Selection of low cost materials for the sorption of copper and herbicides as single or mixed compounds in increasing complexity matrices
Résumé
Low cost materials (sugar beet pulp, corncob, corncob char, perlite, vermiculite, sand, sediment) have been tested for their ability to quickly sorb copper, glyphosate, diuron and 3,4-dichloroaniline (3,4-DCA) as single or mixed compounds. Tests have been performed in increasingly complex liquid matrices: ultra pure water (UPW), runoff water (RW) and sediment extract medium (SEM). Highest sorption levels in UPW are achieved with corncob char for Cu (93%), glyphosate (74%), diuron (98%) and 3,4-DCA (99%). Other ready-to-use adequate sorbents are sugar beet pulp for Cu and sand for glyphosate, diuron and 3,4-DCA. Sorption levels obtained in UPW are significantly altered in SEM as a result of its higher dissolved organic carbon concentration, tenuous changes being obtained with RW. Interactions between herbicides and Cu are pointed out: higher sorption level is observed for glyphosate in mixture with Cu, as it is observed with diuron and 3,4-DCA when mixed with all other pollutants. Langmuir model has been found to better fit the data for copper, whereas Freundlich one has been found more relevant for diuron and 3,4-DCA. Our results stress the need for studying adsorption in different matrices when searching for sorbents to be used in field conditions.