Browsing by Subject "morphology"

Now showing 1 - 4 of 4

Access status: Open Access ,
A morphological characterization of high yield chitin from periwinkle shells
(AGH University of Science and Technology Press, 2021) Chiosa Odili, Cletus; Gbenebor, Oluwashina Philips; Haffner, Henry Adekola; Adeosun, Samson Oluropo
Research on obtaining chitin from periwinkle shell is scarce due to the very low yield of chitin from this kind of shell. This study reports a method of processing periwinkle shells to obtain high yield, bio-medically suitable chitin. The experiment was designed using IM and 2M concentrations of HCl for demineralization and a 1M NaOH concentration for deproteinization. FTIR, SEM, XRD and DTA analytical tools were used to characterize the extracted chitin. The FTIR spectral, XRD patterns and SEM analysis, revealed the complete removal of calcium carbonate by the acid concentrations used. The particle-like form of periwinkle shell was transformed to sheet-like fiber and globular-like fiber of $\alpha$-chitin by increasing the concentration of HCl from1M to 2M respectively. The crystal size increased from 11.2Ǻ (1M HCl) to 13.4Ǻ (2M HCl). The yield of chitin from periwinkle shell also increased from 52% to 71% using 1M and 2M HCl respectively. Thus, acid concentrations can be used to alter the structure of chitin with different mechanical properties.
Access status: Open Access ,
Delaminacja i transformacja morfologii minerałów z grupy kaolinitu
(2007) Matusik, Jakub
Access status: Open Access ,
Effect of organic additives on electrodeposition of tin from acid sulfate solution
(Wydawnictwa AGH, 2018) Rudnik, Ewa; Chowaniec, Grzegorz
Basic electrochemical experiments on the kinetics of tin deposition from an acid sulfate solution containing organic additives were performed. The measurements showed that tin deposits with activation polarization in a narrow potential range. Organic additives like gelatin and ?-naphtol inhibit the charge transfer stage of the cathodic reaction due to the formation of adsorption layers. In turn, the gluconate ions increase the rate of tin deposition due to the bonding of hydrogen ions and inhibiting hydrogen coevolution. This results in serious changes in the morphology of tin deposits from isolated polyhedron crystals (no additive) via rectangular plates (?-naphtol) and thin plates (sodium gluconate) to rounded grains (gelatin).
Access status: Open Access ,
Electrodeposition of silver from nitrate-tartrate solutions
(Wydawnictwa AGH, 2018) Rudnik, Ewa
The electrodeposition of silver from AgNO3 solutions with the addition of L-tartaric acid was investigated. The cathodic reaction was accompanied by low electrode polarization and run under activation control for AgNO3 concentrations of above 70 mM. Tartaric acid only slightly shifted the polarization curves towards more electronegative potentials (by approx. 50 mV), but it did not change the rate-determining step. The activation control of the process resulted in the formation of rough and coherent deposits, while the mixed or diffusion control of the process promoted the formation of dendritic-like structures and spongy deposits.