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Title:INHIBICIJSKA UČINKOVITOST STEARINSKE KISLINE V KISLEM MEDIJU
Authors:ID Grah, Natalija (Author)
ID Fuchs-Godec, Regina (Mentor) More about this mentor... New window
Files:.pdf UNI_Grah_Natalija_2013.pdf (2,26 MB)
MD5: B3899F75EF8B179F9D146A4195739519
 
Language:Slovenian
Work type:Bachelor thesis/paper
Typology:2.11 - Undergraduate Thesis
Organization:FKKT - Faculty of Chemistry and Chemical Engineering
Abstract:Namen diplomskega dela je bil preučiti inhibicijsko učinkovitost nastale plasti, načeloma hidrofobnega karakterja. V ta namen smo uporabili karboksilno maščobno kislino; stearinsko kislino. Feritnemu nerjavnemu jeklu PK2 smo modificirali lastnosti površine s predhodno potopitvijo v etanolno raztopino stearinske kisline. Vse meritve smo izvedli pri sobni temperaturi. Kot korodirni medij smo izbrali klorovodikovo kislino, z naslednjimi koncentracijami; c = 0,1; 0,5; in 1,0 mol L-1. Ker je bila dosežena zaščita pri višje izbranima koncentracijama minimalna, smo v nadaljevanju izvedli meritve le pri c = 0,1 mol L-1. Prav tako smo izbrali tri različne koncentracije stearinske kisline; c = 0,01; 0,05; in 0,1 mol L-1. Nižja koncentracija ni bistveno spremenila lastnosti površine v smislu zaščite, medtem ko se je pri višji koncentraciji na površini vzorca ustvarila zdrizasta plast, ki jo je raztopina HCl takoj odplaknila. Iz tega razloga smo uporabili le koncentracijo 0,05 mol L-1. Ker smo želeli inhibicijsko učinkovitost nastale plasti povečati, karakteristike plasti pa izboljšati, smo v etanolno raztopino stearinske kisline dodali še vitamin E v različnih koncentracijah in sicer: w = 0,25; 0,5; 0,75; 1,0 in 2,0 %. Vse izbrane koncentracije vitamina E so dodatno povečale inhibicijsko učinkovitost. Tako pripravljene vzorce smo izpostavili korodirnemu mediju v različnih časovnih intervalih, za 2,5 ure, 4 in 8 ur. Iz podatkov, dobljenih z gravimetrično metodo izgube mase, smo izračunali korozijsko hitrost in inhibicijsko učinkovitost. Glede na rezultate lahko zaključimo, da je stearinska kislina z dodatkom vitamina E uspešno spremeni lastnosti površine (iz hidrofilnega stanja v hidrofobno) in jo relativno dobro zaščiti v izbranem časovnem intervalu. Dolgotrajnejšo zaščito bi dosegli v manj agresivnem korodirnem mediju. Za potrditev hidrofobnosti površine bi bilo potrebno opraviti meritve kontaktnega kota.
Keywords:korozija, stearinska kislina, inhibicija, vitamin E, nerjavno jeklo
Place of publishing:Maribor
Publisher:[N. Grah]
Year of publishing:2013
PID:20.500.12556/DKUM-41842 New window
UDC:620.193(043.2)
COBISS.SI-ID:17496854 New window
NUK URN:URN:SI:UM:DK:YBPEM27F
Publication date in DKUM:02.10.2013
Views:1615
Downloads:146
Metadata:XML DC-XML DC-RDF
Categories:KTFMB - FKKT
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Secondary language

Language:English
Title:INHIBITION EFFICIENCY OF STEARIC ACID IN ACIDIC MEDIA
Abstract:An objective of the present diploma was to study the inhibition efficiency of the formed layer with hydrophobic nature. In this purpose we used carboxylic fatty acid – stearic acid. With the exposure to the ethanol solution of stearic acid, we wanted to modify the surface of the ferritic stainless steel PK2. All measurements were performed at room temperature. As an acidic medium we used the hydrochloric acid HCl, initially we tested several concentrations (c = 0.1, 0.5 and 1.0 mol L-1), however, we researched in detail only when c = 0.1 mol L-1, since with the other two concentrations the protection was minimal. Further, we have tried with several concentrations of the stearic acid (c = 0.01, 0.05, 0.1 mol L-1). The lowest concentration did not change surface properties significantly, while, at the highest concentration, on the surface of the sample a slimy layer was created, which was washed away by the hydrochloric (HCl) solution. From this reason we used only the concentration of stearic acid of c = 0.5 mol L-1. Because we wanted to increase the inhibition efficiency of the formed layer and improved its characteristics, therefore vitamin E was added vitamin E to the ethanol solution of stearic acid. Vitamin E was added in varying weight percentages (0.25, 0.5, 0.75, 1.0 and 2.0 wt.%). At all chosen concentration of vitamin E the increased of inhibition efficiency was obtained. We exposed steel samples to the corrosive medium for different time interval (2.5, 4 and 8 hours). From the data, collected with the gravimetric method of mass loss, we calculated the corrosion rate and the inhibition efficiency. Regarding the results we can speculated, that the stearic acid with the addition of vitamin E successfully changes the properties of the surface (maybe from hydrophilic to hydrophobic). Moreover, relatively good protection for selected times of exposure was achieved. In less aggressive medium the protection would last longer. To confirm hydrophobic nature of the surface, the contact angle measurement should be performed.
Keywords:corrosion, stearic acid, inhibition, vitamin E, stainless steel


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