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Soil microbial biomass is a primary source of soil organic carbon (SOC) and soil organic nitrogen (SON) and therefore plays a fundamental role in carbon and nitrogen cycling. However, little is known about the fate and transformation of the magnitude of microbial components in the soil. Here we employ Fourier Transform Infrared (FT-IR) spectroscopy...
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... contribute to the abundance of the carbon, phosphorus and sulfur observed in the EDS spectrum of the clay-complex (Fig. 1d). To clarify whether the silicate layers of kaolinite were intercalated by microbes, powdered XRD analysis was performed on pure kaolinite and kaolinite-microbial complex, and the resulting diffraction patterns presented in Fig. 2. The diffraction patterns are characterized by a strong narrow peak at 2Â = 12.2 • , corresponding to a d-spacing [d (0 0 1) ] value of 7.1 ˚ A. This suggests that microbes did not penetrate kaolinite and that adsorption occurred only on the external surfaces of the mineral. This is not surprising as kaolinite is a 1:1 non-expanding ...
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... spectrum at 3671 cm −1 , is now perturbed, due to hydrogen bonding and is no longer observed. Taken together, this provides further evidence of microbial association with kaolinite surfaces. The (OH) bands at 3621, 3652, and 3694 cm −1 , remained unchanged, indicating that kaolinite was not intercalated, as also suggested by XRD patterns (Fig. 2), but rather that clay-microbial interactions involved hydrogen bonding and ligand exchange [34]. Complementary evidence of the adsorption and stabilization of microbial-derived components by kaolinite is provided by a very broad and strong absorption at 3408-3300 cm −1 indicating the presence of an abundance of (OH) phenolic (such as ...
Citations
... This wavelength band corresponds closely to findings in the literature presented by [54]. There was insignificant variation in the peak pattern when the acid concentration rose from 0.5 to 2.5 M. ...
This study aims to improve the pore volume and specific surface area of kaolinite (Kaol) and montmorillonite (Mt) through low-temperature acid treatment to address their limited adsorption capacity. Clay mineral samples underwent sulfuric acid activation at various concentrations and durations. SEM analysis indicated acid activation improved kaolinite pore structure, increasing specific surface area, while montmorillonite exhibited reduced grain size and higher porosity, resulting in greater pore volume and surface area. EDX analysis revealed changes in chemical composition, including a 10% increase in silica and a 13% reduction in aluminium in kaolinite, whereas montmorillonite exhibited a 13% aluminium increase and 9.5% higher silica content. Kaolinite’s XRD pattern remained unchanged, resisting 2.5 M acid activation, while montmorillonite displayed modified patterns, indicating interlayer conversion with increased acid concentration. BET analysis confirmed higher sulfuric acid concentration increased pore volume and surface area, while FTIR analysis showed stable Si–O stretching peaks with changing intensity after 8 h. Montmorillonite exhibited Al–OH and Mg–OH bands, decreasing with higher acid concentration, and Si–O–Fe and Si–O–Al bonds disappeared with acid activation. Thus, the results indicate significantly enhanced pore volume and specific surface area after acid activation, accelerating CO2 adsorption rates. This activation demonstrates a direct relationship between acid concentration and reaction time with clay minerals’ pore characteristics. These clay minerals can be used as adsorbents for CO2 in carbon capture technology, aiding the global goal of achieving ‘net zero’ emissions by 2050.
... The FT-IR spectra in the lattice region between 400 cm − 1 to 1400 cm − 1 for the kaolinite ore and MCCh composite are shown in Fig. 4. The kaolinite ore displays many distinct FT-IR bands due to Si-O, Si-O-Si, Si-O-Al, andSi-OH vibrations at 461 and 493 cm − 1 , 589 and 1094 cm − 1 , 756 cm − 1 , and 3300-3670 cm − 1 (Fig. 4) Cheng et al., 2015;Paluszkiewicz et al., 2011), (Spence and Kelleher, 2012;Parthasarathy et al., 2001;Saikia and Parthasarathy, 2010), (Lotta et al., 1988;Xu et al., 2005). The MCCh composite's characteristic FT-IR spectrum bands, which appear at 3476-3669 cm − 1 (Fig. 4), are attributed to the stretching -OH Auta and Hameed, 2014;Kumar et al., 2019;Parthasarathy et al., 2001). ...
