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1.
Advance analysis of the obtained recycled materials from used disposable surgical masks
Alen Erjavec, Julija Volmajer Valh, Silvo Hribernik, Tjaša Kraševac Glaser, Lidija Fras Zemljič, Tomaž Vuherer, Branko Neral, Mihael Brunčko, 2024, original scientific article

Abstract: The production of personal protective equipment (PPE) has increased dramatically in recent years, not only because of the pandemic, but also because of stricter legislation in the field of Employee Protection. The increasing use of PPE, including disposable surgical masks (DSMs), is putting additional pressure on waste collectors. For this reason, it is necessary to find high-quality solutions for this type of waste. Mechanical recycling is still the most common type of recycling, but the recyclates are often classified as low-grade materials. For this reason, a detailed analysis of the recyclates is necessary. These data will help us to improve the properties and find the right end application that will increase the value of the materials. This work represents an extended analysis of the recyclates obtained from DSMs, manufactured from different polymers. Using surface and morphology tests, we have gained insights into the distribution of different polymers in polymer blends and their effects on mechanical and surface properties. It was found that the addition of ear loop material to the PP melt makes the material tougher. In the polymer blends obtained, PP and PA 6 form the surface (affects surface properties), while PU and PET are distributed mainly inside the injection-molded samples.
Keywords: mechanical recycling, disposable surgical mask, morphology, surface properties, mechanical properties, nonwoven materials, PPE
Published in DKUM: 09.04.2024; Views: 127; Downloads: 5
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2.
Extending the protection ability and life cycle of medical masks through the washing process
Julija Volmajer Valh, Tanja Pušić, Mirjana Čurlin, Ana Knežević, 2023, original scientific article

Abstract: The reuse of decontaminated disposable medical face masks can contribute to reducing the environmental burden of discarded masks. This research is focused on the effect of household and laboratory washing at 50 °C on the quality and functionality of the nonwoven structure of polypropylene medical masks by varying the washing procedure, bath composition, disinfectant agent, and number of washing cycles as a basis for reusability. The barrier properties of the medical mask were analyzed before and after the first and fifth washing cycle indirectly by measuring the contact angle of the liquid droplets with the front and back surface of the mask, further by measuring air permeability and determining antimicrobial resistance. Additional analysis included FTIR, pH of the material surface and aqueous extract, as well as the determination of residual substances—surfactants—in the aqueous extract of washed versus unwashed medical masks, while their aesthetic aspect was examined by measuring their spectral characteristics. The results showed that household washing had a stronger impact on the change of some functional properties, primarily air permeability, than laboratory washing. The addition of the disinfectant agent, didecyldimethylammonium chloride, contributes to the protective ability and supports the idea that washing of medical masks under controlled conditions can preserve barrier properties and enable reusability.
Keywords: medical masks, washing, detergent, didecyldimethylammonium chloride, air permeability, antimicrobial activity, residuals
Published in DKUM: 15.03.2024; Views: 209; Downloads: 8
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3.
Sustainability-oriented surface modification of polyester knitted fabrics with chitosan
Tanja Pušić, Tea Bušac, Kristina Šimić, Mirjana Čurlin, Ana Šaravanja, Katia Grgić, Julija Volmajer Valh, 2024, original scientific article

