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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.

The combined approach of specific surface area (SSA), porosity, microprobe analysis (EMPA), transmission electron microscopy (TEM), scanning electron microscopy (SEM) equipped with EDX and infrared spectroscopy (FTIR) provided the mica mineral physico-chemical and morphological characterisation. The electrostatic surface properties were assessed through the determination of the Point of Zero Charge (pHPZC) by the drift method and the electrokinetic mica mineral features represented by the Isoelectric Point (pHIEP) which was carried out through zeta potential measurements. Adsorption tests were performed to correlate the surface charge behaviour of the mica mineral and its influence on the adsorption efficiency of two different dyes, namely: Safranin Orange (SO), as a cationic dye and Reactive Black 5 (RB5), as an anionic dye. The higher adsorption capacity SO dye was observed at pH 9 and achieved almost 83% of removal, while RB5 dye adsorption on mica surface had the highest result, about 45% of removal efficiency, on pH of 3. In both cases, the main mechanism identified that drove this results is the electrostatic force of attraction between the adsorbent edge surface charge (pHdependent) and the ionic nature (anionic or cationic) of the pollutant dyes particles. The preliminary adsorption experiments demonstrated that the raw grounded mica mineral has a greater potential associated with its application on cationic dye removal in wastewater. The present study aimed to detail the main characteristics of the mica mineral in order to evaluate the potential use of such mineral residues in the removal efficiency of contaminated wastewater info:eu-repo/semantics/publishedVersion

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 an...

This work aims to integrate several hydrogen peroxide (H2O2) activation mechanisms, photolysis (UVC irradiation), chemical electron transfer (TiO2-P25 photocatalysis), and reaction with TiO2-P25 in dark conditions, for reactive oxygen species (ROS) generation towards the removal of contaminants of emerging concern (CECs), in a single unit operated in continuous-flow mode. An H2O2 stock solution is fed by the lumen side of a tubular ceramic membrane, delivering the oxidant to the (i) catalyst immobilized in the membrane shell-side and (ii) annular reaction zone (ARZ, space between membrane shell-side and outer quartz tube) where CECs contaminated water flows with a helix trajectory, being activated by UV light provided by four lamps placed symmetrically around the reactor. First, the effect of several parameters in the removal of a CEC target molecule, amoxicillin (AMX), was evaluated using a synthetic solution ([AMX]inlet = 2.0 mg L-1): (i) light source (UVA or UVC radiation), (ii) H2O2 dose, (iii) H2O2 injection method (radial permeation vs. upstream injection), and (iv) number of TiO2-P25 layers deposited on the membrane. The UVC/H2O2/TiO2 system with radial addition of H2O2 (20 mg L-1) and 9-TiO2-P25 layers provided the highest AMX removal efficiency (72.2 ± 0.5%) with a UV fluence of 45 mJ cm-2 (residence time of 4.6 s), due to the synergic effect of four mechanisms: (i) AMX photolysis, (ii) H2O2 photocleavage, (iii) TiO2-P25 photoactivation, and (iv) chemical reactions between H2O2 and TiO2-P25. The urban wastewater matrix showed a negative effect on AMX removal (~44%) due to the presence of ROS scavengers and light-filtering species.

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...

A presenca de corantes na agua, mesmo em pequenas concentracoes e prejudicial, pois podem impedir a penetracao da luz e prejudicar a eficiencia da fotossintese, causando serios danos a fauna e flora destes locais. Devido a sua alta toxicidade os corantes tambem podem causar danos graves aos seres humanos, como disfuncao nos sistemas renais, do reprodutivo, alem do figado, cerebro e sistema nervoso central. Entre os metodos usados no tratamento de agua, a biossorcao se apresenta como uma alternativa interessante devido sua alta seletividade, eficiencia e baixo custo, propondo a utilizacao de produtos residuais e subprodutos. Tendo isso em vista, o presente estudo avaliou a capacidade de um biossorvente derivado da pinha na remocao do corante vermelho neutro da agua. Os resultados mostraram que o biossorvente proveniente da casca de pinha possui um otimo desempenho na remocao do corante vermelho neutro, removendo mais de 90% desse contaminante do meio aquoso, alem de obter a capacidade maxima de adsorcao de 23 mg.g-1, tornando-se assim, uma possivel alternativa no tratamento de efluentes contaminado com esse corante. A microscopia eletronica de varredura mostrou boa quantidade de poros na superficie do biossorvente, o que favorece o processo de biossorcao, o modelo de melhor ajuste foi pseudossegunda ordem que sugere que o mecanismo de adsorcao seja a quimiossorcao. Como o biossorvente nao precisa passar por nenhum tipo de tratamento quimico, ha uma diminuicao no tempo e custo de operacao, tornando o biossorvente produzido uma alternativa economicamente e ecologicamente interessante para o tratamento de efluentes contendo corantes.