The presence of permanent hardness ions (sulfate and chloride) in drinkable water in large amounts causes many problems, either health effects like bad taste, color, and odor of water or technical effects like the formation of stains and scales in house vessels and pipelines. This paper presented an applicable concept for using a newly prepared composite composed of modified local clay and locally extracted chitosan as a second-stage filter after pressure sand filters in the conventional iron and manganese removal plant to remove sulfate and chloride from raw drinkable groundwater. The morphology and structure of the raw samples and the modified clay/Chitosan (MCCh) composite were explored by using different techniques. Also, this study deals with the experimental batch and column studies to examine the prepared composite ability to remove permanent hardness ions. The adsorption capacity of MCCh for sulfate and chloride ions was investigated under various conditions, e. g., temperature, pH, contact time, various initial concentrations, and adsorbent dosage. Results indicated that the MCCh composite exhibited a good adsorption capacity (3.2 mg/g) for permanent hardness ions at optimized conditions, a pH range of 3-6.5, and 60 min contact time. Regeneration experiments were performed for the MCCh composite for 6 cycles. The % of sulfate and chloride ions removal reached about 92% at a powerful acidic solution and about 70% at a neutral pH for really applied raw groundwater.
... However, due to the complex nature of soils, many studies regarding organo-mineral interactions have narrowed their focus to the use of quantitative descriptors, such as isotherm shapes to yield empirical relationships from which soil carbon dynamics are inferred [5] . On the other hand, only a limited number of studies have focused on a more direct approach using incubation experiments [3] . ...
... Baseline corrections for all spectra were done using the automatic baseline correction method. Samples were analyzed immediately after preparation to minimize the suppression of key signals by KBr-adsorbed atmospheric water [3] . ...
... A Bruker DEFRAC Evaluation Data Collector and an EVA Graphics and Identification software packages were employed to capture and process raw data. Scans were carried out at a speed of 1°2 /min and increments of 0.02 ([°2 ]; [3] . ...
Soil organic matter (SOM) constitutes roughly 60% organic carbon (OC) and therefore plays a crucial role in regulating global climate. However, our understanding of the long-term dynamics of the soil carbon pool remains constrained by limitations in analytical approaches capable of providing high resolution molecular-level information from arguably the most complex biomaterial on the planet. In this contribution, we combine hydrofluoric acid (HF) treatment with a spectroscopic approach as a strategy to provide refined molecular-level information on the interactions between soil minerals and SOM. Critically, we have not seen the use of this combined approach anywhere in the literature and strongly believe that it could allow us to improve our overall understanding to the mechanisms and pathways that regulate SOM transformation. Results clearly illustrates which organic structures are preferentially adsorbed to soil minerals and are likely to be protected from degradation, as well as spatial co-variations of SOM with specific mineral components such as Al3+, Si4+ and dibasic cations such as Mg2+as a function of their importance in the interaction process. • Soil samples were collected from different land-use types in rural farming communities of the Upper Rio Grande Valley. • Samples were oven dried, disaggregated, sieved, treated with 10% HF, rinsed and oven dried. • Oven dried samples were subjected to Mid–infrared (4000–400 cm−1), XRD and ED-XRF analyses.
... The changes in chemical bond vibrations and functional group strengths in montmorillonite before and after bioreduction were analysed through FTIR with a ThermoFisher Nicolet 6700 FTIR apparatus (ThermoFisher, USA). Dried montmorillonite particles were mixed with KBr and pressed into pellets (Spence and Kelleher, 2012). All FTIR spectra were collected over the wavenumber range of 400-4000 cm −1 and represent an average of 500 scans at a resolution of 4 cm −1 . ...
