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Litsea cubeba is a characteristic woody oil resource in Hunan. As a solid waste of woody oil resources, Litsea cubeba kernels are rich in Litsea cubeba kernel oil with a carbon chain length of C10–12 fatty acid. In this work, aliphatic hydroxamic acids (AHAs) with carbon chain lengths of C10–12 were prepared from Litsea cubeba kernel oil via methylation and hydroximation reactions. The adsorption and hydrophobicity mechanism of AHA towards wolframite was explored by contact angle, zeta potential, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The flotation results demonstrated that AHA was a superior collector than the traditional collector such as benzoyl hydroxamic acid (BHA). Zeta potential and contact angle results have shown that AHA was adsorbed on the surface of the Fe(III)-activated wolframite in its anionic form, which significantly improved the surface hydrophobicity of wolframite. FTIR and XPS revealed that AHA was chemically adsorbed on the surface of Fe(III)-activated wolframite in the form of a five-member ring, which made the hydrophobic chain reach into the solution, come in contact with bubbles, and achieve flotation separation. [ABSTRACT FROM AUTHOR]

Arsenopyrite (FeAsS) and realgar (As4S4) are two common arsenic minerals that often cause serious environmental issues. Centralised treatment of arsenic-containing tailings can reduce land occupation and save management costs. The current work examined the remediation schemes of tailings from Hunan Province, China, where by different tailings containing arsenopyrite and realgar were blended with exogenous slag zero valence iron (ZVI). Introducing Fe-oxidising bacteria (Acidithiobacillus ferrooxidans) recreates a biologically oxidative environment. All bioleaching experiments were done over three stages, each for 7 days and the solid phase of all tests was characterised by scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy and selective extraction analyses. The results showed that the mixture group reduced arsenic release by 72.9–74.7% compared with the control group. The addition of 0.2 g ZVI clearly decreased arsenic release, and the addition of 4.0 g ZVI led to the lowest arsenic release among all tests. The decrease of arsenic released from the tailings was due to the adsorption and uptake of arsenic by secondary iron-containing minerals and Fe–As(V) secondary mineralisation. The addition of large amounts of ZVI reduced the arsenic detected in the amorphous Fe precipitates. Therefore, a low cost and integrated strategy to reduce arsenic release from tailings is to mix two typical tailings and apply exogenous slag ZVI, which can apply to the in situ remediation of two kinds or more arsenic-containing tailings. [ABSTRACT FROM AUTHOR]

As an emerging contaminant, tungsten's distribution and speciation in soils are far from understood. In this study, two soil profiles near a typical abandoned tungsten smelter in Hunan Province, China were collected and investigated, to ascertain the binding and association of tungsten with different soil components and subsequently to understand its mobility. The data showed that past tungsten smelting activities resulted in elevated concentrations of both tungsten and arsenic in the soil profiles, both of which ranged from dozens of to a few hundred mg/kg. Nano-scale secondary ion mass spectrometry (NanoSIMS) was employed to quantify the distribution and association of tungsten with various other elements. Combined with sequential extraction and mineralogical analysis, the data from NanoSIMS showed that aluminosilicates including kaolinite and illite were the most important mineral hosts for tungsten, whereas arsenic was predominantly bound to iron (oxyhydr)oxides. Additional data from 13C nuclear magnetic resonance and X-ray photoelectron spectroscopy revealed that soil organic matter retained tungsten in deep soils (>70 cm) by binding tungsten through carboxyls on aromatic rings. Compared to arsenic, tungsten migrated deeper in the soil profiles, suggesting its higher mobility and potential risk to groundwater quality. [Display omitted] • Tungsten migrated deeper in the soil profiles than arsenic. • Aluminosilicates were the most important mineral hosts for tungsten. • Soil organic matter (SOM) was an essential reservoir for tungsten in deep soil. • Carboxyls on aromatic rings played a major role in tungsten complexation with SOM. [ABSTRACT FROM AUTHOR]

• Structural features and evolution from anthracite to meta-anthracite were studied. • The lattice fringes length increases prominently from anthracite to meta-anthracite. • More edge defects, curved layers and vacancies formed with increased coal rank. The structural features and evolution from anthracite to meta-anthracite were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and high-resolution transmission electron microscopy (HRTEM). All the high-rank coals (4.23% < R r < 8.23%) show a broad (0 0 2) peak in their XRD patterns, and the relative intensity of (0 0 2) and (1 0) diffraction peaks increase slightly with coal rank. The crystallite parameters L c and L a derived from XRD data vary around 2 nm and 5.67–9.14 nm, respectively, but do not change significantly with rank. Five types of carbon bonds were peak-fitted from the original XPS spectral profiles, including sp2 hybridized C C (64%–74%), followed by C–C/C–H, carbon–oxygen bonds, and π plasma. The lattice-fringe lengths of anthracites are mainly in the range of 0.6–1.5 nm examined by HRTEM, and trace amount of short aliphatic chains were detected in anthracite samples from micro-FTIR, whereas more aromatic rings condensed into larger polyaromatic clusters in the meta-anthracites and the residual aliphatic carbon atoms are in the form of quaternary aliphatic carbon forming Y-type dislocation. The Y-type dislocation and screw dislocation between edges of lattice-fringes are common in the meta-anthracite compared to anthracite; in addition, bent carbon layers are more frequent. Quantitative information of lattice-fringes was used to investigate the structural evolution of coal. The average diameter of local molecular-oriented domains increases with rank for the meta-anthracite samples, as does the degree of preferential orientation, but these local oriented domains are still distributed randomly at sub-micron scale and without stiff stacked graphene layers. [ABSTRACT FROM AUTHOR]