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    A combined process of chemical precipitation and aerobic membrane bioreactor for treatment of citric acid wastewater
    (Academic Press Ltd- Elsevier Science Ltd, 2023) Belibagli, Pinar; Isik, Zelal; Bouras, Hadj Daoud; Arslan, Hudaverdi; Dizge, Nadir
    The wastewater generated from citric acid production has a high organic loading content. The treatment and reuse of citric acid wastewater with high organic loading become extremely important. In this study, the performance of calcium hydroxide (Ca(OH)2) precipitation as a low-cost and environmentally friendly pre-treatment method and aerobic membrane bioreactor (MBR) combined treatment system was investigated for the treatment of citric acid (CA) wastewater. At the first step, optimization parameters such as agitation speed (100, 150, 200 rpm), temperature (30, 50, 70 degrees C), and reaction time (2, 4, 6 h) for Ca(OH)2 precipitation as a pre-treatment method were investigated using response surface methodology (RSM) to achieve maximum chemical oxygen demand (COD) removal. Experimental sets were designed using Box-Behnken Design. As a result of pre-treatment with Ca(OH)2 precipitation, a COD removal efficiency of 97.3% was obtained. Then, pre-treated CA wastewater was fed continuously to the MBR process for 10 days, which was the second stage of the combined process. As a result of the MBR process, 92.0% COD removal efficiency was obtained for 24 h HRT and 10 days SRT. In total, 99.8% COD removal efficiency was obtained when combined process was used and COD concentration decreased from 52,000-114 mg/L. For the treatment and reuse of wastewater from citric acid production, Ca(OH)2 precipitation and MBR combined treatment systems demonstrated an effective strategy.
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    Antimicrobial and antioxidant activity of phenolic extracts from walnut (Juglans regia L.) green husk by using pressure-driven membrane process
    (Springer India, 2023) Arslan, Hudaverdi; Koc, Eda Ondul; Ozay, Yasin; Canli, Oltan; Ozdemir, Sadin; Tollu, Gulsah; Dizge, Nadir
    In this study, antioxidant (DPPH and metal chelating), DNA cleavage, biofilm, and antimicrobial properties of extracted phenol from the walnut green husk (WGH) and its different concentrate and permeate samples were evaluated. For maximum phenolic compound extraction from the WGH first, the effects of solvent type (deionized water, methanol, n-hexane, acetone, and ethanol), solvent temperature (25-75 degrees C), and extraction time (0.5-24 h) were optimized. Then to concentrate phenolic compounds a pressure-driven membrane process was used with four different membrane types. The phenol contents of the concentrate samples were found to be microfiltration (MF) concentrate 4400 mg/L, ultrafiltration (UF) concentrate 4175 mg/L, nanofiltration (NF) concentrate 8155 mg/L, and reverse osmosis (RO) concentrate 8100 mg/L. LC-MSMS was used to determine the quantification of phenolic compounds in permeate and concentrate streams. In addition, all of the concentrate samples with high phenol content showed a high antioxidant activity as 100% with MF concentrate, UF concentrate, NF concentrated and RO concentrated. Likewise, concentrate samples were found to have very high antibiofilm activity as 82.86% for NF concentrate againts S. aureus, 85.80% for NF concentrate against P. aureginosa, 80.95% for RO concentrate against S. aureus, and 83.61% for RO-concentrate against P. aureginosa. When the antimicrobial activity of the extracted phenol from WGH and its different concentrate and permeate samples were evaluated by micro dilution and disk diffusion methods, it was found that the ability of the concentrate samples to inhibit bacterial growth was much higher than permeate ones. In addition, extracted phenol from WGH and its different concentrate and permeate samples showed significant DNA nuclease activity.
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    Comparison of Cr(VI) adsorption and photocatalytic reduction efficiency using leonardite powder
    (Pergamon-Elsevier Science Ltd, 2022) Arslan, Hudaverdi; Eskikaya, Ozan; Bilici, Zeynep; Dizge, Nadir; Balakrishnan, Deepanraj
    It is very important to treat Cr(VI) from the aquatic environment due to its toxic and harmful effects. Conventional treatment methodology involving biological pathways is generally ineffective for wastewater containing Cr(VI). Therefore, it is necessary to develop environmentally friendly and economical methods to remove Cr(VI) from the aquatic environment. In this study, leonardite, which is a natural mineral that has no harmful effects on the environment, was used for Cr(VI) removal. Leonardite was used in both adsorption and photocatalytic treatment systems by only pulverizing without any chemical treatment. Characterizations of leonardite were obtained using X-ray fluorescence (XRF), fouirer transform infrared spektrofotometre (FTIR), scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX) analyses methods. The effects of solution pH (2-10), particle size (45-300 mu m), adsorbent dose (0.25-3 g/L), and initial concentration (10-30 mg/L) on Cr(VI) removal efficiency were investigated in both adsorption and photocatalytic experiments. In the adsorption process, a complete removal efficiency (100%) was obtained for 3 g/L of adsorbent dose with an initial Cr(VI) concentration of 10 mg/L at pH 2 for 2 h. In the photocatalytic process, 100% removal efficiency of Cr(VI) was obtained when four times less adsorbent dosage was used under the same conditions. In addition, the reuse of leonardite powder was also investigated under optimum experimental conditions. Leonardite powder preserved approximately 70% of its activity in the photocatalytic process while it lost 50% of its activity after 5 reuses in adsorption process.
