The Application of Experimental Design Methodology for the Investigation of Liquid Radioactive Waste Treatment

The sorption properties of waste facade, brick, and asphalt sample towards Sr(II), Co(II), and Ni(II) ions from single and multicomponent solutions were investigated. The highest sorption capacity was found for Ni(II) ions, while the most effective sorbent was facade. Simplex Centroid Mixture Design was used in order to investigate the sorption processes of ions from solutions with different composition as well as the competition between the cations. Based on the statistical analysis results, the equations for data modeling were proposed. According to the observations, the investigated solid matrices can be effectively used for the liquid radioactive waste treatment. Furthermore, the applied methodology turned out to be an easy and operational way for the investigations of multicomponent sorption processes

Applicability of Construction and Demolition Waste in Geopolymers – A Screening Test

In this study, the applicability of construction and demolition waste (C&DW) in geopolymerization technology was investigated. The C&DW components, concrete and solid bricks, were collected from demolition sites in Belgrade, Republic of Serbia. The concrete sample came from a demolished fifty-year-old construction road, while the remains of solid bricks originated from a 1930s building. Prior to mechanical testing, the C&DW components were characterized by XRD analysis for their mineralogical composition. The results showed that the concrete waste consisted mainly of quartz (SiO2) and calcite (CaCO3), while the brick waste sample contained anorthite from the feldspar group (CaAl2Si2O8), wollastonite (Ca0.957Fe0.043O3Si) and mullite (Al2.4O4.8SiO6). The mechanical properties were examined using the screening method on three geopolymer mixtures, one of each mixture of concrete and brick powders and a mixture of both C&DW components. According to the standard SRPS EN 12390-3:2010 for cubic samples, the geopolymer samples were prepared with alkaline activators for testing the compressive strength as the dominant parameter in the mortar and concrete evaluation. The compressive strength values increased in the range of 2.4 MPa for concrete, 10.2 MPa for brick, and 10.8 MPa for the mixed geopolymer sample. The low compressive strength result of the concrete sample was the consequence of the mineral composition, i.e., the absence of aluminosilicate. However, the brick and the sample with a combination of both types of waste showed moderately satisfactory compressive strength, which could be the starting point for further investigations

Primena otpadnih materijala u imobilizaciji teških metala i radionuklida sorpcijom

Trend istraživanja sorpcionih karakteristika raznih prirodnih materijala, odnosno lako dostupnih sirovina, nus-proizvoda ili otpada iz raznih vrsta industrije poslednjih godina je sve više izražen. Upotrebom otpadnih materijala smanjuje se iskorišćenje prirodnih neobnovljivih resursa i/ili iskorišćenje raznih vidova energije za sintezu ili modifikaciju prirodnih sirovina i veštačkih materijala. Takođe, korišćenje otpadnih materijala kao sorbenata izuzetno je prihvatljivo s aspekta zaštite životne sredine s obzirom da utiče na smanjenje količina ovakvih vrsta otpada, troškova njihovog odlaganja i umanjenje opasnosti od hazarda koje neki od ovih otpada potencijalno mogu da izazovu u životnoj sredini. U ovom radu dat je pregled savremenih istraživanja otpadnih materija u imobilizaciji radionuklida i teških metala. Studije su pokazale da korišćenje otpadnih materijala u procesu sorpcije, odnosno kondicioniranja tečnog radioaktivnog otpada i prečišćavanja otpadnih voda može da predstavlja vrlo efikasne i ekonomski isplative alternative standardno korišćenim metodama, odnosno sorbentima. Nedavna istraživanja o primeni različitih otpadnih materijala i nezahtevnih tehnika njihove modifikacije u cilju poboljšanja procesa sorpcije obuhvataju širok spektar otpadnih materijala, kao što su razne vrste muljeva, šljake, elektrofilterskog pepela, biomase, otpada iz prehrambene industrije, građevinskog otpada i s

