Environ Chem Lett (2006) 3: 173–177 DOI 10.1007/s10311-005-0028-8 ORIGINAL PAPER Amine Amine-Khodja · Claire Richard · Bernadette Lav´ edrine · Ghislain Guyot · Olga Trubetskaya · Oleg Trubetskoj Water-soluble fractions of composts for the photodegradation of organic pollutants in solar light Received: 30 September 2005 / Accepted: 14 October 2005 / Published online: 8 December 2005 C  Springer-Verlag 2005 Abstract Composts fractions were extracted by water from composts at the beginning and at the end of the composting process. These water extracts were character- ized by elementary analysis and spectroscopies, and then, tested for their capacity to photosensitize the degradation of three aromatic compounds: Irgarol, fenuron, and 2,4,6- trimethylphenol. In solar light, the water extracts were found to completely degrade 2,4,6-trimethylphenol after 24 h, and afford a transformation of fenuron and Irgarol of 25% and 18%, respectively. Keywords Photoremediation . Oxidant species . Soluble organic matter Introduction A lot of chemicals can be photodegraded through absorp- tion of light and photoreactions can be also mediated by chromophores surrounding the chemical. For instance, hu- mic substances that absorb solar-light are known to pho- tosensitize the transformation of a variety of organic com- pounds in the environment. It is due to their ability to generate reactive species under light excitation (Hoign´ e et al. 1989). It has been very recently demonstrated that A. Amine-Khodja · C. Richard () · B. Lav´ edrine · G. Guyot Laboratoire de Photochimie Mol´ eculaire et Macromol´ eculaire, UMR no.6505, CNRS-Universit´ e Blaise Pascal 63177, Aubi` ere Cedex, France e-mail: claire.richard@univ-bpclermont.fr Tel.: +33-4-73-40-71-42 Fax: +33-4-73-40-77-00 O. Trubetskaya Branch of Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 142290 Pushchino, Moscow, Russia O. Trubetskoj Institute of Fundamental Problems in Biology, Russian Academy of Sciences, 142290 Pushchino, Moscow, Russia humic-like substances that are extracted from composts using alkali treatments exhibit photosensitizing properties. As a proof, complete degradation of Irgarol (10 −5 M) could be achieved by irradiating it in the presence of humic-like substances using artificial solar light (Amine-Khodja et al. 2005). This result sheds light on the photochemical proper- ties of organic matter extracted from composts and suggests a new way of valorization of composts in the field of pol- lutants elimination. However, the way by which humic-like substances, humic-like acids and fulvic-like acids, were recovered are too complicated to make possible such an utilization. In- deed, they were obtained after a several-step treatment, including initial basic treatments applied in order to get all the macromolecules and in particular those tightly attached to minerals, centrifugation and filtration. A possible idea could be to use the water-soluble part of composts in place of humic-like substances as photosensitizers. Indeed, the water-soluble fraction might be easier to recover. It has been previously shown that water can extract organic mat- ter from a great variety of composts. For the main part, these extracts were found to be fulvic-like acids (Wu and Ma 2002). The objective of this work was to investigate the photo- sensitizing properties of water-soluble extracts of composts recovered at the beginning and at the end of the compost- ing process. The former was named immature fraction, and the latter, mature fraction. In a first step, we analyzed the obtained extracts in order to get data on their chemical composition and on their spectral properties, the absorp- tion capacity being a crucial parameter in photochemistry. Then, their photodegrading properties were investigated using probe-molecules able to trap reactive species such as radicals, singlet oxygen, oxidant excited states. In this study, we used three organic compounds to test the photo- sensitizing properties of the water-soluble extracts of com- posts: Irgarol and two electron-rich aromatic compounds (2,4,6-trimethylphenol and fenuron) that were successfully employed before (Canonica et al. 1995; Richard et al. 2004; Sakkas et al. 2002).