Synergistic Degradation of 4-Nitrophenol Using Hydrodynamic Cavitation in Combination with Hydrogen Peroxide

Authors: Mihir N. Bhagat, Mandar P. Badve, Aniruddha B. Pandit

p-Nitrophenol (PNP), a widely utilized intermediate, is a persistent pollutant present in industrial effluent streams. The inherent toxicity of PNP necessitates its treatment before releasing it in the environment. The conventional approach pertaining to degradation of PNP is based on chemical and biological methods for decomposition. Alternatively, Hydrodynamic Cavitation (HC) is emerging as a promising technology for waste water treatment. This study investigates HC as an alternative technology to degrade PNP and subsequently enhance efficiency by varying involved parameters. The HC-H2O2 system is reported to exhibit synergism for pollutant oxidation, the applicability of which is also investigated for degrading PNP. A PNP solution of fixed concentration was subjected to HC using a circular Venturi. Degradation was studied by varying time, pressure, pH and H2O2 concentration. Decompostion of p-Nitrophenol was quantified by UV-Visible Spectroscopy at 405nm. Degradation of PNP was observed to be directly proportional to time at constant pressure and an initial increase in pressure led to higher degradation. However, on achieving a peak decomposition level, the extent of decomposition declined with further increase in pressure. Experiments done at acidic pH resulted in over two times the decomposition than those done at basic pH. The PNP-H2O2 system exhibited 91% more degradation than the sum of degradations affected by PNP and H2O2 individually. Moreover, subjecting PNP:H2O2 in a molar ratio of 1:5 to HC resulted in near-complete (>95%) degradation. This study proposes variations of parameters for optimum decomposition of PNP using HC and explores the HC-H2O2 system as a promising alternative for the degradation PNP.

Comments: 5 Pages. Article in Press at the Int. J. of Sustainable Water & Environmental Systems Volume 8, No. 1 (2016).

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[v1] 2015-12-06 07:49:45

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