Enhanced filtration membranes with graphene oxide and tannic acid for textile industry wastewater dye removal.

A novel modification technique employing a layer-by-layer (LbL) self-assembly method, integrated with a pressure-assisted filtration system, was developed for enhancing a commercial polyethersulfone (PES) microfiltration (MF) membrane. This modification involved the incorporation of tannic acid (TA) in conjunction with graphene oxide (GO) nanosheets. The effectiveness of the LbL method was confirmed through comprehensive characterization analyses, including ATR-FTIR, SEM, water contact angle (WCA), and mean pore size measurements, comparing the modified membrane with the original commercial one. Sixteen variations of PES MF membranes were superficially modified using a three-factorial design, with the deposited amount of TA and GO as key factors. The influence of these factors on the morphology and performance of the membranes was systematically investigated, focusing on parameters such as pure water permeability (PWP), blue corazol (BC) dye removal efficiency, and flux recovery rate (FRR). The membranes produced with the maximum amount of GO (0.1 mg, 0.55 wt%) and TA as the inner and outer layers demonstrated remarkable FRR and significant BC removal, exceeding 80%. Notably, there was no significant difference observed when using either 0.2 (1.11 wt%) or 0.4 mg (2.22 wt%) in the first layer, as indicated by the Tukey mean test. Furthermore, the modified membrane designated as MF/TA0.4GO0.1TA0.4 was evaluated in the filtration of a simulated dye bath wastewater, exhibiting a BC removal efficiency of 49.20% and a salt removal efficiency of 27.74%. In conclusion, the novel PES MF membrane modification proposed in this study effectively enhances the key properties of pressure-driven separation processes.

Advanced graphene oxide-based membranes as a potential alternative for dyes removal: A review.

Graphene oxide (GO) is one of the most well-known graphene derivatives which, due to its outstanding chemical, electrical and optical properties as well as its high oxygen content, has been recently applied in several fields such as in the construction of sensors, as antimicrobial agent for biomedical applications, as well as nanofiller material for membranes applied in wastewater treatment. In this last-mentioned field, the synthesis and functionalization of membranes with GO has proven to improve the performance of membranes applied in the treatment of wastewater containing dyes, regarding antifouling behavior, selectivity and flux. In this review, an overview of water pollution caused by effluents containing synthetic dyes, the advantages and limitations of GO-based membranes and the latest research advances on the use of GO-based membranes for dyes removal, including its impact on membrane performance, are discussed in detail. The future panorama of the applicability of GO-based membranes for the treatment of water contaminated by dyes is also provided.

Deposition of graphene nanoparticles associated with tannic acid in microfiltration membrane for removal of food colouring.

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.

Application of magnetic coagulant based on fractionated protein of Moringa oleifera Lam. seeds for aqueous solutions treatment containing synthetic dyes.

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%).

Water decontamination containing nitrate using biosorption with Moringa oleifera in dynamic mode.

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.

Activated carbon of Babassu coconut impregnated with copper nanoparticles by green synthesis for the removal of nitrate in aqueous solution.

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 10.13 mg g-1 at 45°C for GAC and 45.01 mg 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.