Priprava sferičnih hidrogelnih delcev na osnovi polisaharidov

Marković, Ana (author), Šebenik, Urška (mentor)

Razvoj industrije je poleg številnih ugodnosti in izboljšane kakovosti življenja prinesel tudi nekatere negativne spremembe. Eden izmed največjih izzivov je preprečevanje onesnaževanja okolja. Vsako leto se v okolje izpusti večje količine odpadne vode, ki vsebuje znatno količino okolju in zdravju škodljivih snovi. Problem predstavljajo predvsem težke kovine, barvila in farmacevtske učinkovine. Tovrstna onesnaževala so obstojna, niso biorazgradljiva, imajo sposobnost bioakumulacije in biomagnifikacije, so strupena, mutagena in kancerogena. Ena izmed najučinkovitejših metod za odstranjevanje onesnaževal iz vode je adsorpcija, ki poleg visoke učinkovitosti, cenovne ugodnosti in enostavne uporabe ne povzroča nastajanje stranskih produktov. V zadnjih letih številne raziskave obravnavajo adsorpcijo s hidrogeli zaradi številnih prednosti, kot so: biokompatibilnost, biorazgradljivost, možnost ponovne in enostavne uporabe in izdelave. V sklopu magistrske naloge sem preučevala optimalne parametre za pripravo sferičnih hidrogelnih delcev na osnovi alginata in sferičnih hidrogelnih delcev na osnovi alginata z dodatkom večplastnega grafen oksida (GO) z uporabo brizgalne črpalke. Spreminjala sem naslednje parametre: odstotek zamreževala (CaCl2), premer cevi brizgalne črpalke in hitrost pretoka natrijevega alginata skozi cev črpalke. Ugotovila sem, da na morfologijo sferičnih hidrogelnih delcev vplivata odstotek zamreževala in hitrost pretoka. Najnižji odstotek CaCl2, ki omogoča nastanek stabilnih hidrogelnih sfer je 0,43 m/v % in najvišja hitrost pretoka je 600 ml∙h-1. Po izbiri optimalnih parametrov za sintezo sferičnih hidrogelnih delcev sem preučevala adsorpcijske lastnosti alginatnega hidrogela. Kot adsorbat sem uporabila barvilo metilvijolično (MV) in sem določila vpliv različnih spremenljivk na adsorpcijo, kot so: pH vrednost, razmerje med maso hidrogela in volumnom raztopine barvila MV, začetna koncentracije barvila MV, odstotek zamreževala in dodatek večplastnega GO na adsorpcijo. Ugotovila sem, da je adsorpcija najučinkovitejša pri nižjem odstotku zamreževala (0,43 m/v %) in pri pH vrednosti 7. Prav tako sem ugotovila, da je adsorpcija barvila MV učinkovitejša, kadar hidrogel vsebuje GO in znaša 96 %. Visoko učinkovitost adsorpcije in visoko adsorpcijsko kapaciteto hidrogela z GO sem opazila samo pri nižji koncentraciji barvila (8 mg∙L-1). Pri višjih koncentracijah barvila je učinkovitejši alginatni hidrogel brez GO. Razlagam si, da v tem primeru GO predstavlja oviro za difuzijo barvila MV v notranjost hidrogela. V magistrski nalogi sem prav tako določila reološke lastnosti hidrogelov. Ugotovila sem, da alginatni hidrogel izkazuje psevdoplastične lastnosti, ki jih najboljše opisuje Carreau – Yasuda tokovni model. Za opis viskoelastičnih lastnosti alginatnega hidrogela je najustreznejši Maxwellov model, s pomočjo katerega je mogoče določiti velikost por hidrogela in gostoto zamreženja. Največjo velikost por sem določila za vzorec, ki vsebuje najnižji odstotek zamreževala (0,43 m/v %) in ne vsebuje GO. Velikost por tovrstnega vzorca je bila 6,89 nm.

• Language: Slovenian
• Keywords: hidrogel, alginat, adsorpcija, grafen oksid, reologija
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2022
• PID: 20.500.12556/RUL-140007
• COBISS.SI-ID: 129942531
• Publication date in RUL: 09.09.2022

Secondary language

• Language: English
• Title: Preparation of polysaccharide hydrogel beads

Abstract

In addition to many benefits, rapid industrialization has also brought some negative changes. One of the biggest challenges is environmental pollution prevention. Large amount of wastewater is released in the enviroment every year, which contains a significant amount of harmful substances. Dyes, heavy metals and pharmaceutical ingredients are problematic, because they are perisitent, non-biodegradable, bioaccumulative, biomagnifying, toxic, mutagenic and carcinogenic. One of the most effective methods for removing pollutants from water is adsorption, which has many benefits, such as: easy use, does not cause a formation of by-products and its cheap. Therefore, in recent years many studies have adressed adsorption with hydrogels due to a number of advantages, such as: biocompatibility, biodegradability, reusability and it is easy to use and manufacture. In my master's thesis, the optimal parameters for synthesis of alginate hydrogel beads and alginate hydrogel beads with addition of few layer graphene oxide (GO) using injection pump are investigated. The parameters, such as: percentage of crosslinker (CaCl2), the diameter of injection pump pipe and the flow rate of sodium alginate throug injection pump were varied. The results showed, that morphology of alginate hydrogel beads is influenced by crosslinker percentage and flow rate. The lowest percentage of crosslinker that allows formation of stabile hydrogel beads is 0,43 m/v % and the maximum flow rate is 600 ml∙h-1. After selecting the optimal parameters for the synthesis of hydrogel beads, the adsorption properties of alginate hydrogel beads were studied. Organic dye methyl violet (MV) was used as adsorbate. Different variables that could affect the adsorption process, such as: pH value, hydrogel mass to MV solution volume ratio, crosslinker percentage and GO addition were investigated. According to results, adsorption was more effective at lower crosslinker percentages (0,43 m/v %) and at pH value 7. Furthermore, MV dye adsorption is more efficient when the alginate hydrogel contains GO, and is 96 %. High efficiency and high adsorption capacity of alginate hydrogel beads with GO were observed at lower concentration of MV dye (8 mg∙L-1). At higher concentrations of MV dye, GO represents barrier for the diffusion of MV dye into the hydrogel. In this thesis the rheological properties of algnate hydrogels were also studied. The alginate hydrogel exhibits the pseudoplastic properties, which is best described by Carreau – Yasuda flow model. To describe the viscoelastic properties of alginate hydrogel, the Maxwell model is the most suitable. Based on the parameters obtained by Maxwell model, crosslinking desity and pore size of hydrogel were calculated. The highest pore size was observed in the sample containing the lowest percentage of crosslinker (0,43 m/v %) and without GO. The pore size of this type of sample was 6,89 nm.

• Keywords: hydrogel, alginate, adsorption, graphene oxide, rheology