环境•农林最新文献

In this study, polyethyleneimine-mesoporous silica composite materials were prepared and the effectiveness of the promising sorbents in adsorbing CO₂ was evaluated, along with the impacts of the silica support types (Mesoporous Silica Nanoparticles (MSN) and Mobil Composition of Matter No.48 (MCM-48)), polyethyleneimine (PEI) loading percentages (50 and 70 wt.%), calcination, surface functionalization by alkyl chains (CTMABr), and adsorption temperature (75 and 100 °C). The analysis’s results revealed that the pores of the sorbents were mostly covered with PEI molecules following PEI-functionalization, and the specific surface area and pore volume were also reduced with rising amine content. The highest CO₂ adsorption capacities were achieved for UC-MCM-48–50 and UC-MSN–50 at 2.26 mmol/g and 3.31 mmol/g, respectively. The CO₂ uptake capacities of CC-MSN–50 and CC-MCM-48–50, composed by dispersing CTMABr surfactant with the calcined materials before incorporating PEI, were remarkably similar to those of non-surfactant functionalized adsorbents. When the temperature’s influence on CO₂ adsorption capacity was evaluated, the maximum holding capability adsorbent UC-MSN–50 had a slight increase in adsorption capacity (~ 3.6%), whereas UC-MCM-48–50 had a considerable drop (~ 23.9%) as the temperature elevated to 100 °C. Besides, Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin isotherms were used to model pure CO₂ adsorption data, and a thermodynamic study was applied. In conclusion, a low-cost and more beneficial approach, which included less PEI handling and eliminating the calcination step, was implemented to enhance the CO₂ sorption capacity of composites of PEI with the long alkyl chain template MCM-48 or MSN silica support materials.

Coal mining is a critical economic for Colombia. However, mineral extraction is usually carried out near rivers that provide ecosystem services to riverside populations. Cesar River receives discharges from several open-pit coal mines, as well as from other anthropogenic sources. The aim of this work was to assess the chemical and the toxicity profile of the sediments from this river. Bottom sediment samples were collected from 12 points along the river, including tributaries and a Ramsar site, the Zapatosa Marsh. Trace elements were quantified employing ICP-MS, and mercury (Hg) was measured using a direct Hg analyzer. Aqueous extracts (K-medium) were obtained from dried sediments (1:3 ratio) and tested using Caenorhabditis elegans, assessing mortality, locomotion and growth as end points. Transcriptional effects associated with various toxicity mechanisms were evaluated using GFP-related transgenic strains (mtl-2, sod-4 and gst-1). Some trace metals enriched along the course of the river, especially Hg and V. Sediment extract-induced lethality was low (1.5–6.4%); however, nematode growth and locomotion decreased downstream the river, showing inhibition rates up to 23.3 and 35.4%, respectively. Extracts from downstream points increased the mRNA expression of tested genes compared to that elicited by the most upstream site, with greater values on stations receiving domestic sewage and mining outputs. Cobalt and lead were positively associated with metallothioneins and gst-1 expression. In short, coal mining areas should be closely monitored for trace-element release and their impact on biota. The Colombian government should implement laws and programs to protect key ecosystems from mining activities, as a commitment to sustainable development goals.

Air pollution is widespread and poses significant health risks, including respiratory and cardiovascular diseases, cancer, and even lead to death. Among the strategies to mitigate exhaust gases, biological treatment technology has gained significant attention due to its high treatment efficiency, cost-effectiveness, and environmental friendliness. This technology has become a key area of research. This paper discusses the principles, scope, advantages, and cons of various biological treatment methods, including biofiltration, biotrickling filtration, bioscrubbing, and membrane bioreactors. Noteworthy advantages of current biological treatment for exhaust gases include cost savings, reduced energy consumption, and lower secondary pollution risks. However, limitations exist, such as the treatment of treating low concentration and high flow rate of exhaust gases, and the dependence on specific microbial species and fillers. Combining biological treatments with other technologies could significantly improve effectiveness. The review also explores challenges and future directions, aiming to enhance the application of biological treatments in exhaust gas management towards sustainable development.

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This study investigates aerobic landfill stabilization using three bioreactors with different operational modes: R1 with oxygenated (~ 90% pure oxygen) leachate recirculation and waste mass aeration, R2 with conventional leachate recirculation (without oxygenation) and waste mass aeration, and R3 as an anaerobic control. The waste stabilization was assessed by reductions in COD, ammonia nitrogen, NOx (nitrate and nitrite nitrogen), and total phosphorus removal, as well as reductions in volatile solids and subsidence of waste height. Among the three reactors, R1 exhibited the best performance, with ~ 85% COD removal efficiency likely due to the high DO content during leachate recirculation. Additionally, R1 achieved ~ 99% removal efficiency of ammonia nitrogen through rapid aerobic nitrification. An exponential attenuation model was applied to describe the degradation of organic substances, with degradation rates of COD and NH₃-N increasing from 0.005 and 0.007 d⁻¹ to 0.01 and 0.021 d⁻¹, respectively, when leachate recirculation and oxygenation were applied. Reactor R1 could meet the COD emission limit of 150 mg/L, as specified by WHO surface water regulations, by day 478, while reactors R2 and R3 are expected to achieve this level by days 567 and 742, respectively. The results indicated that the aerobic conditions in R1, supplemented with pure oxygen (~ 90%) aeration, elicited rapid stabilization of the simulated landfill waste, reflected by a high waste settlement of ~ 63.5%. The findings suggest that this strategy can improve landfill stabilization in practice, optimize landfill space reuse, and enhance MSW management by reducing the load on existing leachate treatment facilities.

Oil spills significantly contribute to water pollution, posing severe environmental and health hazards. This study investigates the potential of functionalized composites in treating oily wastewater, utilizing natural fibers as substrates. Specifically, raw cotton was combined with activated carbon and carbon nanotubes to create three types of composites A, B, and C made up of charcoal, activated carbon, and carbon nanotubes generated from walnut shells. These composites were fabricated using ultrasonic treatment, autoclaving, and drying processes, and subsequently evaluated for their oil adsorption capacities and recovery efficiencies. Fourier Transform Infrared Spectroscopy analysis revealed the presence of functional groups such as carboxylic acids, aldehydes, alkenes, esters, and carbonyls, indicating significant chemical interactions between carbon nanotubes and oil. Scanning Electron Microscopy images showed cylindrical and twisted structures of the carbon nanotubes composites, with minor cracks becoming visible at higher magnifications. The initial weights of the charcoal, activated carbon, and carbon nanotubes composites were 1.25 g, 1.25 g, and 1.00 g, respectively, which increased to 6.74 g, 6.98 g, and 6.53 g after treatment. Activated carbon and carbon nanotubes composites demonstrated superior oil removal efficiencies, achieving recovery rates of 97.31% and 99.88%, respectively, and maintaining 100% efficiency over five cycles. In continuous flow systems, the efficiencies of activated carbon and carbon nanotubes were found to be 70% and 74%, respectively. This research underscores the high potential of carbon nanotubes-based composites for water treatment, demonstrating excellent oil recovery and adsorption capabilities.