Odstranjevanje težkih kovin iz trdne frakcije digestata aktivnega blata s pomočjo magnetnih nanodelcev

diplomsko delo visokošolskega strokovnega študijskega programa I. stopnje

Noemi Sep (Avtor), Lidija Čuček (Mentor), Aleksandra Petrovič (Komentor), Olivija Plohl (Komentor)

Povzetek

Namen diplomskega dela je bil odstraniti oziroma zmanjšati koncentracijo težkih kovin, kot so Zn, Cu, Ni in Cd iz trdne frakcije digestata aktivnega blata po anaerobni digestiji, da bi omogočili njegovo uporabo v kmetijstvu. V sklopu diplomskega dela smo sintetizirali maghemitne nanodelce s ko-precipitacijo železovih Fe2+ in Fe3+ ionov, jih prevlekli s približno 3 nm debelo plastjo amorfnega SiO2 ter jih nadaljnje funkcionalizirali z derivatom GOPTS-bPEI, ki je v svoji strukturi bogat z aminskimi skupinami, znanimi kot kelatorji kovin. Aminske skupine smo uporabili za kelacijo kovin in posledično omogočili njihovo odstranitev. Po končani sintezi smo izvedli površinsko ATR-FTIR spektroskopijo in uspešno dokazali prisotnost želenih funkcionalnih skupin v nanodelcih. V diplomskem delu smo združili dve metodi za odstranjevanje težkih kovin iz trdnih materialov in jih uporabili na primeru digestata aktivnega blata. Združili smo kemijsko izluževanje s kislinami ter adsorpcijo kovin na modificirane magnetne nanodelce. Z združitvijo teh metod smo želeli povečati učinkovitost odstranitve težkih kovin. Pred adsorpcijo smo vzorce trdne frakcije digestata izpostavili kislinam. Najprej smo primerjali učinkovitost ekstrakcije glede na vrsto kisline, pri čemer smo uporabljali 0,2 M citronsko kislino in 0,2 M oksalno kislino, zraven tega smo preučevali še učinkovitost ekstrakcije glede na kontaktni čas. Za primerjavo smo izvedli tudi poskuse z digestati, pri katerih smo kovine ekstrahirali le z vodo. V drugem delu smo na pridobljenih ekstraktih izvedli poskuse adsorpcije kovin s sintetiziranimi modificiranimi magnetnimi nanodelci in tako preučili vpliv pH vrednosti ter vpliv mase nanodelcev na učinkovitost adsorpcije težkih kovin. Izračunali smo adsorpcijske kapacitete za posamezne kovine ter določili celokupno adsorpcijsko kapaciteto nanodelcev pri posameznem vzorcu. Koncentracije težkih kovin smo določili z atomsko adsorpcijsko spektroskopijo (AAS). Ugotovili smo, da se je iz testiranih vzorcev ob uporabi citronske kisline izlužilo največ cinka (dosegli smo kar 97,6 % učinkovitost), najmanj pa se ekstrahira bakra. Primerjava učinkovitosti ekstrakcije je pokazala, da je citronska kislina primernejša za izluževanje cinka, niklja in kadmija, oksalna kislina pa je primernejša v primeru bakra. Rezultati odstranjevanja težkih kovin z modificiranimi magnetnimi nanodelci so pokazali, da so nanodelci najučinkovitejši pri odstranjevanju niklja. Najvišjo adsorpcijsko kapaciteto smo dosegli v primeru cinku (24,0 mg/g). Najvišja celokupna adsorpcijska kapaciteta, ki smo jo dosegli, je bila 27,42 mg/g.

Ključne besede

odstranjevanje težkih kovin;digestat aktivnega blata;izluževanje kovin s kislino;adsorpcija;magnetni nanodelci;diplomske naloge;

Podatki

Jezik:	Slovenski jezik
Leto izida:	2020
Tipologija:	2.11 - Diplomsko delo
Organizacija:	UM FKKT - Fakulteta za kemijo in kemijsko tehnologijo
Založnik:	[N. Sep]
UDK:	66.061.34:628.336.3(043.2)
COBISS:	32708355
Št. ogledov:	478
Št. prenosov:	70
Ocena:	0 (0 glasov)
Metapodatki:

Ostali podatki

Sekundarni jezik:	Angleški jezik
Sekundarni naslov:	Removal of heavy metals from the solid fraction of activated sludge digestate using magnetic nonoparticles
Sekundarni povzetek:	The purpose of the thesis was to remove or reduce the concentration of the most critical heavy metals such as Zn, Cu, Ni and Cd from the solid fraction of activated sludge digestate after anaerobic digestion in order to enable its use in agriculture. As a part of the diploma work, magnetic nanoparticles were synthesized with coprecipitation of Fe2+ and Fe3+ ions, coated with an approximately 3 nm thick amorphous SiO2 layer and further functionalized with GOPTS-bPEI derivate, which is in its structure rich in amine groups that are known to form chelates with metals. Thus amine groups were used to chelate metals and they consequently enabled their removal. After the synthesis, surface ATR-FTIR spectroscopy was performed and the presence of the desired functional groups on the nanoparticles was successfully confirmed. In the diploma work, two methods were combined for the removal of heavy metals from solid materials and used in the case of activated sludge digestate. One of the methods was chemical leaching with acids and the other was adsorption of metals on the surface of modified magnetic nanoparticles. By combining these two methods, the goal was to increase the efficiency of heavy metal removal. Prior to adsorption, samples of the solid fraction of the digestate were exposed to acids. First, comparison of the extraction efficiency with respect to the type of acid were made, using 0.2 M citric acid and 0.2 M oxalic acid, followed by the study of the extraction efficiency with respect to the contact time. For comparison, experiments were performed with digestates in which the metals were extracted only with water. In the second part, metal adsorption experiments with synthesized modified nanoparticles were performed on the obtained extracts and studies conducted for the influence of pH value and the influence of modified nanoparticle amount on the adsorption efficiency of heavy metals. The adsorption capacities for individual metals were calculated and the total adsorption capacity of modified nanoparticles in each sample was determined. Heavy metal concentrations were measured by atomic adsorption spectroscopy (AAS). The results showed that from the tested samples using citric acid was extracted mostly zinc (97.6 % removal efficiency was achieved), and that copper was extracted in the smallest amount. After comparing the extraction efficiencies of citric and oxalic acid, it can be concluded that citric acid is more suitable for the leaching of zinc, nickel and cadmium, while oxalic acid is more suitable in the case of copper. The results of removing heavy metals with modified magnetic nanoparticles have showed that modified nanoparticles are most effective for removing nickel. The highest adsorption capacity was achieved in the case of zinc (24,0 mg/g). The highest total adsorption capacity achieved was 27,42 mg/g.
Sekundarne ključne besede:	heavy metal removal;activated sludge digestate;acid leaching of metals;adsorption;magnetic nanoparticles;
Vrsta dela (COBISS):	Diplomsko delo/naloga
Komentar na gradivo:	Univ. v Mariboru, Fak. za kemijo in kemijsko tehnologijo
Strani:	XI, 47 str.
ID:	11984607