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Carbon (C) is major element of most hot springs, yet knowledge on carbonaceous compounds in hot springs and their role in the cycle of elements are limited. Here we analyzed carbonaceous compounds in Zibo hot springs, China, by electron microscopy and chemical analysis. Results display spherical and irregular C-bearing nanoparticles from 50 to 150 nm. Nanoparticles typically contain, in wt%, 40.4–77.6 C, 8.12–15.9 N, 4.27–13.8 O, 0.12–0.13 Mg, 1.47–2.67 Si, 0.09–0.16 S, 0.04–0.20 Cl, and 0.63–34.7 Fe. These findings reveal the occurrence of C nanoparticles in hot springs, accompagnied by several other elements. The biophilic elements N and Fe and biomimetic morphology of nanoparticles suggest a biological origin. We discuss implications for carbon cycling and for the possible use of C-bearing nanoparticles to prospect geothermal resources in the deep Earth. [ABSTRACT FROM AUTHOR]

In terms of secondary resource recovery and environmental impact, fly ash is attracting a great deal of attention in China. This study aimed to investigate the carbochlorination process of titanium oxide to recover titanium. The extraction kinetics mechanism of titanium oxide from fly ash was investigated at temperatures ranging from 850°C to 1050°C. The effect of various experimental parameters was studied. The reactants and reaction residues were analyzed by scanning electronic microscopy and chemical analysis. The results show that the best extraction efficiency of 91.66% was obtained at a temperature of 1050°C, a coking coal content of 34.64 wt.%, a pellet diameter of 8 mm, an average gas flow of 0.35 L/min, and a time of 120 min. The carbochlorination reaction of titanium oxide is controlled by the chemical reaction. The apparent activation energy is approximately 44.45 kJ/mol between 800°C and 1050°C. [ABSTRACT FROM AUTHOR]