Dr Vinicius Diniz

Direct potable reuse (DPR) has emerged as a promising and practical solution to address the challenges of water scarcity (e.g., climate dependency, limited space availability, water waste, and financial constraints) by treating wastewater to meet stringent drinking water quality standards given its potential to reduce water age within the distribution network, enhance water quality, and yield energy savings. Despite the potential benefits, the presence of emerging contaminants in treated wastewater has raised concerns among researchers and policymakers due to their unknown long-term toxicological risks, necessitating continuous research and rigorous monitoring to ensure the safety and sustainability of DPR initiatives. In the present work, ten emerging contaminants were assessed at a pilot-scale treatment plant in the city of Campinas, Brazil, previously selected based on consumption and previous monitoring data. The pilot-scale plant allowed for the evaluation of various treatment configurations, ultimately selecting reverse osmosis + photoperoxidation (UV/H2O2) + activated carbon as the most effective scheme for DPR. The effluent from the pilot plant met the guidelines for potable water set by Brazilian regulations. Among the monitored emerging contaminants, albendazole, carbamazepine, hydrochlorothiazide, sulfamethoxazole, and sucralose were identified as marker compounds for monitoring purposes, as they were detectable in both the influent and effluent of the pilot plant. The findings of this research contribute to the development of robust strategies for monitoring and mitigating the risks associated with emerging contaminants in DPR, ensuring the production of safe and sustainable drinking water sources.

Inverse vulcanization (IV) enables the production of sustainable polymer from sulfur waste, offering hydrophobic, fluorine-free, and superhydrophobic coatings. However, these materials need adhesion improvements for enhanced durability. This study has developed an epoxy-, fluorine-, and metal-free superhydrophobic coating using the spray-coating of carbon nanofibers (CNFs), silica nanoparticles, and IV polymers on glass. An optimized formula of 28% sulfur, 20 mg/mL CNFs, 25 mg/mL silica, and 80 mg/mL polymer–was established. Zn(DTC)2-catalyzed coatings retained superhydrophobicity for 150 tape peeling cycles, up to 250 °C, and 6 h of UV–C exposure, demonstrating a straightforward, eco-friendly approach to durable, versatile superhydrophobic coatings.

Stretchable superhydrophobic materials have gained attention in recent years though challenges remain for widespread use, including the need for rapid, energy-efficient, high-throughput, and fluorine-free fabrication methods. In this study, a stretchable superhydrophobic material is developed by coating parafilm with inverse vulcanization sulfur polymers. Silica (SiO2) nanoparticles are incorporated to create a Cassie–Baxter wetting state, achieving superhydrophobicity. The sulfur polymers are synthesized using perillyl alcohol (PER) at varying sulfur-to-PER ratios. The optimal coating formulation is determined to be 70 mg mL−1 of polymer, 50 mg mL−1 of SiO2 nanoparticles, and a sulfur-to-PER ratio of 1:1 (50% sulfur and 50% PER). The films maintained functionality when stretched due to controlled fragmentation that preserved the Cassie–Baxter wetting state. Mathematical modeling revealed a scaling relation between fragment area and thickness, showing that thicker layers produced larger fragments, impairing superhydrophobicity. This study also showcase the successful use of more sustainable bio-based solvents (2-methyltetrahydrofuran), where previous reports of similar processes have used chloroform. The fabricated films also demonstrated improved ultraviolet (UV-C) stability (150 min) compared to other sulfur polymer coatings reported in the literature. This coating of flexible substrates presents a simple and environmentally friendly method for producing stretchable superhydrophobic films.

