Microwave-assisted regeneration of spent activated carbon from paracetamol wastewater plant using response surface methodology

Abstract

The spent activated carbon used in the petrochemical plant was regenerated by microwave heating. The response surface methodology is utilized to optimize the process parameters. The results revealed that the optimum parameters were: regeneration temperature of 600°C, regeneration time of 10 min and microwave power of 500 W, with the methylene blue number and yield being 202.5 mg/g and 42.22%, respectively. The regeneration activated carbon under optimal parameters was characterized by nitrogen adsorption at 77 K, scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR). The Brunauer–Emmett–Teller surface area, total pore volume and average pore diameter are estimated to be 987.5 m²/g, 1.11 ml/g, and 4.49 nm, respectively. The effect of regeneration cycles on methylene blue number of activated carbon were studied, indicating that the activated carbon still had a certain of adsorption capacity. The activated carbon was characterized by FTIR and SEM. The results of SEM indicate that impurities which covered the surface of activated carbon are cleaned. It can be seen from FTIR analysis that functional groups of activated carbon are changed through microwave heating.

Keywords:

• Activated carbon
• Microwave heating
• Response surface
• Methylene blue number

Acknowledgment

The authors would like to express their gratitude to the Supported by National Natural Science Foundation of China（No: 51504119), the Yunnan Provincial Science and Technology Innovation Talents Scheme Technological Leading Talent (No: 2013HA002), Yunnan Provincial Young Academic Technology Leader Reserve Talents (No: 2012HB008), and the Kunming University of Science and Technology Personnel Training Fund (No. KKSY201252077) for financial support.