Mucosal surfaces are the first mechanical barrier preventing the entry of foreign particles into the organism. The study addresses the detection and analysis of metal-based solid particles in cytological mucus samples from the surface of human hypertrophic tissue in the inferior nasal turbinates in patients diagnosed with chronic rhinitis. Solid particles were characterized by scanning electron microscopy and Raman microspectroscopy; all the biological samples were also subjected to vibration magnetometry. Since the upper airways are the first part of the respiratory tract, which is exposed to inhaled particles, it can be assumed that inhaled particles may be partially deposited in this region. Scanning electron microscopy revealed the presence of metal-based solid particles/clusters in the majority of the analysed cytological mucus samples and also in hypertrophic tissues; in all groups, the particles were of submicron size. Raman microspectroscopy detected the presence of particles/clusters based on amorphous carbon, graphite, calcium carbonate, anatase and barite only in the hypertrophic tissue. The obtained results show that the composition of some of the solid particles (i.e. Ba, Zn, Fe and Ti) detected in the mucus from the surface of the hypertrophic tissues resembled the particles found in the hypertrophic tissue itself. It can be assumed that after the capture of the inhaled particles by the mucus, they penetrate into the deeper layers of tissue.

Biogas production from sewage sludge volatile solids (VS) by anaerobic digestion slows down towards the end of the process, among inhibitory factors being pH increase upon ammonia accumulation, poorly digestible biomaterials, and high fixed solid (FS) content. The possibility of concentrating the digested sludge VS (41.7–56.6% on a dry weight basis) by surface and bottom layer separation with biogas post-production was studied. Furthermore, the potential to recycle concentrated VS and digested sludge back to the process after adjusting pH 7.0 to optimal for biogas-producing microbes and after acid, alkali, thermal, and sonolytic treatments was examined. In general, pH 7.0 control alone improved biogas production from the recycled digested sludge the most. An equally good improvement in biogas production was achieved by recycling the digested sludge, which had been heated until ammonia had evaporated and the pH dropped to 7.0 (1–2 h, 75 °C), and at the same time, VS was degraded. The biogas production from the sonicated and recycled sludge was almost as good as from the pH-adjusted, or heat-treated recycled sludge. After the acid and base treatments of the digested sludge, the recycled sludge yielded often the lowest biogas volume, as the added chemicals increased the FS concentration, which proved to be a more important inhibitory factor than poorly degradable VS. The high FS content significantly reduced the benefits of the treatments. By separating the surface and bottom layers with biogas post-production, the surface layer of VS was concentrated to 51.6–61.8%, while different compositions of the layers affected the biogas production.

Microbiological, physical, chemical, cytotoxic, and genotoxic analyses of waters from ten tubular wells intended for irrigation of a community garden complex in the state of Piaui, northeastern Brazil, were carried out in two periods of 2018 (rainy and drought). All wells in both periods were contaminated with total coliforms, and wells P1, P3, P5, and P10 also had fecal coliforms. The waters, in the two collections performed, presented low concentration of dissolved oxygen, and nitrate and chlorine concentrations higher than allowed by law. Water from P1, P3, P5, and P10 were cytotoxic to root meristem cells of A. cepa in the two periods studied. However, no water sample was genotoxic to root meristems. The results show that the analyzed waters are contaminated with untreated effluents as well as with pesticides. Such conditions are pointed out because the rivers near these wells are degraded by human activities, and the gardens where the wells are found have ditches, sinks, and black cesspools for the disposal of sewage. In view of this, the intervention of the State Government in these places is necessary, since the evaluated wells irrigate community gardens in overcrowded poor neighborhoods, and from there comes part of the food of their residents. Another activity for the government is to put in place management plans for the restoration of rivers and the implementation of public sanitation in the neighborhoods where the wells are located.