Abstract: The existing research deals with the process of modifying polyester knitted fabrics and polyester/cotton knitted fabrics with chitosan and the stability of functionalized surface with chitosan in the washing process according to a standard and an innovative washing procedure. The current research concept aims to evaluate the degree of progressivity and progressiveness: the modification of polyester knitted fabrics with chitosan and an innovative washing process. The polyester and polyester/cotton fabrics modified with chitosan were characterized by a staining test, microscopic analysis, zeta potential measurement, and pilling tendency of the knitted fabrics before and after five and ten washing cycles with reference detergent ECE A. The results of the zeta potential measurement of knitted fabrics functionalized with chitosan confirmed cationization of the polyester and polyester/cotton fabric with chitosan. The presence of chitosan on the washed knitted fabrics in reduced quantities is demonstrated by the staining test, the colour strength (K/S), and the zeta potential values. The staining test and surface charge of the tested knitted fabrics confirmed the research hypothesis regarding the degree of progressivity of the modification of polyester and polyester/cotton knitted fabrics with chitosan and the sustainability of the innovative washing process. The streaming potential proved to be a favorable method for monitoring the stability of chitosan in the washing process in combination with a staining test with the selected dye Remazol Red RB.
Keywords: knitted fabrics, polyester, polyester/cotton, chitosan, washing, surfaces
Published in DKUM: 05.02.2024; Views: 190; Downloads: 12
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4.
Development of pH Responsive Polysaccharide Based Wound Dressings : doctoral disertation
Beste Elveren, 2023, doctoral dissertation

Abstract: In the scope of the Doctoral Dissertation, a polysaccharide based stimuli-responsive smart material with controlled drug release was developed by using electrospinning technique, which allowed to form stimuli-responsive nanofibers with rapid visual detection of pH change in the wound bed along with anti-inflammatory activity. Incorporation of halochromic dyes into electrospun nanofibers has been an intriguing area for wound healing applications. Furthermore, it is known that the pH value within the wound milieu directly and indirectly influences all biochemical reactions taking place in the process of wound healing. It has been proven that the surface pH of a wound plays an important role in wound healing as it helps control infection and increases the antimicrobial activity, oxygen release, angiogenesis, protease activity, and bacterial toxicity. Therefore, visual pH monitoring without the need of removing the wound dressing was one of the aims of the Doctoral Dissertation. Produced stimuli-responsive wound dressings were characterized according to their morphological and chemical properties using well-known techniques such as, rheometry, conductivity, Scanning Electron Microscopy (SEM),CIE Lab, Thermogravimetric Analysis (TGA), UV/VIS Spectrophotometry, and Attenuated Total Reflection Infra-Red Spectroscopy (ATR-IR). Responsiveness of the nanofibers were achieved by integration of different halochromic dyes [bromocresol green (BCG), bromothymol blue (BTB) and thymol blue (TB)] to obtain a range of pH values. To tackle the problem of leaching of the dyes, a complexing agent; poly-diallyldimethylammonium chloride (PDADMAC) was integrated and an analysis on the formation of complexation was performed by using pH-potentiometric titration and Quartz Crystal Microbalance with Dissipation (QCM-D) and Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) techniques. Additionally, release tests were performed to prove that the leaching of the halochromic dyes is reduced significantly up to 97%. Furthermore, the responsiveness of the nanofibers was investigated by exposing the nanofibers to different buffer solutions with pH values 4, 7 and 10. The color change of the nanofibers were analyzed using the CIE Lab system while a visual color shift was observed according to their characteristics. Lastly, diclofenac (DFC), an anti-inflammatory drug molecule was integrated to the system and drug release studies were performed by using Franz diffusion cells. A controlled release of the drug molecule (DFC) to the wound bed is achieved and quantitative evaluations were done. Consequently, the drug release from the smart wound dressings were identified to have two separate profiles during the release. The mathematical models that were identified to fit to the kinetics are, first-order, Korsmeyer-Peppas, and Higuchi release model, confirming the controlled drug release.
Keywords: stimuli-responsive, polysaccharides, wound dressings, halochromism, controlled drug release, smart materials
Published in DKUM: 06.10.2023; Views: 302; Downloads: 31
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5.
Študij uporabe barvil pridobljenih iz odpadnih vej murve v tekstilnem tisku : magistrsko delo
Anita Krajnc, 2023, master's thesis