O objetivo deste trabalho foi a avaliacao da cinetica de adsorcao do corante azul de metileno utilizando carvao ativado impregnado com oxido de grafeno. Realizou-se a sintese do oxido de grafeno pelo metodo Hummers usando o grafite de pilhas zinco-carbono exauridas e a impregnacao do oxido de grafeno no carvao ativado por evaporacao/calcinacao. Foram realizados ensaios cineticos de adsorcao em batelada, com pH inicial 5, concentracao inicial de corante de 100 mg L-1, agitacao constante, temperatura ambiente e amostragem de 5 a 360 min. Pela analise dos dados cineticos, verificou-se tempo de equilibrio para o carvao ativado e o carvao ativado impregnado com oxido de grafeno de 240 e 90 min, respectivamente. Reportam-se alteracoes nas etapas de transferencia de massa em decorrencia da impregnacao do oxido de grafeno destacando-se ausencia da difusao intraparticula nos microporos e indicativo da etapa limitante para este adsorvente ser a difusao intraparticula na superficie externa. As alteracoes no adsorvente, apesar de nao aumentarem a eficiencia global de adsorcao do corante, conferiram maior velocidade ao processo. Estes resultados sugerem que o carvao ativado com oxido de grafeno apresenta potencial de emprego na remocao de corantes.

Activated carbon (AC) is widely used in water treatment, however, it has some technical disadvantages, such as its high cost and difficulty to recover. To overcome these drawbacks, AC particles have been encapsulated within a polymeric support, mainly chitosan and alginate-based. The use of these biological macromolecules results in composites with lower-cost, superior mechanical properties, and higher number of functional groups, advantages that have been attracted the attention of the scientific community. However, the number of publications is relatively low, demonstrating an important research gap yet to be investigated. Thus, this paper aims to review the recent studies concerning the use of chitosan, alginate and other macromolecules as AC immobilizing agents, describing the synthesis methods, characterization analyses and adsorption studies, focusing on the main advantages, disadvantages, gaps and future perspectives. Throughout the review it was verified that the composites were able to remove several water contaminants, mainly dyes and heavy metals, with high efficiency. Synergistic effects were detected, indicating the role of both polymers and AC, which increased the spectrum of contaminants capable of being adsorbed. Finally, it was observed a gap in column experiments, suggesting that future studies are essential to elucidate the applications in the industrial perspective.

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.

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.

Em relação à qualidade das águas subterrâneas, a presença de nitrato está entre os principais indicadores de poluição dos recursos hídricos. Este trabalho teve como objetivo investigar a presença de nitrato e conhecer o processo de remoção do íon nitrato de águas oriundas de fontes subterrâneas da bacia hidrográfica do Ribeirão Borba Gato (BHBG), utilizando carvão ativado. As amostras foram coletadas entre 08/2014 a 08/2015, em 19 poços tubulares e submetidas a análises físico-químicas, onde foi explorada a remoção do íon nitrato por meio de filtro de carvão ativado comercial. A partir das análises foi possível verificar possíveis riscos de contaminação antrópica, por meio das concentrações de nitrato e detectar a quantidade de nitrato que o filtro comercial de carvão ativado retém no processo de filtração lenta. Grande parte das amostras evidenciaram concentrações de nitrato acima dos valores naturais para águas subterrâneas. Verificou-se, portanto, que as fontes subterrâneas da BHBG vêm sofrendo contaminação, podendo apresentar outros poluentes de igual ou superior periculosidade à saúde humana e ambiental.

