Določevanje in odstranjevanje težkih kovin iz rečnih sedimentov

magistrsko delo

Jernej Imperl (Avtor), Mitja Kolar (Mentor), Romana Cerc Korošec (Član komisije za zagovor), Drago Kočar (Član komisije za zagovor)

Povzetek

Pričujoče magistrsko delo obsega študijo odstranjevanja svinca, cinka in kadmija iz vzorčenih sedimentov s postopkom spiranja sedimenta. Vzorčenje sedimenta je bilo izvedeno ob reki Dravi (severni del Ptujskega jezera). Odvzeta sta bila dva sedimenta: sediment S (star), ki je bil na obalo prečrpan pred 15 leti in sediment N (nov), prečrpan pred 1 letom. V ta namen je bil sediment okarakteriziran z vrsto analiz: določeni so bili delež vode (S 4,5 % in N 8,9 %), delež žaroizgube (S 12,6 % in N 10,8 %), z uporabo kislinskega razklopa z dušikovo(V) kislino pa so bili določeni celokupni deleži svinca (pribl. 400 ppm), cinka (pribl. 1100 ppm) in kadmija (pribl. 7 ppm). Prav tako so bili ti deleži določeni v vzorcu sedimenta, ki je bil ločen v velikostne frakcije. Ugotovljeno je bilo, da se z manjšanjem velikosti delcev povečuje delež težkih kovin. Izvedene so bile analize učinkovitosti spiranja sedimenta z različni reagenti: HNO3, HCl, EDTA, citronsko kislino, huminsko kislino, ramnolipidom, saponinom, DL-mlečno, salicilno, L-askorbinsko, jantarno, DL-jabolčno, L-vinsko in ocetno kislino. Pri spiranju sedimenta s tremi reagenti, ki so se najbolje izkazali (EDTA, citronska kislina in DL-jabolčna kislina) je bila opravljena optimizacija treh pogojev spiranja: koncentracije reagenta, časa oz. trajanja spiranja in razmerja med volumnom izpiralne raztopine in maso sedimenta [mL/g] (razmerje R/S). preizkušeno je bilo tudi dvakratno zaporedno spiranje sedimenta. Vse meritve za kvantitativno določitev svinca, cinka in kadmija so bile opravljene z uporabo plamenske atomske absorpcijske spektroskopije (FAAS). Ugotovljeno je bilo, da so vsi uporabljeni reagenti v določeni meri sposobni odstraniti svinec, cink in kadmij iz sedimenta. Najuspešnejši pri tem so bili EDTA (delež odstranjene kovine: Pb 40 %, Zn 15 % in Cd 55 %), citronska kislina (delež odstranjene kovine: Pb 50 %, Zn 60 % in Cd 75%) in DL-jabolčna kislina (delež odstranjene kovine: Pb 45 %, Zn 60 % in Cd 75 %), Slednji sta pri določenih pogojih za vse kovine presegli učinkovitost EDTA. Z optimizacijo spiranja sedimenta s temi reagenti je bil preverjen vpliv pogojev na njihovo učinkovitost odstranjevanja kovin. Določeni so bili optimizirani pogoji za te reagente: EDTA 0,01 M, 16 h in R/S = 5/1; citronska kislina 0,2 M, 16 h in R/S = 10/1; DL-jabolčna kislina 0,3 M, 16 h in R/S = 10/1. S citronsko kislino in z DL-jabolčno kislino izvedeno dvakratno zaporedno spiranje sedimenta je doseglo še višjo učinkovitost odstranjevanja kovin kot optimizirano spiranje. Spiranje sedimenta z različnimi reagenti se je na laboratorijski skali izkazalo za uporaben postopek za odstranjevanje svinca, cinka in kadmija. Nadaljnje raziskave bodo vključevale: frakcionacijsko analizo sedimenta (v kakšni obliki so kovine prisotne), preizkus kombinacij uporabljenih reagentov in uporaba novih (fitinska kislina oz. fitati), apliciranje razvitih postopkov spiranja na certificirane referenčne materiale (CRM) in druge vrste sedimentov ter možnosti predelave izlužene raztopine, ki po spiranju vsebuje visoke koncentracije težkih kovin.

