The adsorption of ethyl acetate, a volatile organic compound, on activated carbons, synthesized from various precursors based on by-products and waste materials—polymer, biomass, coal tar pitch—was studied. The activated carbons were prepared by thermochemical treatment of the precursors, carbonization, and subsequent activation with water vapor. Surface and textural properties of obtained carbon adsorbents were characterized by low-temperature N₂ adsorption, Boehm’s method, etc. The activated carbons are distinguished by relatively high surface area and developed pore structure. The adsorption investigations were performed with water solutions of ethyl acetate, and the obtained results fit well the Langmuir model, as well as the Freundlich model. All activated carbons demonstrated considerably high adsorption capacity in the range 160–450 mg/g. The obtained data indicate that the adsorption ability of activated carbon toward ethyl acetate depends on the surface area, and it increases with increasing the content of mesopores, where ethyl acetate molecules are preferably adsorbed.

Seven full-scale wastewater treatment plants were investigated to highlight the effectiveness of each treatment stage on removing Escherichia coli. The primary sedimentation achieved an average E. coli removal efficiency of 30.5% which was much lower than the suspended solids (58%), thus, revealing the absence of a linear relationship between the two parameters. Biological processes proved to be very important in the removal of E. coli through adsorption inside the sludge flocs and complex decay (mortality). In biological processes with a long retention time, such as activated sludge denitrification-nitrification, the decay was very important, whereas in the more traditional activated sludge process, without nitrification, the contribution of adsorption and mortality was quite balanced. Overall, the mechanical-biological treatment achieved a removal efficiency of 91.8–96.5% depending on the process. Additional removal can be achieved by disinfection. The effectiveness of E. coli removal with sodium hypochlorite was strictly depended on the product of residual chlorine (C R) with the contact time (t). The experimental curve fitted the Collins model well, with a standard deviation of less than 7%.

A new procedure for the determination of chromium species in polluted environmental samples by flame atomic absorption spectrometry was developed in this work. A new material containing 1,5-diphenylcarbazone included in a polymeric matrix was prepared and employed as a solid-phase extraction material for selective separation of Cr(III) ions under dynamic conditions. Chromium(III) ions were retained on this sorbent with high efficiency and repeatability (95 %, RSD = 1 %) from solutions with pH 9.0. The quantitative recovery of analyte was obtained with 0.1 mol L⁻¹ EDTA. The concentration of Cr(VI) ions was calculated from the difference between the concentration of total chromium and Cr(III) ions. The prepared sorbent exhibits good chemical and mechanical stability, sorption capacity and selectivity towards Cr(III) ions in the presence of Cu(II), Ni(II), Mn(II) and Ca(II) ions. The accuracy of the separation method was proved by analysis of reference material of wastewater RES 10.2. The developed procedure was applied for chromium speciation analysis in municipal sewage samples.

Along the southeastern coast of Costa Rica, a variety of pesticides are intensively applied to produce export-quality plantains and bananas. In this region, and in other agricultural areas, fish kills are often documented by local residents and/or in the national news. This study examines principal exposure pathways, measured environmental concentrations, and selected toxicity thresholds of the three most prevalent pesticides (chlorpyrifos, terbufos, and difenoconazole) to construct a deterministic risk assessment for fish mortality. Comparisons of observed pesticide concentrations, along with estimated biological effects and observations during actual fish kills, highlight gaps in knowledge in correlating pesticide environmental concentration and toxicity in tropical environments. Observations of fish kill events and measured pesticide concentrations in the field, along with other water quality indicators, suggest that a number of environmental conditions can interact to cause fish mortality and that current species toxicity datasets may not be applicable for estimating toxicological or other synergistic effects, especially in tropical environments.

Cr(VI) adsorption onto a novel fibrous ethylenediamine-functionalized polyethylene/polypropylene (PE/PP-g-PGMA-EDA) nonwoven fabric was investigated in aqueous solutions. The ethylenediamine functionalities were immobilized on the PE/PP nonwoven fabric through the epoxy groups of poly(glycidyl methacrylate) (PGMA) grafted to the fibers via radiation-induced emulsion graft polymerization in aqueous solution. Optimum conditions for grafting and subsequent modification steps were determined. The adsorbents were characterized by FTIR, XPS, and SEM techniques. Cr(VI) adsorption was studied in batch mode as a function of pH, feed concentration, contact time, ionic strength, and coexisting anions. The nonwoven adsorbent exhibited efficient, rapid Cr(VI) removal; high adsorption capacity; and insignificant interference from coexisting ions. Adsorbed Cr(VI) ions were desorbed using 2 M HNO₃ solution, and the adsorption capacity of the nonwoven fabric was retained for four adsorption–desorption cycles. The data for Cr(VI) adsorption on the nonwoven fabric fitted to the Langmuir isotherm model well. The maximum adsorption capacity for the Langmuir isotherm was 178.9 mg Cr(VI)/g polymer at pH 3.00. Graphical Abstract ᅟ

