University of Architecture, Civil Engineering and Geodesy

About: University of Architecture, Civil Engineering and Geodesy is a education organization based out in Sofia, Bulgaria. It is known for research contribution in the topics: Finite element method & Beam (structure). The organization has 3808 authors who have published 3822 publications receiving 30736 citations. The organization is also known as: Sofia Polytechnic.

Application of biochars obtained through the pyrolysis of Lemna minor in the treatment of Ni-electroplating wastewater

Abstract: A feasible approach was studied for utilizing the harvested Lemna minor to treat Ni-Electroplating Waste Water (NEWW). The Lemna minor was pyrolyzed under oxygen-limited condition at various temperatures to produce biochar firstly and the optimal biochar was selected according to the yield of biochars and the adsorption capacity of biochars to treat the simulated Ni-containing wastewater. A combination method of pre-precipitation and biochar adsorption was proposed and validated by treatment of an actual NEWW. Results indicated that the biochar fabricated from Lemna minor at 400 °C (LM400) was the optimal biochar for Ni2+ adsorption and the adsorption capacity of LM400 was 41.68 mg/g. Precipitation with 5.0 g/L Ca(OH)2 succeeded by two-step adsorption with LM400 could yield qualified treatment streams when the actual NEWW was treated. Moreover, the adsorption mechanism of biochars to Ni2+ could mainly be ascribed to the complexation and ion-exchange reactions of Ni2+ in wastewater with the oxygen-containing functional groups and K+ ions of the biochar according to the results of FTIR and XRD. This study shows that Lemna minor is a viable raw material to produce strong adsorption biochar, which could be used as excellent adsorbents for heavy metals, such as Ni, Cu and Zn. Meanwhile, the actual NEWW treated with the combined process of two steps could meet discharge requirements.

Standing porous ZnO nanoplate-built hollow microspheres and kinetically controlled dissolution/crystal growth mechanism

Abstract: The standing porous nanoplate-built ZnO hollow microspheres with micro/nanostructure are fabricated based on a modified hydrothermal strategy, using citrate as structural director, and subsequent annealing treatment. The hollow spheres are composed of the vertically standing and cross-linked single crystalline porous nanoplates with the exposed surface of nonpolar (10 $$\bar 1$$ 0) planes. Experiments have revealed the structural evolution: the formation of amorphous spheres in the initial reaction stage, followed by surface crystallization and nanoplate outward growth accompanied by inward dissolution of the amorphous spheres. Citrate in the precursor solution plays a dominant role in the formation of such porous ZnO hollow spheres. A model is presented, based on citrate-induced amorphous sphere formation and kinetically controlled dissolution and crystal growth. The model describes the formation of the hollow spheres, thermodynamically and kinetically.

Co, Fe and Ni ion doped CeO2 nanoparticles for application in magnetic hyperthermia

Abstract: For magnetic hyperthermia (MHT) applications the magnetic nano-particles (NPs) should have high saturation magnetization M, low coercive field Hc, Curie temperature TC ≈ 315 K, size d

Preparation of magnetic multi-walled carbon nanotubes and their application in active dye removal

Abstract: Fe3O4 nanoparticles were introduced onto the surface of multi-walled carbon nanotubes (MWNTs) via in situ chemical precipitation method. The products (MWNTs–Fe3O4 nanocomposites) were characterised by X-ray powder diffraction, transmission electron microscope and vibrating sample magnetometer. The MWNTs–Fe3O4 nanocomposites were employed as a new adsorbent for dye removal. The adsorption results showed that adsorption efficiency of MWNTs–Fe3O4 nanocomposites was high for methylene blue. As a magnetic material, it could be separated easily from aqueous solution by an external magnet.