Fe(III) may be reasonably considered as one of the most important electron acceptors in petroleum reservoir ecosystems. The microbial mineralization of clay minerals, especially montmorillonite, is also of great significance to the exploration of petroleum and gas reservoirs. The bioreduction mechanisms of iron-poor minerals in petroleum reservoirs have been poorly investigated. This study investigated the bioreduction of montmorillonite by dissimilatory iron-reducing bacteria (DIRB) in petroleum reservoirs based on culture-independent and culture-dependent methods. Microbial diversity analysis revealed that Halolactibacillus, Bacillus, Alkaliphilus, Shewanella, Clostridium, and Pseudomonas were the key genera involved in the bioreduction of Fe(III). Through the traditional culture-dependent method, most of the key genera were isolated from the samples collected from petroleum reservoirs. Traditional culture-dependent methods can be used to reveal the metabolic characteristics of microorganisms (such as iron-reduction efficiency) to further elucidate the roles of different species (B. subtilis and B. alkalitelluris) in the environment. Moreover, many species with high iron-reduction efficiencies and relatively low abundances in the samples, such as Tessaracoccus and Flaviflexus, were isolated from petroleum reservoirs for the first time. The combination of culture-dependent and culture-independent methods can be used to further the understanding of the microbial communities and the metabolic characteristics of DIRB in petroleum reservoirs. Structural alterations that occurred during the interactions of microorganisms and montmorillonite were revealed through scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray powder diffraction (XRD). The physical and chemical analysis results demonstrated that microorganisms from petroleum reservoirs can dissolve iron-poor montmorillonite and promote the release of interlayer water. The secondary minerals illite and clinoptilolite were observed in bioreduced smectite. The formation of secondary minerals was closely related to the dissolution degrees of minerals based on iron reduction.
... Spence and Kelleher examined kaolinite mineral interactions with organic matter to understand what compounds are likely accessible to microbes as opposed to compounds that are likely to become physically protected through strong associations at the mineral surface. Strong absorption on kaolinite surfaces at 3,408-3,300 cm −1 indicated the presence of phenolic, carboxylic groups, and amides, suggesting a high degree of stabilization of microbial-derived components that could be instrumental in forming stable mineral-organo complexes (Spence and Kelleher, 2012). These applications of FTIR can often complement many techniques to characterize NOM, such as X-ray-based techniques. ...
Determining the mechanisms, traits, and pathways that regulate microbial transformation of natural organic matter (NOM) is critical to informing our understanding of the microbial impacts on the global carbon cycle. The capillary fringe of subsurface soils is a highly dynamic environment that remains poorly understood. Characterization of organo-mineral chemistry combined with a nuanced understanding of microbial community composition and function is necessary to understand microbial impacts on NOM speciation in the capillary fringe. We present a critical review of the popular analytical and omics techniques used for characterizing complex carbon transformation by microbial communities and focus on how complementary information obtained from the different techniques enable us to connect chemical signatures with microbial genes and pathways. This holistic approach offers a way forward for the comprehensive characterization of the formation, transformation, and mineralization of terrestrial NOM as influenced by microbial communities.
... nm and 18382.35 nm, respectively (Bishop et al. 2008;Spence and Kelleher 2012). The results in the present study showed strong peaks for sand contents (19000-20000 nm) and H+ Al (18000-19500 nm), which may be related to such factors. ...
Diffuse reflectance spectroscopy is a promising technique for advances in soil studies. Thus, the objective of this work was to evaluate the efficiency of diffuse reflectance spectroscopy in the mid-infrared range to estimate the sand, silt, clay, pH, H+ Al, sum of bases, organic matter contents, phosphorus, and remaining phosphorus of Argissolo Amarelo distrocoeso típico (Typic Hapludult) in the state of Maranhão, Brazil. Two areas with different characteristics were selected for sampling: Area 1 and Area 2. A square sampling grid
with 121 points was used for each area. Samples were collected from the 0.0–0.2 m soil layer. The spectra were recorded in the mid-infrared range (2500–25000 nm; 4000–400 cm−1) at 8 cm−1 resolution. The data of Area 1 were used for chemometric model calibrations by Partial Least Squares Regression analysis. The data of Area 2 were used for the geostatistical modeling. All attributes presented, in general, positive calibration parameters, with adjusted coefficient
of determination (R2adj) for sand (0.76), silt (0.51), clay (0.77), pH (0.51), H+ Al (0.45), sum of bases (0.75), organic matter contents (0.71) and remaining phosphorus (0.6), and residual prediction deviation equal to or higher than 1.4, except for phosphorus. The lowest prediction errors were found for sand (17%) and silt (19%) contents, pH (15%), and remaining phosphorus (8%). The
distribution of spatial attributes – measured and predicted – presented positive correlation, confirming the potential of diffuse reflectance spectroscopy as an alternative for prediction of soil attributes.
... Considering IR modalities, transmission IR spectroscopy with pressed KBr-matrix sample tablets is the first-born, simplest, and still most widespread modality [38,39]. However, it requires milling in nonaqueous solvents, which, along with not fully chemically inert tablet matrix, may lead to significant chemical composition distortion and structural changes [40,41]. ...
