Biosynthesized nanocomposites are attracting growing interests because they are environmentally friendly. Ag₂S nanoparticles (Ag₂S NPs) are deposited in situ on the surfaces of TiO₂ nanotubes (TNTs) via Shewanella oneidensis MR-1 to form Ag₂S/TNT nanocomposites. The prepared Ag₂S/TNTs nanocomposites are characterized using high-resolution transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and energy-dispersive X-ray spectroscopy. The results show that Ag₂S NPs smaller than 8 nm are successfully synthesized and fabricated on the TNT surfaces with relatively uniform distribution. The catalytic performance of the Ag₂S/TNT nanocomposites is evaluated for catalytic reduction in the presence of NaBH₄ and the photocatalytic degradation of 4-nitrophenol (4-NP) under visible light. The Ag₂S/TNT nanocomposites show excellent catalytic activity and good stability in the 4-NP reduction process. The 4-NP degradation ratio reaches 98.3% in 50 min, and 87% conversion was achieved after eight cycles. The Ag₂S/TNT nanocomposites also exhibit excellent photocatalytic activity for 4-NP at a rate of 0.69 h⁻¹, and the complete degradation of 4-NP was observed within 5 h. Therefore, this study offers an environmentally friendly approach to synthesize nanocomposites for practical applications.

Fine particulate matter (PM₂.₅) is a mixture of multiple components, which is associated with several chronic diseases, including respiratory and cardiovascular diseases. We evaluated the association between daily PM₂.₅ and PM₂.₅–₁₀ exposure and hospital visits for respiratory diseases. Hospital visits for respiratory diseases were collected from Yinzhou Health Information System database. We used generalized additive models to examine the excess relative risk (ERR) and 95% confidence interval for hospital visits for respiratory diseases associated with each 10-μg/m³ increase in PM₂.₅ and PM₂.₅–₁₀ concentration. Non-linear exposure-response relationship between PM exposure and hospital visits for respiratory diseases was evaluated by a smooth spline. The ERRs for hospital visits for respiratory diseases associated with a 10-μg/m³ increase in the 6-day cumulative average concentration of PM₂.₅ and PM₂.₅–₁₀ were 5.40 (95% CI 2.32, 8.57) and 6.37% (95% CI 1.84, 11.10), respectively. The findings remained stable when we adjusted other gaseous air pollution. PM₂.₅ and PM₂.₅–₁₀ were associated with the increased visits for the acute upper respiratory infection, pneumonia, asthma, and COPD. In this time-series study, we found a positive association between daily particulate matter exposure and hospital visits for respiratory diseases.

Copper and zinc composite oxides (Cu₂O/ZnO) were synthesized by an impregnation-reduction-air oxidation method. A series of Cu₂O/ZnO/rGO ternary composites were prepared by coupling with graphene oxide (GO) with different mass fractions in a solvothermal reaction system. The microscopic morphology, crystal structure, and optical characteristics of the photocatalysts were characterized. The degradation of p-Nitrophenol (PNP) and polyacrylamide (PAM) by photocatalytic materials under simulated solar irradiation were studied, and the degradation kinetics were also investigated. The results showed that cubic Cu₂O was modified by ZnO nanorods and distributed on rGO nanosheets. The ternary Cu₂O/ZnO/rGO nanocomposites have stronger simulated solar absorption ability and higher photodegradation efficiency than pure ZnO and binary Cu₂O/ZnO nanocomposites. When the amount of Cu₂O/ZnO/rGO-10 was 0.3 g L⁻¹, the degradation rate of 10 mg L⁻¹ PNP reached 98% at 90 min and 99.6% of 100 mg L⁻¹ PAM at 30 min. The photocatalytic degradation processes of PNP and PAM all followed the pseudo-first-order kinetic model. Free radical trapping experiments showed that superoxide radicals were the main active substances to improve photocatalytic efficiency. In addition, after four recycles, the catalytic efficiency of Cu₂O/ZnO/rGO-10 was still over 90%. It showed that Cu₂O/ZnO/rGO-10 was a promising catalyst for wastewater treatment because of its good photostability and reusability.

