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.

Efficient removal of sertraline hydrochloride from wastewater using banana peels functionalized: performance adsorption, mechanisms and applicability.

The presence of sertraline hydrochloride (SER) has been detected in water bodies and wastewater, which encourages the search for alternative treatments for its control and removal. Agro-industrial residues are considered efficient adsorbents and functionalization with magnetic nanoparticles improve the adsorptive properties of these materials, in addition to facilitating their separation from a fluid by an external magnetic field. Thus, this study developed and characterized a new material via the functionalization of the banana peel with iron oxide nanoparticles (BANFunc) for the adsorption of SER in batch experiments. Physicochemical and spectroscopic techniques indicated that the BANFunc functionalization method was effective and improved the adsorption capacity (0.68 and 39.96 mg g-1 for BANPure and BANFunc, respectively). The adsorption studies revealed a maximum adsorptive capacity of 142.85 mg g-1 at 240 min and 318 K. Furthermore, the process presented spontaneous and endothermic behaviour, with a better fit to the pseudo-first-order and Langmuir models for the kinetic and isothermal, respectively. The reuse of the biosorbent was effective for five cycles, and even in the 3rd cycle, the adsorbent showed more than 80% SER removal. The adsorption process can be explained by hydrogen bonds and π-interactions. In the synthetic mixture treatment, the biosorbent demonstrated a satisfactory removal rate, of 86.91%, and individual removals of 83.23%, 89.36% and 88.15% for SER, safranine orange and chloroquine, respectively. Therefore, BANFunc is a promising material for large-scale applications, considering its sustainable character and high treatment efficiency.

Evaluation of hydrochar from peach stones for caffeine removal from aqueous medium and treatment of a synthetic mixture.

The presence of micropollutants, such as caffeine (CAF), has been detected throughout the world, since conventional treatment plants are not able to properly degrade them. CAF is a widely consumed stimulant, and has been demanding the development of efficient methodologies for its removal. Aiming at the agriculture waste valorization, a new hydrochar was developed based on chemical and thermal modification of peach stones (mod-PS) for CAF removal from water and from a synthetic mixture. The morphology, functional groups and surface electrical charge of the adsorbent were characterized by SEM, FTIR and zeta potential, respectively. Regarding CAF adsorption performance, the equilibrium time was reached at 480 min and the pseudo-second-order model presented the best fit for the experimental data. The maximum adsorption capacity was 68.39 mg g-1 (298 K) and the Langmuir model exhibited a better fit for the isothermal data. The thermodynamic properties confirmed that the process was exothermic, spontaneous and reversible. The main adsorption mechanisms were hydrogen bonds and π-interactions. The global removal efficiency was satisfactory in the synthetic mixture simulating real wastewater (67%). Therefore, the proposed new hydrochar has potential application as a low-cost adsorbent for CAF removal.

Removal of copper ions from alembic cachaça using agro-industrial residues as biosorbents.

Cachaça is a typical Brazilian distilled beverage made from fermented sugarcane juice. The copper levels in alembic cachaça are of great concern among producers, and the removal of this contaminant is important for the quality of the product. The present study aimed to remove copper ions from alembic cachaça by adsorption. Sugarcane bagasse, okara, Moringa oleifera Lam., three different types of zeolites, and two types of commercial charcoal were tested as biosorbents. The heat-treated sugarcane bagasse removed 100% of the copper present in a cachaça sample, while other low-cost natural adsorbents had close to 50% removal as was observed for M. oleifera seeds and okara. All adsorbents had porous and fibrous structures, favorable to adsorption. A kinetic study showed that a pseudo-second-order model was appropriate, with equilibrium times of 15 h for heat-treated sugarcane bagasse, okara, and M. oleifera seeds used as adsorbents. The Langmuir model better fitted the experimental data, indicating monolayer adsorption. The maximum adsorption capacity was 17.00, 0.77, and 5.33 mg of Cu g-1 for the heat-treated sugarcane bagasse, M. oleifera seeds, and okara, respectively. The results presented here are promising indicating three agro-industrial residues were favorable to the adsorption of copper ions from alembic cachaça.

Investigation of two new low-cost adsorbents functionalized with magnetic nanoparticles for the efficient removal of triclosan and a synthetic mixture.

