Catalisador de cobre metálico obtido via tratamento térmico de sal básico lamelar: oxidação de azul de metileno e fenol por reações tipo Fenton

Abstract

The layered hydroxide salts (LHS) are a class of promising clay compounds when it comes to the development of multifunctional materials. They present intrinsic structural characteristics, which, combined with low cost and simple synthesis methods, allow application in several areas. Considering the above and the need to develop efficient wastewater treatment, which has proved to be an eminent problem for the environment, LHSs become an alternative to obtain stable catalysts capable of acting on the degradation of organic compounds with high potential pollutant. In this work, copper(II) hydroxy acetate, Cu 2 (OH) 3Ac.H2 O, was synthesized by the simple precipitation method and used as a metal catalyst precursor, LHS-Cu700, obtained by thermal treatment in inert atmosphere. LHS-Cu700 was applied as a Fenton-like reaction catalyst for the degradation of methylene blue and phenol, both organic compounds that cause damage to the ecosystem and to human health. In addition, the effect of the heat treatment on the original material and the best reaction conditions were evaluated by studying the influence of the initial concentration of the contaminants, the amount of catalyst, the H 2O2 dosage and the temperature of the reaction medium. Cu2 (OH) 3Ac.H2 O showed high crystallinity, and the intercalation of the acetate anions between the flat lamellae of the material was confirmed. The studies also indicated that the thermal treatment at maximum temperature of 700ºC and N 2 atmosphere promoted the gradual reduction of Cu 2+ from the structural of the basic salt to Cu 0 during the heating process, which led to a collapse in the lamellar structure in the catalyst. In addition, the catalytic tests proved to be efficient for both organic compounds, and at 35ºC the highest percentage of dye removal was obtained, while for phenol the total removal was achieved in all reaction conditions. In this way, the work aimed to promote, in a general way, a better understanding on the structure of the clayey material in question, focusing on its application as catalyst precursor, as well as in the process of obtaining and composition of this. In addition, the catalytic tests indicated the efficiency of the LHS-Cu700 for the removal of organic pollutants, which shows the promising abilities of Cu2 (OH) 3Ac.H2O in the production of metallic materials that can be applied in environmental remediation.