Institutional Repository of Institute of Process Engineering, CAS (IPE-IR）
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Selective separation of Nd from La/Ce/Pr using phosphate-based ionic liquids: Solvent extraction studies and density functional theory
No full textSince neodymium (Nd) has similar physicochemical properties to lanthanum (La), cerium (Ce) and praseodymium (Pr), their efficient separation and purification is very difficult. Three new phosphate-based ionic liquids (ILs): N,N-dimethyloctylamine bis(2-ethylhexyl)phosphate ([N-1,N-1,N-8,N-H][DEHP]), N,N-dimethyldecylamine bis(2-ethylhexyl)phosphate ([N-1,N-1,N-10,N-H][DEHP]), N,N-dimethyldodecylamine bis(2-ethylhexyl)phosphate ([N-1,N-1,N-12,N-H] [DEHP]) were synthesized and evaluated for selective separation of Nd(III) from aqueous solution. The influences concentration of Nd(III), phase volume ratio (O/A), cation chain length of ILs, extraction time, extraction temperature, salt concentration, solution acidity have on the performance of ILs for extraction separation of Nd(III) from aqueous solution were systematically investigated. It was found that the extraction efficiency (E) of Nd(III) using [N-1,N-1,N-8,N-H][DEHP] was close to 100% at pH of 4, and that it only required 10 min to reach extraction equilibrium at 303 K. Meanwhile, the separation factors (beta) values of beta Nd/La, beta Nd/Ce, beta Nd/pr using [N-1,N-1,N-8,N-H][DEHP] were all higher than 3. The density functional theory (DFT) results indicated that the interaction between [N-1,N-1,N-8,N-H][DEHP] and Nd were stronger than that between La, Ce and Pr. In addition, almost 100% of Nd(III) could be recycled from the loaded [N-1,N-1,N-8,N-H][DEHP] phase using 0.16 mol center dot L-1 hydrochloric acid via one step, and the E of Nd(III) by regenerated [N-1,N-1,N-8,N-H][DEHP] remained about 97% after eight cycles. Moreover, the extraction mechanism of Nd(III) using [N-1,N-1,N-8,N-H][DEHP] was complexation mechanism based on infrared spectroscopy and slope analysis. This work furnishes a strategy for selective separation of Nd(III) using phosphate-based ILs without diluent
CoaST Maritime Test Centre: an investigation of biofouling propensity
No full textThe performance of fouling control coatings (FCC) is evaluated based on static exposure on test sites worldwide. There are different standards concerning the evaluation of the performance of the FCC. However, to the knowledge of the authors, there is not a standardized reporting guideline for how to evaluate the test site in which the FCC is exposed. Several factors such as water conditions, seasonal biofouling, and accessibility of sunlight can vary dependent on placement within or between test sites. This in turn makes it difficult to compare the performance of FCC exposed at different locations within a or at another test site. In this study, an analysis of the CoaST Maritime Test Centre (CMTC) has been performed to investigate how geographical orientation and changes in depth influence the biofouling propensity on coated panels. The investigation showed no statistical significance in the biofouling propensity between panels exposed to different geographical orientations at the CMTC. Similarly, no statistical significance was found between panels placed at different depths at the CMTC. If similar reporting was performed at other test sites, a better basis for comparison of FCC worldwide would be obtained, and this could be achieved with a standardized reporting guideline
Superior selective adsorption of trace CO2 induced by chemical interaction and created ultra-micropores of ionic liquid composites
