Ecotoxicological effects of the emerging contaminant ivermectin on Rhinella arenarum: A comparative study of active ingredient and commercial formulation.

Ivermectin (IVM) is a broad-spectrum veterinary antiparasitic used worldwide in cattle breeding. The aim of this study was to evaluate the lethal effects of the active ingredient and a commercial formulation of IVM (1 % active ingredient) in the embryonic stage (S. 4-6) and larval stage (S. 25) of the South American amphibian Rhinella arenarum through chronic standardized bioassays. Also, behavior analysis and oxidative stress and cholinergic effects biomarkers were analyzed at 1, 10 and 100 µg IVM/L concentrations. For the embryonic stage, the active ingredient (96 h- LC50: 15900 µg/L) was more toxic than the commercial formulation (96 h-LC50: 51230 µg/L) during the acute period, while at chronic exposure the commercial formulation was more toxic (504 h-LC50: 10.25 µg/L), compared to the active ingredient (504 h-LC50: 312.80 µg/L). For the larval stage, in acute exposure, the active ingredient (96 h-LC50: 800 µg/L) was more toxic than the commercial formulation (96 h-LC50: 1550 µg/L). In the chronic exposure, the commercial formulation (504 h-LC50: 77.33 µg/L) was more toxic than the active ingredient (504 h-LC50: 195.25 µg/L). Overall, larvae exhibited greater sensitivity to both the active ingredient and the commercial formulation. However, during chronic exposure, embryos were more sensitive to the commercial formulation than larvae. The commercial formulation primarily induced oxidative stress, and both forms of the compound affected behavior and cholinergic effect biomarkers, even at low environmentally relevant concentrations (1 µg/L). These results highlight the potential impact of IVM on aquatic ecosystems.

Characterization and Performance of Peanut Shells in Caffeine and Triclosan Removal in Batch and Fixed-Bed Column Tests.

Peanut shells' adsorption performance in caffeine and triclosan removal was studied. Peanut shells were analyzed for their chemical composition, morphology, and surface functional groups. Batch adsorption and fixed-bed column experiments were carried out with solutions containing 30 mg/L of caffeine and triclosan. The parameters examined included peanut shell particle size (120-150, 300-600, and 800-2000 µm), adsorbent dose (0.02-60 g/L), contact time (up to 180 min), bed height (4-8 cm), and hydraulic loading rate (2.0 and 4.0 m3/m2-day). After determining the optimal adsorption conditions, kinetics, isotherm, and breakthrough curve models were applied to analyze the experimental data. Peanut shells showed an irregular surface and consisted mainly of polysaccharides (around 70% lignin, cellulose, and hemicellulose), with a specific surface area of 1.7 m2/g and a pore volume of 0.005 cm3/g. The highest removal efficiencies for caffeine (85.6 ± 1.4%) and triclosan (89.3 ± 1.5%) were achieved using the smallest particles and 10.0 and 0.1 g/L doses over 180 and 45 min, respectively. Triclosan showed easier removal compared to caffeine due to its higher lipophilic character. The pseudo-second-order kinetics model provided the best fit with the experimental data, suggesting a chemisorption process between caffeine/triclosan and the adsorbent. Equilibrium data were well-described by the Sips model, with maximum adsorption capacities of 3.3 mg/g and 289.3 mg/g for caffeine and triclosan, respectively. In fixed-bed column adsorption tests, particle size significantly influenced efficiency and hydraulic behavior, with 120-150 µm particles exhibiting the highest adsorption capacity for caffeine (0.72 mg/g) and triclosan (143.44 mg/g), albeit with clogging issues. The experimental data also showed good agreement with the Bohart-Adams, Thomas, and Yoon-Nelson models. Therefore, the findings of this study highlight not only the effective capability of peanut shells to remove caffeine and triclosan but also their versatility as a promising option for water treatment and sanitation applications in different contexts.

2,4-D Herbicide-Induced Hepatotoxicity: Unveiling Disrupted Liver Functions and Associated Biomarkers.

