Hydrometallurgical recovery of zinc from industrial hot dipping top ash

Top ash from hot-dip galvanizing plant was investigated as a source of secondary zinc to be returned to galvanizing bath. The waste material contained 63% Zn as metallic, oxide and hydroxychloride phases. It was leached in H₂SO₄ solutions (20% and 25%) at various bath loadings (100−300 g/L). Leaching behaviors of zinc, manganese, iron and chloride ions were investigated. A few strategies of iron elimination from leaching liquors were examined. Flocculant addition was harmful for subsequent filtration of iron precipitates due to increased viscosity of solution, while a combination of zinc oxide and calcium carbonate for rising pH resulted in the formation of dense suspension unenforceable to separate from zinc sulphate solution. Zinc electrowinning was carried out at different pH (from −0.5 to 2.8) using a range of current densities (3−10 A/dm²). Optimal conditions for pure metal recovery were: leaching in 20% H₂SO₄ solution at zinc ash content 100−150 g/L, Fe₂O₃·xH₂O precipitation using H₂O₂ and CaCO₃, zinc electrowinning at pH of 0.1−1.0 at 3−6 A/dm². Correlations between pH and free H₂SO₄ concentration in electrolyte solutions were also discussed. pH−acid concentration dependence for zinc electrolyte was between experimental and calculated curves for pure H₂SO₄ solutions, while the curve was shifted towards lower pH if ferric ions were in the solution.     

High-performance SSZ-13 membranes prepared using ball-milled nanosized seeds for carbon dioxide and nitrogen separations from methane

SSZ-13 membranes with high separation performances were prepared using ball-milled nanosized seeds by once hydrothermal synthesis. Separation performances of SSZ-13 membranes in CO_2/CH_4 and N_2/CH_4 mixtures were enhanced after synthesis modification. Single-gas permeances of CO_2, N_2 and CH_4 and ideal selectivities were recorded through SSZ-13 membranes. The effects of temperature, pressure, feed flow rate and humidity on separation performance of the membranes were discussed. Three membranes prepared after synthesis modifications had an average CO_2 permeance of 1.16 × 10~(-6) mol·(m~2· s·Pa)~(-1)(equal to 3554 GPU) with an average CO_2/CH_4 selectivity of 213 in a 50 vol%/50 vol% CO_2/CH_4 mixture. It suggests that membrane synthesis has a good reproducible. The membrane also displayed a N_2 permeance of 1.07 × 10~(-7) mol·(m~2·s·Pa)~(-1)(equal to 320 GPU) with a N_2/CH_4 selectivity of 13 for a 50 vol%/50 vol% N_2/CH_4 mixture. SSZ-13 membrane displayed stable and good separation performance in the wet CO_2/CH_4 mixture for a long test period over 100 h at 348 K. The current SSZ-13 membranes show great potentials for the simultaneous removals of CO_2 and N_2 in natural gas purification as a facile process suitable for industrial application.     

Solvent-Aided Crystallization for Biodiesel Purification

The application of solvent-aided crystallization (SAC) is based on the addition of a solvent, here 1-butanol, to crude biodiesel to catalyze the purification process by separating biodiesel from contaminants via crystallization process. Response surface methodology was applied to optimize the process parameters of SAC, represented by biodiesel purity. The purified biodiesel was analyzed by means of gas chromatography-mass spectrometry for the composition of the present fatty acid methyl ester (FAME). Under the predicted optimum process conditions within the experimental ranges for the highest biodiesel purity, the predicted biodiesel purity was 99.375 %.     

Preparation of mixed matrix composite membrane for hydrogen purification by incorporating ZIF-8 nanoparticles modified with tannic acid

