Hidrotermična degradacija polietilena nizke gostote

magistrsko delo

Blaž Deželak (Author), Mojca Škerget (Mentor), Željko Knez (Co-mentor)

Abstract

V današnjem času težimo k zmanjševanju in ponovni uporabi komunalnih ali industrijskih odpadkov. Polietilen (PE) je eden izmed najpogosteje uporabljenih materialov na svetu in je prisoten v številnih industrijah in segmentih. V zadnjih letih je uporaba plastičnih materialov narasla iz 5 milijonov ton na 100 milijonov ton letno. Največji problem je razkroj plastike, ki povzroča resne okoljske probleme. Razgradnja plastike v subkritični in superkritični vodi je zelo učinkovita metoda za pretvorbo plastičnih odpadkov v širok spekter koristnih produktov, kot so bazne kemikalije, alternativna energija in goriva, specialne kemikalije, brez dragih in pogosto zdravju škodljivih organskih topil. Namen magistrske naloge je bil preučiti hidrotermično degradacijo polietilena nizke gostote (LDPE) v subkritični in superkritični vodi. Eksperimentalni del smo izvedli v visokotlačnem in visokotemperaturnem šaržnem reaktorju v temperaturnem intervalu od 200 do 450 °C. Mešanico LDPE in vode v razmerju 1/5 smo izpostavljali pri reakcijskih časih od 15 min do 120 min. Določali smo vpliv temperature, reakcijskega časa in dodatka katalizatorja ocetne kisline na potek in kinetiko reakcij razgradnje LDPE. Vzorce iz reaktorja smo analizirali in določili produkte degradacije s plinsko kromatografijo in masno spektrometijo (GC/MS). Določili smo še vsebnost celotnega organskega ogljika (TOC). Ugotovili smo, da je pri vseh eksperimentih, ki so bili izvedeni pri temperaturah 425 in 450 °C ter reakcijskem času od 15 - 120 min, prišlo do razgradnje LDPE v subkritični vodi. Razgradne produkte hidrotermične degradacije smo ločili na oljno, plinasto in vodno fazo. Dobljene produkte v oljni in plinski fazi smo analizirali s pomočjo GC/MS, medtem ko smo s TOC analizatorjem določili skupni ogljik v vodni fazi. Ugotovili smo, da je oljna faza v večini sestavljena iz ogljikovodikov (alkanov in alkenov), kjer je prevladoval 2,3-dimetil pentan. Plinasta faza je vsebovala različne pline kot so: dušik, CO2, metan, etan, eten in vse do heksana in heksena. V vodni fazi pa smo določili vsebnost organskih snovi, ki so bile višje pri dodatku katalizatorja ocetne kisline.

Keywords

hidrotermično utekočinjanje;superkritična voda;razgradni produkti;magistrske naloge;

Data

Language:	Slovenian
Year of publishing:	2018
Typology:	2.09 - Master's Thesis
Organization:	UM FKKT - Faculty of Chemistry and Chemical Engineering
Publisher:	[B. Deželak]
UDC:	54-139:678.742.2(043.2)
COBISS:	21925142
Views:	811
Downloads:	31
Average score:	0 (0 votes)
Metadata:

Other data

Secondary language:	English
Secondary title:	Hydrothermal degradation of low density polyethylene
Secondary abstract:	Nowadays there is a tendency to reduce and reuse municipal or industrial waste. Polyethylene (PE) is one of the most commonly used materials in the world and is present in many industries and segments. In recent years, the use of plastic materials has grown from 5 million tonnes to 100 million tonnes per year. The biggest problem is the degradation of plastic that causes serious environmental problems. Decomposition of plastics in subcritical and supercritical water is a very effective method for converting plastic waste into a wide range of useful products, such as basic chemicals, alternative energy and fuels, special chemicals, without expensive and often harmful organic solvents. The purpose of the master's thesis was to study the hydrothermal degradation of low density polyethylene (LDPE) in subcritical and supercritical water. The experimental part was carried out in a high pressure and high temperature batch reactor at a temperature interval of 200 to 450 ° C. The mixture of LDPE and water in a ratio 1/5 was exposed at reaction times from 15 min to 120 min. The influence of temperature, reaction time and the addition of the acetic acid catalyst on the course and kinetics of the degradation reactions of the LDPE was determined. Samples from the reactor were analyzed and degradation products were determined by gas chromatography and mass spectrometry (GC / MS). The content of total organic carbon (TOC) was also determined. We found that in all experiments carried out at temperatures of 425 and 450 °C and with a reaction time of 15 - 120 min, LDPE degradation in subcritical water occurred. The decomposition products of hydrothermal degradation were separated into the oil, gas and water phase. The products obtained in the oil and gas phase were analyzed using GC/MS, while by the TOC analyzer the total carbon in the water phase was determined. We found that the oily phase is mostly composed of hydrocarbons (alkanes and alkenes), where 2,3-dimethyl pentane dominates. The gas phase contained various gases such as: nitrogen, CO2, methane, ethan, ethene and all the way to hexane and hexene. In the aqueous phase, we determined the values of organic substances that were higher when adding the acetic acid catalyst.
Secondary keywords:	hydrothermal liquefaction;supercritical water;degradation products;LDPE;
URN:	URN:SI:UM:
Type (COBISS):	Master's thesis/paper
Embargo end date (OpenAIRE):	2021-12-04
Thesis comment:	Univ. v Mariboru, Fak. za kemijo in kemijsko tehnologijo
Pages:	X, 41 str.
ID:	10978089