Implemenation of FEM and rapid prototyping in maxillofacial surgery

© Faculty of Mechanical Engineering, Belgrade. This paper investigates the opportunity of implementing FE simulations and rapid prototyping tecniques on titanium implant in maxillofacial surgery case based on osteotomy. Maxilla region was recorded by Cone Beam CT with high resolution and optimal radiation. Then, it followed the medical image reconstruction into 3D voxelized model. This model was converted both, to stl surface model for rapid prototyping, CAD modeling and FE mesh for simulation purposes with keeping good volume and dimensional consistency. Stl meshed surface was imported into CAD software, as initial 3d structure, which is used for parametric and customized design of implant. Since, the osteotomy is final application, it wassimulated the cutting and shifting of maxilla for proper correction by digital prototyping. Then, the fixation points for shifted maxilla were determined by surgeon to provide steady and tight joints between implanting screws and maxilla. Applied implant was given in initial standard flat configuration. Flat implant configuration was adapted by complex 3D bending in CAD software to be customized towards surface conformity of maxillofacial anatomy. By FE simulation in MSC Patran/Nastran, it was performed the stress analysis of implant with different thickness configurations and 3D bending, which provides the optimized implant model with best fit dimensions. Optimized implant model and corresponding body model were converted into physical models. RP model of maxilla was post-processed by cutting and boring to provide an adequate implant positioning according to digital prototypes. This approach facilitated the preparation of complex shaped implants in swept and lofted form, what had to be in high degree of conformity to anatomy surface. To approve a good practical opportunity, it was applied and tested in concrete surgery case of maxillofacial osteotomy

Impact of Informal Settlements on the Environment in Southeast Europe – A Review

Impact of Informal Settlements on the Environment in Southeast Europe – A Review. International scientific conference Environmental impact of illegal construction, poor planning and design IMPEDE 201

Modelovanje sorpcionih izotermi jona Ni(II) na otpadnim cementnim materijalima

Otpadni cementni materijali (beton i fasada) su bazirani na kvarcu i kalcitu. Prvenstveno zahvaljujući kalcitu i baznom karakteru, ove matrice su pokazale visok afinitet prema jonima nikla. Ispitivanje uticaja početne koncentracije jona Ni u rastvoru na sorbovanu količinu omogućava definisanje sorpcionih izotermi. U ovom radu su prikazani rezultati matematičkog modelovanja izotermi Langmuir-ovim i Freundlich-ovim modelom. Langmuir-ov model znatno bolje opisuje eksperimentalne podatke dobijene za sorpciju na betonu, dok je sorpcija otpadnom fasadom bolje opisana Freundlich-ovom izotermom

Energy Efficiency and Sustainability of Biofibres-Based Thermal Insulation

Energy efficiency of residential and commercial buildings is acutely important as this sector is responsible for approximately 40% of overall energy consumption and around 35% of CO2 emissions (in the European Union). The construction sector has intense environmental footprint due to exploitation of non-renewable material and energy resources, land use and generation of waste materials during construction and demolition. It is therefore important to develop sustainable building structures, practices and materials with minimal resources and energy use. Utilization of energy efficient, sustainable and resource-saving building materials is of particular importance. The study is carried out to investigate possibilities and evaluate effects of application of biofibres-based structures as non-constructive and/or insulating materials in current building practice. Focus is on natural, dominantly cellulose, fibres, traditionally used in the past (hemp, reed, straw, flax, rice hulls, cotton stalks, sunflower, cattail, bagasse, etc) as well as on some promising grass/reed cultures, such as Miscanthus x Giganteus. The experimental examinations of thermal and mechanical properties decisive for the performance of thermal insulation have been undertaken. Expectedly, the thermal conductivity, as the material characteristic primarily responsible for Operational Energy Consumption, has been found mostly worse than in commonly used, mass produced, thermal insulation materials such as expanded or extruded polystyrene, glass or mineral wool, etc. On the other hand, conclusions of Life Cycle Analysis and examination of Embodied Energy advocates the utilization of designated natural biofibres-based thermal insulation as more sustainable and in the long run (Cradle to Grave) energy efficient alternative to the conventional insulation materials

Selenate adsorption from water using the hydrous iron oxide-impregnated hybrid polymer

Hybrid adsorbent, based on the cross-linked copolymer impregnated with hydrous iron oxide, was applied for the first time for Se(VI) adsorption from water. The influence of the initial solution pH, selenate concentration and contact time to adsorption capacity was investigated. Adsorbent regeneration was explored using a full factorial experimental design in order to optimize the volume, initial pH value and concentration of the applied NaCl solution as a reagent. Equilibrium state was described using the Langmuir model, while kinetics fitted the pseudo-first order. The maximum adsorption capacity was found to be 28.8 mg/g. Desorption efficiency increased up to 70%, and became statistically significant with the reagent concentration and pH increase, while the applied solution volume was found to be insignificant in the investigated range. Based on the results obtained, pH influence to the adsorption capacity, desorption efficiency, Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analysis of loaded adsorbent, it was concluded that the outer-and inner-sphere complexation are mechanisms responsible for Se(VI) separation from water. In addition to the experiments with synthetic solutions, the adsorbent performances in drinking water samples were explored, showing the purification efficiency up to 25%, depending on the initial Se(VI) concentration and water pH. Determined sorption capacity of the cross-linked copolymer impregnated with hydrous iron oxide and its ability for regeneration, candidate this material for further research, as a promising anionic species sorbent