Regarding the rapid progress in the production and consumption of nanobased products, this research considered the behavior of Melissa officinalis toward zinc oxide nanoparticles (nZnO), nanoelemental selenium (nSe), and bulk counterparts. Seedlings were irrigated with nutrient solution containing different doses of nZnO (0, 100, and 300 mg l⁻¹) and/or nSe (0, 10, and 50 mg l⁻¹). The supplements made changes in growth and morphological indexes in both shoot and roots. The mixed treatments of nSe10 and nZnO led to a drastic increase in biomass, activation of lateral buds, and stimulations in the development of lateral roots. However, the nSe50 reduced plants’ growth (45.5%) and caused severe toxicity which was basically lower than the bulk. Furthermore, the nSe and nZnO improved K, Fe, and Zn concentrations in leaves and roots, except for seedlings exposed to nSe50 or BSe50. Moreover, the nSe and nZnO supplementations in a dose-dependent manner caused changes in leaf non-protein thiols (mean = 77%), leaf ascorbate content (mean = 65%), and soluble phenols in roots (mean = 28%) and leaves (mean = 61%). In addition, exposure to nZnO and/or nSe drastically induced the expression of rosmarinic acid synthase (RAS) and Hydroxy phenyl pyruvate reductase (HPPR) genes. Besides, the nSe, nZnO, or bulk counterparts influenced the activities of nitrate reductase in leaves and peroxidase in roots, depending on dose factor and compound form. The comparative physiological and molecular evidence on phytotoxicity and potential advantages of nSe, nZnO, and their bulk counterparts were served as a theoretical basis to be exploited in food, agricultural, and pharmaceutical industries.

Recently, strict standards for ship domestic sewage discharge have been implemented by the International Maritime Organization (IMO). The high salinity of ship sewage was considered a key factor influencing the removal efficiency of ship sewage treatment systems. In the present study, the salinity effect on the removal of chemical oxygen demand (COD) and ammonia nitrogen (NH₄⁺-N) from ship domestic sewage was investigated by using a novel air-lift multilevel circulation membrane reactor (AMCMBR). Enzyme activity analysis and wavelet neural network (WNN) models were built to determine the mechanisms of the process. The experimental results indicate that high salinity levels (> 21 g/L) had a negative impact on COD and NH₄⁺-N removal efficiencies, and low saline concentrations (≤ 21 g/L) caused a negligible effect. The COD and NH₄-N removal efficiencies were 84% and 97%, respectively, at a salinity of 21 g/L, which were higher than those at low salinities (i.e., 7 g/L and 14 g/L). Invertase and nitrate reductase had a close relationship with removal performance, and they can be considered important indicators reflecting the operation effort under saline environments. With high predictive accuracies, the constructed WNN models simulated the complex COD and NH₄⁺-N removal processes well under different saline concentrations, ensuring the long-term stable operation of the AMCMBR under different salinities.

Boron (B) in the irrigation water can be hazardous to human beings and other aquatic or terrestrial organisms when B concentration exceeds a certain level. More importantly, B removal from irrigation water is relatively difficult using conventional processes. In the present experiment, an innovative treatment model based on monoculture and polyculture duckweed wastewater treatment modules was tested for B-rich irrigation water purification and bioelectricity harvesting. Different modules were designed using Lemna gibba L., Lemna minor L., and their combination in order to determine the most optimal duckweed species and vegetation structure for B removal process and bioelectricity generation in a module. In this respect, the module with a monoculture of Lemna gibba achieved the highest net B removal efficiency (71%) when it was exposed to 4 mg/L B (initial concentration). However, B removal efficiencies from all modules decreased when the initial B concentrations reached up to 4 mg/L in the irrigation water. The highest bioelectricity production was measured as 1.04 V with 17783 mWatt/m² power density at a current density of 44.06 mA/m² for module with Lemna gibba in monoculture through sacrificial magnesium anode. Specifically, both monocultures and polyculture removed considerable amounts of organic matter from irrigation water. However, biomass production and total chlorophyll (a + b) concentrations of duckweeds significantly decreased when they were exposed to 32 mg/L B in the irrigation water samples. Consequently, our modules present a holistic perspective to the prevention B toxicity problems in agricultural zones, and are a sustainable strategy for farmers or agricultural experts to produce bioelectricity by a cost-effective and eco-technological method.

The ultrasonic-assisted hydrothermal and ethanol activation method was proposed to synthesize copper-benzene-1,3,5-tricarboxylate (Cu-BTC) metal organic framework and Cu-BTC/graphene oxide (GO) composites (Cu-BTC@GO). The dynamic adsorption behavior of toluene on two adsorbents was studied and compared with that of GO and reduced graphene oxide (RGO). The Cu-BTC@GO exhibited high adsorption capacity (183 mg/g) for toluene, which is nearly three times as much as that of Cu-BTC (62.7 mg/g) with the GO mass fraction of 20%. Furthermore, the adsorption of toluene on Cu-BTC@GO composites was positively correlated with the initial concentration of toluene and the adsorbent dosage, and negatively correlated with the temperature. The adsorption data of toluene on Cu-BTC@GO composites were well in accordance with pseudo-first kinetics model. Langmuir model had a better fit than Freundlich model. The adsorption thermodynamic results showed that the adsorption process was mainly physical adsorption and the adsorption process was spontaneous at low temperature. After five adsorption–desorption cycles, the adsorption efficiency can still reach 82.1%.This study will help to draw a promising roadmap to describe the adsorption performance of Cu-BTC@GO composites for toluene.

