Utjecaj TiO2 na antibakterijska svojstva biorazgradljivih kompozita LDPE/rižine ljuskice

undergraduate thesis

• Title (english): The effect of TiO2 on the antibacterial properties of LDPE/rice husks biodegradable composites
• Author: Antonija Kovačević
• Mentor: Emi Govorčin Bajsić (mentor)
• Committee member: Emi Govorčin Bajsić (predsjednik povjerenstva)
• Committee member: Zlata Hrnjak-Murgić (član povjerenstva)
• Committee member: Dajana Kučić Grgić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2018-09-12, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Chemical Engineering; Chemical Engineering in Material Development

Abstract

Dugi niz godina razni sintetski polimeri kao što su polistiren (PS), polietilen (PE), polipropilen (PP) i polietilen tereftalat (PET) koriste se kao ambalažni materijali za pakiranje prehrambenih i ostalih proizvoda. Manje od 5 % svih plastičnih materijala se reciklira, što predstavlja veliki ekološki problem. Sintetskim polimerima potrebno je dugo vrijeme kako bi se razgradili u osnovne spojeve nakon njihove upotrebe te iz tog razloga njihovo odlaganje ima negativan utjecaj na onečišćenje okoliša i klimatske promjene. Kako bi se smanjila količina sintetskog plastičnog otpada koji se svakodnevno šalje na odlagališta te ovisnost o naftnim derivatima, u posljednjih nekoliko godina sve je veći interes za proizvodnju biorazgradljivih i obnovljivih materijala. Polietilen niske gustoće (LDPE) jedan je od najčešće korištenih sintetskih polimera za izradu folija i drugih ambalažnih materijala, dok su rižine ljuskice biorazgradljiv materijal koji nastaje uslijed proizvodnje riže. Prilikom mljevenja, zrno riže odvoji se od ljuske te one postaju biootpad. Biorazgradljivi kompoziti polietilena niske gustoće i rižinih ljuskica imaju mogućnost potpuno zamijeniti sintetske ambalažne proizvode. Rižine ljuskice dodaju se kao punila u polimernu matricu LDPE. Kako bi se očuvala kvaliteta i sigurnost proizvoda u LDPE/RLJ biokompozite potrebno je dodati antimikrobni agens koji inhibira rast bakterija i time štiti proizvod. Cilj ovog rada bio je odrediti da li TiO2 kao antimikrobni agens posjeduje antibakterijska svojstva na ispitivane bakterijske kulture Escherichiu coli, Pseudomonas aeruginosu i Bacillus subtilis. Provedena su dva tipa pokusa, prvo se ispitao utjecaj različitih masenih udjela TiO2 (2, 3 i 5 mas %) u tekućem i čvrstom stanju na inhibiciju bakterija, te utjecaj TiO2 pomiješanog u kompozit LDPE i RLJ. TiO2 u tekućem stanju nije pokazao antibakterijska svojstva dok je u čvrstom stanju inhibirao rast ispitivanih bakterija. Prema dobivenim rezultatima dodatkom sve većih masenih postotaka TiO2 (0,5 %; 1,0 %; 1,5 % te 2,0 mas %) u biokopozite LDPE/RLJ 60/40 broj stanica bakterijskih kultura se smanjivao iz čega se može zaključiti da TiO2 inhibira rast bakterijskih kultura Escherichia coli, Pseudomonas aeruginosa i Bacillus subtilis.

Abstract (english)

For many years, various synthetic polymers such as polystyrene (PS), polyethylene (PE), polypropylene (PP) and polyethylene terephthalate (PET) have been used as packaging materials for food and other products. In general, less than 5 % of all plastic materials are recycled, which resulted in many ecological problems. After the use, synthetic polymers take a long time to break down into basic components. That is why their disposal has had a negative impact on environmental pollution and climate change. In order to reduce the amount of synthetic plastic waste that is sent to landfills every day, as well as the dependence on petroleum products, there has been an increasing interest in the production of biodegradable and renewable materials over the past few years. Biodegradable materials are associated with the use of renewable raw materials. Low density polyethylene (LDPE) is one of the most commonly used synthetic polymer in the production of foils and other packaging materials. Rice husk (RH) is an inexpensive by-product of rice processing. It is separated from rice grain during the milling process. Biodegradable composites made from an LDPE polymeric matrix and reinforced with rice husks have the potential to completely replace synthetic packaging products. To ensure the quality and safety of the product, an antimicrobial agent should be added to these composites in order to inhibit the growth of bacteria and therefore preserve the product. The aim of this thesis was to determine whether TiO2, as an antimicrobial agent, has antibacterial properties. The tests included its reaction to Escherichia coli, Pseudomonas aeruginosa and Bacillus subtilis. Two types of experiments were carried out. The first one served to examine how different mass fractions of TiO2 (2, 3 and 5 wt %), in liquid and solid states, affect the inhibition of bacteria; as well as the effect of TiO2 added into the composite of LDPE and RH. TiO2 in liquid state showed no antibacterial properties, while in solid state it inhibited the growth of the investigated bacteria. According to the results, with the addition of higher content of TiO2 (0.5 %, 1.0 %, 1.5 % and 2.0 wt %) into LDPE/ RH 60/40 bio-composites, the number of bacterial culture cells decreases. In conclusion, TiO2 inhibits the growth of bacterial cultures of Escherichia coli, Pseudomonas aeruginosa and Bacillus subtilis.

• Keywords: polietilen niske gustoće (LDPE); rižine ljuskice (RLJ); biokompoziti; antimikrobni agensi; titanov dioksid (TiO2)
• Keywords (english): low density polyethylene (LDPE); rice husks (RH); biocomposites; antimicrobial agents; titanium dioxide (TiO2)
• Language: croatian
• URN:NBN: urn:nbn:hr:149:495811
• Study programme: Title: Materials Science and Engineering - Undergraduate study; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka kemijskog inženjerstva (sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka kemijskog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2021-11-22 12:06:43