• Energy Research

Abstract This paper reports the mineralogical and geochemical compositions of the Padhrar (salt-range), Thar (Block Nos. 3 and 5) and Kotli coals. The coal investigated in this study is lignite to sub-bituminous coal, with a broad range of ash yields, volatile matter content and sulfur contents. The mineralogical characteristic, major and trace elements were determined by X-ray diffraction, inductively coupled plasma-atomic emission spectrometry and inductively coupled plasma-mass spectrometry, respectively. The mineral assemblages, sulfur contents, ash yields, and (CaO + MgO + Fe2O3)/(SiO2 + Al2O3) ratio varied significantly in the coal, which is attributed mainly to variation in the depositional environment. Pyritic sulfur is the main form of sulfur in the coals from Padhrar, Kotli and Thar coalfield. The minerals in the studied coals are dominated by quartz, pyrite, kaolinite, illite, along with calcite, feldspar, siderite, montmorillonite and gypsum. Sixteen trace elements, including Li, Be, B, Ti, Sc, V, Cr, Mn, Co, Ni, Cu, Zn, As, Rb, Sr, and Ba and five major elements P, Ca, Al, Fe, and Si, were investigated in this study. The trace element concentrations show variety within the coal seams in the Thar coals and the affinities vary among locations. The concentration of Sr, Ti, Zn, Li, Ni, Cu, Sc, As, Be, and B in the present study are within the range of average Chinese coal values, with the exception of V, Cr, Fe, P, and Rb. On the other hand, compared with world coals, the studied coals have higher contents of B, Cr, Li, Fe, V, Rb, P, and Sc. Based on statistical analyses, most of the trace elements, show an affinity to ash yield and possible association with pyrite, kaolinite, and calcite.

This study was designed to examine the combined effect of bamboo-biochar (BC) and water-washed lignite (LGT) at copper mine tailings (CuMT) sites on the concentration of Cu and other metals in pore water (PW), their bioavailability, and change in geochemical speciation. Rapeseed (first cropping-season) and wheat (second cropping-season) were grown for 40-days each and the influence of applied-amendments on both cropping seasons was observed and compared. A significant increase in pH, water holding capacity (WHC), and soil organic carbon (SOC) was observed after the applied amendments in second cropping-seasons. The BC-LGT significantly reduced the concentration of Cu in PW after second cropping seasons; however, the concentration of Pb and Zn were increased with the individual application of biochar and LGT, respectively. BC-LGT and BC-2% significantly reduced the bioavailability of Cu and other HMs in both cropping seasons. The treated-CuMT was subjected to spectroscopic investigation through X-ray photoelectron spectroscopy (XPS), Fourier transform Infrared spectroscopy (FTIR), and X-ray powder diffraction (XRD). The results showed that Cu sorption mainly involved the coordination with hydroxyl and carboxyl functional groups, as well as the co-precipitation or complexation on mineral surfaces, which vary with the applied amendment and bulk amount of Mg, Mn, and Fe released during sorption-process. The co-application of BC-LGT exerted significant effectiveness in immobilizing Cu and other HMs in CuMT. The outcomes of the study indicated that co-application of BC-LGT is an efficacious combination of organic and inorganic materials for Cu adsorption which may provide some new information for the sustainable remediation of copper mine tailing.

Abstract The influences of pyrolysis conditions on the products yield distribution and physico-chemical characteristics of biochar derived from peanut shell in a fixed-bed reactor were investigated in this study. The pyrolysis conditions included the pyrolysis temperature (300–700 °C), retention time (15–90 min), heating rate (1–10 °C min−1), gas flow rate (20–200 mL min−1) and feedstock particle size (

Potentially toxic elements (PTEs) discharge to the soil environment through increased anthropogenic activities is a global threat. These PTEs can have harmful and chronic-persistent health effects on exposed populations through food consumption grown on contaminated soils. Efforts to investigate the transformation mechanism and accumulation behavior of PTEs in soil-plant system and their adverse health-effects have focused extensively in previous studies. However, limited studies address biochar nanosheets (BCNs) as a potential soil amendment to reduced humans health risks through dietary intake of food-crop grown on PTE-contaminated soil. Here, we showed how BCNs cutback health hazards of PTEs through impacts on bioavailability and phytoaccumulation of PTEs, and their daily intake via consumption of wheat. When BCNs amendment was compared with both conventional organic amendments (COAs) and control, it significantly (P ≤ 0.05) reduced bioavailability and uptake of PTEs by wheat plants. Based on risk assessment results, the hazard indices (HIs) for PTEs in all treatments were <1, however, BCNs addition significantly (P ≤ 0.05) reduced risk level, when compared to control. Furthermore, the cancer risks for Cd, Cr and Ni over a lifetime of exposure were higher in all treatments than the tolerable limit (1.00E-4 to 1.00E-6), however BCNs addition significantly suppressed cancer risk compared to control. Conclusively, our results suggest that BCNs can be used as soil amendment to reduce potential risks of PTEs through consumption of food grown in PTE-contaminated soils.

