Two kinds of palladium-only catalysts loaded mesoporous beta zeolite (Pd/beta) and alumina (Pd/Al₂O₃) have been successfully prepared by the impregnation method and characterized using nitrogen adsorption–desorption, XRD, TEM, H₂-TPR, CO₂-TPD, and XPS. Catalytic activities of the catalysts for methanol oxidation were investigated with CO coexisting. The results showed that the different support determines the metal-support interaction, thus affecting the catalytic behavior. For Pd/beta, the strong basicity and better reductive ability are beneficial for improving the reaction rate of catalytic oxidation for methanol. And the palladium species with a higher oxidation state is responsible for excellent catalytic conversion of methanol and CO resistance. Compared to Pd/Al₂O₃, the T50, T90, and ΔT on Pd/beta catalyst are 145 °C, 160 °C, and 15 °C, respectively, in the case of CO present, which decreased by 45 °C, 91 °C, and 46 °C. So beta zeolite, as a new type of catalyst support material, has a good application prospect to meet the practical needs for emission purification of methanol-gasoline vehicles. Graphical Abstract

Proton adsorption behavior on the surface of Al-substituted goethites as a function of pH and ionic strength was investigated and simulated with the multisite surface complexation (MUSIC) model. In addition, X-ray diffraction, X-ray photoelectron spectroscopy, and field emission scanning electron microscope were used to characterize the crystal structure, chemical composition, micromorphology, and surface properties of the Al-substituted goethite. Al substitution was found to affect the crystal structure and micromorphology of goethite. The morphological differences did not result in significant differences in PZC value but largely affected the surface charge values. Goethite surface charge capacity increased progressively with increasing amount of Al substitution, which was attributed to increases in the density of surface coordinated sites due to the increase in (021)/(110) face ratio. The optimization calculations enabled a satisfactory fitting of the titration data of both pure goethite and Al-substituted goethite, and the MUSIC model facilitated a more specific understanding of the charging behavior of Al-substituted goethite. The singly (≡FeOH⁻⁰.⁵ + ≡AlOH⁻⁰.⁵) and triply coordinated (≡Fe₃O⁻⁰.⁵ + ≡AlFe₂O⁻⁰.⁵) surface groups were most likely responsible for the basic charging behavior of goethite in the pH range of 4–10. All results indicate that the MUSIC model has excellent performance in characterizing Al-substituted goethite, and the model has promising application prospect in other substituted metal (hydr)oxides.

Fruits are the valuable and important components of human diet. Among them, Prunus persica is a rich source of different minerals and dietary fibers. In Pakistan, the total annual production of P. persica is approximately 837,000 tons. In order to enhance agricultural yield and quality, the plant protection agents are employed during fruit production. Ultimately, this in turn leads to the incorporation of pesticide residues in fruits. In present study, an effort has been made for the determination of three selected pesticide residues, i.e., chlorpyrifos (CPF), difenoconazole (DFN), and carbendazim (CRB) in samples of P. persica collected from Swat territory. Samples were analyzed through high performance liquid chromatography (HPLC). Results revealed the occurrence of all three pesticides in studied samples; however, levels of CPF and DFN were found to be higher than MRLs. Moreover, the effects of different mitigation techniques revealed that highest reduction of CPF, DFN, and CRB (86%, 97%, 89%) residues was obtained by treatment with 10% CH₃COOH followed by 10% NaCl (74%, 78%, 84%). The lowest reduction was obtained by treatment with 10% solution of NaOH (52%, 55%, 63%).

Leachate generation is one of the problems present in the landfills and dumps, needing monitoring and quantification for the environmental conservation. The objective of this paper is to evaluate temporal data of leachate contamination in a municipal solid waste (MSW) landfill, located in the midwest of São Paulo state, Brazil. The physical-chemical parameters and chemical compounds of the local groundwater were evaluated during 13 years (2002 to 2015). The methodology included data processing and temporal behavior analysis by Mann-Kendall test. Physical-chemical parameters demonstrated a change from acid to basic medium and decrease of BOD, COD, and TOC concentrations. Chemical compounds demonstrated high concentrations close to the administration building of the landfill, despite the decrease of certain compounds (Al, Fe, Hg, K, Na, Pb, SO₄²⁻, total PO₄³⁻, Zn) over time in the entire landfill area. The results demonstrate that the landfill is in natural attenuation process, and the structures of the surrounding landscape and the location of the MSW disposal are fundamental to understand the presence and rate of each chemical compound.

Anaerobic digestion (AD) is an effective technology to dispose antibiotic mycelial residues, but biogas production is influenced by hydrolysis rates and antibiotic residue. Herein, the effects of thermal hydrolysis pretreatment for AD of spectinomycin mycelial residues (SMRs) were investigated. The results showed that the removal ratio of spectinomycin was increased while the temperature of pretreatment was escalating. Meanwhile, thermal hydrolysis facilitated the dissolution of organic matters. However, non-biodegradable substances measured by fluorescence excitation–emission matrix accumulated and thus had an adverse influence on biogas production. Based on batch assays, the optimal pretreatment temperature for SMRs was 120 °C. The removal of spectinomycin was benefit for biogas production (increasing by 7.6%), and the overall biogas production increased by 27.6% compared with 289.90 mL gVS⁻¹ of untreated SMRs. The microbial community analysis revealed that spectinomycin (265 mg L⁻¹) might influence bacteria in the early stage of AD (first 5 days), while redundancy analysis showed that spectinomycin had a non-significant influence on community succession over the 32 days of fermentation.

