This study examined the transport behavior of nano zero-valent iron (NZVI) coated with three types of stabilizers (i.e., polyacrylic acid, Tween-20, and starch) in saturated sand- and soil-packed columns under varying geochemical conditions. The cations or ionic strength and humic acid (HA) affected the transport of NZVI in varying degrees for different types of surface-modified NZVI (SM-NZVI). The effects of HA on the transport of SM-NZVI were different in sand- and soil-packed columns. In the sand-packed column, the presence of HA exerted an effect on the particle–particle interaction (i.e., aggregation), resulting in either enhanced or decreased transport of SM-NZVI. However, in the soil-packed column, the HA not only influenced the particle–particle interaction but also exerted an effect on the particle–soil grain interaction (i.e., deposition). Additionally, a significant enhancement in the transport of SM-NZVI in the soil-packed column was observed with increasing particle concentration. Moreover, the adsorption of arsenic on the surface of SM-NZVI exhibited insignificant effect on the transport of SM-NZVI. The release of arsenic from the arsenic-loaded SM-NZVI was detected when subjected to flushing with phosphate-containing groundwater. This fundamental understanding of the subsurface transport of SM-NZVI is of critical importance for the benign use and risk management of SM-NZVI.

The ultimate goal of our study is to establish thin-layer chromatography (TLC) as a quick and simple method for identifying the type of refined petroleum products present in the environmental media. As a preliminary step, TLC chromatograms of different petroleum products, including gasoline, kerosene, and diesel, were characterized and compared. Methanol was determined as the optimum carrier solution in TLC analysis. The spherical-shaped TLC chromatogram of gasoline showed the longest migration distance, and thus the highest retardation factor (Rf) of 0.91. This was followed by that of kerosene (0.63) with an elliptical-shaped, and diesel (0.24) with an elongated trapezoid-shaped chromatogram. Rfof kerosene and diesel increased with the dilution factor, while gasoline showed a constant value. Additionally, it was observed that the TLC chromatograms of oils produced the same peak pattern with the corresponding petroleum products in gas chromatography (GC). A mixed sample of kerosene and diesel presented a triangular shaped chromatogram, underlining the need to consider the shape of chromatogram in addition to the Rfvalue, as an indicator of the petroleum type. The findings indicate that TLC has a huge potential to be used as a quick and reliable method for identifying the type of refined petroleum products in the environmental media.

Recent evidence suggests that microplastic pollution is widespread in every oceanic basin; however, there is limited data available for the tropical South Atlantic Ocean. The purpose of this study was to examine the distribution, density and characteristics of plastic particles in plankton samples collected in the western tropical Atlantic Ocean. Neustonic tows (N = 160) were conducted near three important insular environments (Fernando de Noronha, Abrolhos and Trindade), and the presence of microplastics in the ocean surface of these areas was confirmed for the first time. The collected microplastic particles included hard plastic fragments, plastic films, paint chips and fibres and strands, which were classified as a secondary source of microplastics. The stock of plastic originates from both land-based and marine-based sources. This type of marine pollution in the tropical Atlantic Ocean is a potential threat to important ecological species.

To biocontrol algal bloom, a novel algicidal bacterium, Enterobacter sp. NP23, was isolated. This strain has an effective algicidal activity against Chlorella vulgari, Microcystis aeruginosa, Scenedesmus, and Chlorella pyrenoidosa. Meanwhile, the growth factors were assayed to obtain a high cell density of strain NP23. As a result, three growth factors (i.e., KNO₃0.6 %, MnSO₄·H₂O 0.001 %, and K₂HPO₄0.3 %) were determined as the critical roles in enhancing the cell density of 10¹³ CFU/mL. Moreover, algicidal activity assays revealed that strain NP23 exhibited high algicidal activities against M. aeruginosa and Scenedesmus. These results indicate that this wild-type strain would provide a new member for biocontrolling microalgal and cyanobacterial populations in eco-technology.

Ciprofloxacin, griseofulvin, and rifampicin are three human antibiotics that are also widely used in the shrimp culture of Cangio coastal wetland (Vietnam, 10° 24’ 38” N, 106° 57’ 17” E). They have been detected in shrimp larvae pond and receiving water bodies. However, the environmental fate of these antibiotics in coastal wetland milieu is currently unknown. The aim of this study was to determine the degradation potential of these antibiotics in water and sediments from Cangio coastal wetlands. The effects of light, microbial activities, and presence of sediments on the degradation of all three antibiotics were investigated in “water-only” and “water–sediment” experiments. Results indicate that the environmental fate of those antibiotics was quite complex. Photodegradation seemed to play a major role in “water-only” system, since shorter t ₁/₂ was observed for ciprofloxacin, griseofulvin, and rifampicin, with light than in the dark, for both sterile and non-sterile conditions. Biodegradation played a minor role in the disappearance of the antibiotics and was overlaid by photodegradation. In addition, sorption to sediment was of major importance for antibiotics, especially for ciprofloxacin and rifampicin. The t ₁/₂ of these antibiotics in aqueous phase of “water–sediment” system was higher than for “water-only” experiments, indicating that a part of antibiotics were adsorbed by sediment. The biodegradation did not play a major role on sediment sorption of CIP and RIF, since no statistically significant differences between non-sterile and sterile conditions were observed. Only for GRI, the impact of the biodegradation to the sediment sorption could be found and led to the weak affinity to sediment sorption of this antibiotic. All three antibiotics were more sensitive to photodegradation than to biodegradation; however, the degradation rate was low. In addition, the sorption by sediment occurred also with a slow rate, so these antibiotics could recalcitrant persist in the coastal wetland environment.

