Moganite in agates from shungite rocks of the Paleoproterozoic Onega basin (Karelia)

In order to establish a sustainable society, with practical material recycling, it is appropriate to focus on a range of guiding ``Earth principles,'' including the character and application of hydrothermal processes. In this paper, it is demonstrated how information obtained from the study of fundamental Earth principles can be used to inspire the development of new methods for material recycling, such as the following: 1) Hydrothermal hot-pressing processes, simulating the formation of sedimentary rock sequences, can be used for the solidification of toxic and hazardous materials. 2) Organic materials could be formed from CO2 under hydrothermal conditions (using Fe and Ni metals, and low valence Fe oxides), at temperature and pressure conditions consistent with a subduction (tectonic) setting, such as (under Japan) where the Pacific Plate sinks beneath the (Eurasian) continental plate. 3) Diamond-structured carbon may be formed from toxic chlorinated hydrocarbon, in very high pressure regions of the Earth, and at high alkaline hydrothermal conditions, where magma formation may occur. 4) High temperature dry steam in rock fractures (at near critical conditions -i.e. below saturated vapor pressure, but relatively high pressure) is not only a source/carrier of noble metals, including gold, silver and copper, but also ceramic materials, silica and alumina. Its laboratory simulation may also be a guide for the formation of thin layer silicate ceramics on metal plates (e.g. SUS-304 nickel alloy). 5) To design an underground boiler in hot dry rock, non-equilibrium dissolution and deposition hydrothermal processes may be studied using a tube reactor, which simulates fluid flow and temperature gradients in fractured hot rock.

Degradation of xylose residue (XR) was carried out in hydrothermal treatment process (HTP) at various temperatures, residence times, solid–liquid ratios, and particle sizes. The properties of liquid, gas, and solid (hydrochar) products were investigated in anticipation of obtaining the process conditions for the preparation of optimum‐performance hydrochar. It was found that temperature was the most important factor affecting hydrothermal treatment process. For hydrochar, as the temperature rose from 200 to 320°C, the mass yield (MY), volatile matter (VM), and blackness value decreased, but the fixed carbon (FC) content and high heating value (HHV) increased. Compared with XR, the VM of hydrochar decreased from 87.97% to 30.3%, FC content increased from 8.23% to 68.91%, and HHV increased from 17.88 MJ/kg to 28.62 MJ/kg. The best data obtained from hydrochars were the iodine value, 89.03 g/kg, and DBP value, 190 cm 3 /g, which were quite close to that of the commercial carbon black. The gas chromatography coupled to a mass spectrometry (GC–MS) characterization indicated that ketones, phenols, organic acids, and furans were the main components in bio‐oil (the maximum yield of 19.22%). The contents of ketones and phenols increased with the temperature, and the highest relative contents were up to 29.54% and 32.84%, respectively. The gas and loss product yield reached its highest, 61.31%, at 320°C. CO 2 dominated in gas‐phase fractions, accounting for about 90%. H 2 , CO, and CH 4 were clean and efficient energy sources, but were too few. This study was expected to transform XR into high value‐added products and provided new ideas for the resource utilization of waste.

In this contribution, we present the results of mineralogical investigation of the agates in Paleoproterozoic organic carbon-rich sedimentary rocks within the Onega Basin (Fennoscandian shield, Russia) aimed at reconstructing the agate-forming processes. Optical and scanning electron microscopy, EDS microanalysis, thermal analysis, X-ray powder diffraction, Raman spectroscopy, and carbon isotope analysis were used for the study. Three main varieties of agates differing in morphology and texture were identified, including concentrically zoned nodules, fine-banded, and carbon-rich moss agates. Mineralogical evidence indicates the participation of hydrothermal fluids in agate formation. Concentrically zoned nodules could be formed due to the dissolution of carbonate concretions in the organic carbon-rich siltstones and their silicification as a result of late hydrothermal processes. Fine-banded vein agates occur in stockworks crosscutting organic carbon-rich rocks and are widely accompanied by sulfides, selenides, carbonates, sulfates, and iron oxides. Carbonaceous matter in moss agates is present as poorly ordered carbon and is characterized by a low δ13Corg value (−25.64‰), suggesting a biogenic origin. Raman spectroscopy data showed an elevated amount of moganite besides alpha quartz in the concentrically zoned nodules compared to other agate varieties, indicating different ages of the mineralization processes. We suggest that the revealed varieties of agates were formed at different stages of long-term hydrothermal processes occurring in the Onega Basin.