A review of the main pesticides employed in agriculture found that the pesticide groups present in the highest amounts are herbicides, fungicides, and insecticides. For this reason, their occurrence in surface waters around the world, as well as their adverse effects on non-target organisms were reviewed for the period 2012–2019. Among the most common vegetal herbicides is atrazine, followed by metalochlor, both of which are widely-used on soybean and corn crops. Insecticides are used to control insects by agonizing them. Although they present low toxicity for mammals, they are toxic to ecosystems and impact the environment when present. Fungicides are employed to prevent fungal infections by damaging the cellular membrane, causing damage to non-target organisms, tebuconazole and carbendazim were the most frequent fungicides identified in surface waters throughout the world. Once pesticides reach water bodies, they can impact the whole ecological food chain, since other animals, including humans, feed on aquatic animals that may be contaminated. Another concern is the mixing of pesticides, in which case the mixture may be more toxic than any one single compound. Because mixtures of pesticides are commonly found in surface water, the need for suitable water treatment is crucial.

Membrane separation processes are an efficient method to manage the amount of wastewater improperly discharged into water due the use of dyes in industrial processes. Thus, polyethersulfone microfiltration membranes were modified with sulfuric acid, titanium dioxide (TiO2) and graphene oxide (GO) solutions by layer-by-layer self-assembly method via electrostatic interaction through a pressure-assisted filtration system. The characterization indicated that the proposed modification was successfully accomplished. The effect of TiO2 and GO masses deposited on the membrane surface was studied. MFTD1.0+GO2.5 membrane showed the best performance among synthesized series achieving a red bordeaux (BR) dye removal of 93.35 % and a flux recovery ratio of > 80 %. The treatment of dyes twilight yellow (TY) and safranin orange (SO) was investigated in this membrane achieving a rejection rate of 69.98 and 100 %, respectively. For dyes with high removal rates (BR and SO), other filtration cycles were performed and good results were accomplished. The proposed modification resulted in an efficient treatment of dyes with different characteristics as well as improvement of selectivity and antifouling properties of the membranes. Their reuse potential represents an additional environmental advantage of this process.

Chemical products traditionally used in the disinfection of water bodies often pose human health risks. For this reason, studies on natural coagulants such as Moringa oleifera Lam. represent an alternative for the inactivation of pathogenic microorganisms, among which is Escherichia coli. This study evaluated the effect of different concentrations of coagulants obtained from Moringa seed extracts and their protein fractions in the inactivation of E. coli during the coagulation/flocculation process. The coagulants studied were the aqueous extract, saline extract and protein fractions albumin and globulin, highlighting that the protein fractions were more effective on inactivating E. coli. The protein fraction globulin at a concentration of 10.0 mg L−1 showed bactericidal effects against E. coli within 18 min, whereas the albumin showed a bacteriostatic effect within 48 min because it isolated colonies in the sediment sample.

The present study proposes the synthesis and characterization of graphene oxide (GO) and its application in the adsorption of the antibiotic cephalexin (CFX) in aqueous solution. The characterization of graphene oxide was obtained by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and zeta potential. The influence of pH on the batch adsorption process was investigated by analysing adsorption equilibrium isotherms and adsorption kinetics. The images obtained by SEM and TEM presented the typical morphology attributed to GO sheets. The kinetic adsorption tests showed that equilibrium was reached in 420 min, and an adsorption capacity of 164 mg g−1 was obtained. The models that best fit the experimental data were pseudo-second as well as the Langmuir isotherm. Therefore, GO was effective for removing the CFX antibiotic from aqueous solution by using a batch adsorption process.

Various studies concerning sanitary landfill leachate (SLL) characteristics and toxicity identified the presence of endocrine disrupting chemicals (EDCs). A review of the detected EDCs in SLL was performed, in which the 12 most frequent EDCs identified in sanitary landfill sites over the world were ranked: BPA, DBP, DEHP, DEP, NP, BBP, DOP, DMP, 4OP, DiBP, DTBP and nicotine. The presence of these compounds is related to the activities on the dumping site, especially by the presence of plastic and personal care products, insecticides and cleaning agents in the waste bulk. Many diseases in human and animals have been associated with exposure to EDCs, as examples can be cited: disorder in metabolic processes that might end in diaseases, reduction of fertility, bioaccumulation and a high cancer potential. Among the treatment strategies applied to SLL degradation, processes based on Fenton reaction have received increasing attention due to its non-selective oxidation performed by hydroxyl radicals (•OH). Thus, they are able to oxidize/mineralize compounds which are not removed in conventional wastewater treatments. Degradation pathways and byproducts produced after the oxidative process may provide important information around the applicability of these techniques. Integrated treatments are also studied to obtain biosafety of treated wastewater samples. For the SLL treatment, the most employed strategy coupled to Fenton-based processes is the biological oxidation. The integration strategy relies on the SLL characteristics, being two modalities allowed: Fenton-based processes followed by biological systems or the opposite one. Future researches are needed to advance our understanding of the behavior of EDCs in human and animals bodies, as well as its critic concentrations. Also, there still is a lack of research regarding the degradation pathway of EDCs by OH in a SLL matrix, the ecofriendly disposal of iron sludge, the handle of the chemical solution wastes and the economic aspects of these treatments in order to meet a large scale application of this technology. Therefore, these topics have been discussed in this review article.

