Temperature measurement of GAC and decomposition of PCP loaded on GAC and GAC-supported copper catalyst in microwave irradiation

Abstract

A sheltered type-K thermocouple was applied to record the temperature rising courses of granular activated carbon (GAC) in a microwave irradiation field under various conditions. The results showed that GAC could absorb microwave energy effectively and its temperature rose up to 1100 °C in a few minutes. This interaction of GAC and microwave was utilized to the preparation of GAC-supported copper catalyst. The catalyst was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), iodine number and adsorption isotherm. It was found that elemental copper distributed uniformly on the surface of GAC, and after loading copper, the adsorption capacity of GAC decreased due to occupation of adsorption sites by copper. Decomposition of a typical chlorinated organic chemical, pentachlorophenol (PCP), on virgin GAC and copper-loaded GAC was assisted by microwave irradiation. Firstly, PCP in water was adsorbed onto GAC, then PCP-loaded GAC irradiated by microwave in a quartz reactor. The results indicated that most of PCP adsorbed on virgin GAC was decomposed or bound irreversibly to GAC under 850 w microwave irradiation for 10 min, and less than 2% was transformed into intermediates. A more rapid decomposition rate of PCP was observed on copper-loaded GAC with larger amount of intermediates formed. Identification of intermediates was accomplished by gas chromatography/mass spectrometry (GC/MS) analysis.