Membrane filtration techniques are distinguished among methods for wastewater treatment and fully correspond to the requirements of the green concept of chemistry and production. The limiting factor for greater application of these methods is the phenomenon of fouling and the decline of the permeate flux. In this study, polynomial neural network based on group method data handling (GMDH) algorithm was applied to predict the performance of the complexation-microfiltration process for the removal of Pb(II), Zn(II), and Cd(II) from synthetic wastewater. The influence of working parameters such as pH, initial concentration of metal ions, type of complexing agent, and pressure on flux was experimentally determined. The data obtained were used as input parameters for the GMDH model as well as for the multiple linear regression (MLR) model. Root mean square error (RMSE), mean absolute error (MAE), and mean absolute percent error (MAPE) were used for evaluation purposes. Results showed that the developed model has excellent performance in flux prediction with R² of 0.9648.

Environmental fate and impacts of graphene oxide (GO) nanoparticles are strongly influenced by their subsurface behaviors. The present work examined the aggregation and transport behaviors of GO in saturated sand columns under different temperature (6 and 24 °C), surfactant concentration (0.04% and 0.4%), cation valence, and electrolyte concentration conditions. In monovalent electrolyte (NaCl), although the presence of cationic surfactant (CTAB) notably increased GO stability and mobility, GO ripening happened due to their concurrent aggregation and transport in the columns. GO particles were more mobile at a lower temperature probably because the CTAB coating of GO increased with decreasing temperature, leading to stronger electrostatic repulsion. Furthermore, GO retention in the media increased with the increase of NaCl concentration due to the enhanced compression of the electric double layer. In multivalent electrolyte (CaCl₂ or AlCl₃), the presence of CTAB greatly improved GO stability and mobility and no deposition occurred in saturated porous media under all the tested conditions. This is because the CTAB coating of GO diminished the cation bridging effects in both GO-GO and GO-sand systems. Results from extended Derjaguin–Landau–Verwey–Overbeek (XDLVO) theory considering steric repulsion suggest that secondary minimum aggregation and depositions were the main mechanisms of GO retention transport in monovalent electrolyte in saturated porous media.

This study aims to investigate the photocatalytic degradation performance, mechanism, and dynamics of methyl orange (MO) which is a widely used organic dye in textile industries as well a hazardous wastewater pollutant. The degradation process was catalyzed by employing a synthesized Fe₃O₄ magnetic nanoparticle (NP) using the coprecipitation method. The structural and morphological properties of the synthesized Fe₃O₄ NPs were investigated by employing XRD, HR-SEM, and XPS, which proved that acquired Fe₃O₄ NPs were in a pure phase. Moreover, the crystallite sizes fall in the range of 28–31.8 nm and were estimated by applying the Scherrer equation on the XRD spectrum as well as calculated independently by applying a statistical approach on the SEM micrographs. The UV–Vis maximum in the visible range at 468.8 nm consists of two absorption frequency bands due to the effect of the hydrogen-bond interaction between water and the azo nitrogens in the MO. A non-monotonic spectral dynamic accompanied by peak wavelength shifts, as well as the absolute signal amplitude and signal area of the MO band, suggests that a cleavage of the azo bond is not the only and/or the dominant process in the photocatalytic oxidization of the MO in a protic solvent. The overall absorbance process is a complicated response to a combination of nonspecific and specific solute-solvent interactions, dipole-dipole interactions, hydrogen-bonding networks, and other possible intermolecular interactions such as hydrophobic/hydrophilic interactions. A bi-exponential decay was found to be the best fitting function to model the decay of the time-dependent electrical conductivity of the MO aqueous solution under photocatalytic oxidization. The Fe₃O₄ NPs exhibited a 98.3% removal of MO within 110 min. Photocatalytic degradation of methyl orange can be modeled to the first-order model with a rate constant k of 0.037 min⁻¹ taking into account the initial concentration of 1175 ppm of MO. The degradation/decolorization efficiency deduced from the low-frequency band of the visible spectra is around 99.4% after 110 min. The real-time degradation/decolorization efficiencies deduced from the overall absorbance maxima and the low-frequency band have a discrepancy of 50.1% at 20 min and 12.3% at 60 min representing the progressive attenuation of the H-bond impact dissociation of MO (degradation/decolorization).