Optimum experimental conditions for the photo-electro-Fenton (PEF) process using a lab-scale photo-reactor to treat a sanitary landfill leachate (SLL) were determined. The PEF process operational conditions were analyzed with a response surface methodology (RSM) that presented a high total carbon (TC) removal at the central point: current intensity of 2.3 A, H2O2 concentration of 9000 mg·L−1, Fe2+ concentration of 60 mg·L−1, an electrolysis time of 45 min and solution pH controlled at the range 3.5–4.5, reaching a minimum TC residual concentration of 344 mg·L−1 in the SLL, as well as 89 mg Pt-Co·L−1 of color, 254 nm = 0.18 a.u., 315 mg·L−1 5th day biochemical oxygen demand (BOD5), 782 mg·L−1 chemical oxygen demand (COD), improving the BOD5/COD = 0.4 ratio. The reaction byproducts were analyzed with gas chromatography-mass spectrometry (GC–MS). The generated byproducts were less toxic than the parent compounds found in the raw SLL. As the SLL toxicity was reduced, integration treatment strategies containing PEF processes and biological oxidation (BO) were studied. The best treatment strategy enabled the lethal concentration LC50% = 33% and reduced the residual TC concentration to 181 mg·L−1 through application of the PEF process. This possibly transformed recalcitrant compounds from raw SLL into more biodegradable substances (BOD5/COD = 0.53) facilitating the microbial activity in the posterior BO. This treatment strategy also produced a smaller number of identified byproducts, which confirms the good performance of the PEF process followed by BO.

Atrazine is an herbicide which is widely applied in sugarcane and corn crops. Its frequent use has resulted in environmental impacts, and its traces have been verified in surface and groundwater. T...

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 PEI

Glyphosate is a broad-spectrum systemic herbicide widely used in crops. Contamination of groundwater and superficial water sources by glyphosate may suppose an environmental risk due to its chronic toxicity. In this frame, development of water treatment technologies to remove glyphosate is of high relevance. The objective of this work was to evaluate capabilities of electrochemical oxidation (ECO) as emergent environmental friendly technology. The effect of variation of current density (j), pH and initial concentration of supporting electrolyte was studied when employing DSA® expanded anodes of Ti/Ru0.36Ti0.64O2. Special attention was given to the influence of pH due to the characteristic speciation of glyphosate that may influence ECO performance. Almost complete mineralization (>90%) of pure glyphosate was attained after 3 h of ECO treatment with 0.15 M NaCl at 40 mA cm−2 and pH 3.0. Meanwhile, solely 60% of mineralization was achieved under identical conditions when treating commercial glyphosate pesticide products. Degradation by-products and yielded ionic species were identified by chromatography and chromatography mass spectrometry. A reaction sequence for glyphosate ECO mineralization was proposed.

The present study proposes development of an adsorbent based on combination of graphene oxide (GO) and iron oxide (α-γ-Fe2O3) nanoparticles for atrazine removal from water. The synthesized ...

The reduction of the excess fluoride present in groundwater and surface water is of paramount importance to the public supply, given that its excess can trigger various harmful effects on human health, such as dental and skeletal fluorosis. In this context, the objective of the present investigation was to evaluate the defluoridation of groundwater using coagulation/flocculation/sedimentation (C/F/S) process using the natural coagulant Moringa oleifera Lam (MO) followed by ultrafiltration membrane process. C/F/S tests were carried out in a Jar test apparatus with different concentrations of the coagulant and subsequent ultrafiltration in a membrane module. The tests used different initial fluoride concentrations, coagulant dosages, and water samples (distilled, ground, and surface water). Fluoride removal was most effective using 5 ppm of fluoride initial concentration and 5 g/L of MO coagulant dosage; however, an increase in turbidity was observed. The ultrafiltration step was used to improve water quality parameters, and at a pressure of 2 bar, it was obtained 97% of turbidity and color removal and 83% of fluoride removal. Thus, the results obtained applying the combined process of C/F/S followed by ultrafiltration can be considered a promising alternative to defluoridation of groundwater intended for public supply.