“Inverse vulcanization” sulfur polymers present an environmentally friendly approach for producing highly water repellent (superhydrophobic) materials. However, exposure to UV irradiation can lead to the degradation of these polymers into hydrophilic compounds, thereby compromising the long-term superhydrophobic properties of the coatings. In this study, 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (TVTSi) was employed to synthesize sulfur polymers (poly(S-TVTSi) capable of withstanding UV exposure while preserving the photocatalytic properties. Employing a central composite design, poly(S-TVTSi) was combined with inorganic nanoparticles (SiO2 and TiO2) to fabricate superhydrophobic coatings. A variation in the materials composition was used to investigate the influence on the properties of the coatings. Including polymer composition (sulfur:TVTSi ratio), roughness agent composition (TiO2:SiO2 ratio), concentration of nanoparticles (roughness agent), and relative amount of poly(S-TVTSi). The concentration of nanoparticles was identified as the main factor affecting the water contact angle (WCA), whereas all factors (above) generally influenced transmittance, photocatalysis, and UV stability. Using a tailored desirability function, this study demonstrated that a high-performing coating exhibited superior UV stability (up to 300 min) and superhydrophobicity (WCA > 150°). The study also identifies a number of coatings with robust superhydrophobicity, maintaining WCA > 150° across extreme pH and varying concentrations of aqueous NaCl. The coatings also displayed versatile photocatalytic activity against diverse organic contaminants of emerging concern in water bodies, such as caffeine and saccharin. The superhydrophobic coatings made with poly(S-TVTSi) surpass the limited UV stability of sulfur polymers. These materials demonstrate a combined long-term superhydrophobic and photocatalytic performance superior to those previously reported, they present a viable alternative polymer for the production of environmentally friendly and durable superhydrophobic materials.

Sulfur polymers produced through 'inverse vulcanization' exhibit various attributes, such as photocatalytic activity and a high capacity to adsorb heavy metals. Nevertheless, there is a lack of research investigating the use of sulfur polymers as materials for the removal of organic contaminants. In this work, porous sulfur polymers (PSPs) were synthesized from elemental sulfur and 1,3-diisopropenylbenzene, with porosity introduced via salt templating. The result is a material that can strongly adsorb and chemically neutralize a model organic contaminant (caffeine). PSPs show adsorption up to 5 times higher than a leading adsorption material (activated carbon). Furthermore, either the adsorption or degradation processes can govern the removal efficiency depending on the synthesis parameters of PSPs. This is the first-ever report demonstrating sulfur polymers as effective materials for removing emerging contaminants from water. The versatile synthesis of sulfur polymers offers variation, which means that there is much more to explore in this exciting research area.

Wastewater treatment is becoming ever more challenging due to the increasing levels of molecular pollutants that are challenging for existing approaches. Innovative materials are required to help produce potable water from heavily contaminated water sources. One such material is titanium dioxide-activated carbon (TiO2/AC) heterostructures, which combine the photocatalytic properties of TiO2 with the adsorption properties of the ACs. To date, studies on TiO2/AC heterostructures for real-world water purification have yet to be performed. This study aimed to address this gap by comparing the effectiveness of titanium isopropoxide (Ti(OiPr)4) and titanium butoxide (Ti(OBu)4) for synthesizing TiO2/AC heterostructures using four different methods (sol-gel, solvothermal, and microwave-assisted hydrothermal methods [x2]). The elaborated heterostructures were compared with commercial TiO2 materials for their ability to degrade five emerging contaminants (caffeine, hydrochlorothiazide, saccharin, sulfamethoxazole, and sucralose). Hydrochlorothiazide and sulfamethoxazole were demonstrated to be rapidly degraded by UV-C irradiation within 15 min. Caffeine, saccharin, and sucralose were less susceptible to UV degradation. All the elaborated TiO2/AC heterostructures consisted of pure anatase phase, with Ti(OBu)4 syntheses generating larger average crystal sizes and lower surface areas. Sol-gel preparations produced the most effective TiO2/AC heterostructures due to their high surface area. Compared with the commercial TiO2, the heterostructures enhanced the photocatalytic activity of TiO2 by up to 10.0 times. Also, the heterostructures remained effective at environmentally relevant conditions (i.e., concentration of the contaminant and water matrices). The reuse of the materials was tested and showed no reduction in efficiency after four removal/regeneration cycles. Overall, this study presents novel TiO2/AC heterostructures with increased photocatalytic efficiency that can serve as an efficient material for removing contaminants at large scales (e.g., water treatment plants).

