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Nature and hydrocarbon potential of organic matter in offshore Mahanadi Basin, east coast of India.
No full textEvaluating the hydrocarbon-generating potential of buried organic matter in marine sediments is critical in offshore oil/gas exploration. Organic matter sources, total organic matter content (TOC), and maturity state play key roles in hydrocarbon generation when subjected to suitable temperature–pressure conditions. In the present study, we have characterized organic matter source and maturity to evaluate the hydrocarbon-generating potential of organic matter in the offshore Mahanadi Basin along the east coast of India. Although onshore hydrocarbon reservoirs, including coal, coalbed methane (CBM) and shale gas, are extensively explored in the Mahanadi Basin, a systematic characterization of the offshore buried organic matter is lacking. Towards this endeavour, we have adopted an integrated approach using TOC, (TOC/TN)m, Rock-Eval pyrolysis, and bulk carbon isotopic analyses. Organic geochemical screening (Rock-Eval pyrolysis) reveals predominance of type III and IV kerogen, with TOC content ranging from 0.61 to 1.71 wt.%. The hydrogen index (HI) values (37–156 mg HC/gTOC) infer that the organic matter is prone to generate gaseous hydrocarbons (dry to wet gases). Bi-modal distribution pattern of the S2 peak observed in six samples suggests the presence of both labile and refractory organic matter. The (TOC/TN)m ratios and δ13CTOC values indicate that the organic matter is derived from both terrestrial and marine sources
Groundwater geochemistry and risk assessment to human health in North Karanpura Coalfield, India
No full textThe freshwater resource crisis and human health risk due to drinking of contaminated water are the major issues in mining regions. The primary goal of the present study was to assess the major and trace elements concentration in the groundwater of North Karanpura Coalfield (NKC) of Damodar Valley to identify the major governing factors of groundwater chemistry and estimate the possible human health risk via the drinking water pathway. To achieve the objectives, 34 groundwater samples were collected in the NKC, and analysed for pH, electrical conductivity (EC), turbidity, total dissolved solids (TDS), total hardness (TH), major ions and dissolved metals. The results of the present study revealed that TDS, F−, NO3−, TH, Turbidity, Fe, and Mn were the major concerns and exceeded the Bureau of Indian Standards (BIS 2012) acceptable drinking water limits at many locations in the NKC area. The estimated WQI suggests that few locations were not appropriate for drinking uses. Moreover, the calculated heavy metal pollution index (HPI) indicates that 41% of the water samples belong to the medium class. Further, the calculated hazard index (HI) suggest that the child population were at a higher potential health risk than the adult population in the NKC area. The used approaches show that the quality of groundwater in the area was primarily controlled by the dissolution of minerals and weathering of rocks with minor contributions from agriculture, coal mining and other mining-related activities
Review of the progress of solar-driven interfacial water evaporation (SIWE) toward a practical approach
No full textSolar-driven interfacial water evaporation (SIWE), which has shown a promising use in the fields of water evaporation, desalination, wastewater treatment, and other related activities, has emerged as a practical and effective method for capturing solar energy. SIWE device development and upgraded structural design with increased performance have received much attention in the last decade. In this review article, we revise the level of development achieved for different solar absorber materials and substrates, and their conceptual design in terms of light absorptivity, heat and water management, and structural engineering, along with various potential SIWE applications, including desalination, sterilization, wastewater evaporation, energy generation, and others. Finally, the progress regarding the recent advancements in scalable solar-driven clean water generation is presented. This review summarizes the inclusive development in SIWE from laboratory to practical applications, inspiring new thinking with solutions to the practical challenges and serving as an outline for future investigations
Hydrogeochemical characteristics and multivariate statistical approach for monitoring groundwater quality scenario in the vicinity of industrial area of western Himalaya, India
No full textIn the present investigation, 50 groundwater samples were collected from Udham Singh Nagar District of Kumaun Himalaya in the pre-monsoon season and 15 physicochemical parameters were analysed using standard procedures. Here, we represent the chemistry of major cations and anions to know the overall water quality and hydrogeochemical characteristics controlling the solute acquisition processes and sources of elements in the study area. The analytical results revealed that in the groundwater samples, Ca2+ and Mg2+ were the dominant cations and HCO3−
