环境•农林最新文献

Geochemical reactions and anthropogenic activities are a source of heavy metal concentration in aquatic bodies leading to serious detrimental effect to the environment because of its non-biodegradability. Bentonite, a smectite group of minerals has layered structure based on sheets having 2:1 structure i.e. one octahedral sheet sandwiched by 2 tetrahedral sheets. The bentonite was characterised by PXRD, FTIR, TGA and DSC experiments and the surface area was known by BET analysis. A weight loss of 14% and diffraction pattern of PXRD confirmed presence of Montmorillonite unit in the inner part. Bentonite acts as a natural scavenger of heavy metal toxicants .Owing to high cation exchange capacity, high surface area and intercalation properties, bentonite mineral has been used as a potential remover of heavy metals. The kinetic and thermodynamic studies were done in order to determine the remediation potential at pH 2 to 8. Langmuir, Freundlich and Temkin adsorption isotherms were employed to give an insight into the adsorption mechanism. The experimental data revealed that first order kinetics was followed during the adsorption of heavy metals onto modified bentonite. Maximum percentage removal of Cr(VI) and Mn(VII) was 80 and 55.5 respectively. Thus locally available bentonite may be utilised as a low cost and eco-friendly alternative of heavy metal removal.

Chicken manure (CM) is one of the most common animal wastes produced worldwide. The conventional application of CM is as a fertilizer; however, in the present study, we introduce an approach for the straightforward and affordable use of CM for fuel cell applications. It reports the functionalization of carbon nanofibers (CNFs) using CM to confer multiple functionalities. The elements that make up the functionalized CNF are nitrogen (7.40%, atoms ratio, the same below), oxygen (6.22%), phosphorous (0.30%), and sulfur (0.02%), etc., according to energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy studies. It has been verified that following treatment with CM, the morphology of the CNFs remains the same. The CM-modified CNFs exhibit a higher electrocatalytic activity (onset potential: −0.0756 V; limiting current density: 2.69 mA/cm²) for the oxygen reduction reaction (ORR) at the cathode of a fuel cell. The electron transfer number for this sample is 3.68, i.e., the ORR favours a four-electron pathway like Pt/C. The direct method of functionalizing the CNF is more effective; however, treatment of CNFs with Triton X-100 prior to functionalization shields their otherwise exposed open edge sites and in turn affects their ORR activity. A large surface area (99.866 m²/g), the presence of multiple functional elements (oxygen, nitrogen, phosphorous, sulfur, etc.), surface charge redistribution and induced donor–acceptor interactions at the surface of CM-modified CNFs contribute to their enhanced electrochemical activity. This preliminary study reports the suitability of a facile and economical approach for treating CM for the most advanced clean energy applications. Hopefully, this study will pave the way for cutting-edge methods for handling other biowaste materials as well.

Graphical abstract

Biochar-zero-valent iron composites are promising materials for the removal of heavy metals from aqueous solution, but further research is still required on the co-removal of multiple heavy metals. This paper presents the performance, effects and mechanisms of peanut shell biochar (BC)-supported zero-valent iron (ZVI) composites in the co-removal of Cd(II) and Cr(VI) from aqueous solution. Samples were subjected to the isotherm test, the kinetic test, the adsorption performance test and microscopic tests, and impact factors such as initial pH, reaction time, dosage and BC/ZVI mass ratios were considered. The results show that the removal efficiency of biochar-zero-valent iron composites for Cd(II) and Cr(VI) co-removal is significantly higher compared to individual applications of zero-valent iron and biochar. Under the condition of dosage of 0.2 g, initial pH = 4.0, and BC/ZVI mass ratio of 4:1, the removal efficiency of Cd(II) and Cr(VI) can reach 98.66% and 98.45%, respectively. In this case, the maximum adsorption capacity of Cd(II) and Cr(VI) can reach 20.44 mg/g and 3.70 mg/g. The removal of Cd(II) follows the pseudo-second-order and Freundlich model, whereas the removal of Cr(VI) is better fitted by pseudo-first order and Langmuir model. The co-removal process of Cd(II) and Cr(VI) can be divided two phase, and the mechanisms of Cd(II) and Cr(VI) are also remarkably distinct. The reduction, adsorption, complexation or co-precipitation are the dominant mechanisms for Cr(VI) removal, while the complexation of biochar and adsorption of the iron oxyhydroxide layer predominate for Cd(II) removal.