This work investigated the adsorption of five model contaminants of emerging concern (CECs) that are released daily in domestic effluents (caffeine, hydrochlorothiazide, saccharin, sulfamethoxazole and sucralose) onto two activated carbons (ACs), in fixed-bed column experiments with different aqueous matrices (ultrapure water, wastewater treatment plant (WWTP) effluent and WWTP effluent pretreated by reverse osmosis and photoperoxidation (reuse water)). The ACs were chemically similar, but AC1 had smaller particles (0.7–1.7 mm) and lower surface area (551 m2 g−1) than AC2 (1.2–2.4 mm and 716 m2 g−1). AC1 had a higher adsorption capacity (qads) for the CECs in the downflow mode. Overall, the qads values of the CECs followed the order: caffeine > sulfamethoxazole > hydrochlorothiazide = saccharin > sucralose. In the downflow mode, preferential pathways reduced the hydraulic retention time (HRT) of the fixed-bed column loaded with AC, which reduced the useful lifetime of column and the adsorption capacity. Nevertheless, the adsorption capacity and useful lifetime of the fixed-bed columns remained similar in the upflow mode (no preferential pathways were observed) regardless of the AC used. Since the HRTs were also found to be similar, it was evident that the crucial factor influencing the adsorption of the CECs was the HRT, which played a pivotal role in the overall process becoming evident. Compared to ultrapure water, use of the WWTP effluent reduced qads for all the CECs by up to 4.1 times, while reuse water reduced qads by up to 1.2 times. The AC1 could be in-situ regenerated using ethanol, with a global efficiency of 97.2 %. The results showed the importance of pretreatment techniques and optimization of the operational parameters, such as HRT, for enhancing the useful lifetime and qads of fixed-bed columns.

Toxic cyanobacterial blooms in aquatic ecosystems are associated to both public health and environmental concerns worldwide. Depending on the treatment technologies used, the removal capacity of cyanotoxins by drinking water treatment plants (DWTPs) is not sufficient to reach safe levels in drinking water. Likewise, controlling these blooms with algaecide may impair the efficiency of DWTPs due to the possible lysis of cyanobacterial cells and consequent release of cyanotoxins. We investigated the effects of three commercial algaecides (cationic polymer, copper sulfate, and hydrogen peroxide) on the growth parameters of the cyanobacterium Microcystis aeruginosa and the release of microcystin-LR (MC-LR). The potential interference of each algaecide on the MC-LR removal by adsorption on activated carbon (AC) was also tested through adsorption isotherms and kinetics experiments. Most algaecides significantly decreased the cell density and biovolume of M. aeruginosa, as well as increased the release of MC-LR. Interestingly, the presence of the algaecides in binary mixtures with MC-LR affected the adsorption of the cyanotoxin. Relevant adsorption parameters (e.g., maximum adsorption capacity, adsorption intensity, and affinity between MC-LR and AC) were altered when the algaecides were present, especially in the case of the cationic polymer. Also, the algaecides influenced the kinetics (e.g., by shifting the initial adsorption and the desorption constant), which may directly affect the design and operation of DWTPs. Our study indicated that algaecides can significantly impact the fate and the removal of MC-LR in DWTPs when the adsorption process is employed, with important implications for the management and performance of such facilities.

