PRODUCTION OF ZEOLITE-INCORPORATED NANOFIBROUS MEMBRANES FOR WATER FILTER APPLICATION
Authors: PhD.Albana Halili, Prof. Asoc. PhD. Ilda Kazani, Prof. PhD Enkeleida Beqiraj, Prof. PhD. Partizan Malkaj, Prof. Asst. PhD. Arianit A. Reka, BlazoBoev)
In the last decades more and more garbage is generated from the individually packaged food servings ending up in landfills, rivers and seas and influence environment pollution. Among these PETbased packages take place. Researchers have studied the physical, mechanical and thermal properties of PET, and due to some of its advantageous properties such as non-toxicity, strength, lightweight, safety, flexibility, PET became very important and a useful raw material globally recognized as 100% recyclable. Moreover, the structure of PET has polar groups like oxygen, which makes it a highly selective membrane in coupling with specific chemical or biochemical reagents for contaminant removal [1]. No significant physical or chemical properties were observed when PET waste materials were used as recycled PET instead of pure PET samples [2]. So by using recycled PET we can reduce the environmental pollution and achieve low cost nanofibrous membranes as will be the case in our research. Some research groups working on PET characteristics were focused on nanofiber fabrication methods [3] in water filtration [1, 4-6] and smoke filtration [7] applications. For this aim of application, in some previous studies, different polymers such as PA 6 [8-9], PA [10], Nylon 6.6 [11] were used as membrane materials and Ag, TiO2, ZnO, C60, Zeolites [8-13] nanoparticels as water purifying compounds. The last mentioned one, zeolites, are nanoporous crystalline alumino-silicates with a rich variety of interesting properties and industrial applications [14]. They have a wide range of applications, starting from consumer products to industrial processes [15]. The advantages of heterogeneous systems in terms of environmental friendliness and in the ability to control reaction outcome are widely recognized and as a result are attracting the attention of researchers. Furthermore, zeolites represent a quite large mineralogical family and “the structure of each of these minerals is different”, but all have large open “channels” in crystal structure that provide a large void space for the adsorption and exchange of cations. The mineralogical composition of zeolitic material from Munella region in North Albania, that we would like to use in this project, consists of stilbite-stellerite, chlorite, quartz and carbonate. Their cation exchange capacity is CEC = 1.9 -2.42 meq/g and the selectivity for cations was found as: Zn2+< Cu2+< Pb2+ [16-17].The internal surface area of these channels can reach as much as several hundred square meters per gram of zeolite, making zeolites extremely effective ion exchangers [18]. Nanofibrous membranes have been previously produced by different research groups by different methods, such as electrospinning [4, 8-10, 12, 19], pressuride gyration [11], and track etching [6]. Possible advantages of electrospun nanofibers are their high specific surface area, high porosity and small pore size, which make them ideal for water filtration applications. In addition, electrospinning is a simple, rapid and inexpensive method [8-10, 12, 19] and continuous fibers with varying properties can be obtained. Botes et al. [12] has shown that the filtration system can be improved by the use of nanofibers and nanoparticles, which are effective in removing biofouling and viruses in water purification. They have other priorities as well some of which include extended membrane life, low energy consumption, easy cleaning process excluding the use of chemicals, and no toxicity or production of disinfectant by products. Based on our literature search, there is one study focused on the use of recycled PET in electrospinning for microfiltration application. In this study, the surface of the fibers was coated with antimicrobial agents in order to reduce biofouling and to improve the lifetime of the filter mats [5]. The actual environmental problems in our country, regarding the plastic waste and water pollution from biofouling and viruses, and especially the actual global situation, where it looks like COVID-19 coronavirus may be able to live in water for a few days, potentially even a few weeks [20-21], inspired us for this project idea. Here we propose to use PET from water bottles, recycle it and use for the production of electrospun nanofibrous membranes. The novelty of this project will be that the nanofibers will be loaded with natural zeolites from Munella regionin, Albania, and for comparative reasons synthetic zeolites will be incorporared into PET structure as well in order to study their influence on the membrane properties. Referring to the literature, their combination with other polymers is limited [13, 22-23]. Furthermore, due to the above mentioned physico-chemical properties of zeolites (both natural and synthetic), their incorporation into the recycled PET-based electrospun nanofibrous membrane filter, is expected to improve it structurally and its cation exchange capacity as well