scholarly journals Distribution and modes of occurrence of uranium in coals of Eastern Yunnan, China

2021 ◽  
Author(s):  
Xin Wang ◽  
Qiyan Feng ◽  
Qingjun Meng ◽  
Fei Liu ◽  
Qihang Cao ◽  
...  
Keyword(s):  
Coal Mines ◽  
Extraction Procedure ◽  
Uranium Content ◽  
Chemical Extraction ◽  
Modes Of Occurrence ◽  
Average Value ◽  
Sequential Chemical Extraction ◽  
Coal Deposits ◽  
Hazardous Element ◽  
Sedimentation Processes

AbstractUranium is an environmentally hazardous element, and is commonly present at trace levels (2.4 μg/g for world coals) in coal deposits. However, selected coal deposits could be highly enriched in uranium. In this study, 15 coal samples were collected from Eastern Yunnan coal deposits, China, aiming to characterize the distribution and the occurrence of uranium in those coals. In studied samples, uranium content varied from 0.36 to 8.28 μg/g, with an average value of 3.76 μg/g. Generally, uranium content in coals from northern coal mines (3.02 ± 2.44 μg/g, n = 5) were lower than it in southern coal mines (4.13 ± 2.30 μg/g, n = 10). Uranium in coal samples showed no obvious correlation with total sulfur, whereas was positively correlated with ash yield. The results of sequential chemical extraction procedure confirm that organic-bound is the dominant occurrence of uranium. The slight enrichment of uranium in studied coals was probably attributed to sedimentation processes, hydrological conditions and tectonic structure of the coal deposits.

Study on the modes of occurrence of rare earth elements in coal fly ash by statistics and a sequential chemical extraction procedure

Fuel ◽  
2019 ◽  
Vol 237 ◽  
pp. 555-565 ◽  
Author(s):  
Jinhe Pan ◽  
Changchun Zhou ◽  
Mengcheng Tang ◽  
Shanshan Cao ◽  
Cheng Liu ◽  
...  
Keyword(s):  
Rare Earth ◽  
Fly Ash ◽  
Rare Earth Elements ◽  
Coal Fly Ash ◽  
Extraction Procedure ◽  
Chemical Extraction ◽  
Modes Of Occurrence ◽  
Sequential Chemical Extraction

scholarly journals Heavy metals Fractionation in Bagmati River Sediments, Nepal

2016 ◽  
Vol 9 (1) ◽  
pp. 119-128
Author(s):  
Sadhana Pradhanang Kayastha
Keyword(s):  
Heavy Metals ◽  
Total Concentration ◽  
River Sediments ◽  
Extraction Procedure ◽  
Absorption Spectrometry ◽  
Chemical Extraction ◽  
Geochemical Background ◽  
Sediment Samples ◽  
Sequential Chemical Extraction ◽  
Bagmati River

The aim of this work was speciation of heavy metals on the level of the geochemical background; in bottom sediments of the Bagmati River in Kathmandu valley. The distribution and accumulation of heavy metals in the sediments of the Bagmati River were investigated. Sediment samples from six locations were collected and characterized for metals content (cadmium, lead, copper and zinc). The determination of extractable heavy metals such as, Cd, Pb, Cu and Zn, in the sediment samples was carried out by atomic absorption spectrometry. The study has been conducted using five steps sequential extraction procedure described by tessier. Apart from total concentration, the distribution of the above metals into five fractions: exchangeable, bound to carbonates, bound to Fe-Mn oxides, bound to organic matter, and residual, was studied by means of an analytical procedure involving sequential chemical extraction. The result obtained showed total metal concentration to be in the range of Cd 0.89-2.29 mg/kg; Pb 57.58-221mg/kg; Cu 52.2 -198.17 mg/kg and 78.23-362.90 mg/kg in all the areas studied. The fractionated toxic metals like Cd, and Pb were observed to be in the range of 15-36%, and 11- 29%, respectively, in mobile or bio-available fractions of sediments. This potentially mobile fraction could pose a serious threat, with respect to contamination of waterways and aquatic environment.Journal of Hydrology and Meteorology, Vol. 9(1) 2015, p.119-128

scholarly journals Modes of Occurrence of Chromium and Their Thermal Stability in Low-Rank Coal Pyrolysis