Acetaminophen has shown a gradual increase in detection in surface waters. Although present in low concentrations, it should be removed to prevent deleterious effects. Thus, adsorption onto activated carbon is emphasized. Adsorbents may be produced by hydrothermal carbonization (HTC), an environmental-friendly process. Therefore, this work aimed to investigate the use of HTC, verifying its application in acetaminophen removal. Brewer's spent grain (BSG), its hydrochar (HC-BSG) and its activated hydrochar (AHC-BSG) were characterized. HTC provided material with high carbon content. Lignocellulosic breakdown has been demonstrated in HC-BSG and AHC-BSG, but in the latter it was more intense as a result of activation with KOH. Also, a high surface area was found in AHC-BSG (1512.83 m2 g−1), resulting in an adsorption of 318.00 mg g−1. The pseudo-second-order and Langmuir models were fitted to the experimental data. Therefore, HTC was effective as a pretreatment for AHC-BSG, resulting in significant acetaminophen removals.

Adsorption in biomass has proven to be a cost-effective option for treatment of wastewater containing dyes and other pollutants, as it is a simple and low cost technique and does not require high initial investments. The present work aimed to study the adsorption of methylene blue dye (MB) using sugarcane bagasse (SCB). The biomass was characterized by scanning electron microscopy (SEM). Adsorption studies were conducted batchwise. Kinetics, adsorption isotherms, and thermodynamics were studied. The results showed that SCB presented a maximum adsorption capacity of 9.41 mg g&minus, 1 at 45 &deg, C after 24 h of contact time. Adsorption kinetics data better fitted the pseudo-second order model, indicating a chemical process was involved. The Sips&rsquo, s three-parameter isotherm model was better for adjusting the data obtained for the adsorption isotherms, indicating a heterogeneous adsorption process. The process showed to be endothermic, spontaneous, and feasible. Therefore, it was concluded that SCB presented as a potential biosorbent material for the treatment of MB-contaminated waters.

The wide use of dyes has been arousing global concern due to the amount of wastewater improperly discharged into water resources, damaging the environment and human health. In this study, microfiltration polyethersulfone membranes were modified with polyvinyl alcohol (PVA) and graphene oxide (GO) by layer-by-layer self-assembly method and subsequently used for sunset yellow (SY) dye removal. Different masses of PVA (0, 30 and 60 g) and GO (0.5, 1 and 1.5 g) were deposited on the membrane surface, in which the MF/PVA60+GO1+PVA30 achieved the best performance among all modifications, with removal greater than 99.90%, ∼80% flux recovery rate and good regeneration ability (>94% removal after 5 reuse cycles). Moreover, BSA filtration confirmed its antifouling properties. In order to simulate a real wastewater, the SY dye filtration in the presence of dissolved salts was investigated, wherein a satisfactory removal rate (86.17%) was found for MF/PVA60+GO1+PVA30. Filtration tests were also performed with tartrazine yellow and amaranth dyes, which removal outcomes (>99%) confirm the versatility and efficiency of this membrane. The characterization by physical-chemical and spectroscopic techniques indicated that the membrane was successfully modified. Therefore, the proposed modification demonstrated a significant improvement in dyes removal, which allows its application for wastewater treatment purposes.

In recent years, there is an increase of emerging pollutants, such as pharmaceuticals, which are recognized as emerging micro-pollutants that negatively influence the environment, human health and are difficult to biodegrade. Several of these compounds remain in the environment even after water treatment processes, requiring more effective removal methods. The present study proposes the development of new adsorbent materials consisting of the combination of graphene oxide (GO) with iron oxide nanoparticles (αγ-Fe2O3) and cobalt oxide (Co3O4) to intensify the efficiency of the batch adsorption process. The results of the caffeine adsorption tests in GO#αγ-Fe2O3Co3O4 demonstrated removal of 80% and maximum adsorption capacity of 28.94 mg g−1. The study of caffeine adsorption kinetics demonstrated a better fit for the pseudo-second order model. The analysis of the adsorption isotherm model showed that the Langmuir and Temkin models fit well the experimental data. The thermodynamic parameters showed that caffeine adsorption in GO#αγ-Fe2O3Co3O4 was exothermic, spontaneous and thermodynamically favorable. Through the competition of ions, it was found that ions of Na+, K+, Ca2+ and Mg2+ do not interfere in the adsorptive process. In addition, the adsorbent material showed excellent regenerative capacity and ease of separation, exhibiting high efficiency in removing caffeine from water.

