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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...

The use of Moringa oleifera (MO) for cleaner processes in water treatment has been proposed to treat raw water for low-income locations for its abundant availability, low cost, reduced by-product generation, biodegradability, non-toxicity and multifunctional behavior. This review analyzed studies that used MO seeds in coagulation-flocculation processes, identifying the main proteins that presented coagulant activity. It was concluded that its most viable application would be as flocculation aid, since it was possible to reduce the concentration of the chemical coagulant with good removal results. Regarding the use of MO as adsorbent, studies could verify its potential to remove several water contaminants, such as pesticides, dyes and pharmaceuticals. Moreover, hybrid treatments have been investigated, however, a research gap could be verified regarding studies on pilot scale, which are fundamental for verifying the viability in water treatment plants. In this sense, the main trends, challenges and recommendations for further studies were assessed regarding the sustainable application of MO seeds in water treatment.

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.

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.

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

Micropollutants, also called emerging contaminants, consist of an extensive group of synthetic and natural substances, including pharmaceuticals, personal care products, steroid hormones, and agrochemicals. Currently, the monitoring of residual pharmaceuticals in the environment has been highlighted due to the fact that many of these substances are found in wastewater treatment plants effluents and surface waters, in concentrations ranging from ng L-1 to μg L-1. Most of these compounds are discharged into the environment continuously through domestic sewage treatment systems. In the present work, it is presented an overview of water pollution by these pollutants, as well as a review of the recent literature about the use of low-cost adsorbents for the removal of the main pharmaceuticals found in surface water, focusing on municipal and agroindustrial wastes as precursors. It was possible to observe several examples of high adsorption capacities of these compounds with such materials, however other aspects must be considered in order to evaluate the real applicability in water and wastewater treatment, such as competition, recyclability and production cost.

Glyphosate removal from contaminated water using a new adsorbent material was investigated. Graphene-MnFe2O4 nanocomposite supported on vegetal activated carbon (GO-MnFe2O4/VAC) was synthesized. Several characterization techniques such as transmission and scanning electron microscopy, N2 physisorption, energy dispersive X-ray spectrometry, Fourier transformed infrared spectroscopy, X-ray diffraction and Raman spectroscopy were used to have insights to this material. Furthermore, the point of zero charge was determined. GO-MnFe2O4/VAC material was evaluated for glyphosate adsorptive removal in fixed-bed column under different operating conditions of solution concentration and feed flow rate. The results pointed out that glyphosate adsorption using GO-MnFe2O4/VAC was favored at pH values between 2.29 and 6.14. In fixed-bed column, the best results were obtained for the solutions having higher concentrations and also for higher feed flow rates. The equilibrium experimental data were fairly described by Langmuir model with maximum adsorption capacity reaching 6.778 mg g−1. Among the mathematical models evaluated to describe the breakthrough curves, the best fit to the experimental data was obtained by model that considers the intraparticle diffusion and the internal diffusion step was considered to be the mass transfer limiting step. The present results indicated that the adsorbent material synthesized has a great capacity for adsorption and prove the potential of use of GO- MnFe2O4/VAC for glyphosate removal from contaminated water in the continuous mode of operation.

Gravitational filtration column experiments were carried out using granular activated carbon impregnated with metallic compounds for the removal of heavy metals from water. The material produced was characterised by textural characterisation: specific surface area Brunauer–Emmett–Teller, area of micropores (method t), volume and diameter of micropores (Horvath–Kawazoe method) and mesopores (Barret, Joyner and Halenda method); structural characterisation by X-ray diffraction; morphological characterisation by scanning electron microscopy and transmission electron microscopy. The removal of the metals was analysed by atomic absorption spectrometry. Activated carbon (AC) and activated carbon modified with silver and copper metal compounds (ACAgCu) columns were monitored by physical–chemical parameters and efficiency of heavy metals removal. The removal of Pb from water ranged between 93 and 96%, reaching values in accordance with the acceptable standard for both AC and ACAgCu, with a residual of 9 µg L−1 and 5 µg L−1, respectively, at the end of the filtration. For Fe contaminant, the filtration column with ACAgCu was the best with a final residual of 0.18 mg L−1 and average removal of 74%. For AC, the residual was 0.42 mg L−1 with an average removal of 38%. Zn removal was low for AC and ACAgCu, with a final residual of 7.4 mg L−1 (mean removal of 39%) and 8.5 mg L−1 (mean removal of 19%), respectively.