Ključne besede

spiranje sedimenta;težke kovine;svinec;cink;kadmij;analizne metode;atomska absorpcijska spektroskopija;AAS;magistrska dela;

Podatki

Jezik:	Slovenski jezik
Leto izida:	2021
Tipologija:	2.09 - Magistrsko delo
Organizacija:	UL FKKT - Fakulteta za kemijo in kemijsko tehnologijo
Založnik:	[J. Imperl]
UDK:	543.421:546.3(043.2)
COBISS:	89735939
Št. ogledov:	287
Št. prenosov:	86
Ocena:	0 (0 glasov)
Metapodatki:

Ostali podatki

Sekundarni jezik:	Angleški jezik
Sekundarni naslov:	Determination and removal of heavy metals from fluvial sediments
Sekundarni povzetek:	The following dissertation contains a study of the removal of lead, zinc, and cadmium from sampled sediments using a process known as sediment washing. Sediment samples were collected near the Drava River (north side of Lake Ptuj). Two sediment samples were taken: sediment S (old), dredged from the river 15 years ago, and sediment N (new), dredged one year ago. A series of analyses were performed: sediment was characterized by determining water content (S 4.5 % and N 8.9 %) and loss on ignition (LOI) (S 12.6 % and N 10.8 %). Total metal content of lead, zinc, and cadmium was determined by means of acid digestion of the sediment with nitric(V) acid. The approximate values are 400 ppm for lead, 1100 ppm for zinc and 7 ppm for Cd. The same was done for a sediment sample, which was separated by particle size. It was observed that the heavy metal content increases with decreasing particle size. Analyses of metal removal effectiveness were performed using various chemical reagents: HNO3, HCl, citric acid, humic acid, rhamnolipid, saponin, DL-lactic acid, salicylic acid, L-ascorbic acid, succinic acid, DL-malic acid, tartaric acid, and acetic acid. Sediment washing with EDTA, citric acid, and DL-malic acid was optimized. The conditions that were optimized were the concentration the of reagent, the washing time and the ratio between the volume of the washing solution and the mass of the sediment (R/S ratio). Sediment washing with two successive washing cycles was also investigated. All measurements used for the quantification of lead, zinc, and cadmium were done by flame atomic absorption spectroscopy (FAAS). It was found that all reagents tested were able to remove lead, zinc, and cadmium from the sediment to some degree. EDTA (percentage of metals removed: Pb 40 %, Zn 15 % and Cd 55 %), citric acid (percentage of metals removed: Pb 50 %, Zn 60 % and Cd 75 %), and DL-malic acid (percentage of metals removed: Pb 45 %, Zn 60 % and Cd 75 %) proved to be the most successful. Under certain conditions, the two simple carboxylic acids removed even more of the metals than EDTA. For all three reagents, the dependence of their effectiveness of metal removal on sediment washing conditions was investigated by optimizing the procedure. The optimal conditions were also determined for these reagents: EDTA concentration 0.01 M, washing time 16 h and ratio R/S = 5/1; citric acid 0.2 M, 16 h and R/S = 10/1; DL-malic acid 0.3 M, 16 h and R/S = 10/1. Sediment washing with two successive washing cycles was carried out with citric acid and DL-malic acid and proved to be more effective in removing metals than sediment washing under optimized conditions. At laboratory scale, the sediment washing process using different chemical reagents was demonstrated to be effective at removing lead, zinc, and cadmium. Further work will include: speciation of present metals by fractional analysis of the sediment, using a combination of two or more reagents for sediment washing, testing new reagents for sediment washing (phytic acid and phytates), applying the developed sediment washing procedures to CRM materials and other sediment types, and possible remediation of the leaching solution, which contains high concentrations of heavy metals after sediment washing.
Sekundarne ključne besede:	sediment washing;lead;zinc;cadmium;
Vrsta dela (COBISS):	Magistrsko delo/naloga
Študijski program:	1000375
Konec prepovedi (OpenAIRE):	1970-01-01
Komentar na gradivo:	Univ. v Ljubljani, Fak. za kemijo in kemijsko tehnologijo, smer Kemija
Strani:	57 str.
ID:	13805848