2,4-dichlorophenoxyacetic acid (2,4-D) is a widely used herbicide worldwide and is frequently found in water samples. This knowledge has prompted studies on its effects on non-target organisms, revealing significant alterations to liver structure and function. In this review, we evaluated the literature on the hepatotoxicity of 2,4-D, focusing on morphological damages, toxicity biomarkers and affected liver functions. Searches were conducted on PubMed, Web of Science and Scopus and 83 articles were selected after curation. Among these studies, 72% used in vivo models and 30% used in vitro models. Additionally, 48% used the active ingredient, and 35% used commercial formulations in exposure experiments. The most affected biomarkers were related to a decrease in antioxidant capacity through alterations in the activities of catalase, superoxide dismutase and the levels of malondialdehyde. Changes in energy metabolism, lipids, liver function, and xenobiotic metabolism were also identified. Furthermore, studies about the effects of 2,4-D in mixtures with other pesticides were found, as well as hepatoprotection trials. The reviewed data indicate the essential role of reduction in antioxidant capacity and oxidative stress in 2,4-D-induced hepatotoxicity. However, the mechanism of action of the herbicide is still not fully understood and further research in this area is necessary.

CO2-plasma surface treatment of graphite sheet electrodes for detection of chloramphenicol, ciprofloxacin and sulphanilamide.

Graphite sheet (GS) electrodes are flexible and versatile substrates for sensing electrochemical; however, their use has been limited to incorporate (bio)chemical modifiers. Herein, we demonstrated that a cold (low temperature) CO2 plasma treatment of GS electrodes provides a substantial improvement of the electrochemical activity of these electrodes due to the increased structural defects on the GS surface as revealed by Raman spectroscopy (ID/IG ratio), and scanning electron microscopy images. XPS analyses confirmed the formation of oxygenated functional groups at the GS surface after the plasma treatment that are intrinsically related to the substantial increase in the electron transfer coefficient (K0 values increased from 1.46 × 10-6 to 2.09 × 10-3 cm s-1) and with reduction of the resistance to charge transfer (from 129.8 to 0.251 kΩ). The improved electrochemical activity of CO2-GS electrodes was checked for the detection of emerging contaminant species, such as chloramphenicol (CHL), ciprofloxacin (CIP) and sulphanilamide (SUL) antibiotics, at around + 0.15, + 1.10 and + 0.85 V (versus Ag/AgCl), respectively, by square wave voltammetry. Limit of detection values in the submicromolar range were achieved for CHL (0.08 µmol L-1), CIP (0.01 µmol L-1) and SFL (0.11 µmol L-1), which enabled the sensor to be successfully applied to natural waters and urine samples (recovery values from 85 to 119%). The CO2-GS electrode is highly stable and inexpensive ($0.09 each sensor) and can be easily inserted in portable 3D printed cells for environmental on-site analyses.

Ivermectin adsorption by commercial charcoal in batch and fixed-bed operations.

Emerging contaminants were used during the COVID-19 pandemic, including ivermectin. Studies that limit the optimal adsorption parameters of ivermectin are scarce in the literature. In this study, we analyzed the adsorption of ivermectin with a high surface area and porosity charcoal. Isotherms were better fitted to the Koble-Corrigan model. The maximum capacity was 203 µg g-1 at 328 K. Thermodynamics indicated a spontaneous and endothermic behavior. The equilibrium was quickly reached within the first few minutes regardless of the ivermectin concentration. The linear driving force (LDF) model fitted the kinetic data (qexp = 164.8 µg g-1; qpred = 148.1 µg g-1) at 100 µg L-1 of ivermectin. The model coefficient (KLDF) and diffusivity (Ds) increased with increasing drug concentration. Two sloped curves were obtained in the column experiments, with a breakthrough time of 415 min and 970 min. The capacity of the column (qeq) was 76 µg g-1. The length of the mass transfer zone was 9.04 and 14.13 cm. Therefore, it can be concluded that the adsorption of ivermectin is highly sensitive to changes in pH, being favored in conditions close to neutrality. Commercial activated charcoal was highly efficient in removing the studied compound showing high affinity with very fast kinetics and a good performance in continuous operation mode.