was the most dominant anion in the study area. In all the groundwater samples, the content of alkaline earth metals (Ca2++ Mg2+) exceeded the mean content of alkalis (Na+ +K+). In 62% of groundwater samples, the value of weak acid (HCO3−
) exceeded the content of strong acid (Cl− + SO42−
). Piper diagram, molar ratios and statistical techniques indicated that weathering of carbonate and silicate minerals mostly managed the solute acquisition process with very less involvement of human activities. Most of the groundwater samples were found suitable for potable and domestic purposes except for a few locations nearby SIKDKUL or other industries (the eastern and western part of the study area). Correlation analysis revealed the dependency of WQI values on Fe and Mn content
Mine soil properties as influenced by tree species and topography of the re-vegetated coal mine overburden dump
No full textRe-vegetation or natural succession of plant species is an important factor of soil development in postmining overburden dumps. As the parent material (sedimentary rocks and regolith) is more or less uniform in the dump, the topographic position and vegetation are the major factors that affects the mine soil quality. Accordingly, this study was designed for a relative evaluation of the influence of dump topographical position (crest, backslope, toeslope) and tree species (Azadirachta indica, Cassia siamea, and Leucaena leucocephala) on soil quality. Trees growing on the toeslope of the dump were significantly taller with larger diameter at breast height than those at backslope or crest. Soil moisture, pH, total S, available P, and Fe content were significantly (P < 0.05) affected by topographical position of the dump. All these properties were higher in the toeslope, except S in the crest. Tree species affected all the soil properties, except electrical conductivity and Mn. Organic carbon content was significantly lower for the nitrogen fixer L. leucocephala (2.03 %) than A. indica (3.30 %) or C. siamea (3.39 %). Soil dehydrogenase activity (39.79 mg TPF/24hr/kg) and microbial biomass carbon (286 µg/g) was higher under L. leucocephala, and C. siamea, respectively. Based on redundancy analysis (RDA), 87.5 % of the data variation is explained by the tree species, whereas, only 12.5 % by the topography. Principal component analysis revealed that C. siamea contributes significantly for the variation in soil properties of the dump. Re-vegetated plant species are a dominant factor of soil development in post mining dump than the topographical position. C siamea and the toeslope are closely associated with soil microbial biomass carbon. It is recommended to plant C. siamea with relatively higher planting density in crest and backslope than toeslope of the dump
Field and numerical modelling on the stability of underground strata in longwall workings
No full textThe longwall method is one of the feasible and efficient underground mining methods for greater depth of workings. Recently, Singareni Collieries Company Limited (SCCL), the largest coal-producing government company in the Southern part of India, has deployed a high capacity (2 × 1152T capacity) power support system in its Adriyala Longwall Project (ALP) at a depth of 375 m. There was a concern about the stability of the longwall workings and the protective pillars. Thus, research work was carried out with the geotechnical instruments and numerical modelling tools to analyze the stability while retreating the longwall panels. The outcomes revealed that the convergence in the gate roads increased with the longwall face advancement and the area of exposure. The pressure of the powered support legs on the dip side was less than the rise side legs, which implies a stable roof condition over the longwall face. An abutment zone was identified ahead of the line of extraction up to 10–25 m and presumed from the Factor of Safety (FoS) criterion that within this zone, the longwall pillar possibly will be of better stability at every stage of extraction. The results obtained from this study would be helpful for the mining engineers to understand the behaviour of underground strata in longwall workings
Dopant-induced photodegradation of organic water pollutants using cobalt oxide nanostructures of low cytotoxicity
No full textMetal oxides are the simplest and most approachable solutions for attaining multifunctional properties applicable
to modern-day technology. With growing concern over environmental conservation, an evaluation of the cytotoxicity of the metal oxides becomes necessary. The present work focuses on the photocatalytic and cytocompatibility behavior of Co3O4 nanomaterial. It has been observed that the addition of Li to the Co3O4 nanostructure generates a positive impact on the photodegradation of cationic dyes under UV light. The photocatalyst with 1 wt% Li-doped Co3O4 was found to be the most competent among the synthesized samples.
