A study of the photocatalytic degradation of the textile dye CI Basic Yellow 28 in water using a P160 TiO2-based catalyst

The photocatalytic degradation of the synthetic textile dye CI Basic Yellow 28 (BY28) in water, using a recently synthesized P160 TiO2-based catalyst, under Osram ultra-vitalux (R) lamp (300 W) light, was studied. The effects of the operational parameters, such as initial concentration of catalyst, initial dye concentration and pH, were studied. The salt effect (NaCl, Na2CO3, Na2SO4 and NaNO3) was also investigated. It was found that the optimal concentration of catalyst is 2.0 g L-1. A pseudo first-order kinetic model was illustrated using the Langmuir-Hinshelwood mechanism and the adsorption equilibrium constant and the rate constant of the surface reaction were calculated (K-By = 6.126 L mg(-1) and k(C) = 0.272 mg L-1 min(-1), respectively). The photodegradation rate was higher in weak acidic than in high acidic and alkaline conditions. The presence of CO32- ions increased the photodegradation rate while Cl-, SO42- and NO3- decreased the reaction rate. The rate of photodegradation of BY28 was measured using UV-Vis spectroscopy

Biomaterijali

Početak XXI veka nesumnjivo je obeležen interdisciplinarnim i multidisciplinarnim naporima istraživača u različitim oblastima nauke. Jedna od najizrazitijih tendencija ovog tipa uočava se u biomedicinskim istraživanjima, gde se združuju napori lekara, biologa, genetičara i biohemičara, s jedne strane, i biofizičara i inženjera, s druge strane – sa ciljem dubljeg razumevanja zdravlja i bolesti, i primene ovih saznanja u biomedicinskoj praksi, tako važnoj u svakodnevnom životu ljudi.Kao rezultat ovih svetskih trendova, u Srbiji već više godina na nekoliko fakulteta postoji nastava iz oblasti biomedicinskog inženjerstva, sa ciljem da osposobi inženjere ovih usmerenja za multidisciplinarno povezivanje znanja iz oblasti tehnike sa biomedicinskim znanjima. Jedan od bazičnih predmeta ovih usmerenja jesu Biomaterijali, kojima je i posvećen naš udžbenik, čiji je cilj da predstavi pregled teorije i prakse biomaterijala u biomedicinskoj nauci.Nauka o biomaterijalima je nesumnjivo najmultidisciplinarnija od svih nauka, jer zahteva ovladavanje znanjima iz mnogih oblasti nauke i tehnologije, inženjerstva i medicine, kako bi naučnici iz oblasti biomaterijala mogli da se uhvate u koštac sa ovom profesijom. Zato posle uvodnog dela, udžbenik iz Biomaterijala sadrži četiri celine: (I) Osnovni biomedicinski koncepti i reakcije organizma na biomaterijale, (II) Struktura, fizičko-mehanička karakterizacija i modeliranje biomaterijala i tkiva, (III) Savremeni biomaterijali i tehnologije, (IV) Perspektive biomaterijala i tehnologija, iza kojih slede Zadaci sa rešenjima, Ispitna test pitanja i Ispitna teorijska pitanja, koji pomažu studentima da lakše savladaju veoma obimno i kompleksno gradivo. Na kraju svakog poglavlja data su pitanja za rekapitulaciju, kao i spisak dopunske literature za opcionu detaljniju obradu pojedinih oblasti.Grupa od dvadeset četiri profesionalca sa univerziteta i naučnih instituta, pod okriljem Instituta tehničkih nauka Srpske akademije nauka i umetnosti, Beograd, i Društva za istraživanje materijala Srbije (MRS Srbija) doprinela je pisanju ovog kapitalnog udžbenika o biomaterijalima, prvog do sada na srpskom jeziku. Mada uključivanje veće grupe autora nužno dovodi do stilske neujednačenosti, ipak je oblast biomaterijala toliko multidisciplinarna da je ovakav pristup bio neophodan, kako uostalom pokazuju slična svetska iskustva sa uključivanjem i preko pedeset autora. Ipak urednici su se potrudili da koliko je to moguće stilski i pedagoški ujednače udžbenik, kako bi bio korisna literatura za sve studente diplomskih, master i doktorskih studija iz biomedicinskog inženjerstva u Srbiji i okruženju

