Soil components from different environments (forest (OF), semiarid (SZ), and sand (AS)) were separated from fulvic and humic substances, characterized by DRX, EDS(SEM), and zero-charge points were determined. The sorption of U(VI) by these materials was determined considering contact time, concentration of U(VI), pH, ionic strength, and presence of sodium chloride and humic acids. The time to reach the kinetic sorption equilibrium was ca. 1 min for the components of the SZ and AS soils, whereas those from OF required longer times. The zero-charge points of the materials indicate that in the experimental conditions, the surfaces of the materials are positively charged, as are uranyl ions. The sorption kinetic data were well fitted to the pseudo-second-order model, which indicates chemical sorption. The maximum sorption capacities for U(VI) obtained from data fitted to the Langmuir model of OF and SZ were 49 and 19.8 mg g⁻¹ respectively. Sorption isotherm data for AS were best fitted to the Freundlich model (qₑ = 5.4 mg g⁻¹). The maximum values of distribution coefficients (Kd) were 23 ± 7 L kg⁻¹, 545 ± 64 L kg⁻¹, and 1178 ± 229 L kg⁻¹ for AS, SZ, and OF, respectively; these values may depend on pH, contact time, initial concentration of U(VI), and the composition of the materials. Sodium chloride in the aqueous solutions affects U(VI) sorption by the materials SZ and AS. The effect of humic acids depends on pH, only in acid media soluble humate complexes may be formed.

Pyrogenic materials produced from various input materials and with valuable characteristics such as high porosity, extensive surface area, and mineral composition represent alternative to traditional carbon-based materials in area of contaminant immobilization, aqueous solutions purification, and soil remediation. Intensification of industry and technological processes brings increased use of lanthanides and thus potential risk of lanthanide penetration into soil and aquatic systems. This study examined the roles of three different pyrogenic materials: microcrystalline cellulose-derived pyrogenic materials (MCPM), organic cotton-derived pyrogenic material (OCPM), and sewage sludge-derived pyrogenic material (SSPM) produced in the process of slow pyrolysis at 430 °C in N₂ atmosphere as potential Eu immobilization and sorption materials. Produced materials were characterized by determination of wide range physicochemical properties via elemental analysis, SEM, FT-IR, and sorption potential for Eu in batch sorption experiments. The obtained data confirmed that sorption separation of Eu by OCPM, MCPM, and SSPM from aqueous solution is relatively rapid process with reached equilibrium at 24 h. Batch equilibrium experiments revealed maximum sorption capacities 0.602 mg g⁻¹ for MCPM, 1.761 mg g⁻¹ for OCPM, and 2.586 mg g⁻¹ for SSPM. The presence of co-ions such as Al in system reduced sorption potential about more than 50% for all three studied materials. Column leaching test with artificially contaminated soil and 5% (w/w) amendments of pyrogenic materials showed significant retention ability of MCPM, OCPM, and SSPM for mobile Eu forms compared to control soil. Pyrolysis production of pyrogenic materials and their applications as an effective immobilization and separation tools for wide range of xenobiotics can be innovative method in environmental management and waste assessment.

It is well-established that aquatic wildlife is exposed to natural and synthetic endocrine disrupting compounds which are able to interfere with the hormonal system. Although advanced oxidation processes (AOPs) have shown to be effective, their application is limited by a relatively high operational cost. In order to reduce the cost of energy consumed in the AOPs, widely available solar energy instead of UV light may be applied either as photocatalytic oxidation or as photosensitized oxidation. The main goal of the present study was to investigate the sunlight photodegradation of paraben mixture. Two processes, namely the photocatalytic oxidation with modified TiO₂ nanoparticles and photosensitized oxidation with photosensitive chitosan beads, were applied. The oxidants were identified as singlet oxygen and hydroxyl radicals for photosensitized and photocatalytic oxidation, respectively. The toxicity, as well as ability to water disinfection of both processes under natural sunlight, has been investigated. Application of sunlight for the processes led to degradation of parabens. The efficiency of both processes was comparable. Despite the fact that singlet oxygen is weaker oxidant than hydroxyl radicals, the photosensitized oxidation seems to be more promising for wastewater purification, due to the possibility of chitosan bead reuse and more effective water disinfection. Graphical Abstract ᅟ