Hybrid process of adsorption and electrochemically based green regeneration of bentonite clay for ofloxacin and ciprofloxacin removal.

Removal of emerging contaminants, such as antibiotics, from wastewater by adsorption is a simple, low-cost, and high-performance process; however, regeneration and reuse of the exhausted adsorbent are necessary to make the process economically viable. This study aimed to investigate the possibility of electrochemical-based regeneration of clay-type materials. For this, the calcined Verde-lodo (CVL) clay was saturated with the antibiotics ofloxacin (OFL) and ciprofloxacin (CIP) in one-component systems by an adsorption process and then subjected to photo-assisted electrochemical oxidation (0.45 A, 0.05 mol/L NaCl, UV-254 nm, and 60 min), which promotes both pollutant degradation and adsorbent regeneration. The external surface of the CVL clay was investigated by X-ray photoelectron spectroscopy before and after the adsorption process. The influence of regeneration time was evaluated for the CVL clay/OFL and CVL clay/CIP systems, and the results demonstrate high regeneration efficiencies after 1 h of photo-assisted electrochemical oxidation. Clay stability during regeneration was investigated by four successive cycles in different aqueous matrices (ultrapure water, synthetic urine, and river water). The results indicated that the CVL clay is relatively stable under the photo-assisted electrochemical regeneration process. Furthermore, CVL clay was able to remove antibiotics even in the presence of natural interfering agents. The hybrid adsorption/oxidation process applied here demonstrated the electrochemical-based regeneration potential of CVL clay for the treatment of emerging contaminants, since it can be operated quickly (1h of treatment) and with lower consumption of energy (3.93 kWh kg-1) than the traditional method of thermal regeneration (10 kWh kg-1).

Ibuprofen: Toxicology and Biodegradation of an Emerging Contaminant.

The anti-inflammatory drug ibuprofen is considered to be an emerging contaminant because of its presence in different environments (from water bodies to soils) at concentrations with adverse effects on aquatic organisms due to cytotoxic and genotoxic damage, high oxidative cell stress, and detrimental effects on growth, reproduction, and behavior. Because of its high human consumption rate and low environmental degradation rate, ibuprofen represents an emerging environmental problem. Ibuprofen enters the environment from different sources and accumulates in natural environmental matrices. The problem of drugs, particularly ibuprofen, as contaminants is complicated because few strategies consider them or apply successful technologies to remove them in a controlled and efficient manner. In several countries, ibuprofen's entry into the environment is an unattended contamination problem. It is a concern for our environmental health system that requires more attention. Due to its physicochemical characteristics, ibuprofen degradation is difficult in the environment or by microorganisms. There are experimental studies that are currently focused on the problem of drugs as potential environmental contaminants. However, these studies are insufficient to address this ecological issue worldwide. This review focuses on deepening and updating the information concerning ibuprofen as a potential emerging environmental contaminant and the potential for using bacteria for its biodegradation as an alternative technology.

Euterpe oleracea-based biochar for clonazepam adsorption: synthesis, characterization, adsorption properties, and toxicity assays.

The consumption of açaí fruit (Euterpe oleracea) has largely increased worldwide, resulting in a significant increase in the demand for its pulp. As a result, the small producing communities end up with large amounts of açaí endocarp residues, creating local environmental pollution problems. Therefore, chemical and physical routes were investigated for producing açaí endocarp adsorbents to propose a locally viable solution for this problem. The adsorption properties of the produced biochars were tested for clonazepam (CZM) removal, and the toxicity of the final solutions was evaluated. The results revealed that the chemical route generated biochar with about twice the surface area and pore volume (762 m2 g-1 and 0.098 cm3 g-1) than the physical route (498 m2 g-1 and 0.048 cm3 g-1). Furthermore, the Sips isotherm better described the CZM adsorption equilibrium for both biochars, with qs values of 26.94 and 61.86 mg g-1 for the physical- and chemical-activated adsorbents. Moreover, recycling studies were performed, and the chemical-activated biochar was stable for up to three cycles, reaching removal rates superior to 80%. Besides, the final toxicity decreased after the adsorptive treatment. Therefore, chemical activation can be used as a simple and effective method for producing stable and compelling adsorbents as an elegant way of adding value to the residues from açaí production, helping solve local environmental problems.

