Microwave-Assisted Extraction of Polychlorinated Biphenyls and Polychlorinated Dibenzodioxins From Fly Ash

Abstract

The effects of extraction parameters on the microwaveassisted extraction (MAE) of polychlorinated biphenyls (PCBs) and polychlorinated dibenzodioxins (PCDDs) from fly ash were compared. The effects of toluene-isopropyl alcohol (IPA) mixture compositions, solvent volume, temperature, extraction time (rise and hold time), and microwave power on the variation of recoveries were studied. The MAE carried out at 100 C for 35.3 min using 5 mL of toluene-IPA (90 : 10, v=v) was more effective in isolating PCBs and PCDDs from fly ash.Multi-layer column chromatography on neutral and acidic silica gel with n-hexane was used for cleaning up the extracts. High performance liquid chromatography (HPLC) with ultraviolet (UV) detection was employed to identify and quantify the analytes.

Separation strategies of plant constituents–current status

“…For pressurized MAE, a microwave-transparent vessel and solvents with high dielectric constants are used. The solvents absorb the microwave radiation and are therefore heated under pressure to a temperature exceeding their normal boiling points [33,34]. This extraction method is similar to accelerated solvent extraction, because the elevated temperature and pressure facilitate extraction of compounds from the plants.…”