato foi investigado usando uma lâmpada de descarga sem eletrodos como fonte de radiação ultravioleta (UV). O dimetilftalato pode ser degradado rápida e completamente pelo processo. Os efeitos da dosagem fotocatalítica, intensidade de radiação UV, pH inicial e concentração de dimetilftalato, bem como o tempo de irradiação foram detalhamente estudados. Efeitos sinergéticos ocorreram entre a irradiação de microondas e a fotocatálise do TiO 2 , e a maior eficiência do processo pode ser associada aos efeitos não térmicos da irradiação de microondas. Dados experimentais evidenciaram que a irradiação por microondas pode causar significativa geração de radicais hidroxila. Os intermediários formados em maior concentração foram éster monometílico do ácido ftálico, ácido ftálico, o-fenil dietil cetona e anidrido o-ftálico. Com base nos dados experimentais, duas rotas de degradação inicial do dimetilftalato foram propostas.The microwave-assisted photocatalytic degradation (MW/PC) of dimethyl phthalate (DMP) was investigated, using a microwave discharged electrodeless lamp (MDEL) as the UV source. DMP could be rapidly and completely degraded by the MW/PC process. The effects of photocatalyst dosage, UV light intensity, initial pH and concentration of DMP, as well as irradiation time, were studied in detail. Synergistic effects were found to exist between microwave irradiation and TiO 2 photocatalysis, and the greater efficiency of the MW/PC process might be ascribed to nonthermal effects of microwave irradiation. Detection results confirmed that microwave irradiation could give rise to the generation of hydroxyl radicals. The major intermediates of DMP in the MW/PC process were deduced to be phthalic acid monomethyl ester, phthalic acid, o-phenyl diethyl ketone and o-phthalic anhydride. Based on the results, two initial degradation pathways of DMP were proposed.

Degradation of p-nitrophenol using CuO/Al2O3 as a Fenton-like catalyst under microwave irradiation

“…The indirectly determination of cOH was conducted by a uorescence method, as reported in our previous studies. 39,40 The dissolved copper concentration in the solution aer reaction was determined using a ame atom absorption spectrophotometer (PerkinElmer, AAnalyst200). 18 The BET surface area, the average pore volume and the average pore diameter derived from nitrogen physisorption are listed in Table 1.…”

Degrading Endocrine Disrupting Chemicals from Wastewater by Photocatalysis: A Review

“…The degradation rate constant was noticed to increase from 0.0111 to 0.0268 min −1 as the light intensity increased from 2 to 6 W•L −1 . Liao and Wang [101] also observed an enhancement of dimethyl phthalate (DMP) degradation with increasing the UV light intensity. The enhanced degradation efficiency was attributed to the higher light intensity provided more light energy for the breaking of chemical bonds of DMP, and the reactions between the light and the TiO 2 catalyst improved the generation of • OH radicals in the solution.…”

“…Liao and Wang [101] studied the effect of pH in the range of 3 to 11 on the photocatalytic degradation of dimethyl phthalate (DMP) over TiO 2 under UV light irradiation. The efficiency of DMP degradation in acidic solution at pH 5 was found to be higher than the alkaline solution.…”

Microwave Discharge Electrodeless Lamps. Part VIII: Continuous On‐Site Solar Energy Remediation of Contaminated Water

“…Microwave discharge electrodeless lamps (MDELs) have proven useful light sources to decontaminate polluted water since both UV and microwave radiations can be applied simultaneously to induce degradative processes for destroying organics and microorganisms 2–10. For equal power consumption, MDELs are more effective than conventional low‐pressure Hg lamps 11.…”