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  • Küçük Resim
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    Correlation of filtration resistance with microbial polymeric substances extracted from membranes in a submerged membrane bioreactor
    (Wiley-Blackwell, 2014) Kayaalp, Necati; Kınacı, Cumali; Dizge, Nadir; Hamidi, Nizamettin; 0000-0002-6136-5025; 0000-0003-1775-3466; 0000-0002-7805-9315; 0000-0003-0244-0264
    The current understanding of membrane fouling in submerged membrane bioreactors is still insufficient. Therefore, the role of microbial polymeric substances in membrane fouling mechanisms in a submerged membrane bioreactor was systematically investigated in this study. Microbial polymeric foulants accumulated on the membrane surface and in its pores. The foulants were then extracted in three steps, without deforming the membrane structure. Moreover, filtration resistances were determined by the resistance in series model. A strong functional relationship was observed between total polymeric substances accumulated in the membrane and their fouling resistances. The greatest accumulation of polymeric substances occurred in cake layers formed on the membrane surface. Correspondingly, the greatest fouling resistance resulted from the cake layer. The results indicated that more protein accumulated on the membrane surface than carbohydrates because the proteins were stickier. Regarding the analysis of microbial polymeric substances, it was observed that the filtration with a 0.45 mu m pore size filter did not capture all of the polymeric substances that took part in membrane fouling.
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    Preconcentrations of Pb(II), Ni(II) and Zn(II) by solid phase bio-extractor using thermophilic Bacillus subtilis loaded multiwalled carbon nanotube biosorbent
    (Elsevier Ltd., 2023) Özdemir, Sadin; Dündar, Abdurrahman; Dizge, Nadir; Kılınç, Ersin; Balakrishnan, Deepanraj; Prasad, Kashi Sai
    An alternative biotechnological solid phase bio-extraction (SPE) method was developed. Bacillus subtilis loaded multiwalled carbon nanotube was designed and used as biosorbent for the preconcentrations of Pb(II), Ni(II), and Zn(II). The experimental parameters such as sample flow rate, pH of sample solution, amounts of Bacillus subtilis and multiwalled carbon nanotube, volume of sample solution and reusability of column which affects the analytical characteristics of the SPE method were investigated in details. Surface structures were examined by using FTIR, SEM. The best pH was determined as 5.0 and the percentages recoveries of Zn(II), Ni(II), and Pb(II) were determined as 99.1%, 98.7%, and 96.2%, respectively, at a flow rate of 3 mL/min. In this study, in which the profitable sample volume was determined as 400 mL and the amount of multiwalled carbon nanotube (MWCNT) as 50 mg. It was also observed that the column had a significant potential to preconcentrate Zn(II), Ni(II), and Pb(II) even after 25 reuses. The biosorption capacities for Zn(II), Ni(II) and Pb(II) were calculated as 39.67 mg/g, 45.98 mg/g and 51.34 mg/g respectively. The LOD values were calculated as 0.024 ng/mL for Pb(II), 0.029 ng/mL for Ni(II), and 0.019 ng/mL for Zn(II). The linear range was detected as 0.25–25 ng/mL. The concentrations of Pb(II), Ni(II), and Zn(II) in a variety of real food samples were determined by using developed method after application of certified reference sample.
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    Synthesis and characterization of a polydioxanone-coated dipeptide-functionalized magnetic ?-Fe2O3 nanoparticles-modified PES membrane and its biological applications
    (MDPI, 2022) Demirci, Özlem; Gonca, Serpil; Tolan, Veysel; Özdemir, Sadin; Dizge, Nadir; Kılınç, Ersin
    This work is focused on the synthesis of leucyl-glycine-functionalized γ-Fe2O3 magnetic nanoparticles coated by polydioxanone (γ-Fe2O3-CA-Leu-Gly-PDX) as a polyethersulphone (PES) membrane for biotechnological applications. The physicochemical characteristics were investigated by FT-IR, SEM, XRD, a vibrating sample magnetometer (VSM), and ICP-OES. The present investigation also centered on the several biological activities of γ-Fe2O3-CA-Leu-Gly-PDX. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and metal chelating activity was studied for evaluation of its antioxidant activity potential. It exhibited 100% DPPH radical scavenging and 93.33% metal chelating activity. With applicability to antimicrobial photodynamic therapy, DNA cleavage and antimicrobial activity, the cell viability of γ-Fe2O3-CA-Leu-Gly-PDX was investigated in detail. The γ-Fe2O3-CA-Leu-Gly-PDX demonstrated the significant biofilm inhibition activity as being 81.54% and 86.34% for P. aeruginosa and S. aureus, respectively. Moreover, a novel polyethersulphone nanocomposite membrane incorporated with γ-Fe2O3-CA-Leu-Gly-PDX was prepared. The performance of the γ-Fe2O3-CA-Leu-Gly-PDX-blended polyethersulphone (PES) membrane was investigated by measuring the antifouling and E. coli rejection. The nanocomposite membranes demonstrated remarkable antifouling properties in contrast with the pristine PES when BSA (bovine serum albumin) and E. coli were filtrated. A complete rejection was obtained by the composite membrane. After an application of the membrane study, the modified polyethersulphone (PES) membrane blended with γ-Fe2O3-CA-Leu-Gly-PDX removed 100% of the E. coli.