Correlation of Mass Transfer Coefficients in Supercritical CO2 Separation Process

Weighted least squares and error-in-variable statistical methods were used to minimize variations in the experimental data set obtained from literature, and were used to validate Models I and II, S h′ = 0.0015(R e ^1/2 S c ^1/3)^2.58 and S h′ = 0.00084(R e ^0.4299 S c ^0.8783), respectively. Published data were used for the empirical estimation of mass transfer coefficients in separation processes in fixed bed systems using supercritical carbon dioxide extraction with low molecular diffusion. Model I gained accuracy when the Schmidt Number Sc is high (> 70) and the molecular diffusion is weak. The exponential ratio of the Re and Sc of Model II differed from the common ratio of 3:2; however, the exponents of the Sc are unique for both Models I and II.     

Levels of 15 + 1 EU Priority Polycyclic Aromatic Hydrocarbons in Different Edible Oils Available in the Syrian Market

ABSTRACT

The levels of 15 + 1 EU priority polycyclic aromatic hydrocarbons (15 + 1 EU PAHs) have been determined in different edible oils (extra virgin olive oil, virgin olive oil, sunflower oil, corn oil, and soybean oil) available in the Syrian market. The samples have been prepared by donor–acceptor complex chromatography and subsequently characterized by high-pressure liquid chromatography coupled with fluorescence and ultraviolet detection for quantification purposes. Variable levels of contamination have been found within different kinds of edible oil samples, and only chrysene has been detected in all the studied samples. Moreover, the mean total sum of 15 + 1 EU PAHs has shown variation from 29.8 µg/kg (corn oil) to 63.7 µg/kg (virgin olive oil). A total of 11 samples out of 38 samples (28.9%) have not fulfilled the European Union (EU) food law requirements. Nine samples have exceeded the EU legislation limit of benzo[a]pyrene (BaP) (2 µg/kg) and only two samples have exceeded the EU legislation limit of PAH4 (10 µg/kg) and had acceptable level of BaP. Finally, the mean and maximum dietary exposures of PAHs through consumption of edible oils have been estimated.     

Monitoring and Origin of Polycyclic Aromatic Hydrocarbons (PAHs) in Effluents from a Surface Treatment Industry

ABSTRACT

In Europe, polycyclic aromatic hydrocarbons (PAHs) are a source of concern due to their toxic effects and are considered as priority pollutants by water authorities. In this study, we reported the results of qualitative and quantitative monitoring of 16 PAHs in effluents from a surface treatment industry to determine their origin. The results indicated that PAHs were present in the discharge waters at a concentration of 500 ng L^?1 (in average for the PAH sum). However, the further we returned to the start of the industrial process, the more the PAH concentrations increased. Indeed, the highest concentrations (>20,000 ng L^?1 for the PAH sum) were found in the degreasing baths – the first step in the part treatment. The final analyses showed that the PAHs came from the oils left on the metal parts by the suppliers. The important difference in concentrations between the upstream (first baths in the production line) and the downstream (discharge water) of the effluent showed that phenomena including dilution or potentially degradation occurred but that the major part of the PAHs tended to adsorb to sludge during the settling step in the effluent treatment plant.     

Behavior of structural polymer-modified concrete containing recycled aggregates

The use of recycled concrete aggregate (RCA) in structural applications is hindered by the inferior concrete mechanical performance and unpredictable behavior with embedded steel reinforcement. The main objective of this paper is to evaluate whether the addition of small amounts of styrene-butadiene rubber (SBR) polymeric latexes could mitigate the drop in RCA concrete properties. Two series of mixtures prepared with 320 or 440 kg/m³ cement were tested by direct bond and beam-end methods; the SBR addition rates varied from 1 to 3% of cement mass. Test results showed that SBR could remarkably improve RCA concrete workability as well as compressive and splitting tensile strengths. The initial stiffness of load vs. slip curves was considerably accentuated, reflecting increased interfacial shear stresses between the reinforcing bar and surrounding concrete. Also, the responses of ascending curves showed extended nonlinear regions together with higher ultimate bond strengths at failure. The experimental direct bond and beam-end test data are compared with the design bond strengths determined by ACI 318-14, European Code EC-2, and fib Model Code MC2010.     