From 12 mining areas surrounding a manganese mining area in Guangxi, soil samples were collected at different distances from the center of the mining area and different sampling points at the same distance. 16S rRNA gene sequencing was used in extracting and amplifying DNA in the soil samples, and double-terminal gene sequence library comparison was performed. Through OUT clustering, species community, species diversity, and inter-group difference analyses, the composition of microbial community and biological diversity in the mining soil was evaluated. Results showed that the soil around the mining area was affected by heavy metals, and species complexity was positively correlated with distance. Proteobacteria, Firmicutes, Bacteroidetes, and Acidobacteria were the dominant species with high abundance in some soil samples because of their pollution tolerance. The samples closer to the center were more disturbed by mining activities, and species diversity sequencing based on observed species index and Shannon index was consistent with that of cluster analysis. Differences among the sample groups at 2 km from the center were the smallest, and species diversity had the highest similarity. Differences among the sample groups at 1 km from the center were the largest, and species composition significantly varied. Microorganism distribution is an important indicator of soil ecological characteristics, and the analysis of species and diversity of soil microorganisms is important to the assessment of the impact of mining activities and the extent of soil contamination.

In this work was studied the single-component and multi-component abatement of metals in water using a hydrogel based on chitosan. The maximum single-component abatement capacities of cadmium (Cd) and lead (Pb) were 234.84 and 482.83 mg of metal per g of dried hydrogel at pH 6 and 40 °C, according to the Sips isotherm. The value for iron (Fe) was 386.59 mg g⁻¹ at pH 4 and 40 °C, according to the Langmuir isotherm. The best kinetic fits were determined using the pseudo-second-order model, whereas the thermodynamic parameters inferred spontaneous, favorable abatement phenomena. Lower abatement capacities were determined for multi-component studies due to the hydrated ionic radius and electronegativity of the metals. The abatement processes were confirmed by scanning electron microscopy coupled to energy-dispersive X-ray spectroscopy and Fourier-transform infrared spectra, indicating reversible chemical interactions between the hydrogel binding groups and Cd, Pb, and Fe. Such hydrogel proved to be a potential functional biopolymer for the treatment of water and wastewater contaminated by heavy metals. Graphical abstract

In this work, we designed at the level of microscale, subsurface flow wetlands planted with Typha latifolia, and used to remove diclofenac and naproxen from solutions that contained them. The wetlands were operated for 105 days with a hydraulic residence time (TRH) of 5 days. In these conditions, the removal efficiencies for diclofenac and naproxen were 98.4% and 97.7%, respectively. Moreover, we identified cultivable bacteria associated with the roots of plants exposed to either diclofenac or naproxen. We obtained 898 isolates that clustered in 9 morphotypes from the roots of Typha latifolia exposed to diclofenac, and 563 isolates grouped in 7 morphotypes, in the case of naproxen. All isolates were identified by 16S ribosomal sequencing. The BLASTn analysis indicated that 16 morphotypes showed an identity higher than 95% with the 16S rDNA gene of bacteria belonging to the genus Pseudomonas. Biochemical characterization based on plant growth-promoting activities suggests that bacteria contribute to plant growth in the wetland conditions. The results indicate that Typha latifolia and bacteria associated with their roots removed diclofenac and naproxen in subsurface flow wetlands.

Artisanal and Small-scale Gold Mining (ASGM) is one of the main sources of global Hg emissions and is present over a wide territorial in the southern Amazonia. In this region, there is a rapid approximation between agricultural and livestock activities and the impact of this close proximity having little or no evaluation. Thus, we have determined the Hg concentration in soybean plants in an area with ASGMs activities. The concentration of Hg in plants was higher in the vicinity of the ASGMs, where the Hg leaf concentration was three times higher, suggesting a higher atmospheric metal deposition in this area. It is estimated that atmospheric Hg deposition in the vicinity of ASGMs of up to 6.94 g km⁻² during the contact time between leaves and atmosphere. The translocation and bioaccumulation factors reinforce the effect of atmospheric Hg deposition, mainly, in the leaves. No impact was observed on the edible part of the plant due to the proximity of the ASGMs. It can be inferred that our results point to considerable rates of Hg emissions in the southern Amazon region and indicate the need to monitor these emissions so as to facilitate the taking of pollution mitigation actions. Soybean plants have a potential use as a bioindicator species of Hg contamination from ASGM, and the proposed method consists of an viable alternative, which can be used for the biomonitoring of long-term Hg emissions.

Creosote is a multicomponent oil classified as a dense non-aqueous phase liquid (DNAPL) produced from coal tar distillation. The concept of phase distribution is critical in decision-making to remediate contaminated sites. The creosote mass transfer between sorbed, aqueous, vapor, and DNAPL phases is controlled by physicochemical characteristics, geology of the site, and environment conditions. This study evaluated phase distribution of the main polycyclic aromatic hydrocarbons (PAHs) of creosote in a sandy soil with low organic matter content. The creosote was collected from a contaminated site in São Paulo, Brazil, and was characterized by gas chromatography–mass spectrometry (GC-MS). Clean soil was collected upgradient from the same area. Initially, the soil was artificially contaminated with creosote. After, the contaminated soil was put in contact with clean water in sealed vials for 72 h. Samples of the soil, vapor, and liquid phases were collected and analyzed by GC-MS. In total, 50 compounds were identified in the creosote, and 9 PAHs were selected to be studied, which represented around 30% of total creosote mass. The major contaminant concentration was detected in the sorbed phase. For instance, naphthalene mass was distributed in sorbed (33.0%), DNAPL (1.5%), aqueous (3.4%), and vapor (0.2%) phases. The results provided an understanding of the contaminant species partitioning that occurs in a real contaminated site.