No full textEffective capture of trace CO2 in atmosphere or confined spaces to ensure human beings safety draw a lot of attention, however, how to simultaneously improve CO2 capacity and selectivity still faces great challenge. Herein, combining porous molecular sieves (SBA-15 and MCM-41) and the anion-functionalized ionic liquid (IL) tetraethylammonium glycinate ([N-2222][Gly]), a series of hierarchically porous IL composites with different IL loadings were designed and prepared. Compared with pristine supports, the incorporation of [N-2222][Gly] simultaneously improves CO2 capacity and CO2/N-2 selectivity by orders of magnitude, especially for confined spaces (< 5000 ppm) and air (415 ppm). When the IL loading was 60 wt%, novel micropores were created, especially ultra-micropores (< 0.65 nm), which are not present in bare supports and other [N-2222][Gly]@SBA-15 (15, 30 and 45 wt%). Among them, 60 wt%[N-2222][Gly]@SBA-15 showed the highest CO2 uptake of 1.45 and 1.88 mmolCO(2)/g-adsorbent at 0.0005 and 0.005 bar under 313 K along with recyclability, which are much superior to the state-of-the-art reported values. Moreover, superb ideal CO2/N-2 selectivity of 11,545 at 0.005 bar and 288 K was achieved, which was 288 times that of SBA-15. Meanwhile, mixed gas breakthrough experiments demonstrated that 60 wt% [N-2222][Gly]@SBA-15 shows outstanding CO2 separation performance under simulative confined spaces and ambient air. The ultra-high CO2 separation performance was attributed to the synergy of chemical interaction between the IL anion and CO2 as well as newly created micro-and ultra-micropores effect. This work provides guidelines for the design of IL composites with ultra-micropores for efficient trace CO2 removal
Co-pyrolysis behaviors of coal and polyethylene by combining in-situ Py-TOF-MS and reactive molecular dynamics
No full textCo-pyrolysis of waste plastics and low-rank coal is a promising approach to deal with the serious waste crisis and improve the clean utilization of low-rank coal. In this work, the comprehensive co-pyrolysis behaviors of low -rank coal and polyethylene plastics were explored systematically by combining TG experiment, in-situ Py-TOF-MS technique, and ReaxFF MD simulation. The consistent results were obtained among three approaches to demonstrate the positive interaction exists between coal and PE during the co-pyrolysis process, which leads to volatile yield increasing with PE addition. TG experimental results showed that the blending ratio of 7:3 for coal and PE has the strongest synergy during the co-pyrolysis process, while Py-TOF-MS experimental results unraveled that the synergistic effect of coal and PE was determined by changing the content of pyrolysis products rather than by producing cross-reaction products. The PE addition significantly reduced the yield of MAHs and normal alkyl-substituted monophenols and increased the yield of olefins, alkanes, and aromatic derivatives. ReaxFF MD simulation results complement the experimental observation to obtain similar weight loss profiles with TG experiments and consistent identification of major representative tar pyrolyzates with Py-TOF-MS ex-periments. Particularly, the detailed gas evolving trends and the underlying bond-breaking reactions of C-C, C-O, and C-H bonds were revealed by ReaxFF MD, which indicates PE addition promotes bond breaking of C-C and C-H to enhance more tar generation. The combination of experiments and ReaxFF MD simulations can capture the comprehension of the co-pyrolysis process between low-rank coal and PE, which can be extended to other co-pyrolysis applications for related solid fuels
Insights into structural and electronic properties of (LiH)n (n=5-25) clusters: Density functional calculations
No full textFirst principles calculations have been performed to analyze the structural and electronic properties of (LiH)n clusters by combining an artificial bee colony algorithm within the framework of Density Functional Theory (DFT). The structural analysis shows that with an increase in cluster size, the structural shape tends to become more amorphous in which the lithium (Li) atom occupies the central position, surrounded by hydrogen (H) atoms at the vertex sites. The bond length between Li and H was found to be 1.77-2.01 angstrom, which is in good agreement with the previous study. Through stability analysis, the calculated formation energy of LiH clusters increase from n = 5 through n = 25. The projected density of states was calculated and analyzed to get deeper insight of the electronic structure. The charge density distribution and results of density derived electrostatic and chemical (DDEC6) analysis revealed ionic bonding characteristics between Li and H atoms, and charge density difference analysis concludes electron transfers from Li to H atoms