This study aims to compare photoacoustic (FTIR–PAS), diffuse reflectance (DRIFT), and attenuated total reflection (ATR) FTIR modalities in the wide wavenumber range from NIR (7500 cm−1) to FIR (150 cm−1) for the same silicate soil samples under the same conditions. The possibilities of non-destructive rapid qualitative analysis of soils by these modalities without comprehensive data treatment were compared. The assignment of more than 100 bands for the chernozem and sod-podzolic as common types of silicate types of soil was made. The following groups of bands of organic matter and inorganic matrix were reliably found in spectra of all or at least two modalities: 3690–3680 cm−1 (hydrogen-bonded SiO–H…H2O stretch, not ATR), 2930–2910 cm−1 and 2860–2850 cm−1 (methylene stretch), 1390–1380 cm−1, (symmetric stretch carboxylate, DRIFT and FTIR–PAS); 2000–1990 cm−1, 1885 cm−1, and 1790–1783 cm−1 (SiO2 overtones, DRIFT and FTIR–PAS), 1163–1153 cm−1, SiO2 lattice (not FTIR–PAS), 1037 cm−1 (Si–O or Al–O stretch), 796 cm−1 (lattice symmetrical Si–O–Si stretch); 697 cm−1, SiO2; and 256 cm−1 (not FTIR–PAS). Amide I, II, and III bands appear in DRIFT and FTIR–PAS spectra while not in ATR. Except for methylene and carboxylate groups, CH vibrations (3100–2900 cm−1) are not seen in ATR. Bands at 1640–1630 cm−1, 1620–1610 cm−1, 1600–1598 cm−1 (primary water bands and probably carboxylate) appear in the spectra of all three modalities but are unresolved and require data treatment. It is preferable to use all three modalities to characterize both soil organic matter and mineral composition. DRIFT provides the maximum number of bands in all three modalities and should be selected as a primary technique in the NIR and 4000–2000 cm−1 regions for hydrogen-bonding bands, CHX groups, and the silicate matrix. ATR–FTIR complements DRIFT and provides a good sensitivity for soil water and the matrix in 2000–400 cm−1. FTIR–PAS in 4000–1500 cm−1 reveals more bands than DRIFT and shows the highest sensitivity for absorption bands that do not appear in DRIFT or ATR-IR spectra. Thus, FTIR–PAS is expedient for supporting either DRIFT or ATR–FTIR. This modality comparison can be a basis for methodological support of IR spectroscopy of soils and similar organomineral complexes.
... and 2850 cm − 1 (ν as CH2 and ν s CH2 ) and at ∼1735 (ν as C=O ), while the soil aluminosilicates were identi ed by their speci c bands at ~ 1030 cm − 1 (ν Si−O ), 525 (δ Al−O−Si ) and 465 cm − 1 (δ Si−O−Si ) [53] (Fig. 4). Calcium carbonate was identi ed by its main absorption bands at 1405 cm − 1 (ν as CO3 ) and 874 cm − 1 (δ CO3 ) ( Fig. 4). ...
In this study we used an analytical approach based on complementary techniques that targets all structural levels of collagen to investigate the effects of burrial tests on vegetable-tanned lather. For the first time, a group of deterioration markers specific to molecular, fibrillar and and fibrous structure of collagen in leather was associated with the anaerobic condition of burried leather. Gelatin was identified both through the FTIR-ATR spectral markers (molecular alteration of collageneous triple helix structure) and SEM imaging (alteration of fibrils and fibres morphology). Loosening of collagen-tannin interaction and de-tanning were detected by the application of second derivative spectral analysis. Collagen denaturing profile was evidenced by DSC analysis and documented by SEM observations at high magnification, while TG/DTG analysis gave information on the leather thermo-oxidative deterioration. Our results confirmed that the shrinkage temperature measured by MHT method could be misleading. However, this method proved its usefulness in assessing the structural inhomogeneity of collagen in buried leather and identifying gelatin. The complementary FTIR-ATR, DSC, TG/DTG, MHT and SEM analytical protocol proved its high effectiveness and could thus be extended to the challenging study of archaeological leather.
