RESUMO

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.

RESUMO

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.

Assuntos

RESUMO

The present research aimed to evaluate the photocatalytic activity of manganese ferrite (M) and reduced graphene oxide (G) supported on pulverized activated carbon from cow bone waste (PAC-MG). PAC-MG was characterized by different instrumental techniques. The efficiency of PAC-MG was evaluated using solar irradiation under different conditions of photocatalyst concentration, H2O2 concentration, and pH ranges for the discoloration of methylene blue dye (MB). The synergy between the nanomaterials potentiated the photocatalytic activity, reaching 85.5% of MB discoloration when using 0.25 g L-1 of catalyst at neutral pH with no oxidant needed. Furthermore, PAC-MG demonstrated excellent stability in 6 consecutive cycles. Finally, it is expected that the present study can add value to industrial waste and contribute to the development of novel water and wastewater treatment methods, ensuring water quality for human consumption and the environment.

Assuntos

RESUMO

Aerogels are highly porous and ultralight three-dimensional materials with great potential for various applications. To obtain highly porous and structurally stable aerogels, a carefully designed synthesis process is required. These materials offer flexibility in manipulating their properties, allowing the incorporation of modifying agents according to specific needs. In this study, compounds were synthesized using graphene oxide (GO) and nanocellulose fibers (NFC) through the hydrothermal reduction methodology. Two drying techniques were employed: lyophilization and oven evaporation, resulting in materials called cryogel and xerogel, respectively. Various parameters that can interfere with the properties of these nanomaterials were evaluated. The results indicated that the cryogel dried by lyophilization provided the best applicability due to its structural flexibility after compressions, whereas the xerogel obtained through the oven evaporation process resulted in a compound with high rigidity and disintegration. Structural characterizations demonstrated the successful development of the precursors and promising characteristics in the synthesized nanomaterials. With its flexibility, approximately 98% porosity, low shrinkage rate, light weight, and electrical conductivity, the developed cryogel showed high potential in various applications, such as pressure sensors, electromagnetic shielding, and other research and development fields.

RESUMO

Ionized water has been reported to contribute to the tissue repair process and wound healing. Water purifiers can generate ionized water by means of activated charcoal with silver and minerals, the main purpose of which are to reduce microbiological and physicochemical contaminants. Moreover, when water is subjected to a magnetic field an organization of water molecules occurs due to the presence of mineral salts. The resulting water is thus more alkaline, which has been shown to be non-toxic to mice and can actually prolong survival. Cutaneous leishmaniasis is a neglected tropical disease, caused by obligate uni- and intracellular protozoa belonging to the genus Leishmania, that can manifest in the form of skin lesions. Thus, the objective of this study was to compare the evolution of disease in L. amazonensis-infected BALB/c mice that received tap water (TW) or ionized alkaline water (IAW). As a control, additional groups of mice receiving TW or IAW were also treated with the antileishmanial miltefosine. All mouse groups received either TW or IAW as drinking water 30 days prior to infection and the groups continued to receive the respective drinking water for 4 weeks, after which the blood and plasma were collected. Biochemical assays of aspartate aminotransferase, alanine aminotransferase, gamma-glutamyl transferase, creatinine, urea, glucose, triglycerides, and cholesterol were performed, in addition to hematology tests. There was a significant decrease in the volume of the lesion for groups that received IAW, in which the ingestion of ionized alkaline water favored the non-evolution of the lesion in the footpads of the animals. The results of the blood count and leukogram tests were within the normal values for BALB/c mice demonstrating that ionized water has no toxic effects on blood factors.

Assuntos

RESUMO

The clinoptilolite natural zeolites (NZs) posses low herbicide adsorption capacity demanding acid-, alkali-, or salt chemical modifications that enhance its adsorption. However, this may affect the material structure and charge distribution. Alternatively, zeolites may be synthesized at a high cost and time-consuming process. Consequently, new methods, such as the hydrothermal method, for NZ modification needs to be studied. In this sense, a novel surface-modified zeolite (SMZ), using hexadecyltrimethylammonium bromide (CTAB), in acid media was produced by the hydrothermal method and applied for the adsorption of Atrazine (ATZ), Diuron (DIU) and 2,4-D. Commercial NZ and SMZ were characterized by SEM, XRD, TGA, FT-IR, AA spectroscopy, pHPZC, Zeta potential and N2-physisorption. The SMZ chosen for the adsorption experiments was the one with the highest modification yield and adsorption capacity obtained from a complete design of experiments (CTAB=0.74 ; D=12 Mesh; HCl=0.1 M; t=6 h and T=205 ºC). The adsorption experiments revealed that the SMZ adsorption capacity for the herbicide 2,4-D (qmax=9.02 mg/g) was greater than that obtained for ATZ (qmax=2.11 mg/g) and DIU (qmax=1.85 mg/g), which was explained by the presence of the hydroxyl group and by geometric characteristics of the 2,4-D. Adsorption models' fitting showed that the adsorption of 2,4-D onto SMZ were best described by pseudo-second order kinetic (k2=0.005-0.006 g/mg.min; qe,exp=7.122-8.614 mg/g) and Langmuir isothermal model (KL=0.283-0.499 L/mg; qm=7.167-7.995 mg/g). These results indicate that the hydrothermal method is a viable alternative to enable the use of NZs for the adsorption of emerging contaminants from wastewater.