Triclosan (TCS) is widely used in the production of antibacterial products, being often found in wastewater. Therefore, this study developed new materials via soybean hulls (SBHF) and açaí seeds (AÇSF) functionalization with iron oxide nanoparticles to be applied in the TCS adsorption. The characterization confirmed the functionalization of the materials. The adsorption results indicated that the equilibrium of the process occurred after 480 and 960 min for SBHF and AÇSF, respectively. The maximum adsorptive capacity values were 158.35 and 155.09 mg g-1 for SBHF and AÇSF, respectively, at 318 K. The kinetic and isothermal data better fitted to the pseudo-second-order and Langmuir models. Thermodynamics indicated that the processes had an endothermic, spontaneous, and reversible character. The main adsorption mechanisms were H-bond and π-interactions. The pH and ionic strength studies indicated that the adsorption efficiency has not been reduced pronouncedly. The biosorbents reuse was effective for five cycles. In the synthetic mixture, the removal rate was satisfactory (92.53% and 57.02%, respectively for SBHF and AÇSF). These results demonstrate the biosorbents high potential for large-scale application.

Application of activated carbon functionalized with graphene oxide for efficient removal of COVID-19 treatment-related pharmaceuticals from water.

Currently, the COVID-19 pandemic has been increasing the consumption of some drugs, such as chloroquine (CQN) and dipyrone (DIP), which are continuously discharged into water resources through domestic sewage treatment systems. The presence of these drugs in water bodies is worrisome due to their high toxicity, which makes crucial their monitoring and removal, especially by means of advanced technologies. Given this scenario, a new adsorbent material was synthesized through the combination of babassu coconut activated carbon and graphene oxide (GAC-GO). This study was evaluated in batch adsorption processes, aiming at the treatment of water contaminated with CQN and DIP. Characterization analyzes using physicochemical and spectroscopic techniques indicated that the GAC-GO functionalization was successfully performed. The equilibrium time of the adsorption process was 18 and 12 h for CQN and DIP, respectively. Kinetic and isothermal data better fitted to pseudo-second-order and Langmuir models for both drugs. Thermodynamic parameters showed that the process is endothermic and the maximum adsorption capacities of CQN and DIP were 37.65 and 62.43 mg g-1, respectively, both at 318 K. The study of the effect of ionic strength, which simulates a real effluent, demonstrated that the synthesized adsorbent has potential application for the treatment of effluents. Furthermore, satisfactory removal rates were verified for the removal of other contaminants in both simple solutions and synthetic mixtures, evidencing the versatile profile of the adsorbent.

Investigation of Citrus reticulata peels as an efficient and low-cost adsorbent for the removal of safranin orange dye.

Safranin orange (SO) is a cationic dye widely used in industrial sectors. It becomes a threat to the aquatic ecosystem once it reaches water resources, directly affecting photosynthetic activity and dissolved oxygen rate. In view of this scenario and considering the large production of agro-industrial waste, which provides significant disposal costs and environmental impacts, the agricultural by-products such as mandarin peels (MP) are being used as biosorbent materials. Thus, this work proposed the use of MP for SO adsorption. The material was characterized by SEM, zeta potential, and FTIR analysis, in which it was possible to verify heterogeneous porous morphology, predominantly negative surface, and organic functional groups that facilitate adsorption. The results were promising, wherein the maximum adsorption capacity was 464 mg g-1 (318 K), 0.4 g L-1 adsorbent concentration, 120 min equilibrium time and removal percentage of 84.75%. The experimental data showed a better fit to the Langmuir and pseudo-second order mathematical models. The thermodynamic analysis inferred spontaneous, endothermic, and reversible character for SO adsorption onto MP. The main proposed adsorptive mechanisms were hydrogen bonds, π-interactions, and electrostatic interactions. In addition, the reuse of MP showed good efficiency since the adsorption capacity was maintained above 50% after four cycles (from 77.90 to 41.55 mg g-1). Moreover, when evaluating the effect of pH and ionic strength, it verified that the adsorption efficiency was not reduced. Therefore, when compared with other materials, the versatility and potential applicability of MP as a low-cost adsorbent for wastewater treatment is notable.