The relationship between land use and microbial community structure at seven sites along the Lower Mekong River, between Thailand and the Loa People’s Democratic Republic, was investigated using Illumina next-generation sequencing of the V5–V6 hypervariable regions of the 16S rRNA gene. In total, 14,470 operational taxonomic units (OTUs) were observed. Community composition was significantly different between sampling years. Moraxellaceae and Comamonadaceae were the predominant bacterial families in upstream sites, which included agricultural and urban areas in the Loei and Nong Khai provinces of Thailand. Members of the family Comamonadaceae were prevalent in agricultural and urban sites in Bueng Kan Province, while Moraxellaceae and Burkholderiaceae were the major families in a site downstream of an urban area in the Nakhon Phanom Province of Thailand. The bacterial community observed from a forested area of Patam National Park in Thailand showed greatest diversity, and several major bacterial families including Comamonadaceae, Moraxellaceae, and Pseudomonadaceae were more dominant than other sites. The diversity of fecal indicator bacteria, determined by ERIC-PCR DNA fingerprinting, indicated the presence of 29 strains of Escherichia coli and 21 strains of Enterococcus, while TP-RAPD patterns represented six species of Enterococcus. Results of this study indicated that although the difference in the distribution of bacterial phyla and families was found among sampling sites, the bacterial community composition, based on the presence of OTUs, continuously retained its signature across approximately 758 km along the Lower Mekong River, regardless of the type of land use. Water parameters, including temperature, turbidity, DO, and air temperature, also differentially affected the abundance of bacterial families along the Mekong River.

Eleven indigenous arsenic-tolerant fungi were isolated from arsenic-contaminated mine tailing and identified by molecular biology methods. Among them, Aspergillus oryzae (denoted as A. oryzae TLWK-09) had high tolerance and bioaccumulation of As(V). The maximum tolerance to As(V) concentration of A. oryzae TLWK-09 reached 5000 mg/L. As(V) bioaccumulation on A. oryzae TLWK-09 in the aqueous system was investigated under different environmental conditions such as mycelia dosage, contact time, pH, and ionic strength. Bioaccumulation data of As(V) were fitted to Langmuir model, and the maximum uptake capacity of A. oryzae TLWK-09 for As(V) was 54.12 mg/g at 301 K. The morphological structures of mycelia changed obviously under As(V) stress by scanning electron microscope (SEM) and transmission electron microscope (TEM) analysis. The analysis of Fourier transform infrared spectroscopy (FTIR) indicated the presence of carboxyl, hydroxyl, and amino groups on the fungal mycelia, which showed that these groups accounted for As(V) bioaccumulation. These results suggested that A. oryzae TLWK-09 could be an efficient and promising bioremediation material for As(V) pollution.

Gold mining operations in the northern Black Hills of South Dakota resulted in the discharge of arsenopyrite-bearing mine tailings into Whitewood Creek from 1876 to 1977. Those tailings were transported further downstream along the Belle Fourche River, the Cheyenne River, and the Missouri River. An estimated 110 million metric tons of tailings remain stored in alluvial deposits of the Belle Fourche and Cheyenne Rivers. Pore-water dialysis samplers were deployed in the channel and backwaters of the Belle Fourche and Cheyenne Rivers to determine temporal and seasonal changes in the geochemistry of groundwater in alluvial sediments. Alluvial sediment adjacent to the dialysis samplers were cored for geochemical analysis. In comparison to US Environmental Protection Agency drinking water standards and reference concentrations of alluvial sediment not containing mine tailings, the Belle Fourche River sites had elevated concentrations of arsenic in pore water (2570 μg/L compared to 10 μg/L) and sediment (1010 ppm compared to < 34 ppm), respectively. Pore water arsenic concentration was affected by dissolution of iron oxyhydroxides under reducing conditions. Sequential extraction of iron and arsenic from sediment cores indicates that substantial quantities of soluble metals were present. Dissolution of arsenic sorbed to alluvial sediment particles appears to be affected by changing groundwater levels that cause shifts in redox conditions. Bioreductive processes did not appear to be a substantial transport pathway but could affect speciation of arsenic, especially at the Cheyenne River sampling sites where microbial activity was determined to be greater than at Belle Fourche sampling sites.

The commercial resin Dowex Optipore L-493 was evaluated for the removal of the trihalomethanes (THMs) from water. Adsorption amounts were in the order CHBr₃ ≈ CHBr₂Cl > CHBrCl₂ > CHCl₃, insensitive to pH in the range 3.0–7.0, but decreased at pH higher values. They were little affected by the presence of co-existing anions and humic acid, and environmental impurities in a spiked natural water sample were only slightly lower than those obtained with pure water. In a comparison with several other commercial adsorbents, the overall performance of L-493 for adsorption of THMs was comparable with the best of those tested, and superior to IR 120, IRC 748, and powder activated carbon. THM adsorption on L-493 was endothermic, and fitted by the pseudo-second-order kinetic and Langmuir isotherm models; maximum adsorption was 228.6, 247.3, 250.6, and 253.7 μg/g, for CHCl₃, CHBrCl₂, CHBr₂Cl, and CHBr₃, respectively. Charge distributions and dipole moments were calculated for the optimized structures using the hybrid density functional theory (DFT) method. Both hydrophobic effects and electrostatic interactions play important roles in the adsorption process. The L-493 resin was easily regenerated and could be recycled using 0.1 M NaOH, with only a small decrease in its initial adsorption capacities. Overall, this research shows that L-493 is potentially a valuable adsorbent for the removal of THMs during water treatment.

