The interaction between soil organic components and mineral components was explored in this study. Humic acid and kaolin were used for the preparation of organic-mineral complexes with different contents of organic matter, for experimental study of the adsorption of trichloroethylene. The results showed that the adsorption of trichlorethylene fitted the Freundlich isotherm model. The existence of interaction between humic acid and kaolin was indicated by the significant difference between the actual value and the theoretically overlaid value of the adsorption capacity. With various characterizations, such as FTIR and surface area & pore analysis, the mechanism of interaction between humic acid and kaolin was suggested as follows. When their contents were low, humic acid molecules firstly loaded on the surface binding sites of kaolin. Then with the content increased, as O/M( organic-mineral mass ratio) was 0.02-0.04, some surface pores of kaolin were filled by part of the molecules. After reaching a relatively stable stage, as O/M was 0.04-0.08, humic molecules continued to load on the surface of kaolin and formed the first humic molecule-layer. With humic acid content continued increasing, as O/M was 0.08-0.10, more humic molecules attached to kaolin surface through the interaction with the first layer of molecules and then formed the second layer. O/M was 0.10-0.16 as the whole second layer stage, meanwhile the first layer was compressed. Then when O/M was 0.16-0.4, there were still some humic loadings onto the second layer as the third layer, and further compressed the inner humic acid layers. Besides, some humic acid molecules or aggregates might go on attaching to form as further outer layer.
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Sci Total Environ
January 2025
Department of Chemical Engineering, Tennessee Technological University, Cookeville, TN, United States. Electronic address:
The overall objective of the present work was to quantify how shear, coupled with varying salt concentration, affected the particle size distribution and relaxation/aggregation behavior for various organic sources of nonliving natural organic matter (NNOM) in surface water. NNOM has been implicated as a conditioning agent leading to the formation of biofilms such as algae. NNOM is also a responsible in surface waters for facilitated transport of a variety of anthropogenic pollutants.
View Article and Find Full Text PDFSci Total Environ
January 2025
College of Environment and Ecology, Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing, 400045, China. Electronic address:
The increasing frequency of cyanobacterial blooms, particularly those induced by Microcystis aeruginosa (M. aeruginosa), poses severe economic, ecological and health challenges due to the production of microcystins (MCs). Environmental parameters such as light and nutrient availability influence MCs production, while the role of dissolved organic matter (DOM) photochemical processes in regulating these remains unclear.
View Article and Find Full Text PDFSci Total Environ
January 2025
Department of Chemistry, Physics, Environmental and Soil Sciences, University of Lleida - AGROTECNIO-CERCA Center, Rovira Roure 191, 25198 Lleida, Spain.
There is limited research on the influence of environmental variables on the interactions of biodegradable microplastics with chromium. This study reports the results of adsorption experiments with Cr and poly(lactic acid) (PLA) in synthetic aqueous solutions. It addresses the influence of the initial oxidation state, Cr(III) or Cr(VI), the effects of UV irradiation and the presence of organic matter.
View Article and Find Full Text PDFJ Hazard Mater
December 2024
College of Natural Resources and Environment, Northwest A&F University, Yangling 712100, China; Key Laboratory of Plant Nutrition and the Agro-environment in Northwest China, Ministry of Agriculture, Yangling 712100, China. Electronic address:
The interactions between microplastic-derived dissolved organic matter (MPs-DOM) and heavy metals (Cu, Pb, and Cd) regulate the complex environmental transport behavior of pollutants in terrestrial and aquatic environments. In this study, fluorescence excited emission matrix spectroscopy combined with parallel factor analysis (EEM-PARAFAC) and electrospray ionization coupled Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) were employed to investigate the complexation mechanism of MPs-DOM with heavy metals, as well as the effects of different environmental occurrences of MPs-DOM on the transport behaviors of heavy metals in saturated porous medium. The findings demonstrated that MPs-DOM, particularly humic-like substances containing aromatic structures and various oxygen functional groups, could form stable complexes with heavy metals.
View Article and Find Full Text PDFImpact of climate change that stems from gaseous emissions require sustainable materials to eliminate sulfur. This study involves the modification of humic acid with magnetite nanoparticles (Fe₃O₄ NPs) by a microwave-assisted synthesis of an absorbent with reasonable pore volume and diameter for elimination of thiophenic compounds from fuel. The magnetic nano adsorbent designated Fe3O4@HA was characterized using advanced spectroscopic techniques, while their structure and morphology were analyzed through DLS, XPS, XRD, FT-IR, TGA, FESEM-EDX, VSM, and BET-N2 techniques.
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