According to the World Health Organization (WHO), the definition of water quality indicators, including contaminants of emerging concern (CECs), associated with the development of multi-barrier approaches for wastewater treatment, are crucial steps towards direct potable reuse of water. The aims of this study were 1) quantifying twelve CECs (including pharmaceutical, stimulant, and artificial sweetener compounds) in both untreated and treated wastewater samples in a Brazilian wastewater treatment plant (WWTP) using bidimensional liquid chromatography coupled with tandem mass spectrometry, allowing the selection of five marker (i.e., priority) CECs; 2) evaluating the adsorption potential of such selected CECs [caffeine, hydrochlorothiazide, saccharin, sucralose (SUC), and sulfamethoxazole (SMX)] onto coconut-shell granular activated carbon (GAC); and 3) investigating the removal of the same CECs by a multi-barrier system (pilot-scale, 350 L h−1) treating the effluent of the WWTP and composed of reverse osmosis (RO), photoperoxidation (UV/H2O2), and filtration with GAC. Such technologies were tested separately and in binary or ternary combinations. Eleven and eight CECs were detected and quantified on the untreated and treated wastewater samples of the Brazilian WWTP, respectively. For the treated wastewater, the concentrations ranged from 499 ng L−1 (SMX) to 87,831 ng L−1 (SUC). The adsorption onto AC data fitted the Sips isotherm model, indicating monolayer chemisorption, which was also suggested by the mean adsorption energy values (>16 kJ mol−1). SMX and SUC were the most and the least adsorbed CECs (4.33 and 1.21 mg g−1, respectively). Concerning the pilot-scale treatment plant, the ternary combination (RO + UV/H2O2+GAC) removed >99% of the five marker CECs and promoted reductions on water color, turbidity, as well as on nitrogen and phosphorus concentrations. Further studies on water reuse could prioritize the selected marker CECs as quality indicators. While the removal of marker CECs is one of the WHO performance requirements, the RO + UV/H2O2+GAC system showed promising results as a first approach to direct potable reuse of water.

The presence of N-nitrosamines - potentially carcinogenic compounds - is being reported for more than 50 years in pharmaceutical products. However, it only gained notorious prominence in 2018, when regulatory agencies became aware of the presence of N-nitrosodimethylamine in angiotensin II receptor antagonists, drugs that are known as sartans. It did not take long for N-nitrosamine impurities to be identified in other medicines, alerting government agencies and pharmaceutical industries to evaluate and control these impurities in their products to mitigate the risk. The sources of contamination can be numerous, including the use of contaminated raw material, formation in the synthesis of active pharmaceutical ingredients or during storage, the water used in the process, and the packaging material. This review article presents the timeline of the presence of N-nitrosamines in consuming products, toxicological aspects, legislation, and analytical methods. It provides relevant information on possible sources of contamination in the production and storage process that may explain the presence of these compounds considered a cohort of concern in pharmaceuticals.

The main goal of this study is to evaluate the feasibility of using heterogeneous photocatalysis to degrade the organic contaminant gatifloxacin (GAT) and reduce the antimicrobial activity and acute toxicity from different water matrices. Assays were performed using four water matrices (ultrapure water - UW, mineral water - MW, potable water - PW, and simulated surface water - SW) fortified with gatifloxacin (500 µg L−1) as a model antibiotic contaminant and its quantification was followed using online SPE-UHPLC-MS/MS. Initially, the photocatalytic process efficiency towards GAT removal as a function of UV light wavelength (UVA and UVC), catalyst type (TiO2-P25 or TiO2-PC500), photocatalyst loading (from 1 to 200 mg TiO2 L−1), solution pH (from 4 to 9), GAT initial concentration (from 50 μg GAT L−1 to 5000 μg GAT L−1) and water matrix (UW, MW, SW or PW) was assessed. In this context, the TiO2-PC500 system using UVA showed the best removal performance of GAT. With TiO2-PC500 loadings higher than 10 mg L−1, > 90% of GAT degradation was achieved after only 40 min of reaction. Finally, the system efficiency was evaluated according to its ability to reduce the antimicrobial activity of the solutions against Gram-negative and Gram-positive bacteria as well as their acute toxicity to A. fischeri bacterium. The antimicrobial activity in the solutions dropped along the reaction time, but no toxicity variation was observed.

Activated carbon (AC) can be used for the removal of emerging contaminants (e.g., drugs) in water and wastewater treatment plants. In the present study, we investigated the performance of two ACs (from coconut shell and Pinnus sp.) in the adsorption of caffeine, carbamazepine, and ricobendazole considering the compounds separately and in combination in batch-scale experiments. The concentrations of the drugs were determined by a validated method using solid-phase extraction with on-line ultra-high performance liquid chromatography-tandem mass spectrometry. The most mesoporous AC provided higher drug removal. The kinetic data were described by the pseudo-second-order, Elovich, and Weber-Morris models, while the adsorption isotherms showed a better fit to the Freundlich model, indicative of multilayer adsorption. The Dubinin-Radushkevich model was used as a first approach to estimate the mean adsorption energy (E) and the results indicate that chemisorption governed the adsorption process, with E higher than 8 kJ mol−1. In the multicomponent assays, the adsorption of caffeine showed the greatest hindrance caused by the presence of other drugs. Multicomponent assays are fundamental to evaluate the potential adsorption capacity in real water treatment plants. Our study suggests that drugs with different structures and physicochemical properties may interact differently with ACs, especially in multicomponent solutions, with important implications for the design (e.g., volumes and areas of treatment plants) and operation (e.g., water residence time) of the treatment plants.

