Daniel Gherca

Studies on adsorption capacity of cationic dyes on several magnetic nanoparticles

Abstract In this study the dyes used are Basic fuchsin and Methylene blue. The adsorption was studied in relation to the metal in the ferrite, time of exposure and dye concentration. The highest adsorbtion capacity was observed for MgFe2O4 at a dye concentration of 0.06 mM, adsorption percent of 88% in 3 hours. Desorption was also studied by redispersion in ethanol. The main adsorption mechanism is thought to be through electrostatic interaction, mainly due to surfactant groups present on the nanoparticles. The nanoparticles have ferromagnetic behavior under magnetic field which allows for effective separation.

Letter: Study on the mechanism of ferrite-induced dinitrophenol photodegradation

We report here the effectiveness of gas chromatography mass spectrometry techniques in establishing the ferrite-associated photocatalytic degradation mechanism of pesticide 2,4-dinitrophenol (2,4-DNP). Unlike the previously discussed DNP-degradation mechanisms that involve either oxidation or reduction reactions, ferrite-based ultraviolet (UV) photodegradation of DNP affords the nontoxic 6-hydroxy-3,5-dinitrohexa-2,4-dienal by an unusual water addition to the benzene core. We searched for and demonstrated the presence of an epoxide of DNP within the photodegradation process, which may unambiguously explain the novel photochemical mechanism. During the 15 min UV photoinduced process, DNP degradation efficiency on the zinc ferrite catalyst was calculated to be 82%, whereas the first-order kinetic rate constant k was as high as 3.4 × 10−2 min−1.

Correlation Between Size of CoFe 2 O 4 Nanoparticles Determined from Experimental and Calculated Data by Different Mathematical Models

This study reports the synthesis of CoFe2O4 nanoparticles by coprecipitation method in the presence of Linseed Oil as surfactant. The capping agent was used to stabilize the particles and prevent their agglomeration. The characteriza- tion studies were conducted by in situ X-ray diffraction, transmission electron microscopy, thermal analysis (TG-DTA) and FTIR spectroscopy. The average particle sizes obtained by XRD data were used to obtain a correlation with size of CoFe2O4 nanoparticles determined, using mathematical equations based on different models. The statistical studies show that the cubic model gives a good correlation within the whole temperature range (100 - 850 °C). The result of these in- vestigations was very useful for establishing the optimal calcination temperature. FT-IR spectroscopy and thermogra- vimetric analysis (TG) showed that the core-shell structure type of CoFe2O4 nanoparticles is stable below this annealing temperature. TEM analysis indicates that the CoFe2O4 samples during the calcinations treatment were spherical in shape and uniform in morphology and particles size.