The lack of data regarding the mechanisms at work in the coagulation processes of different substances using magnetic coagulants makes it difficult to understand the phenomena involved and, consequ...

The demand for healthier and less processed food preservatives, which also accumulate therapeutic properties, has attracted the attention of consumers and industries, tus boosting the search for new technologies. The aim of the present work was to evaluate the thickening action performance of Moringa seed extracts in the elaboration of yoghurt. For this purpose, we evaluated the impact of the addition of different fractions of Moringa seed saline extract obtained via ultrafiltration in yogurt fermented by culture probiotic lactic production. In order to evaluate the influence of Moringa additives in final products, analysis of texture, pH, total protein content, susceptibility to syneresis, besides rheology assays, were performed throughout a four week storage-refrigerated period. Results revealed that yogurts added with Moringa extracts presented lower syneresis values, higher protein contents, higher consistency index values and more cohesive casein net, when compared to the control. This study endorses the potential application of Moringa seed extracts as thickener agents in food systems, which could represent a new option in the market of natural food additives.

In this work, the adsorption of sodium diclofenac (DCF) on graphene oxide nanosheets (GON) was evaluated. GON was synthesized by the modified Hummers method and characterized regarding its composition, morphology, and surface load. It was applied in batch adsorption tests. The process was evaluated from the kinetic, isothermal and thermodynamic properties, and parameters such as adsorbent mass and solution pH were optimized. The best working condition was observed at the natural pH of the solution (6.2) and 0.25 g L

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

The herbicide removal of Diuron in a fixed-bed column packed with the Moringa oleifera bark biosorbent was investigated experimentally and through phenomenological mathematical modelling. T...

The aim of this work was to determine the optimal Photoperoxi-Electrocoagulation (PPEC) process experimental conditions for the treatment of a tannery industrial wastewater (TIW). The lab-scale PPEC-reactor comprises a pair of iron-flat plates, resulting in a contact effective area of 58.5 cm2; the PPEC reaction was conducted by electrochemical phenomenon associated to a Fenton’s reaction based on the H2O2 concentrations added, the solar UV–vis light was exposed, as well as iron ion dissolved original plate deterioration, resulting in a production of an efficient hydroxyl radical ( OH). An optimising analysis using a response surface methodology was performed; the optimum conditions of the PPEC process were attained at a solution pH of 4, current density of 34.2 mA cm−2, 6 g H2O2 L−1 and an electrolysis time of 120 min. The effects on the removal of chromium and COD were evaluated, suggesting satisfactory results for the PPEC reaction. Based on the low calculated median lethal dose (LD50) values from a lettuce-seed-based ecotoxicity test, untreated TIW samples were completely lethal for doses with 100%, except for samples taken after 90 and 120 min. The PPEC process could be applied as an efficient low-cost alternative treatment for the removal of pollutants from TIW with a low environmental impact.

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.

The presence of textile dyes in waters and effluents is still a global concern since the conventional methods of treatment are not sufficient to completely remove these contaminants. Given this scenario, this study evaluated a hybrid system of coagulation/flocculation (CF) followed by microfiltration (MF) for solophenyl blue (SB) dye removal. The combination of these processes using potato starch (PS) as a natural coagulant and TiO2 to modify the membrane surface is innovative and efficient. The results showed that the processes, when applied separately, were not effective. The pretreatment by CF favored the removal of particles and colloids from the dye. The modification of the membrane surface allowed the mitigation of fouling in the MF process. Thus, the association of CF/MF showed excellent results, achieving a 100% SB removal and a considerable reduction in the fouling rate. The modified membrane preceded by CF, for example, has substantially improved the rejection of SB, as the removal rate has increased by about 57% compared to the pure membrane. Therefore, the proposed hybrid process demonstrated a significant improvement in the quality of the permeate, with high potential for application in the treatment of dye wastewater from textile industries, besides sustainable and economical characteristics.