Processes ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 15
Author(s):  
Xiaobing Wang ◽  
Lingmei Zhou ◽  
Shuquan Zhu ◽  
Hao Zheng ◽  
Yue Ma ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Organic Matter ◽  
Low Rank ◽  
Chemical Extraction ◽  
Coal Pyrolysis ◽  
Low Rank Coal ◽  
Modes Of Occurrence ◽  
Sequential Chemical Extraction ◽  
Gas Products ◽  
Equilibrium Simulation

Chromium (Cr) and the emission of its compounds into the environment have caused long-term environmental contamination. In this study, the modes of occurrence of Cr in low-rank coal and their thermal stability in pyrolysis were investigated by sequential chemical extraction (SCE), single-component samples (SCS) pyrolysis, and thermochemical equilibrium simulation. The results showed that organic matter, aluminosilicate, and carbonate were the dominant modes of occurrence of Cr in low-rank coal. The modes of occurrence and chlorine (Cl) content affected the volatilization of Cr in coal. The characteristic release temperature range of Cr bounded to aluminosilicate was >600 °C and 400–600 °C for Cr bounded to a disulfide. Cr bounded to organic matter almost released completely before 600 °C. Cl enhanced the volatility of Cr and reduced its release temperature in Cr bounded to aluminosilicate. The simulation showed the content of gas products was very low, mainly chlorides. While the content of solid products, sulfides, and oxides, was much higher than gas products, showing their high thermal stability. The sulfides and oxides in chars were closely related to the carbonate and aluminosilicate bound form of Cr. The results of the equilibrium simulation were consistent with the experimental results.

scholarly journals Assessment of heavy metal removal efficiencies by naturally fermented and a. niger fermented pineapple wastes from contaminated sewage sludge

2007 ◽  
pp. 429-438
Author(s):  
Dominica del Mundo Dacera ◽  
Sandhya Babel
Keyword(s):  
Citric Acid ◽  
Sewage Sludge ◽  
Metal Removal ◽  
Heavy Metal Removal ◽  
Extraction Procedure ◽  
Extraction Process ◽  
Chemical Extraction ◽  
Sequential Chemical Extraction ◽  
Removal Efficiencies

Heavy metals in sewage sludge can pose a long term environmental risk due to their toxicity,non-biodegradability and consequent persistence, This study assessed the efficiencies ofvarious organic extractants such as naturally fermented and A�pergillus niger (A. niger)fermented raw liquid from pineapple wastes, in the chemical extraction process, to extract Cr,Cu, Pb, Ni and Zn, from anaerobically digested sewage sludge in Thailand. Pineapple wastesare a good source of sugar and protein and have been utilized experimentally in theproduction of citric acid by fennentation with the fungus A. niger. Comparison of theextraction efficiencies of these extractants with commercial citric acid was also investigated attwo hours leaching time and pH 3 and greater. Results of the study revealed that at pHapproaching 4, A. niger fermented liquid seemed to exhibit the best removal efficiency forpractically all metals studied, attaining as much as 72% removal for Zn, 70% for Ni, 50% forCr and 37% for Cu, although effectivity of removal seemed to be less apparent for Pb. Themost readily solubilized metal seemed to be Zn with the most removal of 92% attained bynaturally fermented raw liquid, The effectivity of removal by A. niger fem1ented liquid maybe due to the presence of citric acid and other carboxylic acids as confirmed by the HPLC andIR studies of the fem1ented liquid, Moreover, variation in metal removal efficiencies may beattributed to the fonns of metals in the sludge, as evidenced by chemical speciation studiesusing sequential chemical extraction procedure, with metals predominantly in theexchangeable and oxidizable phases showing ease of leachability,

scholarly journals Geochemistry of elements associated with Late Permian coal in the Zhongliangshan mine, Chongqing, Southwest China

