Tássia Rhuna Tonial dos Santos

Development of α- and γ-Fe2O3 decorated graphene oxides for glyphosate removal from water

ABSTRACT In this study, the proposed adsorbent composed of graphene oxide (GO) functionalized by magnetic nanoparticles of iron oxide (α-γ-Fe2O3) was obtained by a simple ultrasonication process. This new material was used for the removal of glyphosate in water. The nanoparticulated iron oxide used was synthesized by means of a modified sol–gel method, which does not use organic solvents. The adsorbent material (GO-α-γ-Fe2O3) obtained was characterized by magnetic measurements, and it can be proved that it has superparamagnetic properties, allowing fast and efficient magnetic separation. The equilibrium time for the adsorption of glyphosate when using GO-α-γ-Fe2O3 was 2 hours and the maximum removal was 92% at 15°C, with a maximum adsorption capacity of 46.8 mg g−1. Langmuir model and pseudo-second-order kinetic model correlated satisfactorily to the experimental data. The thermodynamic parameters showed that the adsorption of glyphosate on GO-α-γ-Fe2O3 was spontaneous, exothermic and thermodynamically favorable at temperature of 15–45°C. Thus the adsorbent material GO-α-γ-Fe2O3 proposed in this study is considered a good candidate to be used in the removal of glyphosate from aqueous solutions, presenting high adsorption capacity, low cost and magnetic properties that facilitate the separation of the adsorbent material.

TRATAMENTO DE ÁGUA UTILIZANDO COAGULANTE MAGNÉTICO BASEADO EM EXTRATO DE SEMENTES DE MORINGA OLEIFERA LAM E NANOPARTÍCULAS DE ÓXIDO DE FERRO

Nas estacoes de tratamento de agua, os coagulantes mais empregados sao os inorgânicos, que sao sais trivalentes de ferro e aluminio. Entretanto, a utilizacao de substâncias quimicas para tornar a agua potavel pode acarretar outras contaminacoes, como os subprodutos gerados no processo de desinfeccao por cloracao, os trihalometanos, substâncias com potencial carcinogenico. Alem disto, o aluminio nao e biodegradavel, podendo ocasionar problemas de disposicao e tratamento do lodo gerado. Neste contexto, propoe-se avaliar a eficacia da coagulacao/floculacao (C/F) utilizando o coagulante natural Moringa oleifera Lam (Mo), funcionalizada com nanoparticulas magneticas de oxido de ferro, para obtencao de flocos que sejam atraidos por um campo magnetico externo, permitindo assim uma agil decantacao e separacao do liquido clarificado. Os ensaios foram realizados em Jar Test, utilizando agua proveniente da bacia do rio Pirapo, Maringa, PR. Amostras foram coletadas para avaliar a eficiencia de remocao dos parâmetros de cor aparente, turbidez e compostos com absorcao de UV254nm. Foi possivel constatar que o tratamento de C/F utilizando o coagulante Mo funcionalizada foi capaz de reduzir os valores dos parâmetros fisicoquimicos avaliados sob influencia de um campo magnetico, com reduzido tempo de sedimentacao.