Development and utilization of low-cost and effective adsorbents for the adsorption processes is a research focus in recent years. In this work, the porous and flexible film was prepared without any pretreatment from the feather keratin deposits produced during the extraction of soluble keratin from chicken feathers. Characteristics of the prepared biosorbent were investigated using thermogravimetric apparatus, X-ray diffraction, Fourier transform infrared, and scanning electron microscopy. Batch adsorption assays were carried out to remove methylene blue (MB) from aqueous solution. The results showed that the extent of MB adsorption on the biosorbent increased with an increase in initial dye concentration, contact time, solution pH, and biosorbent dosage. The equilibrium data were best described by Langmuir isotherm than other isotherm models. The maximum monolayer adsorption uptake was 156.5 mg/g at pH 7 for an initial dye concentration of 200 mg/l. Kinetic studies indicated that the adsorption process of MB followed pseudo-second-order kinetics. Nevertheless, the intra-particle diffusion model confirmed that the adsorption of MB was a two-step process: a rapid surface adsorption followed by intra-particle diffusion. Thermodynamic parameters such as ΔG°, ΔH°, and ΔS° were calculated, indicating that the adsorption process was spontaneous and endothermic.

Nuisance odors generation from waste and wastewater treatment plants are a cause of public discomfort and complaints. This situation impairs the air quality and represents a growing social and public health problem, especially in developing countries. Several modeling approaches have been developed and successfully implemented in the frame of a wastewater treatment plant for both the biological treatment and physicochemical processes. The mathematical modeling of the odor generation process is still considered a quite complex issue, mainly due to the fact that olfactory nuisance can be caused by many different chemical compounds and the perception of odors is influenced by subjective thresholds. Moreover, the impact of odor sources on air quality is highly conditioned by complex atmospheric dispersion processes. This review presents a critical state-of-art and assessment where information related to odor emissions impact studies as well as modeling applications are compiled and discussed.

The objective of this study was to investigate the effect of chloride ions (Cl⁻) on Cu²⁺adsorption to carbon nanotubes (CNT). The isotherms showed a significant decrease in adsorption capacity on F-400, pristine, and acid-functionalized CNT in the presence of Cl⁻, but had little effect on alcohol-functionalized CNT. Several inductively coupled plasma (ICP) analyses measured the impurities concentration of (1) aqueous-phase isotherm solute, (2) as-received, and (3) acid-washed CNT solutions. Chemical-equilibrium-modeling software MINEQL⁺calculations were applied to compare ICP results to complexes formation. The model suggested that some solid-phase residual-catalytic metals, such as Cr²⁺, after released in water from as-received CNT, formed aqueous-phase complexes and were readsorbed. The 18-metal ICP results were more than two orders of magnitude lower (<4 μM/g-adsorbent) than the lowest isotherm Cu²⁺concentration (157 μM) without significant impact on the isotherm results. The reduced adsorptive capacity of acid-functionalized CNT was related to the mechanisms of water molecule displacement followed by deprotonation during Cu²⁺sorption in the CNT-surface hydration layer and its interaction with other species, generating different ion exchange forces. Brunauer–Emmett–Teller and pore-distribution measurements defined bulk water structure within CNT bundles. Zeta-charge and pHpzc measurements compared as-received and hybrid-CNT indicating copper chemisorption. Functionalized CNT remained negatively charged above pH 2.7, suggesting consistent adsorptive capacity at pH > 5.1, when less Cu²⁺ions are present in solution. scanning electron microscopy–energy dispersive X-ray spectroscopy analysis showed impurities on as-received F-400 and positively charged surface at pH 5.1 (pHpzc 7.1) explaining possible electrostatic attraction of Cl⁻ions, blocking adsorptive sites, reducing its adsorptive capacity for Cu²⁺.

Aquatic weed Myriophyllum spicatum L. is one of the most invasive water plants known. In many countries, it is usually harvested and landfilled, where aerobic and anaerobic decomposition takes place. In this research, the kinetic, equilibrium, and desorption studies of biosorption of Pb(II), Cu(II), Cd(II), Ni(II), and Zn(II) ions onto compost of M. spicatum were investigated in batch experiments. Biosorbent was characterized by scaning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). SEM analysis showed that ion exchange between divalent cations Ca(II) and selected metals takes place. The results of FTIR exposed that carbonyl, carboxyl, hydroxyl, and phenyl groups are main binding sites for those heavy metal ions. The rate of adsorption of the five heavy metals was fast, which achieved equilibrium in 40 min, and followed the pseudo-second-order model well. Langmuir, Freundlich, and Sips equilibrium adsorption models were studied, and Sips isotherm gave the best fit for experimental data. Desorption by 0.1 M HNO₃did not fully recover the metals sorbed onto the compost, indicating that reusing this material as biosorbent is not possible. Furthermore, the use of spent biosorbent as a soil fertilizer is proposed.

Evaluation of variation in the concentration of heavy metal provides vital information about the spatial behavior of the metals affecting the air quality. In the present study, lichen samples of the species Pyxine subcinerea Stirton were collected in the Rudraprayag valley to investigate the metal profile that bioaccumulated in lichens. Multivariate statistical analysis was carried out to elucidate possible contribution of various sources of pollution including anthropogenic sources on heavy metal profile of lichens. Cluster analysis successfully grouped geogenic and anthropogenic inputs represented by Al and Mn and Cu, Cd, Pb, and Zn, respectively. Principal component analysis also segregated sites based on the origin (major contributors).