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K. Szmuc, M. Kus-Liskiewicz, Ł. Szyller, D. Szmuc, M. Stompor, I. Zawlik, T. Ruman, S. Wołowiec and J. Cebulski

Abstract

The composite containing nanosilver uniformly deposited on matrix composed of CaHPO4 x 2H2O (brushite, ca 89 mass %), CaHPO4 (monteonite, ca 9.5 mass%), and Ag3PO4 (0.5 mas%) was obtained by addition of calcium nitrate and silver nitrate aqueous solution at 30:1 Ca:Ag molar ratio into excess of (NH4)2PO4 solution at pH 5.0 – 5.5. The isolated solid was characterized by STEM, XRD, and LDI mass spectrometry. It has been found that nanosilver was uniformly distributed within composite as <10 nm diameter sized nanoparticles. Determination of silver by AAS showed that 60% of silver is present as Ag(0) nanoparticles, the present as matrix Ag3PO4 as identified by XRD method. The composite showed strong growth inhibition in E. coli and P. aeruginosa strains, and moderate towards S. aureus. The C. albicans cells were the most resistant to the tested material, although still composite was moderately cytostatic for the yeast.

Open access

Mohammed A. Abdulaziz, Abdulrahman A. Bakri, Saleh A. Al-Zahrani, Majed S. Al-Zahrani, Abdulrahman N. Al-Lehebi, Fadil M. Banjar and Mohand I. Nabag

Abstract

This study aims at investigating the potential of Acacia gerrardii pod for the removal of Cr(VI) in batch system. Effect of solution pH, biosorbent dosage, initial concentration of Cr(VI), contact time on the removal process was examined. Complete removal of hexavalent chromium was achieved at pH values 1.0 and 2.0 whereas maximum removal of total chromium was obtained at pH of 3.0. The study showed that the biosorption and bioreduction mechanisms were involved in the removal process. The time required for complete removal of Cr(VI) using the pod of Acacia gerrardii was shortened with an increase in biomaterial dosage and decrease in Cr(VI) concentration. Kinetic data was well described using Park kinetic model. Freundlich isotherm model adequately fitted the equilibrium data indication multilayer adsorption of total chromium on the surface of biomaterial. The pod of Acacia gerrardii could be used efficiently for the removal of hexavalent chromium from aqueous solutions.

Open access

Marcin Nabrdalik and Michał Sobociński

Abstract

The paper presents analysis of stress distribution in the friction node of knee joint endoprosthesis where sleds are made of various titanium alloys and CoCrMo cooperate with spherical polyethylene inserts. Currently used titanium alloys consists of Nb, Ta, Zr or Mo and with lesser value of Young’s modulus than Ti6Al4V alloy, or steel CoCrMo, which significantly varies from other metal materials. The obtained results make it possible to indicate the “weak points” of the accepted solution, and thus counteract the subsequent effects resulting from premature wear of endoprosthesis elements. The analysis was conducted with numerical method of ADINA System 8.6. The Finite Elements Method allowed to compute and present stress distribution quickly in all elements of the model.

Open access

Katarzyna Wilpiszewska

Abstract

The hydrophilic films based on starch and carboxymethyl starch (CMS) were obtained using cast method. The effect of CMS content on the physicochemical properties of prepared films were evaluated. With increasing content of starch derivative the moisture absorption, solubility in water as well as swelling ratio increased. The highest values of mechanical parameters (tensile strength and Young’s modulus) were determined for the starch/CMS film containing the lowest CMS amount, i.e. 10 wt.% (1.1 MPa, 15 MPa, respectively). For the same system the lowest moisture absorption, solubility in water as well as swelling ratio were reported. Thus, it could be concluded that for this system the highest crosslinking density has been achieved, what was confirmed by DMTA results. Such a film could potentially find application in food or agricultural industry.

Open access

Ewa Możdżer, Krystyna Cybulska, Teresa Krzyśko-Łupicka and Edward Meller

Abstract

Therefore the carried out study aimed at determination of the effect of high-calcium brown coal ash and compost being produced from municipal sewage sludge on the content and bioaccumulation of heavy metals in potato tubers, wheat grains and rapeseeds during a three-year period. Rapeseeds contained most Cd whereas wheat rains less. Potato tubers, wheat grains and rapeseeds contained more Mn, Ni and Zn in the fertilization objects with municipal sewage sludge with or without coal ash and compared to those where calcium carbonate or coal ash had been introduced into the soil at a dose corresponding to 1.5 Mg CaO · ha−1 at the beginning of this study. Differences in the Mn, Ni and Zn contents in test plants between the fertilization objects with sewage sludge of with and without addition of ash were not significant.