While the presence of microcystin-LR (MC-LR) in raw water from eutrophic reservoirs poses human health concerns, the risks associated with the ingestion of MC-LR in drinking water are not fully elucidated. We used a time series of MC-LR in raw water from tropical urban reservoirs in Brazil to estimate the hazard quotients (HQs) for non-carcinogenic health effects and the potential ingestion of MC-LR through drinking water. We considered scenarios of MC-LR removal in the drinking water treatment plants (DWTPs) of two supply systems (Cascata and Guarapiranga). The former uses coagulation/flocculation/sedimentation/filtration/disinfection, while the latter has an additional step of membrane ultrafiltration, with contrasting expected MC-LR removal efficiencies. We considered reference values for infants (0.30 μg L−1), children/adults (1.60 μg L−1), or the population in general (1.0 μg L−1). For most scenarios for Cascata, the 95% upper confidence level of the HQ indicated high risks of exposure for the population (HQ > 1), particularly for infants (HQ = 30.910). The water treatment in Cascata was associated to the potential exposure to MC-LR due to its limited removal capacity, with up to 263 days/year with MC-LR above threshold values. The Guarapiranga system had the lowest MC-LR in the raw water as well as higher expected removal efficiencies in the DWTP, resulting in negligible risks. We reinforce the importance of integrating raw water quality characteristics and treatment technologies to reduce the risks of exposure to MC-LR, especially for vulnerable population groups. Our results can serve as a starting point for risk management strategies to minimize cases of MC-LR intoxication in Brazil and other developing countries.

The concerns regarding the occurrence of pharmaceuticals in wastewater treatment plants have increased in the last decades. Gatifloxacin (GAT), the fourth generation of fluoroquinolones, has been widely used to treat both Gram-positive and Gram-negative bacteria and has a limited metabolization. The present study aimed to evaluate ozonation as a technique to degrade GAT. An exchange A UHPLC-MS/MS by an UHPLC-MS/MS method was used to quantify the residual of GAT and to assess its degradation products. The removal efficiency was higher under alkaline conditions (pH = 10), reaching up to 99% of GAT after 4 min. It was also observed that the first ozone attack on the GAT molecule was through the carboxylic group. In contrast, under acid conditions (pH = 3), the ozone attack was first to the piperazinyl ring. The antimicrobial activity was evaluated using Escherichia coli and Bacillus subtilis as test organisms, and it was observed that the residual activity reduced most under alkaline conditions. In contrast, the best condition to remove the residual toxicity evaluated for the marine bacteria V. fischeri was the acidic one. Due to this, ozonation seemed to be an exciting process to remove GAT in aqueous media.

Photoperoxidation (UV/H2O2) was used to degrade three of the worldwide most consumed antidepressant pharmaceuticals—bupropion, escitalopram, and fluoxetine—in ultrapure water, drinking tap water, surface water, and reclaimed water. The study was performed with antidepressants in concentration levels in which these compounds usually occur in the water matrices. Online solid-phase extraction coupled to UHPLC-MS/MS was used to quantify the analytes during degradation studies. The UV/H2O2 process was able to degrade bupropion and fluoxetine in ultrapure water, using 0.042 mmol L−1 of H2O2 and 1.9 kJ of UV-C irradiation. Nevertheless, escitalopram, which had the most recalcitrant character among the studied antidepressants, needed a tenfold more oxidant and UV-C irradiation. The primary metabolites of the antidepressants were identified as the major by-products generated by the UV/H2O2 process, and they persisted in the solution even when the parent compound was degraded. The residual toxicity of the solution was evaluated for two different trophic levels. The UV/H2O2 process reduced the toxicity of the solution to Raphidocelis. subcapitata microalgae after 30 min of reaction. On the other hand, the toxicity of the residual solution increased over the reaction time to the marine bacteria Vibrio fischeri (reaching up to 48.3% of bioluminescence inhibition after 60 min of reaction). Thus, our results evidenced that the toxicity against different trophic levels and the monitoring of the by-products formed are important aspects to be considered regarding the safety of the treated solution and the optimization of the treatment process.

