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Removal of Nitroaromatics from Synthetic Wastewater Using Two‐Step Zero‐Valent Iron Reduction and Peroxidase‐Catalyzed Oxidative Polymerization
Author(s) -
Mantha Ramkrishna,
Biswas Nihar,
Taylor Keith E.,
Bewtra Jatinder K.
Publication year - 2002
Publication title -
water environment research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.356
H-Index - 73
eISSN - 1554-7531
pISSN - 1061-4303
DOI - 10.2175/106143002x140017
Subject(s) - chemistry , hydrogen peroxide , wastewater , zerovalent iron , catalysis , substrate (aquarium) , alum , peroxidase , chromatography , nuclear chemistry , inorganic chemistry , organic chemistry , environmental engineering , adsorption , enzyme , oceanography , engineering , geology
Degradation of nitroaromatics, which are significant environmental pollutants, is difficult to achieve. Zero‐valent iron reduction of nitroaromatics coupled with peroxidase‐catalyzed capture of the resulting anilines as a two‐step strategy for removing nitroaromatics from wastewater and process water is investigated here. The concentration range of nitroaromatics studied was that which would be present in industrial wastewater streams. Studies were done in continuous‐flow columns. The enzymatic treatment following zero‐valent iron reduction was carried out in a plug‐flow reactor using a crude preparation of the enzyme soybean peroxidase extracted from soybean hulls. The complete reaction time for the two steps was 5 to 5.5 hours. Operating parameters including pH, peroxide/substrate ratio, enzyme concentration, and alum concentration were optimized. Optimum conditions obtained were approximately neutral pH with a hydrogen peroxide/substrate molar ratio of 1.5 for all of the nitroaromatics tested. Alum concentrations between 50 and 100 mg/L were useful in removing the apparent color from the treated water.