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    Fabrication of Ag nanoparticles coated leonardite basalt ceramic membrane with improved antimicrobial properties for DNA cleavage, E. coli removal and antibiofilm effects
    (Elsevier Science Inc, 2023) Saleh, Mohammed; Isik, Zelal; Belibagli, Pinar; Arslan, Hudaverdi; Gonca, Serpil; Ozdemir, Sadin; Kudaibergenov, Nurbolat
    This study aimed to fabricate a novel, low-cost, and environmental-friendly ceramic membrane based on basalt and leonardite powders via press and sintering methods. The fabricated leonardite basalt ceramic membrane (LBCM) was coated with silver nanoparticles (AgNPs); to create an antibacterial surface. The capabilities of the bare and coated membranes were examined. In this context, water permeability reached 554 +/- 2.61 and 447 +/- 1.21 L/m2hbar for bare LBCM and AgNPs-coated LBCM, respectively. The fabricated membranes indicated 100% Escherichia coli (E. coli) removal efficiency at a transmembrane pressure of 0.5 bar. The solid surface antimicrobial activity of the LBCM and AgNPs-coated LBCM reached 26.38% and 100%, respectively. The LBCM and AgNPs-coated LBCM were analyzed for the in-vitro 2,2diphenyl-1-picrylhydrazyl (DPPH) antioxidant. Accordingly, AgNPs-coated LBCM exhibited higher antioxidant activities than raw LBCM. The scavenging capacity reached 83.91% with AgNPs-coated LBCM, while only 58.95% was achieved with raw LBCM, indicating that AgNPs-coated LBCM was better than bare LBCM from an antioxidant activities perspective. AgNPs-coated LBCM had a deoxyribonucleic acid (DNA) cleavage activity (single-strand DNA cleavage activity at 50 mg/L and double-strand DNA cleavage activity at 100 and 200 mg/L). In contrast, the raw LBCM did not exhibit DNA cleavage activity at any concentration. AgNPs-coated LBCM showed higher antimicrobial activities (minimum inhibition concentrations (MICs) were 32 mg/L against Enterococcus faecalis (E. faecalis) and 64 mg/L against Staphylococcus aureus (S. aureus), Candida tropicalis (C. tropicalis), and Enterococcus hirae (E. hirae)). The biofilm inhibition of LBCM and AgNPs-coated LBCM powders was tested against S. aureus and Pseudomonas aeruginosa (P. aeruginosa). The maximum S. aureus inhabitations by LBCM and AgNPcoated LBCM were 60.34% and 99.12%, respectively. The inhabitation of P. aeruginosa increased from 52.38% before coating to 96.37% at the end of the coating process. Regarding E.coli microbial cell viability inhibition, LBCM powders and AgNPs-coated LBCM powders were found to inhibit E. coli growth by 68.35% and 100%, respectively. (c) 2023 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.
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    Heterogeneous catalyst production from waste cucumber stems and investigation of production potential in biodiesel
    (Elsevier, 2025) Alterkaoui, Aya; Belibagli, Pinar; Arslan, Hudaverdi; Dizge, Nadir; Balakrishnan, Deepanraj
    The use of heterogeneous catalysts obtained from waste in biodiesel production is of great importance in terms of waste management and waste recovery. In this study, heterogeneous catalyst was successfully obtained from waste cucumber stems (WCS) and its potential for biodiesel production via transesterification was investigated. The heterogeneous catalyst contains Ca, K, Mg, Si elements that play a role in biodiesel production. Biodiesel production potential was designed by selecting different temperature, time, methanol/oil molar ratio, and catalyst amount using response surface methodology (RSM). Waste cooking oil (WCO) was used for biodiesel production. The optimum values of these parameters were found to be 70 degrees C, 120 min, 15 wt% and 20:1, respectively. 93.7 % FAME yield was obtained using the obtained CaO catalyst. The heterogeneous catalyst obtained from WCS showed multiple reuse capacity up to 5 cycles. All these results showed that the heterogeneous catalyst obtained from WCS has strong biodiesel production activity and this approach has great potential in biodiesel production with its economic, sustainability and environmental benefits.