The incompatibility between nanofillers and polymer, caused by the agglomeration of nanoparticles and their weak interaction with each other, is still a challenge to develop mixed matrix composite membrane. Herein, we introduced the ZIF-8-TA nanoparticles synthesized by in situ hydrophilic modification into the hydrophilic poly(vinylamine) (PVAm) matrix to prepare composite membranes for H₂ purification. The dispersion of ZIF-8 in water was improved by tannic acid modification, and the compatibility between ZIF-8 particles and PVAm matrix was enhanced by chemical crosslinking between the quinone groups in oxidized tannic acid (TA) and the amino groups in PVAm. Moreover, the compatibility between hydrophobic polydimethylsiloxane (PDMS) gutter layer and hydrophilic separation layer was achieved by the adhesion of TA-Fe³⁺ complex to the surface of PDMS layer during membrane preparation. The interlayer hydrophilic modification and the formation of separation layer were accomplished in one step, which simplified the preparation process. The experimental results indicated that when the TA addition used for modification was 0.5 g and the ZIF-8-TA_0.5 content in membrane was 12 wt%, the prepared membrane showed the best separation performance with the CO₂ permeance of 987 GPU and the CO₂/H₂ selectivity of 31, under the feed gas pressure of 0.12 MPa.     

含锂工业废料制备电池级碳酸锂工艺研究

随着电池行业的快速发展,电池级碳酸锂的市场需求越来越大。以某公司生产电池的含锂工业废料为原料,采用碳化分解法对其进行提纯除杂,并进行多次滤液滤饼循环,最终得到符合电池级碳酸锂行业标准的产品。碳化过程优化反应条件：固液质量体积比（g/mL）为1∶50,搅拌转速为300 r/min,二氧化碳流速为10 L/min,反应温度为20 ℃,反应时间为60 min。热分解过程优化反应条件：搅拌转速为300 r/min,反应温度为95 ℃,反应时间为60 min。将碳化分解制备的碳酸锂滤饼和滤液进行5次循环反应,即可得到符合电池级碳酸锂行业标准的产品。所得碳酸锂产品纯度达到99.71%,而且其中镁、钙、钾质量分数分别降低至0.005 3%、0.005 0%、0.000 9%,产品收率保持在55%以上,产品形貌呈棒状、大小均匀、分散性良好。     

Simulation of integrated novel PSA/EHP/C process for high-pressure hydrogen recovery from Coke Oven Gas

This paper introduces a novel Coke Oven Gas (COG) hydrogen purification/compression system based on the technologies of Pressure Swing Adsorption (PSA) and Electrochemical Hydrogen Purification and Compression (EHP/C). As the EHP/C tolerates O₂, N₂ and CH₄ impurities, PSA can be utilized solely for CO and CO₂ removal (other COG impurities were not considered in this work). A relaxation of PSA hydrogen purity could significantly enhance its recovery rate. In this study, the suitability of traditional hydrogen PSA as part of the hybrid PSA/EHP/C approach was investigated. Aspen Adsorption and Matlab were used to model the PSA and EHP/C systems, respectively. The effect of adsorption pressure, purge-to-feed-ratio (P/F-ratio) and adsorption time within cycle on PSA performance is reported. This study found that breakthrough of non-detrimental components is typically accompanied with poisonous CO. Hence, the CO removal with traditional H₂-PSA resulted into high purity product. In a two-bed PSA, 36.3% of hydrogen was recovered at 99.9988% purity and 0.18 ppm CO. Subsequently, as a result, the EHP/C purification capability was merely utilized, but polished this hydrogen to >99.999% purity. Simultaneously, hydrogen was isothermally compressed to 20 MPa, consuming a marginal 2.42 kWh/kg. Compared to mechanical compression, this is 31.6% more energy efficient. Recovering hydrogen from by-product COG was found to save 0.5 kg CO₂/kg H₂ compared to hydrogen produced from natural gas. Conventional hydrogen PSA, utilizing 70% Activated Carbon and 30% Molecular Sieve 5A, was found not to be effective to target the removal of CO specifically. To increase synergy between PSA and EHP/C, the PSA requires adequate design and operation using appropriate adsorbents and cycle steps to target elimination of CO. An increased EHP/C catalyst tolerance for CO also contributes to higher flexibility.     