Revealing the heating value characteristics of sludge-based hydrochar in hydrothermal process: from perspective of hydrolysate

A continuous-mode hydrothermal process (CHTP) reactor was developed to convert swine manure into oil. The effects of operating parameters on oil yield and quality were investigated to determine the optimal condition for the continuous-mode process. Operating temperature, pressure, residence time, and the use of carbon monoxide as a process gas were all found to affect oil yield. Results showed an interaction between the operating temperature and pressure. Oil yield increased with hydraulic residence time, but a diminishing benefit was observed beyond 60 min. A slight decrease in yield was found when carbon monoxide was used. The highest oil yield of 70% (of volatile solids) was in the region where temperature was about 300C and pressure was 10 MPa. Increasing the temperature from 285C to 305C was found to increase the carbon content, heating value, and benzene solubility of the oil. However, increasing the pressure negatively affected both the carbon content and heating value of the oil. The addition of carbon monoxide was found to be beneficial in increasing the carbon content of the oil by 7.4% and improving its solubility to benzene. The hydrogen, nitrogen, and sulfur content of the oil were relatively constant for all test cases, with values of 9.6 0.4%, 3.9 0.3%, and 0.3 0.1%, respectively.

Fabrication of a magnetic hydrochar composite via an in situ one-pot hydrocarbonization strategy for efficient herbicide removal

The effect of chitosan oligosaccharides on the shelf-life and quality of fresh wet noodles

Boron, sulphur and copper isotope systematics in the orogenic gold deposits of the Archaean Hattu schist belt, eastern Finland

The origin of Ordovician siliceous rocks and their deposition settings in the Northwest Tarim Basin, NW China

Hydrothermal dewatering process has been made to produce dry-processed coals, which are comparable to bituminous coal. Two types of coals, i.e. low rank and high-rank coals. The low-rank coal came from West Papua while the high one was from Central Kalimantan. The behaviour of raw and processed coals were observed using thermogravimetry and differential scanning calorimetry techniques The change in chemical properties that are based on proximate, ultimate, calorific value and Fourier-transform infrared spectroscopy analyses are studied. Those are closely related to some combustion problems. This process was conducted in a laboratory scale using an autoclave with 5,000 ml/batch in capacity at the temperature of 300 and 330°C for one hour. The results indicate that the processed coals generally have a better combustion behaviour than that of the raw coals. The processed coals have a lower reactivity than that of raw ones, due to the higher ignition temperature (Tig), char burnout temperature (Tbo) as the end of combustion and maximum combustion rate (Rmax) of processed coals. The processing temperature of the process was a slight effect on combustion behaviour. The process is very effective to improve the quality of low-rank coal, nonetheless to high-rank coal, which has low moisture content and high calorific value, and the combustion behaviour of processed coals was not significantly changed.

The structural characteristics of products derived from the hydrothermal carbonization (HTC) of loblolly pine (LP) and straw grass (SG) were investigated via solid-state cross-polarization/magic angle spinning nuclear magnetic resonance (CP/MAS 13C NMR), heteronuclear single-quantum correlation nuclear magnetic resonance (HSQC-NMR), and solution 13C NMR and 31P NMR techniques. Results revealed that after HTC, hydrochars from both LP and SG mainly consisted of a combination of lignin, furfural, and condensed polyaromatic structures with a high level of fixed carbon content and higher heating value (HHV). Hydrochar from LP exhibited a higher aryl to furan ratio, and those from SG contained more aliphatic functional groups. Solution 13C NMR and HSQC revealed that both liquid chemicals were condensed polyphenolic structures with aliphatic groups that exist mainly in the form of side chains. Although the LP products exhibited a higher proportion of aromatic structures, the types of polyphenol and aliphatic C–H were more diverse in the SG products. Results also indicated that reactions such as chain scission and condensation occurred during hydrothermal carbonization processes. Overall, HTC was found to be an effective refinery treatment for converting different waste biomass into valuable energy materials and chemicals.

The conversion of biomass to biofuels as a renewable energy source is continuously gaining momentum due to the environmental concerns associated with using fossil fuels. Biomass is a cost-effective, long-term natural resource that may be converted to biofuels such as biodiesel, biogas, bio-oil, and biohydrogen using a variety of chemical, thermal, and biological methods. Thermochemical processes are one of the most advanced biomass conversion methods, with much potential and room for improvement. Among various thermochemical processes, hydrothermal liquefaction (HTL) is a promising technology that can convert higher water-content feedstocks into biofuel with significantly lower oxygen content and higher calorific value without requiring the biomass to be dried first. In HTL, temperature, pressure, residence time, catalyst, and solvent all play a vital role in bio-oil quality. This study provides a comprehensive review of the research and development on the effects of catalysts and the need to optimise existing catalysts for optimum biomass conversion into high-value bio-oil and other products. The catalyst of interest is ZSM-5, a heterogenous catalyst that has been seen to increase the hydrocarbon content and decrease oxygenated compounds and other unwanted by-products. The use and modification of this catalyst will play a vital role in generating renewable and carbon-neutral fuels.