Polyurethane Foam Wastes Recycling under Microwave Irradiation

Microwave-assisted (MW-assisted) glycolysis of waste-flexible polyurethane (PU) foams using pentaerythritol in combination with glycerin and sodium hydroxide as a PU bond degradation reagent is reported. Split phases appeared after complete foam digestion. The upper phase contained recycled polyol, and the lower phase was a brown liquid with highly functionalized oligomers, amines and unreacted degradation reagents and showed potential for application in rigid polyurethane foam formulation. Our studies showed the dependence of recovered polyol assay to the additional MW irradiation and amine-free polyol were achieved in high yields and purities.     

Lipase‐mediated preparation of epoxy lecithin and its evaluation as plasticizer in polyester laminates

A simple chemoenzymatic method was developed for the preparation of epoxy lecithin that contains epoxy oils and phospholipids. The parameters such as lipase concentration, hydrogen peroxide concentration, and time of the reaction were studied. The product was evaluated as a plasticizer in polyester laminates and compared with virgin polyester laminates. The laminates were prepared using various amounts of epoxy lecithin and evaluated for different properties. The epoxy lecithin modified laminates showed good impact strength, tensile, and chemical resistance properties. These laminates were also evaluated for vicat softening point and water absorption. The epoxy lecithin can be used as a plasticizer in polyester laminates. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Thermal Degradation Kinetics of Carotenoids in Palm Oil

In the present work, a detailed study is performed for carotene thermal degradation in palm oil at four temperatures ranging from 170 to 230 °C. The heating process was carried out with injection of nitrogen, and the samples were collected every 20 min during a total heating period of 140 min. HPLC analysis was conducted to monitor the carotenoids and tocols variations over the heating time at each temperature. The experimental data were then compared to literature data concerning carotenoids thermal degradation. The thermal degradation kinetics of carotenoids in palm oil followed an order superior to 1. The dependence of constant rates with temperature obeyed the Arrhenius relationship. The activation energy for the carotenoids thermal degradation in palm oil was found to be 109.4 kJ/mol.     

废玻璃混凝土最优复掺方式及耐高温性能研究

目前将废玻璃进行填埋处理不仅污染了环境,也是对资源的浪费.将固废物进行资源化利用,实现循环经济是可持续发展战略的重要内容.为提高废玻璃利用率,选取废玻璃粉作为辅助胶凝材料取代混凝土中的部分水泥,同时废玻璃作为粗、细集料取代混凝土中的部分石子、河砂,研究其复掺方式对再生混凝土抗压强度的影响,并确定最优掺加方式.在此基础上...     

再生骨料混凝土空心砌块砌体的抗压性能

利用废弃混凝土加工成的再生骨料制作再生混凝土空心砌块.对再生混凝土空心砌块砌体进行抗压性能实验,研究不同再生粗骨料取代率对其受压性能的影响,分析了砌体的破坏特征和变形过程.研究结果表明:再生混凝土空心砌块砌体的受压性能和普通混凝土砌块砌体的受压性能极为相似,以85％再生粗骨料取代率,配制强度等级为MU5.0的再生骨料混凝土空心砌块是可行的.     

Properties of concrete incorporating fine recycled aggregate

The properties of concrete containing fine recycled aggregate are investigated. Recycled aggregate consisted of crushed concrete (CC) or crushed brick (CB) with particles less than 5 mm in diameter. The free water/cement ratio was kept constant for all mixes. The fine aggregate in concrete was replaced with 0%, 25%, 50% and 100% CC or CB. Generally, there is strength reduction of 15-30% for concrete containing CC. However, concrete incorporating up to 50% CB exhibits similar long-term strength to that of the control. Even at 100% replacement of fine aggregate with CB, the reduction in strength is only 10%. Beyond 28 days of curing, the rate of strength development in concrete containing either CC or CB is higher than that of the control indicating further cementing action in the presence of fine recycled aggregate. More shrinkage and expansion occur in concrete containing CC or CB.