Abstract: Področja krožnega gospodarstva, kot so odpadki, raba naravnih virov in energije, zajemajo tudi tekstil in tekstilno industrijo - strategija o trajnostnem tekstilu in rabi naravnih barvil. Tekstilni materiali (naravni in sintetični) so, glede na potrebe in želje kupcev, obarvani ali tiskani. Skoraj vsa sintetična barvila, ki se množično uporabljajo za te namene, sintetizirajo iz fosilnih derivatov z nevernimi kemijskimi postopki, ki imajo negativen vpliv na okolje. Zato je vse večja zavest potrošnikov o okolju prijaznih izdelkih povzročila porast izdelave tekstilij iz naravnih vlaken, barvanih z okolju prijaznimi naravnimi barvili. Cilj magistrske naloge je bil raziskati različne možnosti ekstrakcije naravnega barvila iz ostankov murvinih vej po spomladanskem obrezovanju, ter iz pridobljenih barvil pripraviti okolju prijaznejše tiskarske barvne gošče. Za pridobivanje naravnega barvila iz vej murv smo uporabili ekstrakcijski postopek v Soxletovem ekstraktorju z dvema različnima topiloma, destilirano vodo in etanolom in njunima različnima razmerjema. Izolirane ekstrakte smo okarakterizirali z UV/VIS spektroskopijo, antioksidativnostjo ter z določitvijo fenolnih skupin. Najustreznejši izoliran ekstrakt smo uporabili v postopku direktnega tiska, pri katerem je bila tiskarska barvna gošča pripravljena iz okolju prijazih kemikalij. Seveda nas je zanimala tudi kakovost in obstojnost oblikovanega tiska. Rezultati kažejo, da je za tisk najprimernejša TBG 3 (tiskarska barvna gošča 3, katera je vsebovala monijev železov(II) sulfat) na bombažni tkanini. Zelo dobre lastnosti ima tudi TBG 2 (tiskarska barvna gošča 2, katera je vsebovala kalijev galun).
Keywords: naravna barvila, murva, barvanje naravnih tkanin, UV/VIS spektroskopija, antioksidativnost
Published in DKUM: 20.09.2023; Views: 390; Downloads: 32
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6.
Razvoj in priprava biorazgradljive aktivne embalaže : magistrsko delo
Žan Jankovič, 2023, master's thesis

Abstract: V magistrskem delu smo razvili biorazgradljivo aktivno embalažo ter fizikalno-kemijsko karakterizirali in ocenili aktivni učinek (antioksidativni in protimikrobni) PLA folij. Nanosi plasti biopolimera hitozana in ekstraktov na PLA folije so bili potrjeni z metodami ATR-FTIR in XPS. Fizikalno-kemijska karakterizacija folij je potekala tudi z določevanjem omočljivosti in prepustnosti kisika. Metode so dokazale, da je z vidika omočljivosti in prepustnosti kisika zelo pomemben premaz iz ekstraktov, ki vpliva na izboljšanje omočljivosti in slabšo prepustnost kisika. Potrdili smo tudi desorpcijo hitozanov in ekstraktov iz površine folij v desorpcijsko kopel. Z analiznima spektrofotometričnima metodama DPPH in ABTS pa smo analizirali antioksidativno aktivnost folij in dokazali, da so vzorci PLA folij premazanih s hitozanoma in ekstraktoma robide ali brina izboljšale antioksidativno aktivnost. Slabše so se odrezale PLA folije premazane s hitozanoma in ekstraktom alge pri obeh metodah. Protimikrobno aktivnost smo določevali na gram pozitivno bakterijo Staphylococcus aureus in gram negativno bakterijo Escherichia coli. Vse testirane folije so imele zelo dobro protimikrobno aktivnost na bakterijo Staphylococcus aureus. Dobro protimikrobno aktivnost na bakterijo Escherichia coli pa je imel le vzorec PLA folije, ki je bil premazan s kvarternim hitozanom in premazom brina. Ker smo v PLA folijah uporabili naravne in okolju prijazne materiale za izdelavo funkcionaliziranih folij prepostavljamo, da so kompozitne folije z okoljskega vidika spremeljive, saj so biorazgradljive.
Keywords: aktivna embalaža, PLA folije, primarni hitozan, kvarterni hitozan, ekstrakti, antioksidativna embalaža, protimikrobna embalaža
Published in DKUM: 12.06.2023; Views: 500; Downloads: 62
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7.
Študij biorazgradnje zaščitnih mask (covid-19) na osnovi respirometrijskih meritev v kompostu : magistrsko delo
Žiga Šrot, 2023, master's thesis