Adsorption of Safranin-O dye by copper oxide nanoparticles synthesized from Punica granatum leaf extract.

The development of new technologies for water and wastewater treatment is a growing need due to the occurrence of micropollutants, such as dyes, in water resources. In this sense, green-synthesized nanoparticles are being extensively studied, due to their low cost, non-toxicity, and high efficiency in adsorption processes. Thus, the present study reports the green synthesis of copper oxide nanoparticles (CuO-NP), obtained from pomegranate (Punica granatum) leaf extract, employed for the removal of Safranin-O (SO) dye. CuO-NP was characterized by physicochemical analysis. These analyzes suggested that the redox process occurred efficiently. Also, the material presented interesting elements for the removal of cationic dyes such as negative surface charge, high specific surface area, and predominance of mesopores. The kinetic data fitted the pseudo-second-order model, reaching equilibrium in 480 min. The equilibrium study resulted in a maximum adsorption capacity of 189.54 mg g-1 at 298 K and the experimental data best fitted the Langmuir model. The effect of pH and ionic strength did not present significant changes, which demonstrates an advantage of this adsorbent over other materials. The regeneration study allowed to verify the possibility of reuse CuO-NP, since after 4 cycles the adsorption capacity was 44% of the initial value. Considering the results found, CuO-NP has a high potential for applicability in the treatment of water contaminated by dyes.

Graphene oxide functionalized with cobalt ferrites applied to the removal of bisphenol A: ionic study, reuse capacity and desorption kinetics.

A new adsorbent material based on graphene oxide (GO) functionalized with magnetic cobalt ferrite nanoparticles (γCoFe2O4) was synthesized via ultrasonication to remove the endocrine-disrupting-chemical bisphenol A (BPA) from aqueous solutions. The synthesized material (GO-γCoFe2O4) was characterized by TEM, SEM, DRX and FTIR analysis. Magnetization measures proved that the adsorbent had superparamagnetic characteristics that facilitated its separation from the aqueous solution. The maximum adsorption capacity obtained was 30 mg g-1 with adsorbent concentration of 1 g L-1, temperature of 55°C and natural pH of the solution. The experimental data were better adjusted to the kinetic models of pseudo-second-order and Langmuir isotherm. The thermodynamic parameters showed that the BPA adsorption on GO-γCoFe2O4 was spontaneous, exothermic and thermodynamically favourable. Desorption kinetics was performed using 50% ethanol as solvent, resulting in an equilibrium time of 4 h with better adjustment to the pseudo-second order kinetic model. The adsorbent showed a high regeneration capacity maintaining adsorptive capacity above 75% after 6 cycles of reuse.

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.

Bisfenol A adsorption using a low-cost adsorbent prepared from residues of babassu coconut peels.

Nowadays, the occurrence of microcontaminants in water resources has become a worldwide concern. Among them, it can be mentioned Bisphenol A, a substance widely used in the chemical composition of plastic such as manufacture of packages, bottles, toiletries, among others. Its use may cause adverse effects on human health and the environment. Thus, a treatment is necessary to remove this compound and adsorption is an interesting alternative due to its low cost, operation and high efficiency. The objective of the present study was to evaluate the adsorption capacity of bisphenol in babassu activated carbon. The obtained results were satisfactory and the best experimental conditions were at 318 K temperature, 1 g L-1 adsorbent concentration and 720 min equilibrium time, resulting in the maximum adsorptive capacity of 49.61 mg g-1. The experimental data fit best with the pseudo-second order and Langmuir models for the kinetic and equilibrium studies, respectively. Thermodynamic parameters indicated endothermic, spontaneous and reversible process. The main adsorption mechanisms were hydrogen bonds and π-π interactions. In addition, the material regeneration study allowed to verify its possibility of reuse. Therefore, it was noticed that babassu activated carbon has high potential applicability in the treatment of contaminated water.

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 graphene nanosheet oxide for atrazine adsorption in aqueous solution: synthesis, material characterization, and comprehension of the adsorption mechanism.

