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

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

Evaluation of the effects of treatment factors on the properties of bio-apatite materials

Animal bones have been studied as a resource of low-crystalline apatite for immobilization of toxic heavy metals. Chemical and thermal treatments can be applied for selective removal of bone organic constituents. In this study, the impact of different treatment factors was determined by experimental design methodology, and comparison of the estimated effects was performed in order to optimize the treatment conditions. Fractional factorial design with five variables at two levels was applied for factors screening. The type of chemical reagent (H2O2 or NaOH), its concentration (0.1 or 2 mol/L), reaction temperature (20 or 60 degrees C), contact time (1 or 3 h) and sample annealing (without or at 400 degrees C) were considered as process variables. Structural properties of bone sorbents, loss of ignition, point of zero charge, surface functional groups, specific surface area, chemical composition, and Cd2+ sorption efficiency, were selected as system responses. Samples significantly differed in respect to the organic phase content and composition, thus mechanisms of Cd2+ sorption were complex. Statistical analysis has revealed that, between all studied factors, temperature treatment was the most important for sorbents increased specific surface area, porosity and cation sorption. Furthermore, NaOH was more effective than H2O2, while the effects produced by variation of other factors were less pronounced. The highest proportion of bio-apatite with desired low crystallinity and high specific surface area was achieved by synergetic effects of chemical treatment with NaOH and thermal treatment at 400 degrees C

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. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III 43009 and Grant no. OI 171007

The applicability of construction and demolition waste components for radionuclide sorption

Following the guiding 3R principle of sustainable development (Reduce, Reuse and Recycle), the potential applicability concerning various components of construction and demolition waste (C and DW) was investigated for radionuclide sorption (Sr, Co, Ni). Collected samples of waste concrete, facade, bricks and asphalt were characterized in respect to mineralogical and surface composition, pH and radioactivity, while their sorption capacities were determined in batch conditions. Selectivity of potential sorbents differed in respect to Co2+ and Ni2+ ions, whereas sorption of Sr2+ was generally low. Concrete and facade have demonstrated both: the highest sorption capacities and the strongest interaction with the investigated cations, as revealed by sequential extraction analysis of loaded sorbents. Taking into account chemical compatibility with mixtures, commonly used for the solidification of radioactive waste, and expressed high affinity for studied cations, waste cement materials and debris are promising matrices for radionuclide immobilization. (C) 2017 Elsevier Ltd. All rights reserved