... This is similar to that reported by Salahudeen N. in his work "Development of Zeolite Y and ZSM5 composite catalyst from Kankara kaolin". Absorbance Analysis ≡ FTIR analysis of raw and calcined Ukpor clay Figure 4 shows FTIR spectra of raw Ukpor kaolin (A) and calcined kaolin (B).For a kaolinite clay mineral, the -OH hydroxyl group is identified at wave number (cm -1 ) of either 3696, 3671 or 3650 [21]. Therefor the peak at 3696.034818 cm -1 for Fig. 4 (A) shows the presence of an -OH group. ...
The present study involved the processing of raw Ukpor clay from Anambra State, Nigeria to kaolin as a precursor for the development of Y-type zeolite. The clay was first subjected to pretreatment by separating the foreign bodies from it using deflocculant (Sodium hexametaphosphate and Sodium hydrogen carbonate). Subsequently, the pretreated clay was calcined at 850 0 C for 6 hours at atmospheric pressure. The calcined clay was formulated by adding sodium hydroxide and sodium metasilicate to produce a gel aged at room temperature for 12 hours. The gel was subsequently heated in a laboratory oven at 100 0 C for 9hrs to produce the Y-type zeolite in a process called crystallization and a product with Si/Al molar ratio of 4.07 was achieved which is suiting for a typical Zeolite Y. The formulated samples were characterized using X-ray Fluorescence (XRF), Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscope (SEM). The results showed possible synthesis of Y-type zeolite from Ukpor kaolinite having a molar ratio of 15Na2O:Al2O3:15SiO2:450H2O. The synthesized product with Si/Al ratio of 4.07, an agglomerated euhedral morphology, and FTIR spectra peak at wavelengths of 719cm-1 and 3424cm-1 , are the basis upon which the conclusion of possible development of Y-type zeolite is drawn.
... However, SOC content showed positive correlation with some indices derived from both Landsat and Sentinel images (such as Clay Index, NDVI, RVI, and SAVI). According to Fig. 3.B, SOC content was positively correlated with the Al-O-Si and Si-O-Si bending vibrations at 550-445 cm − 1 (Spence and Kelleher, 2012), with the Si-O bands at 805 cm − 1 and to the bands at 1030-950 attributed to Si-O clay minerals. The SOC content was highly positively correlated with the bands at 2500-1550 cm − 1 centered at 1600 cm − 1 and 1700 cm − 1 corresponding to the stretching of C--C stretching vibrations and asymmetric -COO − stretching in ketones, carboxyls, and lignine and C--O bonds from ketones, aldehydes, amides and carboxylic acids, respectively (Cole, et al., 2019;Rial et al., 2016;Verchot et al., 2011;Kaiser et al., 2011). ...
Soil Organic Carbon (SOC) content is a key element for soil fertility and productivity, nutrient availability and potentially represents a measurement of the sink for greenhouse gas abatement. Improving our knowledge on the spatial distribution of SOC is hence essential for sustainable nutrient management and carbon storage capacity. The objective of this study was to evaluate the performance of six tree-based machine-learning models when using environmental variables (i.e., remote sensing and terrain attributes - scenario 1), Fourier Transform Infrared Spectroscopy (FTIR) data (scenario 2) and combination of environmental variables and FTIR data (scenario 3) as predictors in prediction of SOC content. The models included Random Forest, Cubist, Conditional Inference Forest, Conditional Inference Trees, Extreme Gradient Boosting and Classification, Regression Trees. Furthermore, we explored if the Bat optimization algorithm can improve the prediction accuracy of the models. The study was conducted across a 7000 ha field in the Miandoab County, Northern Iran, with a total of 80 soil samples collected systematically in a regular grid (700 × 1000 m). According to Leave-One-Out Cross-Validation, the best prediction performance was achieved by the Cubist+Bat model when environmental variables and FTIR spectra (scenario 3) were used (Coefficient of determination = 0.73, Concordance Correlation Coefficient = 0.77, Root Mean Square Error = 0.36, Mean Absolute Error = 0.31, Median Absolute Error = 0.28). FTIR data had the highest influence on the prediction accuracy of SOC. Therefore, it can be concluded that the combination of environmental variables and FTIR data with Cubist+Bat model as a precise approach to monitor SOC in semi-arid soils of Iran. The final Digital Soil Map (DSM) of SOC revealed that improvements in prediction might be possible with the collection of more soil samples in areas where the land use and topography changed over short spatial scales.