Biomaterijali

Početak XXI veka nesumnjivo je obeležen interdisciplinarnim i multidisciplinarnim naporima istraživača u različitim oblastima nauke. Jedna od najizrazitijih tendencija ovog tipa uočava se u biomedicinskim istraživanjima, gde se združuju napori lekara, biologa, genetičara i biohemičara, s jedne strane, i biofizičara i inženjera, s druge strane – sa ciljem dubljeg razumevanja zdravlja i bolesti, i primene ovih saznanja u biomedicinskoj praksi, tako važnoj u svakodnevnom životu ljudi.Kao rezultat ovih svetskih trendova, u Srbiji već više godina na nekoliko fakulteta postoji nastava iz oblasti biomedicinskog inženjerstva, sa ciljem da osposobi inženjere ovih usmerenja za multidisciplinarno povezivanje znanja iz oblasti tehnike sa biomedicinskim znanjima. Jedan od bazičnih predmeta ovih usmerenja jesu Biomaterijali, kojima je i posvećen naš udžbenik, čiji je cilj da predstavi pregled teorije i prakse biomaterijala u biomedicinskoj nauci.Nauka o biomaterijalima je nesumnjivo najmultidisciplinarnija od svih nauka, jer zahteva ovladavanje znanjima iz mnogih oblasti nauke i tehnologije, inženjerstva i medicine, kako bi naučnici iz oblasti biomaterijala mogli da se uhvate u koštac sa ovom profesijom. Zato posle uvodnog dela, udžbenik iz Biomaterijala sadrži četiri celine: (I) Osnovni biomedicinski koncepti i reakcije organizma na biomaterijale, (II) Struktura, fizičko-mehanička karakterizacija i modeliranje biomaterijala i tkiva, (III) Savremeni biomaterijali i tehnologije, (IV) Perspektive biomaterijala i tehnologija, iza kojih slede Zadaci sa rešenjima, Ispitna test pitanja i Ispitna teorijska pitanja, koji pomažu studentima da lakše savladaju veoma obimno i kompleksno gradivo. Na kraju svakog poglavlja data su pitanja za rekapitulaciju, kao i spisak dopunske literature za opcionu detaljniju obradu pojedinih oblasti.Grupa od dvadeset četiri profesionalca sa univerziteta i naučnih instituta, pod okriljem Instituta tehničkih nauka Srpske akademije nauka i umetnosti, Beograd, i Društva za istraživanje materijala Srbije (MRS Srbija) doprinela je pisanju ovog kapitalnog udžbenika o biomaterijalima, prvog do sada na srpskom jeziku. Mada uključivanje veće grupe autora nužno dovodi do stilske neujednačenosti, ipak je oblast biomaterijala toliko multidisciplinarna da je ovakav pristup bio neophodan, kako uostalom pokazuju slična svetska iskustva sa uključivanjem i preko pedeset autora. Ipak urednici su se potrudili da koliko je to moguće stilski i pedagoški ujednače udžbenik, kako bi bio korisna literatura za sve studente diplomskih, master i doktorskih studija iz biomedicinskog inženjerstva u Srbiji i okruženju

Characterization of sepiolite by inverse gas chromatography at infinite and finite surface coverage

The adsorption properties of sepiolite from Andrici, Serbia, were studied by inverse gas chromatography at zero and finite surface coverage between 483 and 513 K. The thermodynamic parameters (free energy, enthalpy, entropy) of adsorption, as well as the dispersive and specific components of the free energy of adsorption and the acid/base of the solid were calculated from the IGC data at zero coverage. The K(D)/K(A) ratio indicated basis character. The adsorption isotherms were used to estimate the specific surface area, isosteric heat of adsorption and the adsorption energy distribution for the adsorption of organic molecules. (C) 2008 Elsevier B.V. All rights reserved

Microwave sintering of fine grained HAP and HAP/TCP bioceramics

The effect of microwave sintering conditions on the microstructure, phase composition and mechanical properties of materials based on hydroxyapatite (HAP) and tricalcium phosphate (TCP) was investigated. Fine grained monophase HAP and biphasic HAP/TCP biomaterials were processed starting from stoichiometric and calcium deficient nanosized HAP powders. The HAP samples microwave (MAT) sintered for 15 min at 900 degrees C, with average grain size of 130 nm, showed better densification, higher density and certainly higher hardness and fracture toughness than samples conventionally sintered for 2 h at the same temperature. By comparing MW sintered HAP and HAP/TCP samples, it was concluded that pure HAP ceramics have superior mechanical properties. For monophase MW sintered HAP samples, the decrease in the grain size from 1.59 mu m to 130 nm led to an increase in the fracture toughness from 0.85 MPa m(1/2) to 1.3 MPa m(1/2). (C) 2009 Elsevier Ltd and Techna Group S.r.l. All rights reserved

Obtaining optimal CaO-lime reactivity for uniform extraction of H2 in the "gas-cellular" building block

