Development of a physical-chemical and enzymatic methods for the removal of phenolic pollutant: Application of chitosan and laccase

Abstract

This paper reports the result of an undergraduate student involvement in research in an Historically Black College and University (HBCU) in a Science Engineering and Mathematics (SEM) Summer Research Training program sponsored by the national Science Foundation and the Office of Naval Research (ONR). The student had an opportunity of working with scientists in two Universities collaborating on an environmental engineering project. Water pollution has been a growing problem for all nations as a result of industrialization. Most of the industrial pollutants are toxic and have been classified as hazardous and carcinogenic. Typical examples generated from dyes used in the textile industry and found in wastewater are phenolic compounds. The development of economically treatment processes to remove these substances has been of research interest worldwide. A physical-chemical method using chitosan and a biochemical method using laccase for the potential removal of phenolic compounds from an aqueous medium was investigated. The dual state behavior of chitosan in acidic and basic medium was taken advantage of in the physical-chemical method. At pH 4, azo dye reacted with chitosan and on increasing the pH to 8, chitosan was precipitated removing the dye from solution. In the biochemical method, at pH 4, laccase degraded the dye. The Michealis Menten constant (K m) and the maximum velocity (V m) for this reaction at room temperature were 8.5 × 10 2g/L and 150 g/L min respectively.