Effectiveness of novel and traditional methods to incorporate industrial wastes in cementitious materials—An overview

Sustainable development and eco-efficiency are urgent and imperative demands for the well-being of our planet, continued growth of a society, and human development. Traditional Portland cement production seems unsustainable due to consumption of huge natural resources and energy and significant CO₂ emissions. The volume of industrial wastes is increasing significantly, leading to a number of economical and ecological problems. Although industrial wastes can be incorporated in cementitious materials by various traditional methods, the substitution ratio of industrial wastes in cementitious materials is relatively low to avoid unacceptable performance loss. Novel methods, such as improving hydraulic activities of metallurgical slags by adding composition adjusting material at high temperature, improving surface cementitious properties of fly ashes by dehydration and rehydration treatment, and arranging cement clinker and industrial wastes in the particle size distribution of blended cements according to their hydraulic activities, are reviewed. These methods provide more effective approach to prepare high performance blended cements with larger amount of industrial wastes, leading to a very significant role in CO₂ emissions reducing, resources and energy conservation of the cement industry.     

A review of the past,present and future of the European loss prevention and safety promotion in the process industries

In 2013, the European Federation of Chemical Engineering (EFCE) celebrates its 60th anniversary. EFCE has continually promoted scientific collaboration and supported the work of engineers and scientists in thirty European countries. As for its mission statement, EFCE helps European Society to meet its needs through highlighting the role of Chemical Engineering in delivering sustainable processes and products. Within this organizational framework the Loss Prevention Symposium series, organized throughout Europe on behalf of the Loss Prevention Working Party of the EFCE, represents a fruitful tradition covering a time span of forty years. The tri-annual symposium gathers experts and scientists to seek technical improvements and scientific support for a growingly safer industry and quality of life. Following the loss prevention history in this paper, a time perspective on loss prevention and its future is presented.     

隧道混合燃料火灾燃烧蔓延特性实验研究

隧道火灾一直是火灾科学研究领域的重要问题之一。近年来,隧道火灾中由于燃油泄漏而引起的火蔓延现象是一个新兴的研究热点。利用小尺寸(1:10)的隧道火灾模拟实验平台,开展了薄油、窄油池机制下不同混合比例下正丁醇-柴油燃烧特性实验研究。结果表明,根据正丁醇比例,可将正丁醇-柴油混合燃料分为两类。当正丁醇比例不大于20%时,主火焰蔓延速度线性增大,闪燃火焰则由间断变为持续存在且波长由14.17 cm减小到8.42 cm;油面温升速率逐渐增大;当正丁醇比例大于20%时,主火焰蔓延速度接近正丁醇蔓延速度(3.33 cm/s),闪燃火焰持续存在且波长在8.3 cm左右;油面温升速率基本相同。研究结果为认识隧道混合燃料火灾燃烧特性提供了参考。     

Influence of thermally activated paper sludge on the behaviour of blended cements subjected to saline and non-saline environments

Background, aim and scope  One of the problems to affect Portland cement matrices is low resistance to aggressive agents, due principally to the presence of a high content of portlandite in the hydrated cements. Pozzolanic materials have played an important role in the improving the durability of cement-based materials for decades. This work studies the behaviour of cement mortar matrices blended with 10% calcined paper sludge (source for metakaolinite) and exposed to different environmental conditions (saline and non-saline environments) after 6 and 12 months of exposure. Materials and methods  Two cements were studied: an ordinary Portland cement (CEM 1, 42.5R), acting as reference cement, and a blended cement formulated by mixing 90% (by mass) of CEM 1, 42.5R with 10% (by mass) of paper sludge calcined at 700°C for 2 h. The specimens were exposed 1 year to saline and non-saline environments. All the mineralogy samples were studied through X-ray diffraction and scanning electron microscopy (SEM) equipped with an energy dispersive X-ray analyser. The in-depth study on ionic mobility was performed on samples subjected to natural exposure (coast and tableland) for 6 and 12 months. Results  Portland cement was composed of quartz, calcite, calcium hydroxide and tobermorite gels. The pozzolanic cement (10% calcined paper sludge) is of the same composition but a high calcite concentration and barium carbonate. SEM analysis from coastline show deposits of variable composition. The deposits are identified on the surface of different mineral components. The minerals from tableland are much fractured, i.e. calcite and feldspars. Inside the fractures, the deposits and the ions are located and trapped superficially. Discussion  SEM analysis of control cement Portland and 10% calcined paper sludge shows deposits on quartz and calcite with a very high concentration of Pb, Zn, Cl and barium sulphate. A very porous aspect is due to the presence of the different aggregate types. This porous configuration permits retention of the ion environment. The pozzolanic cement in environments subject to the saline mist favours the retention and transport of ions observed. Something similar also happens with the increase in exposure to outdoor weather. Non-saline samples show temperature changes (ice or thaw cycles). Barium retention is kept on the surface in fracture lines by the gelification processes. In general, it may be inferred that an increase in exposure time increases the diffusion of ions towards test piece interiors. The chemical composition profiles show that the ions present different penetration speeds. Conclusions  The results indicate the better vulnerability of pozzolanic cements from calcined paper sludge in saline and non-saline environments. The cements with a 10% addition of calcined paper sludge favour retention and transport of ion has been observed. Recommendations and perspectives  Today, projects are centred on a new recycling line for industrial waste of this kind, with special attention on its incorporation in cement manufacture as a pozzolanic material, setting the most appropriate activation conditions of the mineralogical compound in this waste (kaolinite and metakaolinite) and taking them as a starting point for this project. The use of pozzolanic cement with 10% addition of calcined paper sludge is a system which favours ionic retention.     

