Študija adsorpcije mikroplastike iz polietilena na plavajočo rastlino

Blažič, Anej (author), Kalčikova, Gabriela (mentor)

Brez plastike in njenih vsestranskih izdelkov si modernega življenja ne moremo več predstavljati. Prekomerna potrošnja plastike in njeni nepravilni načini odlaganja so okolje močno onesnažili z mikroplastiko. Po vstopu/nastanku v vodnem okolju se mikroplastika razporedi po celotnem vodnem stolpcu, kjer pride v stik z organizmi z različnih trofičnih nivojev. To ogroža celoten vodni ekosistem in posledično tudi zdravje ljudi. V zadnjem času se je zato pojavila velika težnja po razvoju ustreznih tehnik odstranjevanja mikroplastike. Večina sedanjih tehnologij, kot so npr. membranske tehnologije, omogočajo le odstranjevanje mikroplastike iz odpadnih vod, medtem ko metoda odstranjevanja mikroplastike direktno iz vodnega okolja še ne obstaja. Zaradi dobre kapacitete vezave mikroplastike na rastlinsko biomaso predstavlja fitoremediacija obetavno tehnologijo, ki omogoča in situ odstranjevanje mikroplastike. Njeno aplikacijo in razvoj pa je do sedaj omejevalo slabo razumevanje interakcij med rastlinami in mikroplastiko. Namen magistrskega dela je bil podrobneje preučiti vezavo (adsorpcijo) polietilenske mikroplastike na modelno vodno rastlino malo vodno lečo Lemna minor. V magistrskem delu smo pokazali, da je adsorpcije mikroplastike na malo vodno lečo hitra, saj je bila maksimalna kapaciteta vezave že po 24 urah inkubacije. S spreminjanjem začetnega števila členov male vodne leče smo pridobili adsorpcijske izoterme, ki dajejo vpogled v interakcije med adsorbatom (mikroplastiko) in adsorbentom (malo vodno lečo) v ravnotežju. Na podlagi konkavne oblike izoterm in nizke vrednosti adsorpcijske entalpije smo ugotovili, da se med mikroplastiko in malo vodno lečo pojavljajo šibke interakcije, ki so najverjetneje elektrostatske narave. Po določitvi optimalnih parametrov, kot so čas inkubacije, prisotnost/odsotnost stresanja in količina adsorbenta (rastlinske biomase), smo izvedli fitoremediacijski test z uporabo surove in starane mikroplastike. Ugotovili smo, da je odstranjevanje mikroplastike z malo vodno lečo učinkovito, saj se je 15 dneh odstranilo 80 % surove in 50 % starane mikroplastike. Po izračunu fitoremediacijskega potenciala smo ugotovili, da je odstranjevanje starane mikroplastike 3x manj učinkovito od odstranjevanja surove mikroplastike.

• Language: Slovenian
• Keywords: adsorpcijske izoterme, bioremediacijske tehnologije, fitoremediacija, mala vodna leča, mikroplastika
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2023
• PID: 20.500.12556/RUL-149340
• COBISS.SI-ID: 168962051
• Publication date in RUL: 06.09.2023

Secondary language

• Language: English
• Title: The study of adsorption of polyethylene microplastics to a floating plant

Abstract

Without plastics and its versatile products, we can no longer imagine modern way of life. Excessive plastic consumption and improper disposal methods have heavily polluted the environment with microplastics. Once in the aquatic environment, microplastics are dispersed throughout the water column and can come into contact with organisms from various trophic levels. This poses a threat to the entire aquatic ecosystem and consequently to human health. Therefore, there has been a significant tendency recently towards the development of technologies for microplastics removal. Although current methods, such as membrane-based technologies, can remove microplastics from wastewaters, there is currently no method for removing microplastics directly from the aquatic environment. One promising technology for in situ removal of microplastics is phytoremediation, which involves using plant biomass to bind and remove microplastics. However, the application and advancement of phytoremediation are hindered by a limited understanding of the interactions between plants and microplastics. The aim of this master's thesis was to investigate in the binding (adsorption) of polyethylene microplastics to a model aquatic plant Lemna minor, commonly known as duckweed. In the thesis, we showed that the adsorption of microplastics to duckweed is rapid, as the maximum binding capacity was reached after 24 hours. By varying the initial number of duckweed fronds, we obtained adsorption isotherms that provided a better insight into the interactions between the adsorbate (microplastics) and the adsorbent (duckweed) at equilibrium. The isotherms had a concave shape and low adsorption enthalpy, indicating the presence of weak interactions between microplastics and duckweed, likely of an electrostatic nature. After determining the optimal parameters such as incubation time, shaking, and the amount of plant biomass, a phytoremediation test was performed using both pristine and aged microplastics. We concluded that microplastics removal using duckweed was effective, as 80% and 50 % of pristine and aged microplastics was removed, respectively, within 15 days. Calculation of the phytoremediation potential revealed that the removal of aged microplastics was three times less efficient compared to the removal of pristine microplastics.

• Keywords: adsorption isotherms, bioremediation technologies, duckweed, microplastics, phytoremediation