Assuntos

RESUMO

Carbonaceous materials have been widely applied as adsorbents, but there are some factors that affect their efficiency. In this context, advances in nanotechnology provide new and more efficient methodologies for water treatment. This study evaluated the efficiency of a novel carbon-based adsorbent developed from Brazilian polyacrylonitrile textile fiber and functionalized with iron oxide magnetic nanoparticles for the removal of 2,4-dichlorophenoxyacetic acid (2,4-D) from the aqueous medium. The synthesized adsorbent (ACF-Fe3O4) was characterized by FTIR, XRD, VSM, Zeta potential, SEM, EDX, and TEM. The characterization techniques showed that the adsorbent has peaks characteristic of its precursors and superparamagnetic characteristics, confirming the efficiency of the synthesis method. The adsorption tests evaluated the influence of adsorbent dosage, pH of the contaminant solution, contact time and temperature on the removal of 2,4-D. The experimental data were better adjusted by the pseudo-second order kinetic model and by the Langmuir isothermal model. The thermodynamic parameters revealed that the process is exothermic, spontaneous and thermodynamically favorable. Under the best experimental conditions, the maximum adsorption capacity obtained was 51.10 mg g-1 with an adsorbent concentration of 0.33 g L-1, natural pH of the solution, temperature of 288 K at the equilibrium time of six hours. Adsorbent reusage was studied in four desorption cycles. The adsorption mechanism can be explained through π-π bonds, hydrogen bonds and electrostatic interactions. The prepared material presented high-efficiency adsorption capacity of 2,4-D compared to other carbonaceous materials present in the literature, demonstrating its viability for the removal of this contaminant from the aqueous medium.

Assuntos

RESUMO

Eutrophicating compounds promote the growth of cyanobacteria, which has the potential of releasing toxic compounds. Alternative raw materials, such as residues, have been used in efficient adsorption systems in water treatment. The aim of the present study was to apply the residue Okara in its original form and modified by hydrolysis with immobilization of magnetic nanoparticles as an adsorbent. For the removal, the cyanobacteria Microcystis aeruginosa was chosen, as well as its secondary metabolites, L-amino acids leucine and arginine (MC-LR microcystin), from aqueous solutions. The adsorbents presented a negative surface charge, and the x-ray diffraction (DRX) outcomes successfully demonstrated the immobilization of iron oxide nanoparticles on the adsorbents. The adsorbent with the best result was the Okara hydrolyzed and functionalized with iron oxide, which showed a 47% (qe = 804.166 cel/g) and 85% (qe = 116.94 µg/L) removal for the cyanobacteria cells and chlorophyll-a, respectively. The kinetics study demonstrated a pseudo-first-order adsorption with maximal adsorption in 480 minutes, removing 761 µg/L of chlorophyll-a. In this trial, a low organic material removal has occurred, with a removal rate of 5% (qe = 0.024 mg/g) in the analysis of compounds in absorbance by ultraviolet light (UV) monitored by optical density determination in 254 nm (OD254). Nevertheless, the reaction system with the presence of organic material removed 53,28% of the MC-LR toxin, with adsorption capacities of 2.84 µg/L in a preliminary trial conducted for two hours, arising as a potential and alternative adsorbent with a capacity of removing cyanobacteria and cyanotoxin cells simultaneously.

Assuntos

RESUMO

Staphylococcus aureus is often associated worldwide with foodborne illnesses, and the elimination of biofilms formed by this bacterium from industrial surfaces is very challenging. To date, there have been few attempts to investigate plant oils obtained by recent green technologies, applied against biofilms on usual surfaces of the food industry and bacteria isolated from such environment. Therefore, this study evaluated the activity of Moringa oleifera seed oil (MOSO), extracted with pressurized n-propane, against standard and environmental S. aureus biofilms. Additionally, a genotypic and phenotypic study of the environmental S. aureus was proposed. It was found that this bacterium was a MSSA (methicillin-sensitive S. aureus), a carrier of icaA and icaD genes that has strong adhesion (OD550=1.86 ± 0.19) during biofilm formation. The use of pressurized n-propane as a solvent was efficient in obtaining MOSO, achieving a yield of 60.9%. Gas chromatography analyses revealed the presence of a rich source of fatty acids in MOSO, mainly oleic acid (62.47%), behenic acid (10.5%) and palmitic acid (7.32%). On polystyrene surface, MOSO at 0.5% and 1% showed inhibitory and bactericidal activity, respectively, against S. aureus biofilms. MOSO at 1% allowed a maximum reduction of 2.38 log UFC/cm² of S. aureus biofilms formed on PVC (polyvinyl chloride) surface. Scanning electron microscopy showed disturbances on the surface of S. aureus after exposure to MOSO. These unprecedented findings suggest that MOSO extracted with pressurized n-propane is potentially capable of inhibiting biofilms of different S. aureus strains, thus, contributing to microbiological safety during food processing.

Assuntos

RESUMO

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.