2018 ◽  
Vol 36 (6) ◽  
pp. 1655-1673
Author(s):  
Shenjun Qin ◽  
Qingfeng Lu ◽  
Kang Gao ◽  
Penghui Bo ◽  
Shihao Wu
Keyword(s):  
Trace Elements ◽  
Inductively Coupled Plasma ◽  
Southwest China ◽  
Major And Trace Elements ◽  
Chemical Extraction ◽  
Late Permian ◽  
Modes Of Occurrence ◽  
X Ray ◽  
Sequential Chemical Extraction ◽  
Permian Coal

The enrichment and geochemical significance of elements associated with Late Permian coals in Southwest China have always gained widespread interest in the field of coal geology. The present study focuses on the geochemical characterization of Late Permian coal in the Zhongliangshan mine. Twenty-three samples were collected from the K1a coal seam of the Zhongliangshan mine, and the major and trace elements in the coal were analyzed by using X-ray fluorescence spectroscopy (XRF) and inductively coupled plasma mass spectrometry. The composition of minerals in the Zhongliangshan coal, and the modes of occurrence of coal-associated elements, especially those with elevated contents, were studied through a combination of microscopic analyses, X-ray powder diffraction, and scanning electron microscope – energy dispersive X-ray spectrometer. The minerals in coal mainly consist of kaolinite, pyrite, calcite, and quartz, as well as small amount of gypsum and anatase. Compared with the average elemental concentrations in world coal, the Zhongliangshan coal is enriched in Cr, and slightly enriched in Li, U, Sr, V and Ag. Combining the correlation analysis and sequential chemical extraction experiments, it can be inferred that many trace elements in the Zhongliangshan coal have both inorganic and organic affinities. The elements Cr, Li, and V mainly occur in clay minerals, and also are related to organic matter in the coal. Uranium presents firstly in the organic and then silicate states. Strontium shows multiple modes of occurrence including carbonate, silicate, and exchangeable ion states, and Ag primarily occurs in sulfides followed by silicates. The terrigenous debris input from the Emeishan basalt is the major reason for the enrichment of above elements in the Zhongliangshan coal.

Characteristics of various forms of phosphorus and their relationships in the sediments of Haizi Lake, China

2012 ◽  
Vol 66 (12) ◽  
pp. 2688-2694 ◽  
Author(s):  
Dongsu Bi ◽  
Xiaopin Guo ◽  
Zhihong Cai ◽  
Xiufang Gao ◽  
Yan Li ◽  
...  
Keyword(s):  
Extraction Procedure ◽  
Chemical Extraction ◽  
Overlying Water ◽  
Inorganic P ◽  
Sequential Chemical Extraction ◽  
River Region ◽  
Carbonate Fluorapatite ◽  
Exchangeable P ◽  
P Distribution ◽  
Total P

The phosphorus (P) distribution in the sediments of Haizi Lake from the middle reach of the Yangtze River region, China, was investigated using a sequential chemical extraction procedure. P forms and concentrations of sediment samples taken at 25 sites over the whole lake were measured. The relationships between various forms of P in sediments and dissolved P in the overlying water were also discussed. Results showed that the concentrations of total P (TP) in the sediments ranged from 404 to 670 mg kg−1, with an average of 503 mg kg−1. The exchangeable P (Ex-P), Al-bound P (Al-P), Fe-bound P (Fe-P), occluded P (Oc-P), authigenic carbonate fluorapatite + biogenic apatite + CaCO3-associated P (ACa-P), detrital apatite + other inorganic P (De-P) and organic P (Or-P) accounted for, on average, 0.52, 0.04, 10.9, 32.0, 7.4, 20.1 and 29.0% of TP, respectively. Relevance analysis indicated that Oc-P, ACa-P and De-P, as the majority forms of inorganic P, were less correlated to others. The significant correlations between Ex-P, Al-P, Fe-P, Or-P and TP suggested the probability of reciprocal transformation. It was suggested that Ex-P, Al-P, Fe-P, Or-P and TP in the sediments might be released easily to the water interface, resulting in sustained lake eutrophication.

scholarly journals Impact of Mining Dump on the Accumulation and Mobility of Metals in the Bytomka River Sediments