Nutrient recycling of aqueous phase for microalgae cultivation from the hydrothermal liquefaction process

Orbital remote sensing has shown that some regions of the ancient Martian crust contain hundreds of discrete terrains covered by chloride‐rich evaporites. In terrestrial evaporitic systems, evaporite sequences typically begin with the deposition of carbonates, followed by sulfates, and finally chlorides, a depositional sequence that has not yet been found on Mars. Instead, sulfate deposits are always separated spatially and temporally from chlorides, suggesting two different depositional regimes. Here, we present a model driven by the Martian chlorine geochemical cycle that allows the formation of chlorides whilst simultaneously inhibiting sulfate and carbonate precipitation. In this model, the chlorides are produced under reducing and acidic conditions. Chloride deposition was driven by hydrothermal alteration of the Martian crust associated with faults, followed by precipitation from ascending saline solutions along the tectonic conduits. These processes occurred under a relatively thick and reducing atmosphere (1–0.1 bar). The crustal circulation of chloride‐precipitating fluids may have been driven by tectonic suction and pumping processes. Parental brines from hydrothermal activity sourcing chloride might also have contributed to the sulfates found in Cross and Columbus craters of Terra Sirenum. Our study integrates orbital imaging, topography, and spectroscopy with geochemical modeling and terrestrial analogs. We propose that the Terra Sirenum chloride deposits derive from subsurface brines, with deposition driven using tectonic and hydrothermal processes. Under inferred reducing and anoxic conditions, chloride formed with minimal co‐precipitation of sulfates and carbonates. Unlike isolated chloride deposits confined to topographic lows, the Terra Sirenum chlorides are associated with linear features interpreted as faults.

Granite-related wolframite-quartz veins are the world's most important tungsten mineralization and production resource. Recent progress in revealing their hydrothermal processes has been greatly facilitated by the use of infrared microscopy and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analysis of both quartz- and wolframite-hosted fluid inclusions. However, owing to the paucity of detailed petrography, previous fluid inclusion studies on coexisting wolframite and quartz are associated with a certain degree of ambiguity. To better understand the fluid processes forming these two minerals, free-grown crystals of intergrown wolframite and quartz from the giant Yaogangxian W deposit in South China were studied using integrated in situ analytical methods including cathodoluminescence (CL) imaging, infrared microthermometry, Raman microspectroscopy, and fluid inclusion LA-ICP-MS analysis. Detailed crystal-scale petrography with critical help from CL imaging shows repetition of quartz, wolframite, and muscovite in the depositional sequence, which comprises a paragenesis far more complex than previous comparable studies. The reconstruction of fluid history in coexisting wolframite and quartz recognizes at least four successive fluid inclusion generations, two of which were entrapped concurrently with wolframite deposition. Fluctuations of fluid temperature and salinity during precipitation of coexisting wolframite and quartz are reflected by our microthermometry results, according to which wolframite-hosted fluid inclusions do not display higher homogenization temperature or salinity than those in quartz. However, LA-ICP-MS analysis shows that both primary fluid inclusions in wolframite and quartz-hosted fluid inclusions associated intimately with wolframite deposition are characterized by strong enrichment in Sr and depletion in B and As compared to quartz-hosted fluid inclusions that are not associated with wolframite deposition. The chemical similarity between the two fluid inclusion generations associated with wolframite deposition implies episodic tungsten mineralization derived from fluids exhibiting distinct chemical signatures. Multiple chemical criteria including incompatible elements and Br/Cl ratios of fluid inclusions in both minerals suggest a magmatic-sourced fluid with the possible addition of sedimentary and meteoric water. Combined with microthermometry and Raman results, fluid chemical evolution in terms of B, As, S, Sr, W, Mn, Fe, and carbonic volatiles collectively imply fluid phase separation and mixing with sedimentary fluid may have played important roles in wolframite deposition, whereas fluid cooling and addition of Fe and Mn do not appear to be the major driving factor. This study also shows that fluid inclusions in both wolframite and coexisting quartz may contain a substantial amount of carbonic volatiles (CO2 ± CH4) and H3BO3. Ignoring the occurrence of these components can result in significant overestimation of apparent salinity and miscalculation of LA-ICP-MS elemental concentrations. We suggest that these effects should be considered critically to avoid misinterpretation of fluid inclusion data, especially for granite-related tungsten-tin deposits.