The extensive use of pesticides has promoted the agricultural production, but the NGO’s activities have drawn the concern of governments to be aware of groundwater and surface water pollutions. In the most populated techniques the photocatalysis has emerged as a powerful method. In this thesis, the photocatalytic degradation of an organophosphorus pesticide malathion was investigated using a very cheap catalyst, the blast furnace slag. The morphology and structure of slag was well characterized by a scanning electron microscope (SEM), X-ray diffraction (XRD), FTIR, and X-ray flouresance spectroscopy (XRF). The photocatalytic experiments revealed that an aqueous solution of malathion (with concentration of 38 ppm) was degraded 100% in 120 min at pH = 7.4 under UV irradiation by using 100 mg of slag. However, the slag was deactivated after use, but because of many advantages such as cheapness and availability it could be a valuable resource for industrial applications. The second project was aimed to develop chitosan-EDTA films and evaluate their efficiency for removal metal contaminations from water. These catalysts were coated with silica and zirconium oxides and were used for the removal of the lead metal. The catalysts were characterized by FT-IR analysis. The results showed that the conjugate of chitosan/EDTA was not successful for adsorption of lead metals.