Palladium-modified TiO2 films in a photocatalytic microreactor: evaluation of radiation absorption properties and pollutant degradation efficiency.

Pure (TiO2) and 0.1 nominal atomic percent of palladium-modified TiO2 (Pd-TiO2) films were synthesized via a sol-gel method and compared through their physicochemical properties and photocatalytic activity in the degradation of an emerging contaminant, 17-α-ethinylestradiol (EE2). The activity of the films was studied using a continuous flow, planar microreactor under simulated sunlight. Catalysts characterization included X-ray diffraction, UV-Visible diffuse reflectance and transmittance spectroscopy, atomic force microscopy, transmission electron microscopy, Raman spectroscopy, N2 physisorption analysis, and X-ray photoelectron spectroscopy. The modification of TiO2 with palladium confined the size of anatase phase crystallites, increased the specific surface area and improved radiation absorption. PdO domains on TiO2 were observed. In all the tested conditions, higher conversion of EE2 was achieved with the Pd-TiO2 film compared with the TiO2 film, presenting an 80% increase in the reaction rate. The performance of the catalytic films was also assessed by the calculation of two efficiency parameters: radiation absorption efficiency and quantum efficiency of reaction. The Pd-TiO2 film showed a notable enhancement of the absorption of the incident radiation and a more efficient utilization of the absorbed photons to degrade the target pollutant.

In vitro evaluation for estrogenic mechanisms of the disinfectant benzalkonium chloride as an emerging contaminant

This study aimed to evaluate in vitro the possible mechanisms underlying the estrogenic potential of benzalkonium chloride (BAC) as a disinfectant emerging contaminant. Effects of BAC at the environmentally-relevant concentrations on estrogen synthesis and estrogen receptor (ER) signaling were assessed using the H295R steroidogenesis assay and the MCF-7 proliferation assay, respectively. Results showed that exposure to BAC at concentrations of 1.0-1.5 mg/L for 48 h significantly increased estradiol production of H295R cells in a concentration-dependent manner. Transcription of steroidogenic genes 3β‐HSD2, 17β‐HSD1, 17β‐HSD4, and CYP19A were significantly enhanced by BAC. In ER-positive MCF-7 cells, exposure to 0.5-1.5 mg/L BAC for 48 h significantly promoted cell proliferation and increased the expressions of ERα and G-protein coupled estrogen receptor 1. Flow cytometry analysis showed that 0.5-1.5 mg/L BAC significantly decreased the percentage of cells in G0/G1 phase, increased the percentage in S phase, and BAC at concentrations of 1.0 and 1.5 mg/L increased the G2/M phase cells. Findings of the study suggested that BAC at environmentally-relevant concentrations might act as a xenoestrogen through its inhibitory effect on steroidogenesis and ER-mediated mechanism.

Chronic exposure to realistic concentrations of metformin prompts a neurotoxic response in Danio rerio adults.

Metformin (MET) is among the most consumed drugs around the world, and thus, it is considered the uppermost drug in mass discharged into water settings. Nonetheless, data about the deleterious consequences of MET on water organisms are still scarce and require further investigation. Herein, we aimed to establish whether or not chronic exposure to MET (1, 20, and 40 µg/L) may alter the swimming behavior and induce neurotoxicity in Danio rerio adults. After 4 months of exposure, MET-exposed fish exhibited less swimming activity when compared to control fish. Moreover, compared with the control group, MET significantly inhibited the activity of AChE and induced oxidative damage in the brain of fish. Concerning gene expression, MET significantly upregulated the expression of Nrf1, Nrf2, BAX, p53, BACE1, APP, PSEN1, and downregulated CASP3 and CASP9. Although MET did not overexpress the CASP3 gene, we saw a meaningful rise in the activity of this enzyme in the blood of fish exposed to MET compared to the control group, which we then confirmed by a high number of apoptotic cells in the TUNEL assay. Our findings demonstrate that chronic exposure to MET may impair fish swimming behavior, making them more vulnerable to predators.