Neutralization is the necessary operation to ensure the Fenton effluent pH. In situ coagulation can be induced during neutralization. In this study, three types of alkaline neutralizers (Ca(OH)₂, NaOH, and Ca(OH)₂ + NaOH) were added into the Fenton oxidized PSE to control the effluent pH of 6 to 9. The coagulation behavior, floc structure, and properties were investigated. The results indicated that the coagulation with the adding of three neutralizers can remove 9.68 to 24.02% of the TOC. Ca(OH)₂ exhibited the highest TOC removal efficiency at the dosage of 0.4 g/L. Charge neutralization ability was in the following order: Ca(OH)₂ > Ca(OH)₂ + NaOH > NaOH. Ca(OH)₂ and Ca(OH)₂ + NaOH showed the increase of floc growth rate with the increase of agent dosage, especially for Ca(OH)₂ + NaOH. Moreover, Df of NaOH flocs was higher than that of Ca(OH)₂ and Ca(OH)₂ + NaOH, indicating the floc formed by NaOH was more compact than that of Ca(OH)₂. The main coagulation process of three neutralizers was different, and it was also affected by the agent dosage (or pH). When the dosage was 0.35 g/L (pH 6–7.5), the complexation, adsorption, and bridging were the predominant processes while charge neutralization gradually became the main coagulation process for Ca(OH)₂ and Ca(OH)₂ + NaOH with the increase of dosage (pH 7.5–9).

The ability of the agricultural residue of Phragmites australis to serve as an absorbent material used to remove phenol from aqueous solutions in batch and continuous fixed-bed columns was investigated. Prepared adsorbents were characterized by SEM, FTIR, and pHpzc methods. The equilibrium adsorption (qe) of phenol was increased from 9.61 to 29.40 mg/g when the initial phenol concentrations increased from 50 to 150 mg/L. The max adsorption capacity of Phragmites australis was found to be 29.60 mg/g at 30 °C. In column studies, a higher flow rate, higher initial concentration of phenol, and shorter packing layer height increase the column adsorption capacity of phenol. In a batch and continuous fixed-bed column studies, the experiment data was evaluated by some classic models. Fitting degree between the experimental results shows that the pseudo-second-order adsorption kinetics and Langmuir model were the best. Thomas and Yoon-Nelson models were in good agreement with the experimental breakthrough curve data. Both batch and continuous investigation indicated that Phragmites australis could be used as a fine adsorbent to remove phenol and that the adsorption efficiency improved significantly in the column experiment.

Organic and elemental carbon were measured both in daily PM10 and PM2.5 and in 6 h range time PM2.5 samples collected from September 2015 to October 2015 in a coastal rural site near Brindisi in the Apulia region (Italy), in order to determine factors affecting the carbonaceous aerosol variations. Carbon content (total carbon TC) represented a considerable fraction for both PM10 and PM2.5. In particular, in PM10 samples, organic carbon (OC) varied from 1.06 to 18.32 μg m⁻³ with a mean concentration of 5 ± 4 μg m⁻³ and EC varied from 0.11 to 0.88 μg m⁻³ with a mean value of 0.41 ± 0.19 μg m⁻³. In PM2.5 samples, OC varied from 0.54 to 12.91 μg m⁻³ with a mean concentration of 3.5 ± 2.8 μg m⁻³ and EC varied from 0.11 to 0.85 μg m⁻³ with a mean value of 0.35 ± 0.18 μg m⁻³. The highest values for both parameters were recorded when the air masses were coming from NE Europe and when Saharan Dust events were recognized. The results show that OC and EC exhibited higher concentrations during the night hours, suggesting that stable atmosphere and lower mixing conditions play important roles for the accumulation of air pollutants and promote condensation or adsorption of semivolatile organic compounds. In samples from a Saharan Dust event and in samples with the lowest and the highest OCₛₑc, ATR-FTIR analysis allowed us to identify organic functional groups including the non-acid organic hydroxyl C–OH group (e.g., sugars, anhydrosugars, and polyols), carbonyl C=O group, carboxylic acid COOH group, aromatic and aliphatic unsaturated C=C–H group, aliphatic saturated C–C–H group, and amine NH₂ group. Some inorganic ions were also identified: carbonates, sulfate, silicate, and ammonium. The dusty samples are mainly characterized by the presence of carbonate and hydrogen sulfate ions and by kaolinite (absorption at 914 and 1010 cm⁻¹), while in samples with air masses coming from the NE, OC is mainly characterized by aliphatic and aromatic C–H and O–H and N–H groups (absorptions in the range 3500–2700 cm⁻¹) and by the presence of organonitrate, aromatic amide and amine, and carboxylic acids (absorptions at 1630 and 1770–1700 cm⁻¹). Graphical abstract ᅟ