Experimental study on explosion characteristics of ethanol-gasoline blended fuels

In the present work, a series of experiments have been performed to analyze the explosion characteristics of ethanol-gasoline with various blended ratios (0%, 5%, 10%, 15%, 30%, 50%, 70%, 80%, and 100%). A vented rectangular vessel with a cross-section of 100 mm × 100 mm, 600 mm long and a 40 mm diameter vent on the top is used to carry out the experiments. The flame propagation is recorded by a phantom high-speed camera with 5000 fps, while the histories of the explosion overpressure are measured by two PCB pressure sensors and the explosion sound pressure level is obtained by a CRY sound sensor. The results indicate that the maximum overpressure and flame propagation speed increases linearly as the blended ratio increases when the initial volume of blended fuel is 1.0 mL; While the change of explosion overpressure and flame propagation speed shows a trend of decreasing at first and then increasing as the concentration increases to 1.8 mL. It is also found that the peak of the sound pressure level exceeds 100 dB under all tests, which would damage the human's hearing. What's more, relationships between explosion overpressure and sound pressure level are examined, and the change of the maximum overpressure can be reflected to some extent by the measurement of the maximum sound pressure level. The study is significant to reveal the essential characteristic of the explosion venting process of ethanol-gasoline under different initial blended ratios, and the results would help deepen the understanding of ethanol-gasoline blended fuels explosion and the assessment of the explosion hazardous.     

改性膨润土对晴纶混纺织物染色废水脱色处理的研究

文章介绍了晴纶纸纺织物在染色时所产生的染色废水的特征,针对该废水在处理时具有脱色难的难题,寻找具有针对性的凝聚剂,最后选用改性膨润土作凝剂.试验结果表明:用CaO调pH值为7、凝聚剂投加质量分数为8%的条件下,废水脱色率可达100%,同时,由于提高了废水的可生化性,为后续深加工处理提供了有利条件.     

PVDF ultrafiltration membranes of controlled performance via blending PVDF-g-PEGMA copolymer synthesized under different reaction times

PVDF blended different graft ratio of PVDF-g-PEGMA were systematically studied. Tuning the amphiphilic copolymer synthesis time to control membrane performance. The PVDF membrane with PVDF-g-PEGMA at 19 h possesses most surface oxygen content. The synthesis time of PVDF-g-PEGMA at 9 h is good for high flux UF membrane. Polyvinylidene fluoride grafted with poly(ethylene glycol) methyl ether methacrylate (PVDF-g-PEGMA) was synthesized using atomic transfer radical polymerization (ATRP) at different reaction times (9 h, 19 h, and 29 h). The corresponding conversion rates were 10%, 20% and 30%, respectively. PVDF was blended with the copolymer mixture containing PVDF-g-PEGMA, solvent and residual PEGMA under different reaction times. In this study, we explored the effect of the copolymer mixture additives with different synthesis times on cast membrane performance. Increasing the reaction time of PVDF-g-PEGMA causes more PVDF-g-PEGMA and less residual PEGMA to be found in the casting solution. Incremental PVDF-g-PEGMA can dramatically increase the viscosity of the casting solution. An overly high viscosity led to a delayed phase inversion, thus hindering PEGMA segments in PVDF-g-PEGMA from migrating to the membrane surface. However, more residual PEGMA contributed to helping more PEGMA segments migrate to the membrane surface. The pure water fluxes of the blended membrane with reaction times of 9 h, 19 h, and 29 h are 5445 L·m⁻²·h⁻¹, 1068 L·m⁻²·h⁻¹and 1179 L·m⁻²·h⁻¹, respectively, at 0.07 MPa. Delayed phase inversion can form smaller surface pore size distributions, thus decreasing the water flux for the membranes with PVDF-g-PEGMA at 19 h and 29 h. Therefore, we can control the membrane pore size distribution by decreasing the reaction time of PVDF-g-PEGMA to obtain a better flux performance. The membrane with PVDF-g-PEGMA at 19 h exhibits the best foulant rejection and cleaning recovery due to its narrow pore size distribution and high surface oxygen content.     

Spray and explosion characteristics of methanol and methanol-benzene blends near azeotrope formation: Effects of temperature,concentration, and benzene content

The explosion hazard of flammable liquids leaking to form spray in storage and transportation at ambient temperature has not been systematically investigated. This work presents new results from experimental investigations of the atomization and explosion characteristics of methanol, and methanol-benzene blends forming near the azeotrope under different initial conditions (initial temperature (298.15–318.15 K), methanol concentration (198–514.8 g/m³) and benzene content (41–81%)) in a 20-L spherical vessel. The empirical formulas for Sauter Mean Diameter (SMD) of the droplets and the maximum explosion pressure with respect to the initial temperature and methanol concentration were obtained from the quantitative analysis. Compared to the explosion hazard of pure methanol and methanol-benzene blends spray, the results showed that the maximum rate of pressure rise and maximum explosion temperature of methanol-benzene blends were relatively low. Furthermore, the effect of carbon soot formation on the explosion hazard during explosion development was analyzed.