环境•农林最新文献

The adsorption of organic pollutants on soil surfaces impedes their oxidative degradation efficiency within the soil medium. Understanding the distribution patterns of different petroleum hydrocarbon components on the soil medium surface can provide effective theoretical guidance for the technical regulation and efficiency improvement of in situ chemical oxidation (ISCO). Therefore, this study designed experiments involving interface diffusion, static desorption, and intensive desorption, and investigated adsorption patterns and component analysis. Fast-desorbing petroleum hydrocarbon components in on-site oil sludge were identified, including amines (e.g., 2-Phenylethylamine, 2,4,6-Trimethyl-m-phenylenediamine), acids (e.g., Benzoic acid, Octadecanoic acid). Relatively fast-desorbing components included phenols (e.g., Phenol), alcohols (e.g., Phenylmethanol, Dihydroxybenzene), ketones (e.g., Cyclohexa-2,5-dien-1-one, Cyclohepta-2,4,6-trien-1-one, and Pyrimidine-2,4,6(1H,3H,5H)-trione). Slow-desorbing components comprised carboxylic esters (e.g., Ethyl carboxylic acid ester), benzenoid olefins (e.g., 1'-(Cyclopenta-2,4-dien-1-yl)-1,4'-bipiperidine, 6-Allyl-1-methylnaphthalene). Finally, the remaining components in the soil were measured by extraction method as strongly adsorbed petroleum hydrocarbon components, including long straight-chain alkanes (e.g., Tetradecane, Hexadecane, Heptadecane, Octadecane, Icosane), and benzene esters (e.g., Dimethyl 5-methyl-1,3-benzene-dicarboxylate). It provides a theoretical basis for the accurate desorption of petroleum hydrocarbons from the soil surface.

Graphical Abstract

The purpose of this study is to assess the efficacy of an integrated system for treating tannery effluents from Fez City. The system includes aeration as a pretreatment, followed by a binary oxidation process using hydrogen peroxide (H₂O₂) and persulfate (K₂S₂O₈) (PS) as oxidants, with UV-A irradiation, and ultrasound (US) as activators (US-UV-PS-H₂O₂). Aeration effectiveness as a preliminary treatment was evaluated, resulting in a 71% and 78% reduction in chemical organic demand (COD) and color, respectively. The US-UV-PS-H₂O₂ process effectiveness was further evaluated in terms of COD and color removal. A factorial design with two levels was used to optimize the operating parameters (pH, H₂O₂ concentration, and K₂S₂O₈ dose). The findings showed that, under optimal conditions (pH = 3; [H₂O₂] = 225 mg/L and [K₂S₂O₈] = 3670 mg/L), the highest COD and color reduction rates in the tannery effluent were 85% and 93%, respectively. Additionally, phytotoxicity assessments, based on seed germination and root elongation tests, revealed promising results in toxicity reduction, with a germination rate of 75% for both M. sativa and wheat seeds. Overall, the sequential treatment involving aeration followed by US-UV-PS-H₂O₂ process proves to be an effective and practical strategy for the sustainable management of tannery wastewater, with a total treatment cost of $8.07/m³.

A natural, HEU-type zeolite embedded with Fe-oxyhydroxides was prepared by a simple and fast precipitation method. The natural and treated sorbents were characterized by a variety of methods including X-Ray Diffraction, Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy and BET surface area, revealing the amorphous nature of the oxyhydroxides consisting of ferrihydrite and poorly crystalline goethite. The interactions of the sorbents with uranium aqueous solutions under varying conditions were subsequently investigated. Iron oxyhydroxide deposition enhanced the sorption properties of the natural zeolite (from 194.6 to 237.9 mg g^–1 at pH 4) while parameters such as pH, initial metal concentration, and presence of competing ions (Na⁺, Ca²⁺) as background electrolytes greatly affected the sorption capacities. Results from the materials characterization before and after sorption accompanied by fitting the experimental isothermal and kinetic data to mathematical models as well as thermodynamic calculations, showed that the sorption was due to a combination of surface complexation and ion exchange processes. Desorption and leaching tests provided insight into the influence of iron oxyhydroxides on uranium sorption behavior.