2014 ◽  
Vol 40 (2) ◽  
pp. 3-19 ◽  
Author(s):  
Magdalena Jabłońska-Czapla ◽  
Sebastian Szopa ◽  
Czesława Rosik-Dulewska
Keyword(s):  
Heavy Metals ◽  
Ion Exchange ◽  
Bottom Sediments ◽  
River Sediments ◽  
Extraction Procedure ◽  
Residual Fraction ◽  
Chemical Extraction ◽  
Coal Waste ◽  
Waste Dump ◽  
Sequential Chemical Extraction

Abstract The research aim was to determine the long-term impact of the mine waste stored at the coal waste dump Hałda Ruda on the content of heavy metals in the bottom sediments of the Bytomka River. It is a watercourse flowing along this coal waste dump and has been under its influence for over fifty years. The research also attempted to determine the seasonality of changes (2 years) and mobility of selected elements. The article presents total contents of Cr, Mn, Ni, Cu, Zn, As, Cd and Pb in the bottom sediments collected from the Bytomka River. It also focuses on the distribution of these elements in particular geochemical fractions determined with the Tessier's sequential chemical extraction procedure. Total element contents were determined with an EDPXRF (Energy Dispersive X-ray Fluorescence) technique. The extractants of particular Tessier's fractions were determined quantitatively with an ICP-MS (Inductively Coupled Plasma Mass Spectrometry) spectrometer. The research results show that the stored waste significantly influences the contents of heavy metals in the Bytomka River bottom sediments. The lowest concentration of heavy metals was observed at the B1 spot (above the dump), while the highest one was measured at the B3 spot (below the dump). Sequential chemical extraction of the bottom sediments indicates that the Zn content in the ion-exchange and carbonate fractions diminished within a year. Nevertheless, Zn bound to Fe and Mn oxides acted in the opposite way. Mn, Zn and Pb are the most dangerous elements from the viewpoint of environmental hazards, as their total concentrations were high. Moreover, their high contents were observed in the most mobile (ion-exchange and carbonate) fractions. Extremely toxic Cd was bound to the oxide fraction to the largest extent. Cu was mainly bound to the organic fraction while environmentally hazardous Cr was bound to the residual fraction.

scholarly journals Polarity-Based Sequential Extraction as a Simple Tool to Reveal the Structural Complexity of Humic Acids

Agronomy ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 587
Author(s):  
Vojtěch Enev ◽  
Petr Sedláček ◽  
Leona Kubíková ◽  
Šárka Sovová ◽  
Leoš Doskočil ◽  
...  
Keyword(s):  
Structural Parameters ◽  
Extraction Procedure ◽  
Physicochemical Characterization ◽  
Structural Complexity ◽  
Structural Features ◽  
Chemical Extraction ◽  
Spectroscopic Techniques ◽  
Humic Material ◽  
Sequential Chemical Extraction ◽  
Organic Fractions

A sequential chemical extraction with a defined series of eluotropic organic solvents with an increasing polarity (trichloromethane < ethyl acetate < acetone < acetonitrile < n-propanol < methanol) was performed on peat-bog humic acid. Six organic fractions were obtained and subjected to a physicochemical characterization utilizing methods of structural and compositional analysis. Advanced spectroscopic techniques such as Attenuated Total Reflectance (ATR-FTIR), total luminescence, and liquid-state 13C NMR spectrometry were combined with elemental analysis of the organic fractions. In total, the procedure extracted about 57% (wt.) of the initial material; the individual fractions amounted from 1.1% to 19.7%. As expected, the apolar solvents preferentially released lipid-like components, while polar solvents provided organic fractions rich in oxygen-containing polar groups with structural parameters closer to the original humic material. The fraction extracted with acetonitrile shows distinct structural features with its lower aromaticity and high content of protein-like structural motifs. The last two—alcohol extracted—fractions show the higher content of carbohydrate residues and their specific (V-type) fluorescence suggests the presence of plant pigment residues. The extraction procedure is suggested for further studies as a simple but effective way to decrease the structural complexity of a humic material enabling its detail and more conclusive compositional characterization.

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