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Industrial wastewater usually contains large amounts of butanols which form azeotropic mixtures with water. Efficiently and cleanly separating these azeotropes while saving energy is an urgent problem to solve. This study used two types of solvents to measure the ternary liquid-liquid equilibrium (LLE) data for extracting n-butanol, sec-butanol, and tert-butanol from water at 298.2 K and 101.3 kPa. The obtained data was correlated with NRTL and UNIQUAC models to obtain relevant binary interaction parameters. The reliability of the binary interaction parameters was verified using a Gibbs energy topology-based mixture surface analysis method. The root mean square deviations of the two models were less than 0.0061 and 0.0072, respectively, indicating that both the NRTL and UNIQUAC models could correlate the experimental data well. The extraction performance was evaluated using the distribution coefficient (D) and the separation factor (S). Isopentyl acetate showed better extraction performance, and the differences in the molecular structures of butanols also showed regularity during the extraction process. Combined with quantum chemistry calculations, the hydrogen bond donors and acceptors between six ternary systems were analyzed using the COSMO-SAC method. The intermolecular interaction energies were calculated using the Dmol3 module. Finally, through IGMH and AIM analysis, it was proved that the difference in hydrogen bond strength between isopentyl acetate/ethyl acetate and butanols with different molecular structures is the reason for this difference. This study provides basic data and parameters for the design of butanols extraction processes through a combination of experiments and quantum chemistry calculations. • The LLE data for water + n-butanol/sec-butanol/tert-butanol + solvents were measured. • The NRTL and UNIQUAC models were applied to correlate the LLE data. • Differences in the extraction processes of primary/secondary/tertiary alcohols were studied. • Quantum chemical methods for analyzing the mechanism of extraction processes. [ABSTRACT FROM AUTHOR]

Wastewater from coking and pharmaceutical processes often contain a significant amount of 2-methylpyridine, which forms an azeotropic mixture with water. Effectively and cleanly separating 2-methylpyridine from wastewater while conserving energy and obtaining high purity products is an urgent challenge. In this study, ternary liquid-liquid equilibrium (LLE) data for the extraction of 2-methylpyridine from wastewater were measured using three distinct solvents at temperatures of 303.2 K, 313.2 K, and 323.2 K. The obtained ternary data were subsequently correlated with thermodynamic models (NRTL and UNIQUAC) to get relevant binary interaction parameters, bridging a gap in Aspen Plus simulations of 2-methylpyridine separation by octanol solvents. Furthermore, the GUI tool was used to validate these parameters and the results confirmed the reliability of the obtained parameters. It was observed that as the temperature increased, the extraction performance of all systems decreased, indicating that elevated temperature are not conducive to the extraction process. Among the various components, iso-octanol showed the highest separation factor indicating better extraction efficiency of 2-methylpyridine. Additionally, this study integrated quantum chemical calculations to reveal the interaction mechanisms between different solvents, 2-methylpyridine, and water at the microscopic level. The computational results indicated that iso-octanol exhibited the most robust binding affinity with 2-methylpyridine, suggesting that iso-octanol has more excellent extraction properties. • The LLE data for the ternary system of water + 2-methylpyridine + solvents were measured at 303.2 K, 313.2 K, and 323.3 K under atmospheric pressures. • The distribution coefficient and separation factor were calculated. • The NRTL and UNIQUAC models were applied to correlate the LLE data. • The binary interaction parameter values were obtained from the data correlation. • The interaction of 2-methylpyridinel between different media was discussed. [ABSTRACT FROM AUTHOR]

We experimentally demonstrated the all-fiber erbium-doped Q-switched fiber laser based on the evanescent field interaction with lead sulfide (PbS) as saturable absorber (SA). The SA was fabricated by depositing the dispersion of PbS nanoparticles onto the taper of the microfiber with a diameter of ∼10 μm. The intensity-dependent nonlinear optical absorption of SA was investigated, and its saturation intensity and modulation depth were ∼3 MW/cm2 and ∼30.9 %, respectively. By incorporating the SA into the erbium-doped fiber laser (EDFL), stable Q-switched pulse at the central wavelength of 1558.68 nm can be obtained when the pump power was increased from 30 mW to 220 mW. The repetition rate frequency was increased from 17.21 kHz to 71.72 kHz, meanwhile, the pulse duration exhibited a decreasing trend from 10.67 μs to 2.74 μs and the signal-to-noise ratio was 48.31 dB. The maximum pulse energy was 53.24 nJ when pump power at 200 mw. On account of the results of the work, the PbS nanoparticles demonstrated a potential application value as an SA for fiber laser. [ABSTRACT FROM AUTHOR]