The present study aimed to investigate the application of graphene oxide (GO) as adsorbent material for the removal of atrazine (ATZ). The material produced was characterized to investigate the characteristics and applied as an adsorbent. The material obtained after the synthesis process presented oxygenated functional groups, which contributed to the development of a good adsorbent material. Studies were carried out to verify the influence of adsorbent material mass and initial pH of ATZ solution in adsorption capacity. Kinetic study determined that pseudo-second-order model best describes adsorbate-adsorbent interaction, with equilibrium time of 72 h. The effect of temperature on the material adsorption capacity was also studied. The Langmuir isotherm is the best fit to describe adsorption process GO-ATZ and maximum adsorption capacity obtained was 23.844 ± 0.694 mg g-1, at 318 K. Variations in process energies were determined, being a spontaneous adsorption, endothermic and characteristic of physical and chemical adsorption. Finally, influence of salts in solution on adsorption capacity was studied; the conclusion was that the presence of electrolytes affects the adsorption capacity of the material.

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%).

Biopolymer extracted from Moringa oleifera Lam. in conjunction with graphene oxide to modify membrane surfaces.

A novel modification through pressurized filtration technique of commercial polyethersulfone membranes was proposed using a biopolymer extracted from Moringa oleifera Lam. (MO) along with graphene oxide (GO), in order to decrease fouling and improve the membrane selectivity for the removal of methylene blue dye. The effect of these agents over the morphology and performance of the membranes were studied through the evaluation of permeability, dye removal and fouling parameters. The characterization of the membrane indicates a significant decrease in pore size, as confirmed by the filtration experiments. Also, according to FTIR and SEM analysis the modification was effectively accomplished. All modified membranes presented low fouling rates (<10.55%) and high dye removal rates (from 2.85% to 96.73%). Furthermore, it is the first time that MO has been used as a natural polymer to improve and confer new characteristics on membranes, creating new possibilities for further study of this promising environment-friendly biopolymer in membrane separation processes.

Hybrid treatment of coagulation/flocculation process followed by ultrafiltration in TIO2-modified membranes to improve the removal of reactive black 5 dye.

Many efforts have been made to minimize the polluting effect of wastewater containing dyes that are potentially toxic to the environment. The association of the coagulation/flocculation (CF) process, using saline extract of Moringa oleifera Lam (MO) seeds and subsequently ultrafiltration (UF) in TiO2-modified membranes was performed to remove reactive black 5 dye (10 ppm, RB5) from aqueous solution. The efficiency of the hybrid process was measured by the removal of the dye concentration, apparent color and fouling parameters. The membranes were successfully modified as supported by characterization methods of SEM, FTIR-ATR and WCA. The efficiency of the processes, when applied separately was low. However, after CF and subsequently the filtration in a TiO2-modified membrane both parameters assessed (dye concentration, apparent color) reached 100% of the removal rate. The modified membranes substantially improved permeate fluxes, for instance, after CF the dye flux for modified membrane enhanced around 49% compared with the flux in the pristine membrane. According to these results, the combination of methods was able to effectively remove RB5 dye, in addition to improving permeate fluxes and keeping fouling at low levels.

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.

Environmentally friendly biosorbents (husks, pods and seeds) from Moringa oleifera for Pb(II) removal from contaminated water.

Lead is a heavy metal considered highly toxic, responsible for causing several health problems as well as being extremely harmful to fauna and flora. Given this fact, several techniques have been studied for the removal of this metal from contaminated water, in which stands out adsorption. In this sense, the objective of this study was to evaluate the potential of lead(II) biosorption from contaminated water by seed husks, seeds and pods of Moringa oleifera Lam (moringa). Biomass was characterized by energy-dispersive X-ray spectroscopy, Scanning Electron Microscopy and Fourier transform infrared spectroscopy analyses. From the studied parameters, the optimal conditions obtained for the three analyzed biosorbents are: 30 min to equilibrium, pH 6 and 25°C temperature. The pseudo-second-order kinetic model was the best fitted to the experimental data for the three evaluated biosorbents. Regarding the adsorption isotherms, the model that best fitted to the experimental data for seed and seed husk was that proposed by Freundlich, and for the pod the Langmuir model. The analysis of the obtained thermodynamic data showed that the adsorption process is favorable and of exothermic nature. Through the results it was concluded that the evaluated biosorbents are efficient in lead(II) biosorption.