17β-Estradiol (E2) is one of the main compounds responsible for estrogenic activities in sewage and natural waters and has been found in these matrices all around the world, thereby justifying the development of technologies for its removal. In this work, pure or TiO₂-containing molecularly imprinted polymers (MIPs) and non-imprinted polymers (NIPs) were prepared using E2 as template. The materials were characterized by infrared spectroscopy, X-ray diffraction, adsorption/desorption of N₂, and scanning electron microscopy (SEM). The characterization analyses showed that TiO₂ was incorporated in the polymers and that all materials could be characterized as mesoporous and had surface areas ranging from 238 to 279 m²g⁻¹. Adsorption studies showed MIP-TiO₂ had a high capacity to adsorb E2 from the water phase leading to qₘₐₓ values of 15.16 to 26.49 mg g⁻¹ at temperatures from 25 to 45 °C, respectively. In addition, the thermodynamic study showed that the adsorption process is endothermic, spontaneous, and entropically driven. The results also showed that the presence of TiO₂ decreases the adsorption performance of MIP-TiO₂ when compared with MIP (without the photocatalyst) during the adsorption. However, the application of MIP-TiO₂ in a process of adsorption followed by photocatalysis resulted in 100% of E2 removal allowing the reuse of adsorbent. In addition, MIP-TiO₂ maintained its E2 removal capacity even after five cycles of regeneration–reuse, which shows the ability of UV light to regenerate the specific adsorption sites. The results presented in this paper show MIP-TiO₂ has potential to be applied in water treatment systems to remove E2.

In this work, an ordered mesoporous carbon material CMK-3 was synthesized and tested in the adsorption of Cr(VI) in water with an activated carbon material (AC) as the control. Properties of CMK-3 have been characterized by means of Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. In the adsorption of Cr(VI) in water, the adsorption rate and adsorption capacity of CMK-3 were found to be better than that of AC. A careful study on the adsorption kinetics and isotherms of Cr(VI) on CMK-3 was taken. The adsorption data of Cr(VI) on CMK-3 had been analyzed by pseudo-first-order, pseudo-second-order, particle diffusion, Elovich, Double constant, and Exponential function kinetic models, which revealed that the kinetic adsorption of Cr(VI) on CMK-3 is well accorded with pseudo-second-order kinetic model. The corresponding parameters for each model are obtained. According to the fitting of Langmuir, Freundlich, and Temkin models, the adsorption of Cr(VI) on CMK-3 was well described by Langmuir model to be a single-molecule layer adsorption. The adaptation of the adsorption of Cr(VI) on CMK-3 to Langmuir adsorption model and pseudo-second-order model suggests that the adsorption of Cr(VI) on CMK-3 can be highly affected by its chemical property although its textural properties also can remarkably affect its adsorption behavior.

Carbon nano-onions (CNOs) are fascinating zero-dimensional carbon materials owning distinct multi-shell architecture. Their physicochemical properties are highly related to the parent material selected and the synthesis protocol involved. In the present work, we report for the first time novel CNO structures encompassing discrete carbon allotropes, namely, H₁₈ carbon, Rh6 carbon, and n-diamond. These structures were cost-effectively synthesized in gram scale by facile flame pyrolysis of paraffinum liquidum, a highly refined mineral oil. The as-synthesized and chemically refashioned CNOs are quasi-spherical self-assembled mesopores, manifesting remarkable stability and hydrophilicity. The CNO structures exhibit excellent dye adsorption characteristics with high removal capacity of 1397.35 mg/g and rapid adsorption kinetics with a minimal adsorbent dosage of 10 mg/L, for a low concentration of 20 mg/L methylene blue dye. The novel CNOs assure potential implementation in the remediation of low concentration and high volume of dye-contaminated wastewater.Graphical abstract

The evaluation of the concentration of pesticides in drinking water presents a real concern. In this study, a simple and rapid method based on solid-phase microextraction (SPME) followed by gas chromatography–mass spectrometry and electron capture detectors was developed aiming at multiclass determination of 23 pesticides regulated by the Brazilian legislation. The extraction was carried out by direct immersion mode (DI-SPME) using DVB/Car/PDMS fiber coating. In order to improve the extraction efficiency, parameters such as temperature, salting-out effect, and extraction time were optimized. The method was evaluated using drinking water samples spiked with the analytes at different concentrations, and it showed good linearity in the range studied. The values obtained for limits of quantification (LOQ) were below the limits established by Brazilian regulations. Accuracy and precision of the method exhibited satisfactory results, providing relative recoveries from 70 to 123.34% at three spiked levels, and the relative standard deviations ranged from 0.53 to 24.8%. The method was applied in 20 drinking water samples from 13 cities in the State of Santa Catarina, Brazil.

