Institutional Repository of Institute of Process Engineering, CAS (IPE-IR）
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Preparation and properties of anorthite-based ceramics by using metallurgical solid waste and fly ash
No full textA large amount of metallurgical solid waste accumulation poses a serious threat to the environment. Study on synergistic reinforcement of synthetic process of metallurgical solid waste-based ceramics with fly ash is of great significance in reducing environmental pollution and resource utilization. A metallurgical solid waste-based ceramic used as building ceramic was developed with the erosion part of used MgO-C bricks and fly ash as main raw materials, and the amount of solid waste added to the prepared ceramics was at least 60 wt% and up to 90 wt%. The effects of fly ash content and sintering temperature on the crystalline phase transitions, morphologies, and the main physical and mechanical properties of ceramics were investigated by X-ray diffraction, scanning electron microscopy, and mechanical testing. The results show that the obtained ceramics presented maximum bending strength and minimum water absorption, 80.14 MPa and 5.04%, respectively, when the raw material proportions were the erosion part of used refractories accounted for 60 wt%, fly ash 20 wt%, pyrophyllite 10 wt%, and quartz sands 10 wt%, and the process parameters were the sintering temperature 1150 degrees C, sintering time 120 min, and molding pressure 15 MPa
Snowball flower-like g-C3N4/ZnFe2O4 mesoporous hollow microspheres with enhanced triethylamine sensing properties
No full textHerein, the snowball flower-like g-C3N4/ZnFe2O4 mesoporous hollow microspheres, in which two-dimensional (2D) g-C3N4 nanolayers were loaded onto the surface of ZnFe2O4 hollow microspheres, were constructed by a simple solid phase reaction. The effect of the g-C3N4 concentration on the structure, morphology and gas-sensing performance of the g-C3N4/ZnFe2O4 composites had been explored. On the basis of gas sensitivity test results, the composites owned lower working temperature (160 degrees C) and better selectivity toward TEA in comparison with pure ZnFe2O4. Notably, the sensor based on the g-C3N4/ZnFe2O4-15 hollow microspheres (adding 15 ml of g-C3N4 aqueous solution) exhibited outstanding sensing properties, including superior response (18.3) toward 100 ppm TEA at optimum work temperature of 160 degrees C, speedy response-recovery time (33, 30 s) and outstanding stability. And the sensor maintained high response of 4.3 to low concentration TEA (5 ppm). The improved gas-sensing performance of the composites could be attributed to the porous ZnFe2O4 hollow microspheres loaded by 2D g-C3N4 nanolayers with large specific surface area and the heterostructure formed between them. Hence, a potential application of the g-C3N4/ZnFe2O4 microspheres might be achieved in detecting TEA at a low optimum work temperature
Comparison of various structure designs of SO2-depolarized electrolysis cell
No full textSO2-depolarized electrolysis (SDE) is the key step of the hybrid sulfur (HyS) process, which is one of the simplest thermochemical cycles for producing hydrogen by water splitting. Exploration and optimization of flow field/structure design is essential for improving the efficiency of SDE. In this work, graphite plates with different flow channels, together with porous graphite felts or carbon papers as diffusion layers are adopted to fabricate SDE cells with different structures. Evaluation of the cell structures is carried out, by comparing the SDE performance and taking into account the fluid resistance (pressure drop) of anode side. The effects of graphite felt compression ratio, hydrophilicity or hydrophobicity of carbon papers, anodic fluid flow rate, and operating temperature on the SDE performance are investigated. Square porous flow fields provided by graphite felts show excellent performance. Serpentine channel covered by hydrophobic carbon paper reveals advantages when adopted on the cathode side. Combination of above two flow fields and using them on anode and cathode sides respectively, could achieve excellent SDE performance. Under the condition of 40 degrees C and 360 mL/min anolyte flow rate, the current density could reach 760 mA/cm2 at the cell voltage of 1.19 V. (c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved
PET pyrolysis and hydrolysis mechanism in the fixed pyrolyzer
No full textIn the conventional polyethylene terephthalate (PET) pyrolysis process, the formation of char by excessive pyrolysis is mainly due to the dehydration mechanism, so water is considered an auxiliary agent that can effectively inhibit excessive pyrolysis. The preparation of terephthalic acid (TPA) by steam-assisted pyrolysis of PET is an effective method to achieve closed-loop recycling of waste PET. To ensure that the reaction is mild enough to reduce excessive cracking products such as char and benzoic acid and thus increase the yield of TPA, it is critical to reduce the reaction rate while maintaining a sufficient excess steam coefficient. Under the optimal operating conditions, when the temperature rise rate was 0.5 degrees C min(-1) and the excess steam coeffi-cient was 150, the yield of TPA was 72.5 wt.%, and the purity was 85.5%. Noticeably, the steam-assisted pyrolysis system is a heterogeneous reaction sys-tem whose reaction mechanism is different from the conventional hydrolysis and pyrolysis reactions and has a unique reaction path. The mechanistic study indicates that, in addition to the thermal cracking of PET molecules occurring in conventional pyrolysis, hydroxyl attack and transfer, and supplementation of benzene ring hydrogen also occur between water and intermediate mole-cules. Meanwhile, it has also been proven that the intermolecular hydrogen transfer between intermediate molecules and water molecules is the key to reduce the intensity of the reaction and inhibit the formation of char. This dis-covery illustrates the mechanism of the reaction between water and PET in the steam-assisted pyrolysis process in the fixed pyrolyzer and justifies the distinc-tion between it and the pyrolysis and hydrolysis processes of PET. It provides a theoretical basis for optimizing the pyrolysis process of PET, which is essential for the industrialization of TPA preparation from PET steam-assisted pyrolysis
(NH_4)_2SO_4和Na_2SO_4混合溶液中(NH_4)_2SO_4结晶动力学及铁/铝/锰/铬等离子对(NH_4)_2SO_4结晶的影响规律
No full text湿法冶金、三元前体制备等过程均会产生含硫酸钠与硫酸铵的高盐废水。研究高盐废水中硫酸铵的结晶动力学,并考察常见金属离子的影响规律对高盐废水处理具有重要意义。本文以含硫酸钠与硫酸铵混合溶液中硫酸铵的结晶过程为例,系统考察了硫酸铵的结晶动力学及铁、铝、锰、铬对硫酸铵结晶的影响规律。含硫酸钠与硫酸铵混合溶液硫酸铵结晶动力学研究结果表明,硫酸铵生长速率和成核速率方程分别为为B = 1.303 × 10~(-16)G1.069MT1.801,G = 15.708σ1.387;在硫酸钠与硫酸铵混合体系中,溶液过饱和度影响硫酸铵成核及生长速率,溶液过饱和度减小,晶体的成核及生长速率都会减小,与单体系硫酸铵结晶动力学结果相比,动力学参数均有所下降。铁、铝、锰、铬对硫酸铵结晶的影响规律研究结果表明,铁、铝抑制了硫酸铵晶面生长,结晶粒度减小;锰、铬对硫酸铵结晶有一定的促进作用,结晶粒度增大。金属离子改变了硫酸铵晶习,锰使结晶呈现三棱柱状,铁、铝使硫酸铵结晶片状生长。不同金属离子条件下的结晶动力学方程表明,铁和铝对结晶成核过程作用更为显著,锰和铬可以促进硫酸铵生长过程
工业乳化废液破乳剂研究趋势与进展
No full text针对工业中乳化废液的破乳除油需求与难题,首先分析了各类工业乳化废液的水质情况,然后探讨了近年来主流化学破乳剂的破乳机理,并讨论了机理间的协同作用。对近年来关注度较高的聚醚类破乳剂、星型/超支化破乳剂、天然破乳剂及其改性破乳剂和磁性纳米颗粒破乳剂的结构和性能特点进行了综述,并对不同类型的破乳剂的优缺点进行评价与总结。在此基础上,提出了各类破乳剂在研究及应用过程中存在的某些共性问题,如不具有普遍适用性、缺乏对实际乳化废液使用情况的精确分析测试、在研发与应用方面存在局限性。因此,为了提高破乳效能,除了研究破乳剂本身以外,更要针对各领域的实际乳化废液进行破乳分析测试,以获得效率更高、普适性更强的高效破乳剂