Benzimidazoles (BZ) are among the most used drugs to treat parasitic diseases in both human and veterinary medicine. In this study, solutions fortified with albendazole (ABZ), fenbendazole (FBZ), and thiabendazole (TBZ) were subjected to photoperoxidation (UV/H2O2). The hydroxyl radicals generated by the process removed up to 99% of ABZ, and FBZ, in the highest dosage of H2O2 (i.e., 1.125 mmol L-1; 4.8 kJ L-1). In contrast, 20% of initial TBZ concentration remained in the residual solution. In the first 5 min of reaction (i.e., up to 0.750 mmol L-1 of H2O2), formation of the primary metabolites of ABZ—ricobendazole (RBZ), albendazole sulfone (ABZ-SO2), and oxfendazole (OFZ)—was observed. However, these reaction products were converted after the reaction time was doubled. The residual ecotoxicity was investigated using the Raphidocelis subcapitata microalgae and the marine bacteria Vibrio fischeri. The results for both microorganisms evidence that the residual solutions are less harmful to these microorganisms. However, after 30 min of reaction, the treated solution still presents a toxic effect for V. fischeri, meaning that longer reaction times are required to achieve an innocuous effluent.

Ciprofloxacin (CIP) is an antimicrobial “pseudo-persistent” in aquatic ecosystems. Once dispersed in the water compartments, it can also affect the microalgae. Thus, the evaluation of its long-term ecotoxicological effects is necessary. CIP interactions with other pharmaceuticals are not well known. In this study, we investigated the toxic effects of CIP alone and combined with caffeine (CAF), using the modified Gompertz model parameters and the chlorophyll-a production of the microalga Raphidocelis subcapitata as endpoints, throughout a 16-day exposure assay. The exposure to CIP alone led to significant reductions of the growth rate and the cell density of the microalgae compared to control groups. The combination with CAF lowered the adverse effects of CIP to R. subcapitata. However, as the toxicity is dynamic, our results indicated that the toxic effects in respect to the studied endpoints changed throughout the exposure period, reinforcing the need for longer-term ecotoxicity assessments.

Pharmaceutically active compounds (PhACs) are emerging contaminants that have been widely detected in water bodies in the last decades, with ecological effects toward aquatic biota that have not been fully elucidated. Most studies concerning their toxicity to microalgae have only considered short-term individual PhAC exposure, rather than combined exposure to several compounds for longer time periods. In this study, we investigated the effects of albendazole (ABZ) (anthelmintic) and carbamazepine (antiepileptic), alone and in combination with caffeine, on the growth and production of chlorophyll-a of the microalgae Raphidocelis subcapitata, during 16 days of exposure. ABZ alone had a more significant effect than carbamazepine alone on the growth rate and maximum cell density of the microalgae (p < .05; analysis of variance). These results were probably related to the effect of ABZ in inhibiting enzyme complexes and cell membrane proteins related to adenosine triphosphate synthesis, which is important for cell growth. The presence of caffeine lowered the toxicities of ABZ and carbamazepine to the microalgae, probably due to its antioxidant properties, positively affecting chlorophyll-a production, growth rate, and maximum cell density. Thus, caffeine had an antagonistic interaction with the studied PhACs. The results reinforce the importance of ecotoxicological assays that compare individual and combined PhAC exposure conditions. Our findings highlighted that caffeine can be a relevant factor influencing such assays, considering its widespread occurrence in impacted water bodies.