Abstract: Magistrsko delo obravnava tematiko biorazgradnje zaščitnih mask. Zaščitne maske iz naravnih in sintetičnih materialov smo zakopali in pomešali s kompostom. Zaradi vse višje globalne onesnaženosti s plastičnimi odpadki in akumulacije mikroplastike v ekosistemih moramo nujno strmeti k alternativnim, bolj trajnostnim metodam spopadanja z odpadki. Eksperimentalni del smo opravili na respirometru slovenskega proizvajalca ECHO Instruments d.o.o. Pred samo raziskavo biorazgradnje smo izvedli preliminarni test, s katerim smo določili aktivnosti izbranih kompostov in tistega z najvišjo aktivnostjo določili za nadaljnje delo. Izbran kompost in razrezane koščke mask smo po standardu ISO 14855-2:2018 natehtali in pomešali v reaktorjih. Napolnjene reaktorje smo preko cevk povezali s senzorskim sistemom respirometra, kjer smo zagotavljali konstantne pogoje. Respirometrične meritve o biorazgradnji materialov smo zbirali dva meseca in pol. Stopnjo biorazgradljivosti materialov smo izračunali na podlagi meritev produkcije ogljikovega dioksida v reaktorjih in meritev vsebnosti organskega ogljika v materialu ter izračunane vrednosti primerjali z referenčno snovjo – mikrokristalno celulozo. Rezultate o biorazgradljivosti materialov smo preverili še z FTIR spektrometrijo in s posnetki pod mikroskopom. Vzorci mask iz naravnih materialov so se razgradili precej dobro, najbolje med njimi delci maske iz mešanice lanu in bombaža (v 71,63 %), medtem ko so se delci maske iz polipropilena razgradili v 1,89 %.
Keywords: biorazgradnja, kompostiranje, mikrokristalna celuloza, zaščitne maske, FTIR spektoskopija, respirometrija.
Published in DKUM: 05.04.2023; Views: 488; Downloads: 59
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8.
Analiza biorazgradnje zaščitnih mask za preprečevanje širjenja virusa SARS-CoV-2 v vodnih medijih : magistrsko delo
Jernej Jelenko, 2023, master's thesis

Abstract: Pandemija COVID-19 je povzročila široko uporabo zaščitnih medicinskih mask za enkratno uporabo. Prekomerna uporaba plastičnih zaščitnih mask povzroča resno škodo naravnemu ekosistemu. Zaradi tega je nastala velika potreba po metodah za hitro izdelavo biorazgradljivih zaščitnih mask po nizki ceni bodisi iz bioplastike bodisi iz naravnih vlaken. Številne raziskave opisujejo biorazgradnjo polimerov v zemlji in kompostu, manj raziskav pa je narejenih za vodne medije. Vendar pa velika količina zavrženih zaščitnih mask konča ne samo na tleh, ampak tudi v vodnih sistemih. Biorazgradljivost je lastnost sistema in jo je treba obravnavati v kontekstu prevladujočih okoljskih razmer. Z okoljskega vidika so zato laboratorijski testi v nadzorovanih pogojih obvezni, vendar sami po sebi le prvi pokazatelj stopenj biorazgradnje plastičnega materiala v naravnem okolju. V magistrskem delu smo se osredotočili na določevanje aerobne biorazgradnje zaščitnih mask v vodnih medijih. Stopnjo biorazgradnje materiala v odvisnosti od časa smo določili preko sproščenega CO2, ki smo ga merili z ECHO respirometrom. Teste smo izvajali po standardu ISO 14855 in ISO 14852, a smo ugotovili, da je primeren le standard ISO 14852, ki je specifično namenjen določevanju biorazgradnje polimerov v vodnih medijih. Za inokulum vodnega medija je bil izbran kompost Humovit. Določili smo stopnjo biorazgradljivosti za referenčni material mikrokristalne celuloze (58,4 % v 75 dneh), masko iz lana/bombaža (67,1 % v 75 dneh), masko iz konoplje (59,6 % v 75 dneh), masko iz pihane celuloze (37,2 % v 21 dneh) in medicinsko kirurško masko (0,5 % v 21 dneh oz. se ni razgrajevala). Za določitev učinkovitosti biorazgradnje smo naredili še FTIR analizo zaščitnih mask pred in po eksperimentu biorazgradnje. Iz dobljenih FTIR spektrov smo potrdili prisotnost novih funkcionalnih skupin na površini zaščitnih mask, ki so posledica procesa oksidacije.
Keywords: biorazgradnja, zaščitne maske, COVID-19, respirometrija, biopolimeri, vodno okolje
Published in DKUM: 04.04.2023; Views: 547; Downloads: 47
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9.
Proučevanje vpliva silažne folije na okolje : magistrsko delo
Nejc Lebar, 2022, master's thesis