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 ...

In this work, a physical-chemical, elemental and microbiological groundwater monitoring was performed on wells of the Serra Geral aquifer, located in the western region of the Brazilian state of Paraná, along with an evaluation of the elemental composition of soil sediments in the region of groundwater monitoring. The monitoring was carried out in 10 wells distributed throughout the rural area of the municipality of Toledo-PR. Elemental analyses were performed using the analytical technique of total reflection X-ray fluorescence spectrometry. From the results obtained, it was observed that in some wells, iron and lead concentrations were above the maximum limits allowed by the Brazilian legislation in some months, demonstrating that the evaluated groundwater is susceptible to contamination. By the analysis of the soil sediments, the presence of iron and lead in the region soil/rock was verified, which may be associated to rainwater percolation making it necessary to periodically monitor the groundwater consumed by the population of the municipality of Toledo-PR.

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.

A distributed parameter model and two lumped parameter models were used in order to find the rate-limiting step in the adsorption process of a herbicide (Diuron) by Moringa oleifera husks, a possib...

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 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...

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...

In this study, the association of functionalized magnetic nanoparticles with proteins from Moringa oleifera seeds to treat surface water with high turbidity was investigated. With the proposed methodology, it was possible to synthesize magnetite nanoparticles that were susceptible to functionalization with the protein extract, which was characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), zeta potential and vibrating sample magnetometry (VSM). The functionalized nanoparticles were applied to the coagulation/flocculation and sedimentation (CFS) process of superficial raw water under the influence of an external magnetic field. This showed a removal efficiency of 96.8% for turbidity, 97.1% for the apparent colour and 58.3% for the UV254nm after 10 min of magnetic sedimentation, proving that the CFS process can be optimised and that the sedimentation time can be reduced from 30 min to 10 min. The reuse assays indicated that the functionalized magnetic nanoparticles can be reused for up to two times consecutively without significant loss in efficiency in removing the evaluated parameters. Furthermore, the residual values obtained for the turbidity and apparent colour parameters were sufficient to meet the values proposed by the Brazilian legislation after 10 min of magnetic sedimentation, without needing of a secondary processes of treatment, such as filtration. This highlights the ample potential of this coagulant and its applicability.

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.

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) have caused widespread pollution of water environments as they are highly persistent in aqueous media, toxic and bioaccumulative. Adsorption processes have been proven effective for separating PFAS from various types of contaminated water. While activated carbon technology is the most extensively used method for removing PFAS from water and wastewater at commercial scales, it is limited by lower efficiency for removing short-chain PFAS compounds, competitive adsorption of other organics, use of the non-renewable source of materials, and the requirement for energy-intensive thermal regeneration. In recent years, there has been a growing interest in developing alternative adsorbents that originate from abundant renewable natural sources or other low-cost sources such as solid wastes to address these issues. However, it is a lack of a holistic understanding of the efficacy of these non-conventional adsorbents, particularly the effects of their physical and chemical characteristics on PFAS adsorption capacities. This review is focused on the recent advancements in a range of emerging adsorbents, with a view to critically evaluating their potential as environmentally friendly and more efficient alternatives to conventional activated carbon products for PFAS separation from the contaminated water. The adsorption behavior of the different natural and renewable material-based adsorbents for PFAS are compared, and the underlying removal mechanisms are discussed. Their practicality in terms of treatment of real water/wastewater, reusability, and continuous operation is also examined. Moreover, prospective applications of such adsorbents and the research needs for their further development are suggested.

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.

Green technologies are environmentally friendly operations that limit the negative impacts of traditional industrial activities and can contribute to solving the challenge of sustainable water management. This work aims to develop a green water treatment sequence using a natural coagulant (Moringa oleifera) and a natural activated carbon (vegetable coconut palm) to remove Microcystis aeruginosa and natural organic matter in an integrated process. The proposed sequence, coagulation/flocculation/dissolved air flotation and activated carbon, is an eco-friendly and innovative option for water treatment managers, since it includes environmentally friendly products for the contaminant removal from water, replacing the traditional inorganic/synthetic coagulants and adsorbents. Results demonstrated that waters with concentrations as high as 150-200 mu g/I. of chlorophyll a and natural organic matter between 5 and 16 mg C/L presented removals higher than 80% for turbidity and chlorophyll a, 70-80% for dissolved organic matter and 80-90% for UV254nm. Moringa oleifera natural coagulant removed almost 80% of Microcystis aeruginosa cells in coagulation/flocculation/dissolved air flotation processes. The coconut palm activated carbon showed a high capacity to adsorb DOC from water with a maximum adsorbed capacity of 51.8 mg/g at equilibrium. The values obtained in treated water for the parameters measured are very encouraging, so this innovative integrated sequence may be used for improving water quality, benefiting human health and wellbeing. (C) 2017 Elsevier Ltd. All rights reserved. CNPq (National Counsel of Technological and Scientific Development) CAPES (Coordination for the Improvement of Higher Education Personnel) info:eu-repo/semantics/publishedVersion