This work is concerned with the cyanide removal from aqueous solution by oxidation with hydrogen peroxide H₂O₂ catalyzed by copper zinc oxide (CuO-ZnO) nanoparticles prepared by co-precipitation method. The influences of catalyst dose, hydrogen peroxide concentration, temperature, and catalyst stability on cyanide removal were examined. The use of CuO-ZnO nanoparticles made it possible to increase the reaction rate, thus showing good catalytic activity. The cyanide removal percentage was increased after 75 minutes of reaction time from 70% to 100% by raising the catalyst dose from 0.25 g/L to 1.0 g/L. Increasing the temperature from 24 °C to 35 °C enhanced cyanide removal rate, the apparent activation energy was then found to be equal to 48 KJ/mol. The nanocatalyst was used again for four successive times and exhibited good stability. The kinetics of cyanide elimination was found to be pseudo-first order with respect to cyanide.

The widespread use of fossil fuels in daily commuting vehicles poses a significant health risk to urban populations. This study aims to quantify the escalation of black carbon (BC) emissions from traffic and assess their environmental impact. BC monitoring was conducted using a motorcycle to estimate mobile concentrations emitted by vehicles along two distinct routes during three phases (M-period, A-period, and E-period). The average mobile BC concentration (± SD) was found to be 32.57 ± 22.78 μg m-3, with the highest average value observed during the E-period at 34.1 μg m-3 for route-1. In route-2, BC concentration was 29.12 ± 21.08 μg m-3, with the mean highest at 33.4 during the E-period. The likelihood of increased BC emissions is evident when individuals venture out to markets in the evening. Weekend BC concentrations (25.76 μg m-3) were generally lower than weekdays (39.38 μg m-3) during the analysis of route-1. A similar trend was observed in route-2, attributed to reduced traffic volume and vehicular emissions resulting from the closure of schools and offices on weekends. Throughout the study, BC levels ranged from 10.91 to 149 μg m-3 in TR-1 and 9.76 to 114 μg m-3 in TR-2. Notably, at five intersection points on TR-1, BC concentrations at T102 were 34% higher during evening times than at T105. Similarly, among the four intersection points on TR-2, BC levels at T201 were 55% higher than T203 during the evening. Our analysis also showed that inhalation doses (IDOSE) were highest during peak traffic times, with motorcyclist IDOSE ranging from 15.29 to 25.01 µg. This study highlights the concerning levels of BC exposure during daily commuting, emphasizing the need for measures to mitigate the health impacts associated with urban traffic emissions and promote a safer environment for urban populations.

Limited data on rural Poland's atmospheric ion concentrations exists, with no publicly available monitoring data in urban areas. These knowledge gaps hinder the comparison of concentrations across environments and the identification of their sources. This study examines water-soluble ions across five rural locations in Poland over four years to investigate their concentrations and sources in the atmosphere. This study explores aerosol origins, performing a four-year correlation analysis across five locations to reveal ion relationships. Notably, sulfate (SO₄²⁻), nitrate (NO₃⁻), and ammonium (NH₄⁺) exhibit significant correlations ranging from 0.3 to 0.8, suggesting a common pollution source in all analyzed rural locations. Interestingly, magnesium (Mg²⁺) and sodium (Na⁺) in two locations demonstrated a strong correlation, ranging between 0.4 and 0.9, suggesting the influence of sea spray on these sites. Principal component analysis is used to investigate the factors influencing ion concentrations, revealing distinctive patterns for each location and explaining the total variances ranging from 74.9% to 84.8%. This underscores the significance of geographical and environmental factors. The study's novelty lies in its thorough and long-term analysis of water-soluble ion concentrations across rural Poland, providing an extensive dataset for the region. The study fills a data gap on rural pollution sources and reveals consistent ion patterns across different sites and seasons. The findings emphasize geographical and environmental impacts on aerosol composition and suggest common pollution sources for all areas. This research encourages further investigations into the stability and origins of ions in rural environments, providing valuable insights for local and broader atmospheric studies.

In order to control the eutrophication of rivers or lakes by dredging, a large amount of sediment has been generated, making the treatment of dredged sediment a challenging issue. In response to this problem, we have successfully synthesized an innovative composite amendment for reusing dredged sediment, which included Fe-loaded biochar (Fe@BC), clinoptilolite, wheat straw, and 3,4-dimethylepyrazole phosphate (DMPP). Tests for adsorption and characterization showed that Fe@BC and clinoptilolite, as the main components of the amendment, have excellent adsorption performance for orthophosphate (Ortho-P) and ammonium nitrogen (NH₄⁺-N)/potassium ions (K⁺), respectively. The results of column leaching experiment demonstrated that the addition of 4%-5% amendment of the sediment mass could not only significantly reduce the leaching of nitrogen (N), phosphorus (P), and potassium (K), but also effectively slowed down the movement of N, P, and K in the sediment profile. Moreover, the bulk density, moisture retention, and particle size of sediment were simultaneously improved.