Feasibility and sustainability analyses of carbon dioxide – hydrogen separation via de-sublimation process in comparison with other processes

Hydrogen (H₂) plays a vital role both as a reactant in petrochemical processes and as an energy carrier and storage medium. When produced from carbon-containing feed stocks, such as fossil fuels and biomass, hydrogen is typically produced as a mixture with carbon dioxide (CO₂), and must be subsequently separated by the associated energy, with an invertible energy penalty. In this study, the process for the removal of carbon dioxide from CO₂ - H₂ mixtures by de-sublimation was analysed. This process is particularly relevant to the production of liquid hydrogen (LH₂) at cryogenic temperatures, for which cooling of the H₂ stream is already necessary. The solid – gas equilibrium of CO₂ - H₂ was studied using the Peng-Robinson equation of state which provided a wide range of operating conditions for process simulation. The de-sublimation process was compared with selected conventional separation processes, including amine-based absorption, pressure swing adsorption and membrane separation. In the scenario in which the resulting products, carbon dioxide and hydrogen, were subsequently liquefied for transportation and storage at 10 bar and −46 °C, and 1 bar and −251.8 °C, respectively. The overall energy consumption per kg of CO₂ separated (MJ/kgCO₂₎, was found to follow the order: 8.19–11.21 for monoethanolamine (MEA) absorption; 1.81–8.93 for membrane separation; 1.53–5.69 for pressure swing adsorption; and 0.81–3.35 de-sublimation process. Each process was evaluated and compared on the bases of electricity demand, cooling water usage, high-pressure steam usage, and refrigeration energy requirements. Finally, the advantages and disadvantages were discussed and the feasibility and sustainability of the processes for application in the production of liquid hydrogen were assessed.     

一株产低温脂肪酶酵母菌的鉴定及酶学性质

低温脂肪酶已成为工业低温工艺良好候选物，在生物质能源、食品、皮制品、废水处理等领域发挥重要作用。本文从实验室保藏的55株产低温脂肪酶酵母菌株中筛选出一株高产菌株NYNU 19160，通过形态学、生理生化以及ITS和26S rDNA序列分析，将该菌株鉴定为Papiliotrema fonsecae。经过硫酸铵分级沉淀、透析、浓缩将该脂肪酶纯化后，对酶学性质进行了研究。结果表明，该脂肪酶最适反应温度为20℃，最适作用pH为7.5，属于低温碱性脂肪酶；Cu²⁺显著促进该酶的水解活性，而Li⁺表现为显著抑制作用；有机溶剂乙腈、甲醇、乙酸对酶活性有较强的促进作用，而苯和正己烷则抑制了该酶的活性；该酶对对硝基苯酚丁酸脂（pNPC₄）底物表现出较强特异性。     

超重力在冶金和金属材料领域的研究进展及展望

超重力作为一种外场强化新技术,基于其优越的传质和相际分离特性,引起了广泛的关注。本文着重介绍了我国超重力技术在金属熔体提纯、冶金固废中有价物质的富集提取分离、金属材料凝固组织细化、非金属夹杂物的去除以及矿石气基还原等冶金和金属材料领域的研究进展和成果,提出了其应用过程中存在的科学问题,并展望了超重力技术的发展前景。虽然,目前还以实验室研究阶段为主,并未实现普适化。但作为一种外场强化新技术,其在冶金和金属材料凝固控制等相关研究体系中已突显出强大的熔体提纯、有价组分富集提取、组织细化、夹杂物去除等作用效果,这为进一步拓展超重力技术在冶金和金属材料领域的研究和开发应用提供了参考价值。超重力有望凭借自身的优点成为冶金和金属材料领域生产过程中一种新的外场技术。随着超重力设备的发展及相关科学问题的研究探索,相信在不久的将来,超重力技术必会在冶金和金属材料研究领域得到广阔的应用前景。     

Effect of Methionine Sulfoxide on the Synthesis and Purification of Aggregation-Prone Peptides

A two-step synthesis for methionine-containing hydrophobic and/or aggregation-prone peptides is presented that takes advantage of the reversibility of methionine oxidation. The use of polar methionine sulfoxide as a building block in solid-phase peptide synthesis improves the synthesis quality and yields the crude peptide, with significantly improved solubility compared to the reduced species. This facilitates the otherwise often laborious peptide purification by high-performance liquid chromatography. The subsequent reduction proceeds quantitatively. This approach has been optimised with the methionine-rich Tar-DNA-binding protein 43 (307–347), but is also more generally applicable, as demonstrated by the syntheses of human calcitonin and two aggregation-prone peptides from the human prion protein.