Catalytic destruction of PCDD/Fs (polychlorinated dibenzo-p-dioxins and furans) over V₂O₅-CeO₂/TiO₂ catalyst was investigated at a low temperature range of 140–180 °C, in the absence and presence of ozone (200 ppm). Nano-TiO₂ support was used to prepare the catalyst by step impregnation method. A stable PCDD/Fs-generating system was established to support the catalytic destruction tests. In the presence of ozone alone, destruction efficiencies of PCDD/Fs are between 32.2 and 43.1 % with temperature increasing from 140 to 180 °C. The activity of V₂O₅-CeO₂/TiO₂ catalyst alone on PCDD/Fs destruction is also studied. The increase of temperature from 140 to 180 °C enhances the activity of catalyst with destruction efficiencies increasing from 54.7 to 73.4 %. However, ozone addition greatly enhances the catalytic activity of V₂O₅-CeO₂/TiO₂ catalyst on PCDD/Fs decomposition. At 180 °C, the destruction efficiency of PCDD/Fs achieved with V₂O₅-CeO₂/TiO₂ catalyst and ozone is above 86.0 %. It indicates that the combined use of ozone and catalyst reduces the reaction temperature of PCDD/Fs oxidation and offers a new method to destroy PCDD/Fs with high destruction efficiency at a low temperature. Furthermore, the destruction efficiencies of 17 toxic PCDD/F congeners, achieved with ozone alone, catalyst alone, and catalyst/ozone are analyzed.

The drastic desiccation of the Aral Sea has led to severe desertification of the former lake areas. Dust storms occur frequently, causing regional environmental degradation of the Aral basin and a serious ecological disaster. Knowledge of the temporal variability in dust emissions and the potential diffusion characteristics of dust aerosol originating from the Aral Sea basin in recent years are, however, lacking. To address this knowledge gap, we studied the interannual and intraannual changes in dust aerosol from the Aral Sea basin and its potentially seasonal diffusion characteristics from 2005 to 2013 using Ozone Monitoring Instrument (OMI) aerosol data (2005–2013) and the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model. Results show that the OMI aerosol index (AI) annual mean, standard deviation, median, and maximum values exhibit a strong increasing trend because of the continuous decrease in the water level since 2005. The annually mean OMI AI increases to 1.47 by 2013. Peak AI values are recorded in spring (March–May) and early winter (November–January of the following year), indicating notifying seasonal differences. The potential distance and height of air parcel trajectories to the northeast are greater than those to the west and south, whereas the air parcel trajectory proportion of the former is lower than that of the latter. The potential transport distance of dust aerosol to the northeast is greatest in spring and winter. This transport distance is less in autumn, with the minimum observed in summer. Dust transport distance to the west and south in different seasons is not significantly different. The present results may help in further understanding the emission, long-range transport, and deposition of dust from the dry lake bed of the Aral Sea as well as providing a motivation for the sensible use and protection of these tail-end lakes.

Soil–air partitioning is an important diffusive process affecting the environmental fate of organic compounds. In this study, the soil–air partition coefficients (K SA) for dichloro-diphenyl-trichloroethane and its metabolites (designated as DDTs, the sum of p, p′- and o, p′-isomers of DDT, DDD, and DDE) over a temperature range from 5 to 50 °C in artificial solid media were determined by a solid–fugacity meter. The results showed that log K SA gradually increased with soil organic carbon content (f OC). A reversed relationship was observed between log K SA values and the environmental temperatures (T). The enthalpy changes (ΔH SA) indicated that o, p′-isomers required more energy to release from artificial solid media to the gas phase. Moreover, with increasing temperature, the slope of the regression line of log K SA vs. log K OA (octanol–air partition coefficient) was approaching to 1. Based on factors influencing soil–air partitioning and the experimental data, a multiple parameter (T, f OC, and K OA) model was used to predict the K SA values for DDTs.

In this study, the water quality of the Marreco River in the municipality of Toledo, PR, Brazil was investigated as part of a monitoring program. Conventional water pollution parameters (pH, turbidity, conductivity, COD, DO, ammonia, and total phosphorus) and metal elements were analyzed. Acute toxicity bioassays were conducted by the bacterial bioluminescence method, using the indicator Vibrio fischeri to evaluate the toxic effect of the contaminants. Principal components analysis (PCA) and Pearson’s correlation were applied to assess the statistical correlation between the physicochemical parameters and metals in the water samples. There is strong evidence, supported by Pearson and PCA analyses, of the presence of elevated levels of K and Ca associated with anthropogenic activities installed in the river basin.

Triclosan (TCS) is an antimicrobial agent that is extensively used in personal care products (PCPs), and its residue is frequently reported in aquatic environments. In this study, we investigated the reaction behavior of TCS during enzyme-catalyzed oxidative coupling reactions (ECOCRs) by laccase from Pleurotus ostreatus and determined how the presence of natural organic matter (NOM) influenced the formation of the products. Results indicated that the optimum pH for TCS transformation was 6.0 in laccase-mediated ECOCRs. At pH values below 5.0 and above 7.0, the pseudo first-order kinetic rate constants (k) of TCS transformation declined significantly. Moreover, the k values of TCS transformation increased as the laccase activity increased (0.1179–0.5757 h⁻¹). A total of four product peaks were generated, and they were more hydrophobic than TCS. High-resolution mass spectrometry (HRMS) analysis indicated that these products could be the oligomers resulting from TCS self-coupling reactions. The relative peak areas of these oligomers displayed strong linear correlations with the different initial TCS concentrations, and the saturation point of laccase (3.0 U mL⁻¹), when the binding with TCS was 40 μmol L⁻¹. In the presence of NOM (i.e., humates and fulvates), humates in particular strongly inhibited TCS transformation and lowered the extent of its self-coupling, which likely resulted from the cross-coupling between TCS and NOM. Our study improves a better understanding of the reaction behavior of TCS in the natural aquatic environment during laccase-mediated ECOCRs.