Pyrrolidinium and morpholinium ionic liquids as a novel effective destabilising agent of mineral suspension

Beneficial effects of a polysaccharide-based grinding aid on magnetite flotation: a green approach

Grinding is the most energy-intensive step in mineral beneficiation processes. The use of grinding aids (GAs) could be an innovative solution to reduce the high energy consumption associated with size reduction. Surprisingly, little is known about the effects of GAs on downstream mineral beneficiation processes, such as flotation separation. The use of ecofriendly GAs such as polysaccharide-based materials would help multiply the reduction of environmental issues in mineral processing plants. As a practical approach, this work explored the effects of a novel polysaccharide-based grinding aid (PGA) on magnetite's grinding and its reverse flotation. Batch grinding tests indicated that PGA improved grinding performance by reducing energy consumption, narrowing particle size distribution of products, and increasing their surface area compared to grinding without PGA. Flotation tests on pure samples illustrated that PGA has beneficial effects on magnetite depression (with negligible effect on quartz floatability) through reverse flotation separation. Flotation of the artificial mixture ground sample in the presence of PGA confirmed the benefits, giving a maximum Fe recovery and grade of 84.4 and 62.5%, respectively. In the absence of starch (depressant), PGA resulted in a separation efficiency of 56.1% compared to 43.7% without PGA. The PGA adsorption mechanism was mainly via physical interaction based on UV-vis spectra, zeta potential tests, Fourier transform infrared spectroscopy (FT-IR), and stability analyses. In general, the feasibility of using PGA, a natural green polymer, was beneficial for both grinding and reverse flotation separation performance.

Solvent-free continuous flow hydrogenation of N-methylpyrrolidone to N-methylpyrrolidine catalyzed by bimetallic Pt/V on HAP

The continuous flow hydrogenation of N-methylpyrrolidone which catalyzed by Pt/V/HAP (Pt/V molar ratio = 1 : 0.5) was achieved running for 100 h with solvent-free, and the N-methylpyrrolidine yield was above 85.21%.

Rhamnolipids as Effective Green Agents in the Destabilisation of Dolomite Suspension

In this paper, we describe an application of mono- and dirhamnolipid homologue mixtures of a biosurfactant as a green agent for destabilisation of a dolomite suspension. Properties of the biosurfactant solution were characterised using surface tension and aggregate measurements to prove aggregation of rhamnolipids at concentrations much lower than the critical micelle concentration. Based on this information, the adsorption process of biosurfactant molecules on the surface of the carbonate mineral dolomite was investigated, and the adsorption mechanism was proposed. The stability of the dolomite suspension after rhamnolipid adsorption was investigated by turbidimetry. The critical concentration of rhamnolipid at which destabilisation of the suspension occurred most effectively was found to be 50 mg·dm-3. By analysing backscattering profiles, solid-phase migration velocities were calculated. With different amounts of biomolecules, this parameter can be modified from 6.66 to 20.29 mm·h-1. Our study indicates that the dolomite suspension is destabilised by hydrophobic coagulation, which was proved by examining the wetting angle of the mineral surface using the captive bubble technique. The relatively low amount of biosurfactant used to destabilise the system indicates the potential application of this technology for water treatment or modification of the hydrophobicity of mineral surfaces in mineral engineering.

X-ray Crystal Structure and Hirshfeld Analysis of Gem-Aminals-Based Morpholine, Pyrrolidine, and Piperidine Moieties

The gem-aminals of 1,2-dimorpholinoethane (1) and 1-morpholino-3-morpholinium bromide propane (2) were synthesized by reaction of two molar ratio of morpholine with the halogenating agents in the presence of basic condition (K2CO3) in acetone at room temperature (RT) overnight. The structures of the centro-symmetric compound 1 and the morpholinium salt derivative 2 were assigned unambiguous by single crystal X-ray diffraction analysis and compared with the 1,2-di(pyrrolidin-1-yl)ethane 3 and 1,2-di(piperidin-1-yl)ethane 4. The 1,2-dimorpholinoethane molecule has a center of symmetry at the midpoint of the C-C bond of the ethyl moiety leading to two equivalent halves. It crystallized in monoclinic crystal system and P21/n space group, while the unit cell parameters are determined to be a = 6.0430(3), b = 8.0805(3), c = 11.1700(4) Å, and β = 97.475(2)° with unit cell volume of 540.80(4) Å3 and Z = 2 at 170(2) K. The less symmetric analogue 2 crystallized in the lower space group P21 with unit cell parameters of a = 6.37450(10), b = 11.1378(2), c = 9.6549(2) Å, and β = 93.358(2)°, while the unit cell volume is 684.30(2)Å3 at 120(2) K. Using Hirshfeld analysis, the molecules of 1 are mainly packed by weak N…H (4.2%), O…H (16.8%), and H…H (79.0%) interactions. In contrast, the molecules of 2 are packed by significantly short O…H (14.4%) and Br…H (11.6%) interactions in addition to the relatively long H…H (73.3%) interactions. DFT calculations predicted the molecular geometry of the studied compounds showing a good agreement with the experimental X-ray structures. Due to symmetry considerations, compounds 1, 3, and 4 are nonpolar with zero dipole moment, while the less symmetric molecule 2 has a dipole moment of 6.914 Debye. Their electronic aspects, such as natural population charges, HOMO, and LUMO energies as well as the corresponding reactivity descriptors, were also calculated and discussed.

Measurements of Activity Coefficients at Infinite Dilution for Organic Solutes in the Ionic Liquids N-Ethyl- and N-Octyl-N-methylmorpholinium Bis(trifluoromethanesulfonyl)imide. A Useful Tool for Solvent Selection

In recent years, many papers describing ionic liquids (IL) as promising solvents in separation techniques have been published. The conscious choice of appropriate ionic liquid as absorption media in effective extraction of selected types of analytes requires deeper understanding of the analyte-IL interactions. Therefore, intensive research is conducted to determine the values of activity coefficient at infinite dilution, which allows us to characterize the nature of these interactions. Based on the inverse gas chromatography retention data, activity coefficients at infinite dilution γ 13 ∞ of 48 different organic compounds in the ionic liquids N-ethyl-N-methylmorpholinium bis(trifluoromethanesulfonyl)imide [C2C1Mor][TFSI] and N-octyl-N-methylmorpholinium bis(trifluoromethanesulfonyl)imide [C8C1Mor][TFSI] were determined. The measurements covered a broad range of volatile organic compounds, including n-alkanes, n-alkenes, n-alkynes, alcohols, aldehydes, ketones, aromatic compounds and common polar solvents, representing different types of interactions. Activity coefficients at infinite dilution were measured in the temperature range from 313.15 to 363.15 K. The excess partial molar enthalpies and entropies at infinite dilution were determined. Selectivity at infinite dilution was also calculated for exemplary separation processes in the hexane/benzene system. The obtained results were analyzed and compared with literature data for ionic liquids containing the same anion [TFSI]¯ and different cations. The study results indicate that some potential applications of the investigated ionic liquids in separation problems exist.