Bisphenol A (BPA) and phthalates are endocrine disruptors that can induce oxidative stress. Serum bilirubin has antioxidant properties and may serve as a biomarker of oxidative stress. The objective of this study was to explore the relationship of BPA and phthalates with serum bilirubin levels in a Korean population. Urinary concentrations of BPA and six phthalate [mono-n-butyl phthalate (MnBP), mono-iso-butyl phthalate (MiBP), mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP), mono-(2-ethyl-5- hydroxyhexyl) phthalate (MEHHP), mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP), and mono-benzyl phthalate (MBzP)] were measured in 709 participants. Serum concentrations of BPA and three phthalate metabolites [MnBP, MiBP, and mono-(2-ethylhexyl) phthalate (MEHP)] were measured in 752 participants. After excluding missing variables, associations between above chemicals and serum bilirubin levels were analyzed using multivariate linear regression with age, sex, BMI, GGT, GOT, GPT, and alcohol intake adjustment. Participants were further stratified by sex. Among the urinary chemicals, BPA and four phthalate metabolites (MnBP, MEOHP, MEHHP and MECPP) were inversely associated with serum bilirubin levels (BPA: β = − 0.071, P < 0.0001; MnBP: β = − 0.055, P = 0.025; MEOHP: β = − 0.101, P < 0.0001; MEHHP: β = − 0.106, P < 0.0001; MECPP: β = − 0.052, P = 0.003). In a case of serum chemicals, only MiBP showed significantly positive association (β = 0.036, P = 0.016). After stratification by sex, the associations of urinary BPA remained both in male and female, of which urinary phthalates disappeared in female. The association of serum MiBP was disappeared after stratification. Urinary BPA and phthalate metabolites were inversely associated with serum bilirubin levels, whereas serum MiBP showed positive association with bilirubin. These results could provide clues for understanding the mechanisms of endocrine disruptor from oxidative stress to excretion from our body.

Nail polish has been widely used around the world. However, the hazards of nail polishes discarded in the environment are still poorly investigated. Thus, the toxicogenetic effects of solubilized (SE) and leached (LE) extracts from nail polishes were investigated, simulating their disposal on water and landfill, respectively, and identifying their physicochemical properties and chemical constituents. Organic compounds and metals were detected in both extracts. SE and LE only induced mutagenic effects in TA98 Salmonella strain in the presence and absence of exogenous metabolic activation. Although both extracts did not significantly increase the frequency of micronucleated HepG2 cells, the cell viability was affected by 24-h exposure. No DNA damage was observed in gonad fish cells (RTG-2) exposed to both extracts; however, the highest SE and LE concentrations induced significant lethal and sublethal effects on zebrafish early-life stages during 96-h exposure. Based on our findings, it can be concluded that if nail polishes enter aquatic systems, it may cause negative impacts to the environment.

The objective of this study was to investigate whether δ¹³C values can be used to identify pollen specie in the atmosphere. A Burkard 7-day recording volumetric spore trap was used to collected pollens in the atmosphere in Tainan City, Taiwan, from January 2 to December 28, 2006, and a light microscope was used to identify the pollen species and concentrations. A Burkard cyclone sampler was used to collect particulate matter and an elemental analyzer with an isotope ratio mass spectrometer was used to analyze the δ¹³C values. Our data showed that the predominate pollen specie in the atmosphere was Broussonetia papyrifera pollen and that the annual average concentration was 27 grains/m³ (pollen season, 36; nonpollen season, 9 grains/m³). The average δ¹³C value was − 26.19‰ for particulate matter in the atmosphere (pollen season, − 26.00‰; nonpollen season, − 26.28‰). No significant association was observed between δ¹³C values and Broussonetia papyrifera pollen concentrations. However, the δ¹³C value in the atmosphere was associated with the levels of Broussonetia papyrifera pollen among the samples with a diameter of particulate matter smaller than 10 μm at a level lower than 40 μg/m³. In addition, the relative contribution of Broussonetia papyrifera pollen to the carbon in the atmosphere using a two end-member mixing models was found to be associated with the Broussonetia papyrifera pollen concentration. In summary, our study suggested that δ¹³C values can be applied in the assessment of Broussonetia papyrifera pollen specie under specific conditions in the atmosphere.

