magistrsko delo
Mateja Potočnik (Author), Aleksandra Lobnik (Mentor), Aljoša Košak (Co-mentor)

Abstract

Nanomateriali in med njimi nanodelci, so med najbolj obetajočimi adsorpcijskimi materiali za čiščenje oljnih razlitij, saj imajo visoko specifično površino in jih lahko obdamo z molekulami, ki kažejo visoko afiniteto do adsorpcije olj. Kadar pa ti nanodelci izkazujejo še ustrezne magnetne lastnosti, jih lahko ob prisotnosti zunanjega magnetnega polja enostavno in hitro ločimo iz raztopine, kar je dodatna prednost teh materialov. Z metodo soobarjanja smo sintetizirali magnetne nanodelce kobalt ferita (CoFe2O4), jih elektrostatsko stabilizirali in funkcionalizirali z različnimi silani (difenildimetoksisilan (DPDMS), trimetoksi(3,3,3-trifluoropropil)silan (F-TriMOS), 1H,1H,2H,2H-perfluorodeciltrietoksisilan (FDTES), propiltrimetoksisilan (P-TriMOS), metiltrimetoksisilan (M3MS), etiltrimetoksisilan (ETMS), etiltrietoksisilan (ETES), dimetildiklorosilan (DMDCLS), metiltriklorosilan (MTCLS), trimetoksi(1H,1H,2H,2H-nonafluoroheksil)silan (NFHTMS)) v različnih množinskih razmerjih (P=[TEOS]/[silan]=2, 1, 0,5 in 0,25). Pripravljene nanomateriale smo okarakterizirali z metodami rentgenske praškovne difrakcije (XRD), presevne elektronske mikroskopije (TEM), infrardeče spektroskopije s Fourierjevo transformacijo (FT-IR), prav tako smo določali specifično površino nanodelcev z metodo BET, specifično magnetizacijo (VSM), stični kot z vodo in kapaciteto adsorpcije olja na nanodelce. Z rentgensko praškovno difrakcijo smo dokazali spinelno kristalno strukturo nanodelcev CoFe2O4, katerih velikost smo določili na tri načine, in sicer s presevnim elektronskim mikroskopom (TEM) (11,5 ± 1,9 nm), z metodo BET (14 nm), in iz XRD difraktograma (11,4 nm). Rezultati meritev FT-IR nakazujejo, da smo vse vzorce uspešno funkcionalizirali z izbranimi silani, saj se na IR spektrih pojavljajo značilni absorpcijski vrhovi za karakteristične vezi, ki nastanejo pri funkcionalizaciji CoFe2O4 nanodelcev z izbranimi silani. Specifična magnetizacija nasičenja (Ms) vzorca CoFe2O4 pa je bila 52,0 emu/g. Z meritvami VSM smo ugotovili, da pri večini vzorcev specifična magnetizacija upade zaradi nemagnetne prevleke okoli magnetnega jedra nanodelca. Pripravljeni materiali so kljub temu dobro magnetno odzivni in primerni za magnetno ločevanje, kar smo potrdili tudi pri poskusih določevanja kapacitete adsorpcije olja na pripravljene nanodelce. Pri meritvah specifične površine vzorcev se je izkazalo, da ima večina vzorcev pri večji množini dodanega silana manjšo specifično površino, pri adsorpciji olj pa so se bolje izkazali vzorci z večjo specifično površino. Površine funkcionaliziranih nanodelcev kažejo večjo stopnjo hidrofobnosti kot nefunkcionalizirani nanodelci. Kapaciteta adsorpcije olja je znašala največ 3,5 g motornega olja/ g nanodelcev, in sicer pri vzorcu P-TriMOS@SiO2@CoFe2O4 pri množinskem razmerju P= 1. Tudi ostali vzorci, z izjemo vzorcev z močno fluorirano silikatno prevleko (NFHTMS@SiO2@CoFe2O4 in FDTES@SiO2@CoFe2O4), so izkazovali relativno dobro adsorpcijo olja (med 2,6 in 3,5 g olja/g nanodelcev). Na dveh vzorcih, ki sta se izkazala kot najboljša (P-TriMOS@SiO2@CoFe2O4 pri P=1 in M3MS@SiO2@CoFe2O4 pri P=1), smo preizkusili možnost regeneracije in ponovne uporabe ter ugotovili, da je regeneracija precej uspešna, saj kapaciteta adsorpcije po ponovni uporabi bistveno ne upade (<3%) in da z magnetnim ločevanjem dokaj uspešno ločimo nanodelce iz onesnažene vode (~90%). Sklepamo torej, da sta testirana vzorca nanodelcev primerna za ponovno uporabo. Večina pripravljenih adsorpcijskih materialov torej izkazuje dober potencial za uporabo pri čiščenju realnih oljnih razlitij.