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.

Moringa oleifera (MO) seed is a natural plant with active bio-coagulate compounds that can be used for water clarification since it reduces the use of chemical-based coagulants. This study aims to evaluate the impact of Moringa oleifera (MO) seeds and MO seeds with a reduced amount of oil as coagulants in conventional water treatment to remove cyanobacteria from different natural surface waters. Tests were performed for waters with low (5-10 NTU) and high (30-60 NTU) initial turbidity with and without Microcystis aeruginosa cells and for MO integral powder, MO oil-extracted with ethanol and with a pressurized technique, and MO extracted with NaCI. The results show that MO oil-extraction is not necessary when using MO seeds as a coagulant in coagulation/flocculation/sedimentation (CF/S). Chlorophyll a and turbidity removals were up to 85% for high-turbidity waters, with 50 mg.L-1 MO obtained, for MO integral powder and for all of the MO extraction methods used. Therefore, for these waters, integral powder (without any extraction) can be used. For low-turbidity waters and using a 1 M saline extraction of the active coagulant compound, chlorophyll a and turbidity removals were approximately 60%. It was also demonstrated that MO is capable of removing some of the organic matter present in water, namely, aromatic organic matter, between 40 and 50% when using MO extracted with NaCI. However, dissolved organic matter results showed an increase independent of the type of MO extraction used. (C) 2016 Elsevier B.V. All rights reserved. info:eu-repo/semantics/publishedVersion

A phenomenological mathematical modeling approach was applied in order to describe the biosorption of binary heavy metal systems. The mathematical modeling here proposed was verified with the biosorption of Cu(II)–Ni(II) systems onto residue of alginate extraction from Sargassum filipendula. Equilibrium studies were carried out in order to elucidate the competition between the ions in the process. The Cu(II) ions showed a higher affinity with the biosorbent, while the Ni(II) removal was highly dependent on the presence of Cu(II) ions (i.e., the Cu(II) ions inhibit the removal of Ni(II)). According to the Akaike criterion, the equilibrium experimental data was better described by the Langmuir-Freundlich model, which considers the competition among ions for the active sites. The phenomenological mathematical modeling of the kinetics of biosorption was based on binary equilibrium equations, material balances and possible limiting mass transfer steps instead of the empirical models usually applied. The model was then adjusted to the experimental kinetic data and validated by a simulation in a different condition. According to the model, the internal mass transfer resistance (intra-particle diffusion) is the limiting step that controls the kinetics of the process. Therefore, due to its high predictive capacity, the phenomenological approach described in this work can be applied as a tool for design and optimization of binary heavy metal adsorption systems.

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.

Quinoxyfen has been recently identified as a priority hazardous substance in the field of the European water policy. In this work, its fate in aqueous samples and solid supports under UV and solar radiation is investigated. Diverse degradation experiments were carried out, at lab scale, using spiked aliquots of different aqueous matrices (ultrapure, treated wastewater and river water) irradiated at different wavelengths (λ = 254 nm, λ = 365 nm and solar light). Half-lives of quinoxyfen (2-26 min) depended on the wavelength and the intensity of radiation whilst the nature of the aqueous matrix did not play an important role in degradation kinetics. Moreover, experiments under solar radiation of doped silicone tubes were performed to simulate degradation when quinoxyfen is adsorbed on plant leaves or soil. As the compound is not completely mineralized, the identification of quinoxyfen transformation products (TPs) was performed by liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) injection of different irradiated time aliquots. The full-fragment ion spectra, at different collision energies, allowed the elucidation of the chemical structure of TPs formed by hydroxylation, cyclization or cleavage reactions. Five out of seven identified TPs have not been reported previously. The ecotoxicity simulation by software (TEST and ECOSAR) for TPs revealed that some of them could cause harmful effects to organisms such as Daphnia magna or Fathead minnow in a similar extent to the precursor; moreover, the time course profiles of major TPs (TP1 and TP2) revealed a much higher resistance to further photodegradation than quinoxyfen. Graphical abstract Quinoxyfen phototransformation pathways.

