Bentonitas modificadas com NiO e ZnO aplicadas na fotodegradação de azo-corantes

Abstract

Currently, contamination of water bodies is a major problem, mainly because of the volume of domestic and industrial effluents that contribute to most part of the polluting load. In particular, effluents of textile industries contain a high amount of dyes composed of several organic substances that are harmful to the environment. Thus, implementing cleaner, environmentally correct, and economically viable technologies for water treatment is important to reduce impacts related to this process. Heterogeneous photocatalysis has been extensively applied to the degradation of pollutants in water bodies because it is a technology with potential to completely mineralize organic pollutants using metal oxide semiconductor catalyzers. Therefore, this study aims to synthetize inorganic/organic hybrids based on bentonites modified with nickel oxide (NiO) and zinc oxide (ZnO) using the coprecipitation method and apply them to the photodegradation of anionic dyes. Thus far, XRD and XRF tests were conducted to identify the formation of the desired hybrids. FTIR, will also be conducted to evaluate the effective formation of the hybrids. For the synthesis of hybrids, a sodium bentonite with cation exchange capacity (CEC) of 88 cmol (+) /kg was used, which was constantly shaken with a solution with the precursor salts of nickel and zinc, heated up to 60 ºC using ammonium hydroxide as a precipitating agent, and maintained in these conditions for 5 h. In sequence, the solids obtained were washed, dried in oven at 70 ºC, calcined at 500 ºC for 3 h to obtain the hybrids NiO-Bent and ZnO-Bent, and characterized. The XRD patterns of the hybrids NiO-Bent and ZnO-Bent demonstrated the occurrence of characteristic peaks of montmorillonite, NiO, and ZnO. The XRF results agreed with those of the XRD. Moreover, they indicated the absence of NiO and ZnO in the raw bentonite, whereas these oxides were both present at the hybrids obtained, indicating the formation of the desired hybrids using the method applied. In sequence, the synthetized hybrids will be applied in the photodegradation of dyes and different parameters will be varied and analyzed.