In this paper quicklime CaO used for the production of aerated blocks needs to have a specific reactivity in order to ensure that hydrogen H2 in "gas-cellular" building blok is released evenly. In the production of gas silicate, the agent used for the creation of pores is usually aluminum powder, which reacts with Ca(OH)2 to release hydrogen, which in turn causes the swelling of the material and the forming of pores. To generate quicklime CaO with a specific reactivity, it is necessary to accurately determine the rock mass, calcination temperature and residence time in the calcination zone during the calcination process. The theoretical and experimental method was used in the paper. The obtained results have been verified in practice and according to these CaO reactivity parameters, the XELLA company produces "gas-cellular" blocks

Densification and crystallization behaviour of colloidal cordierite-type gels

Three cordierite-type gels were prepared from an aqueous solution of Mg(NO3)(2). a boehmite sol and silica sols of very small particle sizes. The effect of varying the silica particle size on the crystallization and densification behaviour was studied. Phase development was examined by thermal analysis and X-ray diffraction, while the densification behaviour was characterized by measuring the linear shrinkage of pellets. The activation energy of densification by viscous flow was determined using the Franckel model for non-isothermal conditions and a constant heating rate. The results show that spinel crystallizes from the colloidal gels prior to cristobalite, and their reaction gives alpha -cordierite. which is specific for three-phase gels. Decreasing the silica particles size lowers the cristobalite crystallization temperature and the alpha -cordierite formation temperature The activation energy of densification by viscous flow is lower and the densification more efficient. the smaller the silica particles are

Synthesis and properties of nano-hydroxyapatite/poly (methacrylic acid) composite hydrogels

Goals. The goal of this study was a development of biocompatible composite hydrogels, structurally similar to native bone tissue, by incorporation of ~60 wt % of calcium hydroxyapatite (HA) into a matrix of hydrogels. Also, a possibility to control swelling kinetic and equilibrium swelling degree (SDeq) of hydrogels, by altering the degree of neutralization of the precursor (DN) was examined. Methods. Composite hydrogels, based on HA and poly(methacrylic acid) (PMAA), were synthesized by free-radical polymerization with different DN. Theoretical content of HA in synthesized composites was 60 wt %. Composites were synthesized by methods of dynamic mechanical analysis and scanning electron microscopy. SDeq and swelling kinetic were examined in distilled water and simulated body fluid. Results. Morphological observations revealed uniform distribution and strong bond of spherical HA particles within the polymer matrix. Swelling analyses demonstrated that SDeq is directly proportional to DN, while rheological examinations indicated inverse proportion between DN and storage modulus, but due to the HA particles inclusion, mechanical properties of composites were significantly better compared to monophasic PMAA hydrogels. Significance. Simple method of synthesis of composite hydrogels with high content of filler nanoparticles is presented. Incorporation of HA nanoparticles significantly improved mechanical properties of hydrogels, while at the same time was demonstrated a possibility to control swelling kinetic by influencing the DN

Phase-transformation kinetics in triphasic cordierite gel

A triphasic cordierite-type gel was prepared from silica sol, boehmite sol, and an aqueous solution of Mg(NO3)(2). 6H(2)O. The silica sol was obtained from water glass by the ion exchange method, while boehmite sol was obtained by peptization of freshly prepared Al(OH)(3), Phase transformations occurring in the get were studied by differential scanning calorimetry, x-ray diffractometry, and Fourier transform infrared spectrometry. Spinel was observed to crystallize from the gel prior to cristobalite; their reaction subsequently yielded alpha -cordierite, At higher temperatures, alpha -cordierite transformed into modulated beta -cordierite. Kinetic parameters of alpha -cordierite formation and alpha -cordierite to modulated beta -cordierite transformation were determined by differential scanning calorimetry under nonisothermal conditions. Formation of alpha -cordierite was found to be a diffusion-controlled process. with an overall activation energy Of E-a = 1232 +/- 66 kJ/mol. During the alpha -- GT beta -cordierite transformation, a modulated phase was formed by surface transformation of alpha -cordierite, The overall activation energy for the formation of the modulated structure is E-a = 583 +/- 77 kJ/mol

Densification and crystallization behaviour of colloidal cordierite-type gels

Three cordierite-type gels were prepared from an aqueous solution of Mg(NO3)(2). a boehmite sol and silica sols of very small particle sizes. The effect of varying the silica particle size on the crystallization and densification behaviour was studied. Phase development was examined by thermal analysis and X-ray diffraction, while the densification behaviour was characterized by measuring the linear shrinkage of pellets. The activation energy of densification by viscous flow was determined using the Franckel model for non-isothermal conditions and a constant heating rate. The results show that spinel crystallizes from the colloidal gels prior to cristobalite, and their reaction gives alpha -cordierite. which is specific for three-phase gels. Decreasing the silica particles size lowers the cristobalite crystallization temperature and the alpha -cordierite formation temperature The activation energy of densification by viscous flow is lower and the densification more efficient. the smaller the silica particles are