This study evaluates the application of the vegetal activated carbon (AC), vegetable AC impregnated with Ag and Cu (0.08% m/m) and cationic SupergelTM SGC650H resin for adsorption of Fe3+ and Pb2+ ...

The objective of this study was to impregnate the surface of palm coconut activated carbon with nanoparticles of iron compounds using Moringa oleifera leaf extracts and pomegranate leaf by a green synthesis method and to evaluate its adsorption capacity for sodium diclofenac. The adsorbent material was characterized by zeta potential, X-ray diffraction (XRD), N2 adsorption/desorption (BET method), transmission electronic microscopy (TEM), and scanning electronic microscopy (SEM) coupled to dispersive energy spectrometry X-ray (EDX) methods. To evaluate the adsorption capacity of sodium diclofenac, the influence of pH, kinetics, isotherms, and thermodynamic properties were analysed. The impregnated adsorbents showed efficiency in the adsorption of sodium diclofenac. The kinetic model that best fit the experimental data was the pseudo-second-order model, and the equilibrium model was the Langmuir model. As for the thermodynamic study, it was verified that the adsorption reaction for all adsorbents occurs in a spontaneous, favourable way, and it is endothermic by physisorption. Therefore, this process is promising because it is a clean and non-toxic method when compared with chemical methods for the synthesis of nanoparticles.

A solar-driven advanced oxidation process at a lab scale was studied for the degradation and mineralization of the known endocrine disrupting chemical (EDC), bisphenol A (BPA). Preliminary tests were performed varying the irradiation source, BPA/H2O2 ratio, temperature, initial H2O2 concentration, initial solution pH, and initial BPA concentration, then, the operational conditions of the UV-solar/H2O2 were optimized by a response surface methodology (RSM), providing the following responses: UV-solar/H2O2 process at pH 3.0, [BPA]0 = 25 mg L−1, [H2O2] = 350 mg L−1, T = 50 °C, achieving BPA degradation of 77.4% and BPA mineralization of 38.2%, H2O2 consumption of 230 mg L−1. From the optimized condition, different pH ranges were tested (3.0; 5.0; 7.0; 9.0; and 11.0), where, at solution pH 5.0 the best removal rates were achieved (89.2% BPA degradation and 49.0% BPA mineralization). The BPA amount in solution was monitored by High Performance Liquid Chromatography (HPLC) and a study of the intermediate reaction by-products was performed by Gas Chromatography–Mass Spectrometry (GC–MS) analyses, highlighting the lower amount of by-products identified when the solution pH 5.0 was employed, rather than the solution pH 3.0. Genotoxicity tests with Zebrafish (Danio rerio) and cytotoxicity tests with Allium cepa were performed aiming to evaluate errors in the cells and nuclear abnormalities of the tested organisms induced by BPA raw samples, as well as by the BPA samples treated by the UV-solar/H2O2 process. Therefore, the bio-toxicity levels for an animal and a vegetal bio-indicator were reduced by applying a renewable source of energy as the irradiation source for the UV/H2O2 process, representing an efficient and eco-friendly alternative for BPA treatment in aqueous solutions.

The textile industry generates large amounts of effluents, often treated by coagulation/flocculation. The tannin-based coagulants produce a high-quality treated effluent and a more biodegradable sludge. Efforts have been made to reuse the sludge, however, the synthesis of hydrochars and activated hydrochars from this residue was never evaluated before. Therefore, this study aimed to produce a novel sludge-based adsorbent, through hydrothermal carbonization (HTC) and KHCO₃ activation, from real laundry wastewater treated with tannin (Tanfloc SG), in order to remove methylene blue (MB) from aqueous solutions. Tanfloc SG coagulant was more effective to reduce color and turbidity than chemical oxygen demand. The best coagulant concentration (140 mg L−1) was selected to produce sludge, the hydrochar (HC-S), and activated hydrochar (AHC-S). The characterization demonstrated that activation volatilized the organic matter, leaving coke and inorganic solids. However, despite the lower carbon content, AHC-S presented a notorious surface area (3005.57 m² g−1). Minerals were presented in the adsorbents and AHC-S showed graphene-like layers. Regarding MB adsorption, pseudo-second-order and Langmuir models fitted kinetic and equilibrium data, respectively. HC-S and AHC-S obtained qmax of 69.77 and 808.83 mg g−1, respectively, and the latter was higher than other activated hydrochars, demonstrating the potential of the adsorbent.

