No abstract

No abstract

Strontium-doped lanthanum manganites, La 1-x Sr x MnO 3 (LSMO), are promising and affordable catalysts for oxidative degradation of volatile organic compounds. LSMO catalysts (x = 0, .1, .2, and .3) were prepared by the citrate-nitrate autocombustion (CNA) and coprecipitation synthesis. The phase composition was confirmed by X-ray diffraction and Rietveld refinement analysis, while the oxygen content was determined by Mohr's salt permanganate titration.Morphology and porosity of prepared catalysts was correlated to catalytic oxidation of benzene, toluene, ethylbenzene and o-xylene. It was observed that both synthesis methods yielded catalysts of similar average pore size diameter and specific surface area, but the pore size distribution differed: CNA-prepared catalysts had a multimodal pore size distribution, while the coprecipitated ones had a single maximum at 4 nm. Catalysts prepared by the CNA method have shown a higher catalytic activity in the temperature range 373-723 K, as the presence of Mn 3+ /Mn 4+ mixed valences increased their reducibility.

P49U ovom radu pripremljene su polimerne mješavine polilaktida (PLA), polietilena visoke gustoće (PE-HD) i polietilena niske gustoće (PE-LD) u različitim omjerima. Umješavanje polimera i njihovih mješavina izvršeno je pomoću ekstrudera i gnjetilice, nakon čega su im određena mehanička, toplinska i morfološka svojstva.Rezultati mehaničkih ispitivanja pokazali su da dodatak polietilena (PE-LD i PE-HD) čistom polilaktidu znatno mijenja njegova mehanička svojstva. Analiza provedena na pretražnom elektronskom miskroskopu (SEM) i razlikovnom pretražnom kalorimetru (DSC) pokazala je da ispitani polimeri nisu mješljivi. Ispitivane polimerne mješavine djelomično su biorazgradljive, a postignuto je i smanjenje cijene materijala u usporedbi s čistim polilaktidom.