In this study, a sensitive and low-cost multi-wavelength spectrophotometric method for the determination of hydrogen peroxide (H₂O₂) in water was established. The method was based on the oxidative coloration of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) via Fenton reaction, which resulted in the formation of green radical (ABTS•⁺) with absorbance at four different wavelengths (i.e., 415 nm, 650 nm, 732 nm, and 820 nm). Under the optimized conditions (CABTS = 2.0 mM, CFₑ²⁺ = 1.0 mM, pH = 2.60 ± 0.02, and reaction time (t) = 1 min), the absorbance of the generated ABTS•⁺ at 415 nm, 650 nm, 732 nm, and 820 nm were well linear with H₂O₂ concentrations in the range of 0–40 μM (R² > 0.999) and the sensitivities of the proposed Fenton-ABTS method were calculated as 4.19 × 10⁴ M–¹ cm–¹,1.73 × 10⁴ M–¹ cm–¹, 2.18 × 10⁴ M–¹ cm–¹, and 1.96 × 10⁴ M–¹ cm–¹, respectively. Meanwhile, the detection limits of the Fenton-ABTS method at 415 nm, 650 nm, 732 nm, and 820 nm were respectively calculated to be 0.18 μM, 0.12 μM, 0.10 μM, and 0.11 μM. The absorbance of the generated ABTS•⁺ in ultrapure water, underground water, and reservoir water was quite stable within 30 min. Moreover, the proposed Fenton-ABTS method could be used for monitoring the variations of H₂O₂ concentration during the oxidative decolorization of RhB in alkali-activated H₂O₂ system.

Assessing the potential impacts of nonpoint source (NPS) pollution and proposing sound control strategies are significant global challenges. However, few studies have provided insights into the quantitative risk analysis and efficient management of NPS pollution. This study formulated four evaluation criteria to characterize both the generation and migration of diffuse phosphorus. Multicriteria analysis and the technique for order preference by similarity to ideal solution were combined to develop a NPS pollution risk index model for the evaluation of the potential phosphorus loss at the basin scale. The proposed model is a simple and efficient tool that considers most factors that affect diffuse phosphorus. In the GIS environment, the spatial distribution of the risk index of diffuse phosphorus could be mapped and visualized in the Huai River Basin. With the natural breaks classification method, the study area was divided into the following five regions: a potentially polluted region (3.5%), a lightly polluted region (15.4%), a moderately polluted region (40.7%), a highly polluted region (31.5%), and a seriously polluted region (8.9%). Based on land use composition, geographical location, and sources of diffuse phosphorus of these five regions, corresponding prevention measures were introduced, thus facilitating the management of NPS pollution for policy makers.

Fifty biological sand filters (BSFs) housed in 70-L plastic containers were built and installed in the West Pokot County of Kenya. Half of the BSFs were installed in June 2010; the remainder were installed in June 2012. BSF performance was analyzed during June 2012 and 2015. Performance indicators included the removal of turbidity and fecal and total coliforms. In 2012, 17 of the original 25 BSFs installed were operational, and their performance was evaluated. In 2015, 15 of the BSFs were operational. BSF performance during 2015 showed an average fecal coliform removal of 98.9%. The most common reasons provided to explain why the BSF installed was no longer in use included the family moved and the BSF was too heavy to carry, and the effluent pipe broke. Relative affluence was observed using the Progress out of Poverty Index (PPI)™. With an increase in elevation, we noted a decrease in PPI. The average PPI for homesteads with operation BSFs was 10 points higher than homes where the BSFs were in disrepair. An assay to estimate Escherichia coli presence and concentration was modified, and the results were compared with more traditional field enumeration methods. The field assay used a five-compartment bag to quantify the most probable number (MPN) of E. coli to provide a low-tech option to field workers in developing country to test the viability of drinking water sources. We used a Hach medium, varying from that prescribed by Aquagenx. Results from using the modified method compared well with the more traditional field assay.

Soil washing is an effective technology for the remediation of soils contaminated with various metals. However, the bioavailability of residual metals in soils and soil properties can be changed during the washing processes. In this study, we used four amendments to revitalize mixed chelator (MC)–washed soils (WS). These amendments included zeolite, CaCO₃, biochar, and chicken manure. Results showed that inorganic amendments reduced the available Cd and Zn concentrations, while organic amendments, particularly chicken manure, reduced the Pb bioavailability in WS. The combination of 0.2% CaCO₃ and 2% chicken manure amendments reduced the Cd, Pb, and Zn bioavailability by 45.8%, 77.8%, and 15.0% compared with the control treatment, respectively. The inorganic amendments should increase the seed germination rate of Chinese cabbage (Brassica rapa L.). However, the shoot growth decreased significantly. The combination of amendments cannot increase the seed germination but can significantly increase the shoot growth of Chinese cabbage compared with the control. The combination of amendments enhanced the fertility of WS, particularly available P and exchangeable K, which may improve plant growth. These results suggested that the combination of amendments, especially CaCO₃ (0.2%) and chicken manure (2%), can be used to revitalize MC-WS.