Browsing by Subject "Wastewater treatment"
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Item Open Access Amine modified electrospun PIM-1 ultrafine fibers for an efficient removal of methyl orange from an aqueous system(Elsevier, 2018) Satılmış, B.; Uyar, TamerPolymers of Intrinsic Microporosity (PIM-1) is a promising material for adsorption and separation applications. While PIM-1 displays high affinity for neutral species, it shows lack of interaction with charged molecules in an aqueous system due to non-polar nature of it. Functionalization of PIM-1 provides an advantage of tailoring the interaction ability as well as the adsorption performance of PIM-1 towards target pollutants. In this study, electrospun Polymer of Intrinsic Microporosity (PIM-1) fibrous membrane (PIM-FM) was reacted with borane dimethyl sulfide complex to obtain amine modified PIM-1 fibrous membrane (AM-PIM-FM). Furthermore, PIM-1 film, which is referred as PIM-1 dense membrane (PIM-DM), was also modified under the same conditions as a control material. Structural analyses have confirmed that nitrile groups of PIM-1 have been fully converted to amine group as a result of the reduction reaction. Average fiber diameter of parent PIM-1 fibers was found 2.3 ± 0.3 μm, and it remained almost the same after the amine modification. In addition, no physical damage has been observed on fiber structure based on the SEM analysis. Both amine modified PIM-1 dense and fibrous membranes became insoluble in common organic solvents. Before the modification, water contact angle of PIM-FM was 138 ± 2° which also remained almost the same after the modification, showing water contact angle of 131 ± 8°. The insolubility along with amine functionality make membranes promising materials for adsorption of anionic dyes from wastewater. Here, dye (i.e. Methyl Orange) removal ability of AM-PIM-FM from an aqueous system was investigated and compared with parent PIM-1 (PIM-FM) as well as dense membrane form (AM-PIM-DM). AM-PIM-FM shows extremely higher adsorption capacity than that of PIM-FM and AM-PIM-DM. The maximum adsorption capacity of AM-PIM-FM was found 312.5 mg g−1 for Methyl Orange. Langmuir isotherm model was found more favorable for the adsorption. AM-PIM-FM was employed effectively in continuous adsorption/desorption studies for several times without having any damage on fiber morphology using batch adsorption process. Furthermore, AM-PIM-FM was successfully used as a molecular filter for the removal of methyl orange from an aqueous system. The results indicate that AM-PIM-FM could be a promising adsorbent for removal of anionic molecules from an aqueous system.Item Open Access Systematic hydrolysis of PIM-1 and electrospinning of hydrolyzed PIM-1 ultrafine fibers for an efficient removal of dye from water(Elsevier, 2017-12) Satilmis, B.; Budd, P. M.; Uyar, TamerIn this study, the Polymer of Intrinsic Microporosity (PIM-1) was systematically hydrolyzed in the presence of sodium hydroxide by varying the concentration of base, washing procedure and the time of the reaction. The chemical structure analyses confirmed that PIM-1 could be hydrolyzed by 65% up to 99% conversion depending on the synthesis procedure. The hydrolyzed PIM-1 samples have shown improved solubility which facilitates the fabrication of hydrolyzed PIM-1 ultrafine fibers by electrospinning technique. Extensive optimization studies were performed for the electrospinning of uniform and bead-free fibers from hydrolyzed PIM-1 with different degree of hydrolysis (65%, 86%, 94% and 99%). The electrospun hydrolysed PIM-1 fibrous samples have average fiber diameters (AFD) ranging from 0.58 ± 0.15 μm to 1.21 ± 0.15 μm, depending on the polymer concentration and applied electrospinning parameters. After electrospinning, self-standing hydrolyzed PIM-1 fibrous membranes were obtained which is useful as a filtering material for the adsorption of organic dyes from wastewater. Here, the capability of hydrolyzed PIM-1 electrospun fibrous membranes for the removal of dyes from aqueous solutions was investigated by using a batch adsorption process. The maximum adsorption capacity of fully hydrolyzed PIM-1 fibers was found 157 ± 16 mg g− 1 for Methylene Blue and 4 mg g− 1 for Congo red when the adsorption was conducted by 20 mg L− 1 dye solution without using any dilution. Moreover, maximum dye adsorption was also studied by using concentrated Methylene Blue solutions showing up to 272 mg g− 1 adsorption maximum. In addition, the self-standing fibrous hydrolyzed PIM-1 membrane was employed to separate Methylene Blue from an aqueous system by filtration without the necessity of additional driving force. The results indicate that hydrolyzed PIM-1 electrospun nanofibrous membranes can be a promising filtering material for wastewater treatmentItem Open Access ZnO nanostructures on electrospun nanofibers by atomic layer deposition/hydrothermal growth and their photocatalytic activity(Materials Research Society, 2014) Kayaci, Fatma; Vempati, Sesha; Ozgit-Akgun, Cagla; Biyikli, Necmi; Uyar, TamerA hierarchy of nanostructured-ZnO was fabricated on the electrospun nanofibers by atomic layer deposition (ALD) and hydrothermal growth, subsequently. Firstly, we produced poly(acrylonitrile) (PAN) nanofibers via electrospinning, then ALD process provided a highly uniform and conformai coating of polycrystalline ZnO with a precise control on the thickness (50 nm). In the last step, this ZnO coating depicting dominant oxygen vacancies and significant grain boundaries was used as a seed on which single crystalline ZnO nanoneedles (average diameter and length of ∼25 nm and ∼600 nm, respectively) with high optical quality were hydrothermally grown. The detailed morphological and structural studies were performed on the resulting nanofibers, and the photocatalytic activity (PCA) was tested with reference to the degradation of methylene blue. The results of PCA were discussed in conjunction with photoluminescence response. The nanoneedle structures supported the vectorial transport of photo-charge carriers, which is crucial for high catalytic activity. The enhanced PCA, structural stability and reusability of the PAN/ZnO nanoneedles indicated that this hierarchical structure is a potential candidate for waste water treatment.