This review discussed the occurrence, ecological impacts, and effects of metformin, a drug used for type 2 diabetes among other diseases. It is one of the most commonly found medicines in aquatic environments owing to its incomplete metabolism in the human body, and is eventually disposed in wastewater. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses were followed as a guide. After searching various databases, 48 eligible studies were selected for the review. Metformin reportedly occurs in different environmental matrices, as measurable concentrations of metformin are found in sewage (urban and hospital), influent/sludge/effluent from wastewater treatment plants, surface water (rivers, lakes, estuaries, oceans, and non-specific sources), tap/drinking water, and sediment (lake and recipient seawaters). Data on metformin detection in aquatic environments in 14 countries were studied, but a consensus on the risk patterns of pharmaceutical products was not determined. Many studies have been conducted on different test organisms, demonstrating that metformin can drive the expression of diverse genes, particularly those responsible for endocrine hormone pathways. Chronic exposure to metformin can be tested using models and other tools to understand this field, which remains largely unexplored. Our results contribute to the current ecotoxicology knowledge related to typically used drugs and provide a basis for further investigations.

Chicha-do-cerrado (Sterculia Striata St. Hil. et Naud) is a Brazilian native plant whose nuts have interesting nutritional value. However, the fruit shells (CH) have never been evaluated for potential uses. This study aimed to characterize the biochar (BC–CH) and the activated carbons synthesized by chemical (K–CH) and physical (C–CH) processes. The activated carbons were evaluated on metformin adsorption and treatment of a synthetic mixture. Pyrolysis increased the carbon content and the H/C ratio indicated higher aromatization for C–CH. BC–CH presented low surface area, which was increased mainly with KOH activation (1273.6 m2 g−1). FTIR demonstrated the degradation of lignocellulosic compounds and zeta potential inferred a higher number of oxygenated groups for C–CH. Regarding the adsorption studies, the kinetics demonstrated an equilibrium time of 60 min and the isotherm resulted in a maximum experimental adsorption capacity of 33.75 and 45.50 mg L−1 for C–CH and K–CH, respectively. Interestingly, C–CH presented the highest removal percentage of the synthetic mixture, indicating the role of Cu (II) interactions and synergistic effects. In summary, it was verified the potential of the adsorbents in wastewater treatment, and the importance of evaluating the composition of the aqueous matrix, which can alter the adsorption mechanisms.

A wide variety of chemical compounds are used in human activities; however, part of these compounds reach surface water, groundwater and even water considered for potable uses. Due to the limited efficiency of water treatment by the Water and Wastewater Treatment Plants, the presence of these compounds in natural and human consumption waters can be very harmful due to their high persistence and adverse effects; these characteristics define the contaminants of emerging concern (CECs). Water treatment by Electrochemical Advanced Oxidation Processes (EAOPs) has been evaluated as a promising process for the removal of persistent and recalcitrant organic contaminants. With this background, the present review aims to gather studies and information published between 2015 and 2020 regarding the occurrence of CECs in surface, potable and groundwater, its treatment by EAOPs, the main operating conditions and by-product generation of EAOPs, contaminant toxicity assessments and international statutory guideline values concerning CEC standards and allowable concentrations in the environment and treated drinking water. Therefore, in this review it was found that the compounds bisphenol A (BPA), diethyltoluamide (DEET), 17α-ethinyl estradiol (EE2), perfluorobutanoic acid (PFBA), carbamazepine, caffeine and atrazine were the most frequently detected in water sources, with concentrations ranging from 35.54–4800, 1.21–98, 0.005–38.5, 5–742.904, 0.0071–586, 0.89–1040, and 100–323 (ng L-1), respectively. Among the operational conditions of EAOPs, current density, pH and oxidant concentration are the main operational parameters that have an influence on these treatment technologies, besides the by-products generated, which might be removed by the integration of EAOPs with biological digestion treatments. Regarding the values of water quality standards, many CECs do not have established standard allowable concentration values, which represents a concern toward the possible toxic effects of these compounds on non-target organisms.