Abstract Vacuum carbonization is considered to be an effective and promising thermochemical-tool for resource and energy recovery by collecting and reusing pyrolysis products and volatiles. In this study, thermochemical conversion of orange peel to biochar under low- and medium-vacuum pyrolysis conditions were investigated for product distribution and stability characteristics of biochar. The pyrolysis experiments were executed under three different conditions i.e., N2 atmosphere (without vacuum), low-vacuum (1013.2 Pa) and medium-vacuum (101.3 Pa) in the temperature range of 300–700 °C. The derived biochars were characterized for its aromaticity, polarity, elemental composition, pH, electrical conductivity, surface area, thermal decomposition, FTIR spectroscopy and chemical oxidation properties. Results revealed that low and medium-vacuum pyrolysis had an overriding effect on the H/C (aromaticity) and O/C (polarity) ratios, surface functional groups, as well as on the chemical oxidation potential of derived biochars. A significant reduction in biochar yield (1.1–1.9 folds), increased aromaticity with low H/C (1.3–2.0 folds) and O/C (1.95–4.75 folds) values was observed with increased pyrolysis temperature, under low- and medium-vacuum pyrolysis compared to the N2 atmosphere. It was also found that biochar produced in the temperature range of 300–700 °C, under low and medium-vacuum pyrolysis were comparatively preferable to biochar stability. It is concluded that biochar produced at low-medium vacuum pyrolysis conditions shows higher carbon sequestration potential compared to the N2 atmosphere.

Bioenergy is considered a sustainable substitute to fossil-fuel resources and the development of a prudent combination of renewable and innovative conversion technologies are essential for the valorization and effective conversion of biowaste to value-added commodities. Here, a negative pressure-induced carbonization process was proposed for the valorization of lignin-enriched biowaste precursor to bio-oil and environmental materials (biochar) at various temperatures. The high heating values (HHV) of the as-prepared biochars from the lignin enriched precursor under negative pressure (low-medium vacuum) were within 25.9-31.5 MJ/kg, which matched satisfactorily to the commercial charcoal. Whereas, the bio-oils produced from the lignin enriched precursor under vacuum conditions was a blend of complex aromatic and straight-chain hydro-carbons, including aldehyde, ketone, phenol, and furans, exhibiting ability as potential heating-oil with HHV within 21.2-28.2 MJ/kg. Moreover, the biochars produced under vacuum environments at higher temperature showed greater stability (22.5-35.9%) than those produced under N2 atmosphere.

Abstract Biomass, as a renewable and sustainable energy resource, can be converted into environmentally friendly and practically valuable biofuels and chemical materials via pyrolysis. However, the process optimization and pyrolysis efficiency are restricted by the limited perception of the complicated mechanisms and kinetics for biomass pyrolysis. Here, to establish an in-depth mechanism model for biomass pyrolysis, we presented a novel investigation for the thermal evolutions and pyrolysis kinetics of the functional groups in peanut shell matrix by using in-situ Fourier transform infrared spectrometry (in-situ FTIR) and thermogravimetric analysis-Fourier transform infrared spectrometry-mass spectrometry (TG-FTIR-MS). The in-situ FTIR spectrum deconvolution for the solid matrix was innovatively introduced to identify and quantify the real-time evolution and thermal dynamics of the functional groups during peanut shell pyrolysis. The result for the first time proposed that the pyrolysis mechanisms of total OH at 20–380 °C, aliphatic C-Hn groups at 20–500 °C, C O groups at 260–500 °C, and C–O groups at 300–500 °C were dominant by diffusion and order-based chemical reactions. The TG-FTIR-MS analysis was conducted for the online monitoring of the released volatiles and gases, the amounts of which were in the sequence of C O > CO2 > aliphatic C–O-(H) > C–O-(C) in esters > aromatics > H2O > phenolic hydroxyl > aliphatic hydrocarbons > CO. The study established a novel methodology to evaluate the biomass pyrolysis mechanisms at the molecular level, which provided valuable information for developing advanced pyrolysis techniques on a large scale for sustainable ecosystem.

Abstract In terms of net intensification in the greenhouse effect ie., rise of global temperature which has triggered melting of glacier thus increasing sea level and acidification of sea, carbon dioxide alone contributes approximately three-fourth of the net greenhouse radiative forcing by man-made (anthropogenic) greenhouse gases emissions. Carbon dioxide capture and storage (CCS) technology; a promising strategy for capturing of carbon dioxide from point sources before its release to atmosphere by using various sorbents is gaining global interest. In this study, the established carbon capture technologies with methods of carbon dioxide separation along there pros and cons are discussed. Carbon-based adsorbents are considered as the most versatile adsorbents for carbon dioxide due to their extraordinary physical and chemical properties. In this manuscript, recent developments on carbonaceous adsorbents (biochar, activated carbons, and graphene-based adsorbents) and their role in carbon dioxide capture during different combustion processes and conditions have been comprehensively focused.

Abstract Ragweed (Ambrosia artemisiifolia L.), a metal-accumulator invasive species, was pyrolyzed under a range of pyrolytic conditions to investigate their influence on immobilization and environmental safety of potentially toxic elements (PTEs) in the produced biochar. Conditions tested included temperature, retention time, heating rate, gas flow rate and particle size. Temperature and particle size had pronounced effects on product yields and physico-chemical characteristics of the produced biochar. All PTEs were enriched in the biochar, and the effect was more pronounced with higher temperature over 500 °C. However, fractionation of PTEs in biochar by following the sequential extraction process indicates that the mobile (bioavailable) fraction of most of the PTEs was transformed into more stabilized (residual) form (P