Keywords

nanomateriali;magnetni nanodelci;odstranjevanje olj;hidrofobnost;adsorpcija;oljna razlitja;kobalt ferit;magistrske naloge;

Data

Language: Slovenian
Year of publishing:
Typology: 2.09 - Master's Thesis
Organization: UM FS - Faculty of Mechanical Engineering
Publisher: [M. Potočnik]
UDC: 628.3:544.723.2(043.2)
COBISS: 19895318 Link will open in a new window
Views: 1750
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Other data

Secondary language: English
Secondary title: Preparation and characterization of new adsorption materials for oil spills removal from water
Secondary abstract: Nanomaterials, including nanoparticles, are among the most promising adsorption materials for oil spill cleanup as they have high specific surface area and can be functionalized with molecules with high affinity for oil adsorption. Moreover, magnetic nanoparticles can be quickly and easily separated from polluted water. In our work, magnetic cobalt ferrite (CoFe2O4) nanoparticles were synthesized by the co-precipitation method, electrostatically stabilized and functionalized using various silanes (diphenyldimethoxysilane (DPDMS), trimethoxy(3,3,3-trifluoropropyl)silane (F-TriMOS), 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FDTES), propyltrimethoxysilane (P-TriMOS), methyltrimethoxysilane (M3MS), ethyltrimethoxysilane (ETMS), ethyltriethoxysilane (ETES), dimethyldichlorosilane (DMDCLS), methyltrichlorosilane (MTCLS), trimethoxy(1H,1H,2H,2H-nonafluorohexyl)silane (NFHTMS)) in different molar ratios P (P=[TEOS]/[silane]=2; 1; 0,5 and 0,25). Prepared materials were analyzed using X-ray powder diffraction (XRD), transmission electron microscopy (TEM), infrared spectroscopy (FT-IR), BET specific surface area analyzer, vibrating sample magnetometer (VSM), contact angle goniometer. Additionally, adsorption capacity of oil was determined and the possibility of material reuse assessed. Using XRD, we proved the spinel crystal structure of CoFe2O4 nanoparticles. Their size was determined from XRD difractogram (11,4 nm), TEM images (11,5±1,9 nm) and BET measurements (14 nm). Characteristic absorption peaks on FT-IR spectra prove that materials were successfully functionalized by selected silanes. Specific saturation magnetization (Ms) of sample CoFe2O4 was 52,0 emu/g. Most of the samples, coated with non-magnetic silica layer, showed decrease of Ms. However, most of prepared materials were magnetically responsive and are suitable for magnetic separation from solutions. Results of BET surface area analyses show that the quantity of silane used and the chain length of the chosen silane influence the specific surface area of the sample. The majority of samples, functionalized with lower P ratio or with longer fluorocarbon or alkyl chains have lower specific surface area, which is less favorable in oil spill cleanup applications. The surfaces of functionalized nanoparticles show a higher degree of hydrophobicity than CoFe2O4 nanoparticles. The highest oil adsorption capacity was determined using sample P-TRIMOS@SiO2@CoFe2O4 (P=1), which was 3,5 g of engine oil per g of nanoparticles. Also other samples, excluding samples with strongly fluorinated silicate coating (NFHTMS@SiO2@CoFe2O4 and FDTES@SiO2@CoFe2O4), showed relatively high oil adsorption capacities (between 2,6 and 3,5 g of oil per g of nanoparticles). Nanoparticles reuse possibility was tested on two of the best samples (P-TriMOS@SiO2@CoFe2O4 at P=1 and M3MS@SiO2@CoFe2O4 at P=1). Regeneration of these samples is quite successful, as the adsorption capacity does not decrease significantly (<3%). Magnetic separation of nanoparticles was also quite successful as we collected around 90% of nanoparticles. Tested materials are suitable for re-use, which is desired from economic and environmental perspective.
Secondary keywords: nanomaterials;nanoparticles;oil spill removal;hydrophobicity;adsorption materials;oil spills;cobalt ferrite;
URN: URN:SI:UM:
Type (COBISS): Master's thesis/paper
Thesis comment: Univ. v Mariboru, Fak. za strojništvo
Pages: XX, 151 str.
ID: 9141082