Open access

Syed Sadiq Ali, Mohammad Asif and Avijit Basu

Abstract

Biodiesel is a promising energy substitute of fossil fuels since it is produced from renewable and biodegradable sources. In the present work, reactive distillation (RD) process is designed and simulated using Aspen Plus process simulator to produce biodiesel of high purity through esterification reaction. The simultaneous reaction and separation in same unit enhances the biodiesel yield and composition in RD process. Two flowsheets are proposed in present work. In the first flowsheet, the unreacted methanol is recycled back to reactive distillation column. Biodiesel with 99.5 mol% purity is obtained in product stream while the byproduct stream comprises 95.2 mol% water, which has to be treated further. In the second flowsheet, a part of methanol recycle is split and purged. In this case, the biodiesel composition in product stream is 99.7 mol% whereas water composition is 99.9 mol% in byproduct stream, which can be reused for other process without treatment.

Open access

Wioletta Drożdż, Hanna Boruczkowska, Tomasz Boruczkowski, Ewa Tomaszewska-Ciosk and Ewa Zdybel

Abstract

Fruit and vegetable processing by-products, undervalued until recently, are rich sources of nutrients. This study investigated properties of extruded corn puffs with addition (5–20%) of blackcurrant or chokeberry pressings. We assessed expansion rate, water absorption index (WAI) and water solubility index (WSI) of the produced extru-dates, the concentration of polyphenols, and antioxidant activity measured by FRAP method and ABTS method. The puffs with addition of chokeberry pressings had higher WSI values, higher phenolic acids, flavonols, and anthocyanins content, and higher antioxidant activity than puffcorn with addition of blackcurrant pressings. The corn puffs with addition of fruit pressings contained much higher concentrations of phenolic compounds and were characterized by much higher antioxidant activity than pure puffcorn. This confirms the usefulness of addition of such fruit processing by-products in order to manufacture functional food.

Open access

Maciej Mrówka, Tomasz Machoczek, Paweł Jureczko, Małgorzata Szymiczek, Magdalena Skonieczna and Łukasz Marcoll

Abstract

The purpose of the conducted study was to analyse new materials intended for contact with the human body in view of their physical, chemical and biological properties. The authors have put to test six commercially available materials, four out of which were composite polyamide 12-based materials, while two were polyurethanes. The examined materials were assessed in terms of the surface. Subsequently, their hardness and biocompatibility were tested. The authors devoted major attention to the tests of absorption and emissivity of water, the pH = 7.4 PBS buffer solution and pH = 4.3 artificial sweat in temperatures of 21°C and 37°C. The results of the tests have confirmed the non-toxicity of all the tested materials and allowed to provide their characteristics in terms of their surface, hardness, as well as absorption and emissivity of various body fluids. Both polyamide 12 and the tested polyurethanes are classified as thermoplastics that may be used in additive technology.

Open access

H. Geiplová, L. Mindoš, J. Mrázek, D. Majtás, P. Macová and P. Pokorný

Abstract

The paper follows the paper describing the condition of wrought iron structure of main railway station [1]. In this paper the investigation of condition of paint system corrosion surface treatment is given and the restoration procedure is described. The withdrawal samples of paint systems were analysed by stratigraphy, FTIR and XRF analysis. Due to identification of Pb pigment presence in primer the water jet technology was chosen which minimalised the danger waste formation.

Open access

P. Pokorný, M. Hrabánek and H. Geiplová

Abstract

This article presents the results of the corrosion survey of the load-bearing structure of the main hall of the Main railway station in Prague. The chemical composition and microscopy view of the metal alloy has been explored, the current state of the anti-corrosion protection system as well as its composition were also evaluated. The corrosion damage of sheets and reinforcements of individual columns of the peron hall is also reported. The corrosion damage of the plates and reinforcements is locally very significant and is related to the drainage of rain water from the damaged roof structure. Renovation is also necessary for the protective coating system. The article concludes a restoration project that fully respects the historical form of the construction of the early twentieth century with minimal compromise.