Adsorption of caffeine using steel wastes.

Caffeine is the most widespread active pharmaceutical compound in the world, generally studied as a tracer of human pollution, since caffeine levels in surface water correlate with the anthropogenic load of domestic wastewater. This work investigated the use of different steel wastes named as SW-I, SW-II, SW-II, SW-IV, SW-V, and SW-VI in the adsorption of caffeine. These materials were pretreated and characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and point of zero charge. The samples are mainly composed of iron (hematite and magnetite). The caffeine adsorption test indicated that SW-VI (steel slag dust) is the most efficient and promising (removal around 51.68%) in relation to the other residues, which it was selected for further studies. Equilibrium time was reached within 96 h of contact between the adsorbent and the adsorbate, with removal of 84.00%, 81.09%, and 73.19% for the initial concentrations of 10 mg L-1, 20 mg L-1, and 30 mg L-1 of caffeine. The pseudo-first-order, pseudo-second-order, and Elovich models presented a good fit to the experimental data. However, the pseudo-first order model described better the experimental behavior. Adsorption isotherms were performed at three temperatures (298, 308, and 318 K). The maximum adsorption capacity was 17.46 ± 2.27 mg g-1, and experimental data were better fitted by the Sips isotherm. Values of ΔG° and parameters equilibrium of the models of Langmuir, Sips, and Temkin were calculated from the standard enthalpies and standard entropies estimated. The values of ΔG° were negative for the temperatures studied indicating that the adsorption process is viable and spontaneous. Negative values for ΔH° were also found, indicating that the process of caffeine adsorption by SW-VI is an exothermic process (0 to -40 kJ mol-1). Thus, the adsorption of caffeine by SW-VI is a physical process. The SW-VI material showed economic viability and promising for the adsorption of caffeine in aqueous media.

Adsorption of Methylene Blue and Tetracycline by Zeolites Immobilized on a PBAT Electrospun Membrane.

The detection of emerging contaminants in bodies of water has steadily increased in recent years, becoming a severe problem threatening human and ecosystem health. Developing new materials with adsorption properties to remove these pollutants represents an important step toward a potential solution. In this paper, a polybutylene adipate terephthalate (PBAT) nanofibrous membrane incorporating clinoptilolite zeolite was developed and its excellent performance in removing tetracycline (TC) and methylene blue (MB) from water was demonstrated. The composite membrane was prepared in two steps: firstly, a homogeneous dispersion of clinoptilolite (1 wt% respect to polymer) in a PBAT solution (12.6 wt%) was electrospun; secondly, the electrospun membrane was subjected to an acid treatment that improved its wettability through the protonation of the surface silanol groups of clinoptilolite. The resulting membrane was hydrophilic and showed higher adsorption for TC (800 mg/g) and MB (100 mg/g), using a low dose (90 mg/L) powdered zeolite. The maximum removal capacity was obtained at neutral pH, being the cation exchange reaction the main adsorption mechanism. Pseudo-second-order kinetics and Henry's law agree well with the proposed chemisorption and the high affinity of TC and MB for the adsorbent. The material can be reused after the removal process without generating additional contamination, although losing some effectivity.

Graywater treatment of emerging pollutant linear alkylbenzene sulfonate by adsorption with leather shave waste activated carbon.

