Preparation of styrene-vinylimidazole copolymeric nanofibers and its use in adsorption of metal ions

Nowadays , access to clean water resources in the world has become more difficult with global warming and increasing population. For this reason, wastewater treatment techniques are being developed and used. In this thesis, Poly-Styrene-Vinylimidazole (PS-VIM) copolymer was synthesized to be used to clean heavy metal ions from wastewater and turned into nanofibers to be developed in filter use by using electrospinning method. During the synthesis of PS-VIM copolymer, two different initiator and solution concentrations were used. The polymer obtained by using 8 g of monomer (Styrene:Vinylimidazole, 6:2), initiator at a ratio of 0.1 w/w, and 5 mL of toluene solvent was named PS-VIM-P1. Monomer and initiator ratio 16 g monomer (Styrene: Vinylimidazole, 12:4) 0.05 w/w initiator and 5 mL toluene solvent obtained by using the polymer was named PS-VIM-P2. While the synthesis efficiency of PS-VIM-P1 copolymer was 38%, the synthesis efficiency of PS-VIM-P2 copolymer was 44%. During the production of nanofibers, 25% wt/v concentrations of PS-VIM-P1 and PS-VIM-P2 polymers in DMF/THF 4:1 solvent were used. The voltage values applied during the nanofiber production of PS-VIM-P1 polymer were determined as 25 kV. Flow rate values were determined as 0.8 mL/h and the distance between the plates was 16 cm. The voltage values applied during the nanofiber production of PS-VIM-P2 polymer were determined as 26 kV and 28 kV. Flow rate values were determined as 1 mL/h, 1.2 mL/h and 1,4 mL/h the distance between the plates was determined as 15, 16 and 18 cm. The diameter length of the nanofiber obtained as 1mL/h, 28kV and 16cm distance between the plates of PS-VIM-P2 polymer was determined as 2.44 µm ideally. According to the obtained SEM images, the low molecular weight of PS-VIM-P1 polymer caused the formation of droplet structures in the nanofiber structure. It has been determined as ideal for use in Cu(II) and As(V) adsorption. To determine the ideal medium pH value for Cu(II) ion adsorption of PS-VIM-P2 copolymer, the pH value were 3,00, 4,00, 5,00 and 6,00 by using HCl and NaOH. The highest adsorption value was determined as pH 5,00 and PS-VIM-P2 copolymer nanofiber reached 3,78 mg Cu(II)/g polymer capacity in 10 ppm Cu(II) solution at this value. The effect of initial concentration on Cu(II) adsorption was investigated at 1, 10, 50 and 100 ppm concentrations. The capacity of PS-VIM-P2 copolymer nanofiber at 100 ppm As(V) concentration was calculated as 26,18 mg Cu(II)/g polymer. To determine the ideal medium pH value for As(V) ion adsorption of PS-VIM-P2 copolymer, the pH valuee were 2,00, 3,00, 4,00, 5,00 and 6,00 by using HCl and NaOH. The highest adsorption value was determined as pH 3,00 and PS-VIM-P2 copolymer nanofiber reached 1,18 mg As(V)/g nanofiber capacity in 10 ppm As(V) solution at this value. The effect of initial concentration on As(V) adsorption was investigated at 1, 10, 50 and 100 ppm concentrations. The capacity of PS-VIM-P2 copolymer nanofiber at 100 ppm As(V) concentration was calculated as 88,95 mg As(V)/g polymer. According to the MALDI-MS results of PS-VIM-P1 and PS-VIM-P2 polymers, random styrene and vinylimidazole sequences were observed in both polymers. According to the calculation made in the Polymerix Program by using MALDI-MS values, the molecular weight of PS-VIM-P1 polymer by weight; While Mw=2830 g/mol was determined, the number of molecular weight was determined as Mn=1650 g/mol. The of molecular weight of PS-VIM-P2 polymer was determined as Mw=2990 g/mol, the number of molecular weight was determined as Mn=1960 g/mol. Structural characterization was performed by FTIR scanning and according to the information obtained, it was determined that PS-VIM-P2 polymer nanofiber was caused by the decrease in the characteristic imidazole endpoint at 665 cm-1 wave number, which was realized by the imidazole ring during the adsorption of Cu(II) and As(II) ions.