Separacija vrednih spojin iz koruznih storžev z uporabo ekstrakcije s podkritično vodo

diplomsko delo univerzitetnega študijskega programa

Doroteja Kovač (Author), Mojca Škerget (Mentor), Maja Čolnik (Co-mentor)

Abstract

Živimo v obdobju energetske krize in nenehnega onesnaževanja okolja. Večina odpadkov iz biomase se pusti na polju, da se ti naravno razgradijo, zavržejo na odlagališčih ali pa se sežgejo, posledica česar je resno onesnaževanje okolja, kot so emisije toplogrednih plinov in poslabšanje kakovosti zraka. Torej, običajno odpadno biomaso le zavržemo, medtem ko le-ta vsebuje bogate komponente, katere bi lahko ponovno uporabili. Koruzni storži so zraven koruzne lupine glavni stranski produkti koruze in se štejejo kot stranski proizvodi z nizkim dobičkom. Te vrste kmetijskih stranskih proizvodov so v naravi široko dostopne in obnovljive. Koruzni storž je, kot ostala lignocelulozna biomasa, sestavljen iz hemiceluloze, celuloze in lignina, ter z nizko vsebnostjo beljakovin in maščob. Ta rastlinska biomasa je industrijskega pomena, saj lahko s primernimi tehnikami iz nje pridobimo vredne spojine kot so glukoza, ksiloza, acetat, furfural, levulinska kislina, hidroksimetilfurfural ter lignin. Z uporabo podkritične vode, kot zelene tehnologije, smo iz koruznih storžev ekstrahirali te vredne komponente pri različnih reakcijskih pogojih, in sicer pri različnih temperaturah (150 °C, 170 °C, 200 °C in 250 °C) ter pri različnih reakcijskih časih (10 min, 30 min in 60 min). Pri tem smo preučili vpliv reakcijskih pogojev na izkoristke ekstrakcij, antioksidativno aktivnost, vsebnost totalnih fenolov, vsebnost celokupnih ogljikovih hidratov in vsebnost furfuralov, prav tako pa smo opravili tudi FTIR analizo. Ugotovili smo, da so izkoristki ekstrakcije s časom in temperaturo naraščali do 200 °C in 10 min, kjer smo dosegli tudi najvišji izkoristek. Z nadaljnjim podaljševanjem reakcijskega časa in višanjem temperature pa je izkoristek ekstrakcije pričel upadati. Z DPPH smo preučili antioksidativno aktivnost in pri tem smo ugotovili, da v vseh primerih vrednosti ne presežejo več kot 50 %. V splošnem antioksdiativna aktivnost narašča z naraščanjem temperature in podaljševanjem reakcijskega časa. Pri temperaturi 200 °C in reakcijskem času 60 minut smo zaznali najvišje vsebnosti totalnih fenolov (9,44 mg GA/g materiala), celokupnih ogljikovih hidratov (25 mg COH/g materiala) in furfuralov (694,59 mg furfuralov/g ekstrakta). S tem smo potrdili, da so koruzni storži res pomembna biomasa za proizvodnjo furfurala. Ti so organske molekule lignocelulozne biomase in so pomembni za pridobivanje topil, monomerov in farmacevtskih izdelkov. V nadaljevanju smo z FTIR analizo material pred in po separaciji vrednih komponent iz koruznih storžev ustrezno okarakterizirali, in potrdili prisotnost značilnih funkcionalnih skupin: alkoholna skupina, C-H skupina, alkenska skupina, acetilna skupina in izocianatna skupina.

Keywords

koruzni storži;podkritična voda;biomasa;vredne spojine;furfurali;diplomske naloge;

Data

Language:	Slovenian
Year of publishing:	2023
Typology:	2.11 - Undergraduate Thesis
Organization:	UM FKKT - Faculty of Chemistry and Chemical Engineering
Publisher:	[D. Kovač]
UDC:	66.061.3:[604.4:633.15](043.2)
COBISS:	167262467
Views:	141
Downloads:	18
Average score:	0 (0 votes)
Metadata:

Other data

Secondary language:	English
Secondary title:	Separation of valuable compounds from corn cobs using subcritical water extraction
Secondary abstract:	We are living in a period of energy crisis and constant pollution. Most biomass waste is left in the field to decompose naturally, discarded in landfills or incinerated, resulting in serious environmental pollution such as greenhouse gas emissions and deterioration of air quality. So, normally, waste biomass is just thrown away, whereas it contains rich components that could be reused. Next to maize husk, maize cobs are the main by-products of maize and are considered as low profit by-products. These types of agricultural by-products are widely available and renewable in nature. The maize cob, like other lignocellulosic biomass, is composed of hemicellulose, cellulose and lignin, and is low in protein and fat contents. This plant biomass is of industrial importance because, with appropriate techniques, it can be used to extract valuable compounds such as glucose, xylose, acetate, furfural, levulinic acid, hydroxymethylfurfural and lignin. Using subcritical water as a green technology, these valuable components were extracted from corn cobs at different reaction conditions, namely at different temperatures (150 °C, 170 °C, 200 °C and 250 °C) and reaction times (10 min, 30 min and 60 min). The influence of the reaction conditions on the extraction yields, antioxidant activity, total phenolic content, total carbohydrate content and furfural content was investigated, and FTIR analysis was also performed. It was found that the extraction yields increased with time and temperature up to 200 °C and 10 min, where the highest yields were obtained. However, as the reaction time and temperature increased further, the extraction yield started to decrease. The antioxidant activity was examined by DPPH and it was found that in all cases the values did not exceed 50 %. In general, the antioxidant activity increases with increasing temperature and reaction time. At a temperature of 200 °C and a reaction time of 60 minutes, the highest contents of total phenols (9,44 mg GA/g material), total carbohydrates (25 mg COH/g material) and furfurals (694,59 mg furfurals/g extract) were detected. This confirmed that maize cobs are indeed an important biomass for furfural production. These are the organic molecules of lignocellulosic biomass and are important for the production of solvents, monomers and pharmaceuticals. In the following, FTIR analysis was used to characterise the material before and after separation of the valuable components from corn cobs and to confirm the presence of the characteristic functional groups: alcohol group, C-H group, alkene group, acetyl group and isocyanate group.
Secondary keywords:	corn cobs;subcritical water;biomass;valuable compounds;furfurals;
Type (COBISS):	Bachelor thesis/paper
Thesis comment:	Univ. v Mariboru, Fak. za kemijo in kemijsko tehnologijo
Pages:	1 spletni vir (1 datoteka PDF (X, 42 f.))
ID:	19828635