The purpose of this research is to evaluate the use of leather shave waste activated carbon (ACLW) as an alternative for the treatment of wastewater containing linear alkylbenzene sulfonate (LAS). Batch adsorption tests were carried out (pH effect, isotherms, kinetics). The activated carbon was tested for its life cycle by desorption with solvent and it was further evaluated as real wastewater treatment for bath graywater. Under the optimum pH of 2.5, kinetic studies showed a better correlation with the pseudo-second order model, with an activation energy of 27.5 kJ mol-1. Equilibrium isotherms correlated better with the double layer model, indicating hemi-micelle formation and performing a high-affinity isotherm. Adsorption was shown to be endothermic (∆H0 = + 73.89 kJ mol-1), entropy driven (∆S0 = + 0.46 kJ mol-1 K-1), and occurring spontaneously. The use of ethanol solution was effective for the regeneration of the adsorbent. Adsorption was applied in real wastewater, removing contaminants from bath graywater, especially anionic surfactants with up to 95% removal efficiency.

"pySiRC": Machine Learning Combined with Molecular Fingerprints to Predict the Reaction Rate Constant of the Radical-Based Oxidation Processes of Aqueous Organic Contaminants.

We developed a web application structured in a machine learning and molecular fingerprint algorithm for the automatic calculation of the reaction rate constant of the oxidative processes of organic pollutants by •OH and SO4•- radicals in the aqueous phase-the pySiRC platform. The model development followed the OECD principles: internal and external validation, applicability domain, and mechanistic interpretation. Three machine learning algorithms combined with molecular fingerprints were evaluated, and all the models resulted in high goodness-of-fit for the training set with R2 > 0.931 for the •OH radical and R2 > 0.916 for the SO4•- radical and good predictive capacity for the test set with Rext2 = Qext2 values in the range of 0.639-0.823 and 0.767-0.824 for the •OH and SO4•- radicals. The model was interpreted using the SHAP (SHapley Additive exPlanations) method: the results showed that the model developed made the prediction based on a reasonable understanding of how electron-withdrawing and -donating groups interfere with the reactivity of the •OH and SO4•- radicals. We hope that our models and web interface can stimulate and expand the application and interpretation of kinetic research on contaminants in water treatment units based on advanced oxidative technologies.

Oxidative stress as a potential mechanism by which guanylurea disrupts the embryogenesis of Danio rerio.

Metformin is one the most prescribed drug to treat type 2 diabetes. In wastewater treatment plants, this drug is bacterially transformed to guanylurea, which occurs at higher concentrations in the aquatic environments than its parent compound. Since there is a huge knowledge gap about the toxicity of this metabolite on aquatic organisms, we aimed to investigate the impact of guanylurea on the embryonic development and oxidative stress biomarkers of zebrafish (Danio rerio). For this effect, zebrafish embryos (4 h post fertilization) were exposed to 25, 50, 100, 200, 250, 25,000, 50,000, 75,000 µg/L guanylurea until 96 h post fertilization. Guanylurea led to a significant delay in the hatching process in all exposure groups. Furthermore, this transformation product affected the embryonic development of fish, inducing severe body alterations and consequently leading to their death. The most pronounced malformations were malformation of tail, scoliosis, pericardial edema, yolk deformation and craniofacial malformation. Concerning oxidative stress response, we demonstrated that guanylurea induced the antioxidant activity of superoxide dismutase, catalase, and glutathione peroxidase in zebrafish embryos. In addition, the levels of lipid peroxidation, protein carbonyl and hydroperoxide content were also increased in the embryos exposed to this transformation product. However, the integrated biomarker response (IBR) analysis carried out in this study demonstrated that oxidative damage biomarkers got more influence over the embryos than antioxidant enzymes. Thus, we can conclude that guanylurea induces oxidative stress in zebrafish embryos, and that this transformation product impair the normal development of this freshwater organism.

Surfactant and temperature as forcing functions on the growth of Egeria densa and Chara sp.: a modeling approach.