As a consequence of the inadequate disposal of pharmaceutical products and a residual portion that is not absorbed by the organism and is disposed into domestic sewage, antibiotics have been found in water resources. This results in serious problems for the environment and for human health, thus, efficient methods to remove these compounds from aqueous effluents are necessary. In this study, carbon with silver and copper oxide nanoparticles supported in activated carbon (CA-NPsAg/CuO), silver and copper oxide nanoparticles supported in graphene (OGR-NPsAg/CuO), and graphene oxide impregnated with silver and copper oxide nanoparticles supported in activated carbon (CA-OGR-NPsAg/CuO) to remove the cephalexin antibiotic in aqueous solution was investigated. These adsorbents were characterized through scanning electron microscopy and zeta potential. Adsorption equilibrium data were obtained for those three adsorbents at pH 6.7 (natural) and temperature 25 ∘C and the isotherm models of Langmuir, Freundlich, Sips, Sigmoidal Langmuir, and Dubin-Astakov were investigated to describe the data. Langmuir model was the one that better described the experimental equilibrium data for the adsorbent CA-OGR-NPsAg/CuO, while for the adsorbent CA-NPsAg/CuO, it was the Sips model, and Freundlich model for the adsorbent OGR-NPsAg/CuO. At low cephalexin concentration levels, the better performance regarding removal capacity was the adsorbent CA-NPsAg/CuO.The maximum adsorption capacity of each adsorbent was 756.8 mg g−1, 557.7 mg g−1, and 95.82 mg g−1 for CA-OGR-NPsAg/CuO, CA-NPsAg/CuO, and OGR-NPsAg/CuO, respectively. The knowledge about those studied adsorbents can improve the treatment of water contaminated with cephalexin antibiotic.

A phenomenological mathematical modeling has been applied in order to describe the dynamic behavior of the biosorption of heavy metals in fixed-bed columns. The mathematical model hereby proposed was evaluated on experimental breakthrough curves of the ions Cu(II), Ni(II) and Zn(II) in monocomponent systems using the residue of alginate extraction from Sargassum filipendula as biosorbent. Some authors have studied mathematical models to describe the biosorption of heavy metals, however, in most cases, they have fitted the models to the experimental data without evaluating the prediction capacity of the model in different operational conditions. This capacity is inherent of phenomenological models. Therefore, in addition to the breakthrough curves used to obtain the kinetic parameters of the models, an extra set of breakthrough curves has been studied outside the range evaluated for the fitted parameters in order to validate the model. The equilibrium data for the three studied ions was adequately represented by the Langmuir isotherm. The quantity of Ni(II) removed was very similar to the quantity related to the Zn(II) removal and the removal of Cu(II) ions was far superior than the other ions. The high values for the breakthrough time obtained for the Cu(II) ions represent a high removal efficiency and affinity with the biomass. The mathematical model was able to predict the dynamic behavior of removal for the three investigated ions, indicating that the internal mass transfer resistance is the rate limiting-step. The validation of the model demonstrated the prediction capacity in the different evaluated conditions, characterizing it as a useful tool when analyzing and designing heavy metal biosorption processes in fixed-bed columns.

Moringa oleifera Lam. has been reported as a natural coagulant in the treatment of surface waters; however its use presents some disadvantages such as low performance in the coagulation/flocculation of low turbidity waters and organic matter increase in the treated water. In addition, there is little specialized literature about coagulation proteins present in Moringa seeds and their characterization. Thus, this work had as objective the fractionation of Moringa oleifera seeds protein, characterization of the fractions obtained and evaluation of potential coagulant activity in different water turbidity. Based on the results obtained it was found that the globulin and albumin presented the highest values for protein fraction in Moringa seeds with 53% and 44% respectively. Percentage removals of 87.40% of color, 89.71% of turbidity and 79.46% of UV254nm were reached using 13 mg/L of the globulin coagulant for treatment of low turbidity water (50 NTU) without entailing excessive increase of the dissolved organic carbon in the treated water, even being considered a natural coagulant. Therefore, the use of fractionation as initial purification technique proved to be beneficial by producing a coagulant with high efficiency in the treatment of the low turbidity water.