RESUMO
A modified microfiltration (MF) membrane was prepared by flow-through coating method. First the sulfuric acid solution was vacuum filtered on the polyethersulfone (PES) MF membrane, providing the introduction of a sulfonic acid group to the backbone of PES. Sequentially, the polyethyleneimine solution was vacuum filtered to provide amine groups on the membrane surface. Finally, the graphene oxide solution, functionalized with different masses of tannic acid, was vacuum filtered on the membrane surface, producing the cross-linked modified membranes. These were efficient in the removal of anionic food colouring, achieving high removal rates and low fouling, compared to unmodified membrane. The best membrane in terms of bright blue dye removal was the MF PEI5GO1TA4, capable of removing all the feed solution, and demonstrating its possibility of reuse in five cycles of operation.
Assuntos
Corantes de Alimentos , Grafite , Nanopartículas , Filtração , Membranas Artificiais , TaninosRESUMO
The aim of the present study was to evaluate the efficiency of a new magnetic coagulant, obtained from Moringa oleifera seeds protein functionalized with iron oxide nanoparticles to remove four anionic synthetic dyes with coagulation/flocculation assays followed by magnetic sedimentation. The results showed that the presence of a magnetic field during sedimentation considerably accelerates the separation and increases the dye removal efficiency. Amaranth dye removal increased from 45 to 86% and Sunset Yellow from 15 to 69% with the presence of magnetic field, while Reactive Black 5 and Brilliant Blue reached 94% and 52% removal, respectively. For AM and SY dyes, the best protein concentration is 150 mg L-1, for RB5 dye is 115 mg L-1, and for BB dye is 75 mg L-1. The sedimentation time decreased from 30 to 5 min with magnetic sedimentation. The residual value of AM dye decreased from 10.76 mg L-1 to approximately 2.71 mg L-1, and with SY the residual concentration decreased from approximately 16.79 mg L-1 to 6.36 mg L-1. The removal of BB and RB5 dyes reached an approximate final value of 48.2 mg L-1 (52%) and 1.18 mg L-1 (94%).
Assuntos
Moringa oleifera , Purificação da Água , Corantes , Fenômenos Magnéticos , SementesRESUMO
This study was conducted to assess the feasibility of using Moringa oleifera Lam. (MO) seeds in the biosorption of nitrate present in aqueous solutions by means of batch and fixed-bed column biosorption processes. The batch assays showed that nitrate biosorption is enhanced under experimental conditions of pH 3 and a biosorbent mass of 0.05 g. For the experiments in dynamic mode, the results obtained from the statistical parameters showed that lesser pH, lesser feed flow rate, and higher initial concentration will result in an increase of the maximum capacity of the bed. These conditions were confirmed by experimental analysis. The best experimental conditions, according to the values for percentage removal (91.09%) and maximum capacity (7.69 mg g-1) of the bed, were those used in assay 1, which utilized pH 3, feed flow rate of 1 mL min-1, and initial nitrate concentration of 100 mg L-1.
Assuntos
Moringa oleifera/química , Nitratos/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Concentração de Íons de Hidrogênio , Sementes/química , Água , Purificação da Água/métodosRESUMO
The present study was conducted to impregnate the surface of a carbon of vegetable origin with copper nanoparticles by the green synthesis method with the aqueous extract of Hibiscus sabdariffa flowers, rich in phenolic compounds, which are responsible for the reduction and impregnation of metal nanoparticles. Batch adsorption assays were conducted aimed at nitrate removal with pure (GAC) and impregnated (IGAC) carbon, for comparative purposes. It was found that impregnation increases the efficiency of the carbon by four times in terms of the maximum adsorption capacity, which was 10.13â mgâ g-1 at 45°C for GAC and 45.01â mgâ g-1 at 15°C for IGAC, indicating that this is a promising material for the removal of nitrate in waters with an excess of this ion.