The wide use of detergents combined with rising water temperature is currently issuing of environmental concern. To evaluate the effect of sodium dodecyl sulfate (SDS) and temperature on macrophyte and talophyte growth, bioassays were conducted with distinct SDS concentrations (0.5 and 8.0 mg L-1) and temperatures (25 and 27 °C). The length of the Egeria densa and Chara sp. and the number and lengths of shoots were measured. Kinetic models were used to verify the temperature and SDS concentrations, as driving factors in the growth. The 2 °C increase in thermal condition interfered positively in both elongation and shoot development in the E. densa growth. For Chara sp., this tendency was not observed for the relative contribution of the shoots, but the number was higher at 25 °C. The higher concentrations of SDS (8.0 mg L-1) reduced the shoots' number and the relative contribution for Chara sp. and E. densa; meanwhile, the decrease in the growth coefficient was observed only for E. densa at 25 °C. In the Chara sp. development, the SDS addition interfered negatively in the growth coefficient. The predicted response of growth models will bring comprehensive knowledge of macrophytes and talophyte metabolism, and the interaction between plant species and forcing functions in modeling approaches will assist in finding the key processes driving plant growth under specific stressors.

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

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

Photodegradation of Emerging Contaminant 2-(tiocyanomethylthio) Benzothiazole (TCMTB) in Aqueous Solution: Kinetics and Transformation Products.

Direct photolysis of the emerging contaminant 2-(thiocyanomethylthio) benzothiazole (TMCTB) was performed in aqueous solution at different concentrations with high-pressure mercury lamp (5.0, 8.0, 13.0, 16.0, 20.0, 23.0, 27.0, 35.0, 40.0, 45.0, and 50.0 mg L- 1) and with natural sunlight radiation (6.0, 30.0, and 60.0 mg L- 1). TCMTB underwent rapid degradation by direct photolysis with a high-pressure mercury lamp in aqueous solutions, with 99% removal after 30 min at all concentrations studied. For sunlight photolysis, TCMTB degradation was observed with 96%, 81%, and 64% removal for initial concentrations of 6.0, 30.0, and 60.0 mg L- 1, respectively, after 7 h of exposure to sunlight. The degradation of TCMTB in lab-scale wastewater had kinetic constant and t1/2 in the same order when compared to the photodegradation of TCMTB in aqueous solutions. In addition, the results showed that photolysis with a high-pressure mercury lamp and sunlight were governed by the same kinetic order, however the kinetic parameters showed that degradation with sunlight was 40 times slower than photolysis with the mercury lamp. Twelve transformation products (TP) were identified, and eight of the TP have not been described in the literature. Furthermore, prediction of toxicity with ECOSAR software was carried out for fish, daphnids, and green algae species. It showed that photolytic treatment is efficient for reducing the toxicity of the compound, since the degradation formed compounds with lower toxicity than the primary compound. In conclusion, this study suggests that photolysis is an efficient way to remove the studied contaminant, and it highlights the potential of this technique for the degradation of emerging contaminants in industrial wastewater treatment plants.

2,4-dichlorophenoxyacetic acid (2,4-D) micropollutant herbicide removing from water using granular and powdered activated carbons: a comparison applied for water treatment and health safety.

Activated carbons are well-known porous materials as an effective adsorbent used for the removal of emerging contaminants, such as herbicides, which are increasingly present in water bodies. Most water treatment plants, specially in Brazil, are unable to completely remove such contaminants by the conventional process and advanced treatment using activated carbons is required. The aim of this paper was to verify the influence of the activated carbons granulometry and specific surface area on the 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide removal efficiency using distilled-deionized water and filtered water collected from a conventional Water Treatment Plant. Commercial activated carbons samples used in this work were obtained from two different manufacturers. Activated carbons were analyzed by the specific surface area, pore size and volume distribution, nuclear magnetic resonance, infrared and x-ray spectroscopy, moisture, volatile matter and ash contents. Batch adsorption isotherms experiments were used and performed by Langmuir and Freundlich models. Granular and powdered activated carbons removed over 99% of 2,4-D in distilled water and near to 99% using filtered water. The activated carbons evaluated in this work presented high performance and played a key role in water treatment by removing 2,4-D herbicide, ensuring the protection of human health and the ecosystem.