The natural clay is an abundant, accessible, and low-cost material that has the potential for use in the water and wastewater industry. In this paper, Iranian natural clay and clay/Fe-Mn composite were used to remove toxic arsenic from the liquid environment. The natural clay and clay/Fe-Mn composite were characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), energy-dispersive X-ray (EDX), X-ray diffractometry (XRD), thermo-gravimetric analysis (TGA), and atomic force microscopy (AFM) techniques. The effects of parameters (initial pH, temperature, sorption dose, and contact time) on the efficiency and behavior of the arsenic(V) adsorption process were studied. Freundlich (R² = 0.945 and 0.989), Langmuir (R² = 0.922 and 0.931), modified Langmuir (R² = 0.921 and 0.929), and Dubinin–Radushkevich (R² = 0.706 and 0.723) models were fitted to evaluate the equilibrium data of arsenic(V) adsorption process by natural clay and clay/Fe-Mn composite, respectively. The Langmuir adsorption capacity of arsenic(V) by the natural clay and clay/Fe-Mn composite was determined to be 86.86 mg/g and 120.70 mg/g, respectively. The arsenic(V) adsorption process followed the pseudo-second-order model. Negative values of ΔG° and ΔH° showed that the arsenic(V) sorption by the studied materials is thermodynamically spontaneous and exothermic. According to the findings, the natural clay and clay/Fe-Mn are suitable and recyclable sorbents for arsenic(V) adsorption from aqueous solutions. Also, the composite of clay with iron and manganese can improve the efficiency of clay in the removal of arsenic.

Conventional activated sludge (CAS) process is one of the most commonly applied processes for municipal wastewater treatment. However, it requires a high energy input and does not promote energy recovery. Currently, high-rate activated sludge (HRAS) process is gaining importance as a good option to reduce the energy demand of wastewater treatment and to capture organic matter for valorizing through anaerobic digestion (AD). Besides, food waste addition to wastewater can help to increase the organic matter content of wastewater and thus, energy recovery in AD. The objective of this study is to evaluate the applicability of co-treatment of municipal wastewater and food waste in a pilot-scale HRAS system as well as to test the minimal hydraulic retention times (HRTs) such as 60 and 30 min. Food waste addition to the wastewater resulted in a 10% increase in chemical oxygen demand (COD) concentration of influent. In the following stages of the study, the pilot-scale system was operated with wastewater solely under the HRTs of 60 and 30 min. With the decrease of HRT, particulate COD removal increased; however, soluble COD removal decreased. The results demonstrated that if the settling process is optimized, more particulate matter can be diverted to sludge stream.

The number of restaurants is increasing rapidly in recent years, especially in urban cities with dense populations. Particulate matter emitted from commercial and residential cooking is a significant contributor to both indoor and outdoor aerosols. The PM₂.₅ emission rates and source profiles are impacted by many factors (cooking method, food type, oil type, fuel type, additives, cooking styles, cooking temperature, source surface area, pan, and ventilation) discussed in previous studies. To determine which cooking activities are most influential on PM₂.₅ emissions and work towards cleaner cooking, an experiment design based on multi-factor and level orthogonal tests was conducted in a laboratory that is specifically designed to resemble a professional restaurant kitchen. In this cooking test, four main parameters (the proportion of meat in ingredients, flavor, cooking technique, oil type) were chosen and five levels for each parameter were selected to build up 25 experimental dishes. Concentrations of PM₂.₅ emission rates, organic carbon/elemental carbon (OC/EC), water-soluble ions, elements, and main organic species (PAHs, n-alkanes, alkanoic acids, fatty acids, dicarboxylic acids, polysaccharides, and sterols) were investigated across 25 cooking tests. The statistical significance of the data was analyzed by analysis of variance (ANOVA) with ranges calculated to determine the influence orders of the 4 parameters. The PM₂.₅ emission rates of 25 experimental dishes ranged from 0.1 to 9.2 g/kg of ingredients. OC, EC, water-soluble ions (WSI), and elements accounted for 10.49–94.85%, 0–1.74%, 10.09–40.03%, and 0.04–3.93% of the total PM₂.₅, respectively. Fatty acids, dicarboxylic acids, n-alkanes, alkanoic acids, and sterols were the most abundant organic species and accounted for 2.32–93.04%, 0.84–60.36%, 0–45.05%, and 0–25.42% of total PM₂.₅, respectively. There was no significant difference between the 4 parameters on PM₂.₅ emission rates, while a significant difference was found in WSI, elements, n-alkanes, and dicarboxylic acids according to ANOVA. Cooking technique was found to be the most influential factor for PM₂.₅ source profiles, followed by the proportion of meat in ingredients and oil type which resulted in significant difference of 183.19, 185.14, and 115.08 g/kg of total PM₂.₅ for dicarboxylic acids, n-alkanes, and WSI, respectively. Strong correlations were found among PM₂.₅ and OC (r = 0.854), OC and sterols (r = 0.919), PAHs and n-alkanes (r = 0.850), alkanoic acids and fatty acids (r = 0.877), and many other species of PM₂.₅.