Photocatalytic degradation of 2,4-dichlorophenoxyacetic acid using nanocrystalline cryptomelane composite catalysts

2,4-Dichlorophenoxyacetic acid is a common systemic herbicide used in the control of broadleaf weeds. It is the third-most widely used herbicide in the world. 2,4-D heterogeneous photocatalysis has emerged as a useful process to aid remediation of wastewater contamination. Manganese oxide with 2 x 2 tunnel structure, cryptomelane show good results in the photodegradation of 2,4-D and excellent performance in the photodegradation of methylene blue. The later as a consequence of the S-Mn interaction that favours the adsorption step in the photodegradation process. The existence of microporous manganese oxide minerals with the OMS structure may be an acceptable environmental solution for the remediation of wastewaters. (C) 2007 Elsevier B.V. All rights reserved.