In this study, graphene oxide (GO) was prepared using modified Hummer’s method and doped with Fe-Ni nanoparticles. Morphological characterization of the Fe-Ni nanoparticles showed flake-like structure correlating to taenite phase, while Raman spectroscopy suggested that graphene oxide was multi-layered. Batch adsorption experiments were performed to determine the effect of solution pH, initial uranium (VI) concentration, adsorbent dosage, contact time, and specific anions (SO₄²⁻ and NO₃²⁻) on the adsorption of U (VI). Solution pH had significant effect on U (VI) sorption on Fe-Ni/GO, with maximum removal of 98.4% at pH 4, while it was 98% at pH 8 for GO. Sorption kinetics revealed fast adsorption within 15 min. The kinetic and equilibrium data was evaluated using pseudo-first-order, pseudo-second-order, Elovich, Langmuir, Freundlich, and Temkin models. The mechanism of U (VI) sorption appeared to be a combination of chemisorption and possible pore diffusion of the U (VI) moieties to the porous structure of GO and Fe-Ni/GO. Overall, Fe-Ni/GO was a better adsorbent than GO with higher sorption capacities. U (VI) sorption on GO and Fe-Ni/GO followed pseudo-second-order reaction kinetics (R² > 0.99). Good fit to Langmuir isotherm model (R² > 0.98) suggested favorable monolayer adsorption, with a maximum U (VI) adsorption capacity on Fe-Ni/GO to be 25.64 mg/g. Moderate to insignificant effect of specific anions even at high concentrations on U (VI) removal capacities makes Fe-Ni/GO an excellent candidate.

The accumulation of heavy metals by crops irrigated with wastewater has been considered as a serious environmental problem in many developing countries, where the wastewater irrigation has emerged as a common practice. In this research, we were concerned with the highly toxic metal lead (Pb) in water, agricultural soils, and wheat crops, and the possible risk on human health in the peripheral agricultural regions of Punjab, Pakistan. Various types of irrigated water (ground, sewage, industrial), soil, and wheat plant (root, shoot, grain) samples of five different varieties (Seher-2006, Punjab-2011, Faislabad-2008, Watan, and Galaxy-2013) were collected from seven different districts and then pooled up to make one composite sample and analyzed for Cd concentration. The various pollution and mobility indices (pollution load index, enrichment factor, daily intake of metal, health risk index, translocation factor, bioaccumulation factor, and bio-concentration factor) were also calculated. The descending order for Pb concentration was as follows: water>soil>wheat plant. The range of concentration of Pb in all types of water, soil, and wheat plant (root, shoot, grains) samples was (7.05–7.83 mg/l), (6.32–7.74 mg/kg), (3.23–4.82, 1.14–2.75, 0.09–0.51 mg/kg), respectively. The concentration of Pb in all types of water samples exceeded the maximum permissible limit. There were values found to be < 1.00 in all the pollution and mobility indices for all types of samples. These results reveal that high levels of Pb in irrigated water may pollute the soil and wheat plants of these regions in the near future, if various control measures have not been taken. It may pose a great health risk to the local human and animal populations. Preventive measures should be taken to reduce heavy metal pollution of irrigation water and soils to protect both human and animal health in various regions of Punjab, Pakistan.

17α-Methyltestosterone (MT) is widely used synthetic androgenic steroid in the tilapia aquaculture industry for masculinization: a sex reversal process in which hormones are utilized to induce production of male fish. Although MT is beneficial for aquaculture, release of residual MT can cause adverse effects on wild organisms. The aims of this study were to identify MT-degrading bacteria and to characterize their degradation abilities under the conditions experienced in the environment. Nocardioides nitrophenolicus S303, Acinetobacter radioresistens B051, and Ochrobactrum haematophilum B052 were the most efficient MT-degrading bacterial strains, with the shortest degradation half-life of 10–70 h. The MT degradation by Acinetobacter and Ochrobactrum has not been reported before. After comparing their degradation rates and for reason of biosafety, N. nitrophenolicus S303 was selected for further study. Although this strain degraded MT and testosterones, it could not degrade estrogens (estrone, 17β-estradiol, nor 17α-ethinylestradiol). Glucose amendment did not affect the MT degradation rate. No metabolites with androgenic activity were observed after 264-h treatment with this strain under aerobic conditions. Methandrostenolone was found as the major intermediate during 39–90 h. This is the first report indicating the 1,2-dehydrogenase activity in steroid clevage in N. nitrophenolicus. Our study provides important information concerning the application of N. nitrophenolicus S303 to enhance MT degradation in the environment.