Abstract: Vsesplošna rast rabe plastičnih materialov je vidna na vseh področjih, tudi na področju kmetijstva, kjer ima nekatere pozitivne učinke. Pozitivne lastnosti plastičnih materialov v času rabe postanejo okoljsko breme po koncu uporabe, ko je material treba odstraniti. V raziskovalnem delu smo opazovali in okarakterizirali degradacijo folije iz polietilena nizke gostote (LDPE), ki se uporablja za zaščito silaže in bal za seno. Oceno degradacije materiala zaradi izpostavljenosti okoljskim vplivom smo izvedli z laboratorijskimi simulacijami teh pogojev v vodnem mediju, v zemlji in s pomočjo komore za simulacijo vremenskih vplivov (ksenon test). Za karakterizacijo materiala smo uporabili infrardečo spektroskopijo s Fourierjevo transformacijo, termogravimetrično analizo, goniometrijo, gravimetrijo, optično mikroskopijo, karakterizacijo sežiga materiala in analizo vodnega medija. Glavne ugotovitve karakterizacije LDPE folije so, da na degradacijo najbolj vpliva ultravijolično sevanje, vendar je material obdelan tako, da v kratkem času izpostavljenosti vremenskim vplivom ne pride do drastičnih sprememb lastnosti. Zaradi tega je pomembno kaj se z materialom zgodi po uporabi, ko ga zavržemo.
Keywords: silažna folija, polietilen nizke gostote (LDPE), degradacija, ksenon test, izpostavljenost v zemlji, izpostavljenost v vodi.
Published in DKUM: 05.01.2023; Views: 789; Downloads: 72
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10.
Ekologija plemenitilnih procesov : navodila za vaje
Darinka Fakin, Selestina Gorgieva, Alenka Ojstršek, 2022

Abstract: Poseben problem odpadkov v tekstilni industriji predstavljajo odpadne tehnološke vode, predvsem tiste, ki nastajajo pri plemenitenju tekstilij. Te odpadne vode so močno obremenjene, vsebujejo različne kemikalije in tekstilna pomožna sredstva, imajo ekstremne pH-vrednosti in visoke KPK in BPK vrednosti, različne tipe organskih barvil, kar povzroča obarvanost, vsebujejo fosfate, sulfate in ostale soli, tenzide, maščobe in olja ter različne tipe težkih kovin. Tekstilne odpadne vode so zelo heterogene po sestavi, zato je čiščenje takšnih voda kompleksna naloga, za katero ni idealne in v naprej izdelane metode. Glede na proizvodni proces je potrebno izbrati fleksibilno in ekonomsko upravičeno tehnologijo čiščenja. Pri izbiri tehnologije čiščenja odpadnih voda moramo upoštevati njihovo količino in kakovost, ki jo ovrednotimo s specifičnimi in sumarnimi ekološkimi parametri.
Keywords: tekstilna odpadna voda, plemenitenje, čiščenje odpadnih vod, ekološki parametri
Published in DKUM: 15.11.2022; Views: 547; Downloads: 27
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