A suite of CrCe oxides facilitated hierarchical porous biochars from walnut husks and rice straws (XCr_yCe_1-y/WSAC) were readily synthesized for formaldehyde (HCHO) abatement. BET, XRD, XPS, SEM, H₂-TPR, TG-DTG, and in situ DRIFTS were adopted to disclose their physicochemical properties and the elimination mechanism of HCHO. 18%Cr_0.5Ce_0.5/WSAC exhibited splendid HCHO abatement efficiency (99.2%) at 280 °C. The effects of O₂, SO₂, H₂O for HCHO abatement over 18%Cr_0.5Ce_0.5/WSAC were trialed, and the strangulation influences of SO₂ counteracted the furtherance effect of O₂ to some extent, which was relieved by the facilitation of H₂O. CrO_x-CeO_x co-facilitated WSAC presented better performance than Cr or Ce oxide separately facilitated WSACs, which was associated with the redox cycle of Cr⁶⁺ + Ce³⁺ ↔ Cr³⁺ + Ce⁴⁺, resulting in higher redox capability, better dispersion of active ingredient, more oxygen vacancies and superior active oxygen mobility. Furthermore, the hierarchical porous support accelerated the diffusion and mass transfer of reactants and intermediates. Noteworthily, the effects of CrO_x-CeO_x and the hierarchical porous structure of the support on the tolerance to SO₂ and H₂O were deeply and systematically investigated. Ultimately, 18%Cr_0.5Ce_0.5/WSAC emerged desirable prospects in practical applications thanks to splendid catalytic performance and satisfactory resistance to SO₂ and H₂O.

Graphical Abstract

This study explores the enhancement of methylene blue (MB) adsorption from aqueous solutions using hydroxyapatite (HAp) grafted with aminotrimethylphosphonate (AMP). Leveraging Morocco's natural phosphate resources, HAp was synthesized and modified with varying concentrations of AMP (5%, 10%, 15%, and 20%) to evaluate its adsorption performance. Dynamic Light Scattering (DLS) analysis indicated a reduction in particle size with increasing AMP content, which improved the dispersion and stability of the HAp particles. Zeta potential measurements revealed that AMP grafting reduced the negative surface charge, particularly in acidic conditions, favoring the adsorption of the cationic MB molecules. X-ray diffraction (XRD) patterns showed increased crystallinity in the AMP-grafted composites, which provided a more stable adsorbent structure. Infrared spectroscopy (FTIR) confirmed successful AMP incorporation, leading to changes in the vibrational modes of key functional groups. The equilibrium adsorption capacity (qe) of the composites increased with AMP content, with the HAp + 20% AMP composite achieving the highest qe of approximately 0.0854 mg/g, demonstrating the effectiveness of AMP grafting in enhancing the adsorption properties of HAp. These findings suggest that AMP-grafted HAp composites are highly efficient adsorbents for methylene blue removal, offering a sustainable solution for wastewater treatment.

Microplastic contamination in freshwater fish poses a significant global threat but remains underexplored in biodiversity hotspots like the Western Ghats of India, where rivers exhibit elevated microplastic levels. This study investigates microplastic contamination in the endemic and near-threatened bagrid catfish, Mystus malabaricus, sampled from the Ulhas River, Maharashtra. Microplastics were isolated and analysed for physical attributes (size, shape, colour) using light microscopy and for chemical composition through µ-Raman spectroscopy. Our findings indicate that 50% of the catfish contained microplastics, averaging 2.54 ± 0.41 particles per fish, with five morphotypes identified, predominantly transparent and grey films made of polyethylene (89.3%) and polypropylene (10.7%). The observed characteristics of microplastics reflect a direct relationship to secondary anthropogenic sources, revealing inadequacies in regional waste management infrastructure. This contamination may adversely affect fish development and pose risks to fish consumers and artisanal fisheries. We propose mitigation strategies based on the findings of this and previous studies on the Ulhas River.

Polar Organic Chemical Integrative Sampler (POCIS) is a passive sampler employed to monitor organic compounds in water (e.g. pesticides, drugs, etc.); in our case consists of a receiving phase, Oasis HLB, enclosed between two polyethersulfone (PES) membranes. In most cases, the analytes were extracted only from the receiving phase but recent works show that some compounds were also adsorbed on the PES membranes. Many aspects on the membrane behaviour are still unknown and this work aims to fill some knowledge gaps exploring the capability of PES membranes to adsorb pesticides. From experiments conducted in a controlled environment, it was seen that more than half of the investigated compounds were adsorbed more effectively by the PES membrane than the Oasis HLB phase. The affinity of these pesticides towards the two sampler compartments, can be explained only partially by the polarity of the compounds. However, a significant adsorption of the most hydrophobic compounds by the PES membrane was noticed, especially for values of LogKow higher than 4. From these experiments, it was possible to calibrate POCIS by comparing the pesticide concentration in water with the amount adsorbed by the two sampler compartments over time, with the estimation of two values of sampling rate for each pesticide (R_S,HLB and R_S,PES). It was seen that the combination of the two adsorbent substrates allowed to intercept almost all the studied compounds satisfactorily and this behaviour was also confirmed by a field sampling campaign.