Further, the sample has been employed for photocatalytic removal of the hazardous pollutant, pyrocatechol
(PyC), in the presence of visible light. A photocatalytic efficiency of 84.5% (after 9 h) and high stability (86%
after 5 cycles) is observed. A noteworthy revelation is the lower toxicity observed for Li-doped samples when
compared to the pristine Co3O4. The (3-(4,5-dimethylthiazolyl-2)− 2,5-diphenyltetrazolium bromide) (MTT)
assay carried out on mouse skin fibroblast cell lines reveals cytotoxicity inhibition by the doped nanostructures
for up to 10 μg mL− 1 concentration and excellent cell proliferation up to 24 h. The superior catalytic behavior
and non-toxic nature of the Li-doped Co3O4 nanostructures provide ample opportunity for their integration into
water remediation and effluent treatment system
Feedstock and pyrolysis conditions affect suitability of biochar for various sustainable energy and environmental applications
No full textCurrently, the substitution of continuously depleting coal, a predominant source of global energy, and the
treatment of contaminated soil and water bodies with sustainable means are the major concerns. Accordingly,
biochars derived from slow pyrolysis of wood and rice residues (400–1000 ◦C) were observed to improve their
properties over related feedstocks, among noticeable characteristic variations depending on the biomass type and
pyrolysis temperature. Low-temperature pyrolysis produced high-yield biochars, and high-temperature pyrolysis
produced low-yield, higher-C, and higher-HHV biochars. Wood residue biochars had higher HHV (21.25–24.05
MJ/kg) and lower H/C and O/C atomic ratios (0.643–0.201 and 0.326–0.084) than rice residue biochars
(16.61–18.60 MJ/kg) and (1.22–0.259 and 0.720–0.558), respectively. Thus wood residue biochar, because of its
substantially higher HHV than the threshold for an adequate solid fuel, have the potential for energy applica-
tions. The wood residue biochars (600–1000 ◦C) have higher C (>85%) than expected for pulverized coal in-
jection (PCI, 75%C); and for coke, coke breeze, and recarburiser (85%C), together with much less ash and S
content than required for blast furnace (BF). It can be utilized as PCI in BF (100%); as sintering solid fuel and BF
nut-coke (50–100%); as BF carbon/ore briquette and steelmaking recarburiser (0–100%); and as a coal blend
(2–10%) for coke-making, together with reduced onsite emissions. Wood residue biochars from 400 ◦C have the
characteristic potential to replace 22.8% PCI and as a blend with lignite in existing coal-fired power plants. Wood
residue biochars (600–1000 ◦C), with less H/C and O/C atomic ratios and a similar polarity index to pulverized
fuel combustion coal, can be well applied in power-generating systems. Rice residue biochars (400–1000 ◦C),
with poor persistence (O/Corg ratio, 1.228–0.799), higher alkali and alkaline earth metals content, and less HHV
than the threshold for an adequate solid fuel, have weak prudence for fuel applications. But with other adaptable
properties viz., higher pH, ash, (O/C and N/C) atomic ratios, polarity index, surface functional groups, plant
nutrients, and moderate surface areas, can be selectively and judiciously utilized for soil amendment, soil-
remediation, C-sequestration, wastewater treatment, and other pollutant abatements. Decision tree ap-
proaches, based on the characteristic pertinence of these biochars with literature values, have been developed for
their various sustainable energy and environmental usages; and associated environmental concerns and needs to
promote them to industrial-level applications have been discussed
Characterization of Coal Combustion Residues Using Transmission Electron Microscopy Technique
No full textIndian coal-based thermal power stations produces huge amount of coal combustion residues.
Proper disposal, management and utilization of these ashes have always been a challenge before
the thermal power plant management people. In order to find out the potential use of coal
combustion residues one need to explore and look deeply into its various characteristic properties.
In the present study the coal combustion residue samples from thermal power station of eastern
India were used for characterizing ashes on the basis of Transmission Electron Microscopy
technique. The study of the micrographs of Transmission Electron Microscopy showed that the coal
combustion residue samples consisted of all the three viz. crystalline, polycrystalline and
amorphous phases. The coal combustion residue samples were found to consist of single crystal,
single crystal with hexagonal structure, polycrystalline substances and closed packed hexagonal
structure. Concentric circles as seen in the diffraction pattern show the presence of polycrystalline
substances in the samples. Presence of plerosphere in the coal combustion residue samples can
also be seen from some SEM micrographs as well as one of TEM images. XRD studies show the
presence of various crystalline substances present in the coal combustion residues. The study
shows that the CCR samples are typically formed of Si-Al-Fe system with traces of sodium,
potassium, calcium, magnesium, sulphur and titaniu
Major ion chemistry and hydrochemical processes controlling water composition of Teesta River catchment, Sikkim Himalaya, India
No full textThe study determines the major ion chemistry of the Teesta River catchment in the Eastern Himalayan region and evaluates hydrochemical processes controlling water composition of the catchment area. Water of the Teesta River basin was in neutral to alkaline condition. HCO3−, Ca2+, Na+, Mg2+ and SO42- were identified as the dominant ionic species in the Teesta catchment water composition and Ca-Mg-HCO3 as the dominant hydrochemical facies. Higher contribution of (Ca2++Mg2+) and HCO3− towards the TZ+ and TZ−, high ionic ratios of (Ca2++Mg2+)/(Na++K+), HCO3−/(Cl−+SO42-) and low (Na++K+)/TZ+ ratio suggest carbonate weathering as a major contributor of dissolved ions in the Teesta basin water. Under-saturation with respect to both carbonate and sulphate phase minerals suggests that water can dissolve these minerals during water-rock interaction. Concentration of the analysed water quality parameters were well below the specified drinking and irrigation water limits