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    Investigation of the Effect of Sintering of Waste Welding Powder on Antioxidant and Antimicrobial Activity
    (Springer Int Publ Ag, 2022) Eskikaya, Ozan; Arslan, Hudaverdi; Ozdemir, Sadin; Gonca, Serpil; Dizge, Nadir
    The use of waste as a material that can be useful in other areas can reduce both waste generation and the need for resources. Welding powder with high heavy metal content should be used for other purposes. For this reason, the welding powder, which is frequently used in the metal industry and released after the welding process, is desired to be used as an agent against microorganisms in this study. Several biological activities of welding powder and its sintered forms also investigated. The welding powder and its sintered forms showed moderate antioxidant and antimicrobial activity. Welding powder without sintering is called WP. Welding powders sintered at 300 ?degrees C, 600?degrees C, and 900?degrees C are named as WP300, WP600, and WP900, respectively. DNA cleavage activity was tested, and it showed single-stand cleavage against pBR 322 plasmid DNA. They displayed excellent biofilm inhibition activity, and the biofilm inhibition of WP, WP300, WP600, and WP900 against S. aureus and P. aeruginosa were found as 99.34%, 99.21%, 98.99%, and 99.12% and 98.32%, 96.11%, 96.38%, and 95.39%, respectively, at concentrations of 500 mg/L, respectively. They also demonstrated significant cell viability activity against E. coli.
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    Optimization of water removal from oil by eggplant stems using response surface methodology
    (Emerald Group Publishing Ltd, 2023) Ordu, Zehra; Belibagli, Pinar; Yalvac, Mutlu; Arslan, Hudaverdi; Dizge, Nadir
    Eggplant stems are among the most produced organic wastes. Unfortunately, the burning and irregular storage of eggplant stems outdoors causes both global air pollution and environmental pollution. Environmental impacts can be minimized by recycling eggplant stems, turning them into valuable products and using them as valuable additives. In this study, the water-binding capacity (WBC) and water-binding capacity in oil (WBCO) potential of eggplant stems was investigated. In the first step, optimization of the alkaline treatment of eggplant stems was carried out. Alkaline treatment optimization parameters such as sodium hydroxide (NaOH) concentration (0.050, 0.125 and 0.200 M), temperature (20, 40 and 60 degrees C) and reaction time (30, 90 and 150 min) were investigated using response surface methodology. In the second stage, WBC and WBCO tests of eggplant stems were carried out. According to the experimental results, capacity efficiencies of 30.64 and 98.20% were obtained for WBC and WBCO, respectively, at 0.125 M sodium hydroxide concentration, 60 degrees C temperature and 150 min reaction time. In addition, eggplant stems demonstrated the ability to retain water effectively for up to five cycles. The high WBC of eggplant stems in oil after alkali treatment showed that they could be a suitable and inexpensive candidate for use in biodiesel purification and methane production.
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    Production of Waste Tomato Stem Hydrochar (TS-HC) in Subcritical Water Medium and Application in Real Textile Wastewater using Photocatalytic Treatment System
    (Springer Int Publ Ag, 2022) Alterkaoui, Aya; Eskikaya, Ozan; Gun, Melis; Yabalak, Erdal; Arslan, Hudaverdi; Dizge, Nadir
    Dye-containing wastewater emerges in many fields, especially in the textile industry. This type of wastewater has to be treated because of its negative effects on the environment. The treatment of wastewater containing dyes employs a variety of treatment techniques. However, it is important to use treatment systems that use nanoparticles of biomaterial origin. In this study, the use of photocatalytic treatment system with hydrochar obtained from tomato stems (TS-HC) in the purification of Methylene Blue (MB) and Remazol Brilliant Blue R (RBBR) dyes was investigated. For the optimization of the photocatalytic treatment system, light source, pH, TS-HC amount and initial dye concentration were tested. Furthermore, TS-HC reuse tests were carried out at the found optimal conditions and it was determined that both dyes had 10 reuse cycles. Optimum conditions for MB dye was obtained by adding 1 g/L catalyst into the solution with a pH value of 8 and an initial concentration of 15 mg/L, and 100% dye removal efficiency under UVA light. 97.4% dye removal efficiency was obtained by adding 2 g/L catalyst to the wastewater (pH 2) containing 15 mg/L RBBR dye under UVA light. Characterization analyzes with SEM, EDX and XRD of hydrochar obtained from waste tomato stem were performed. As a result of the photocatalytic experiments, TS-HC catalyst was used in the decolorization of real wastewater. It has been determined that the catalyst can decolorize the dye-containing real wastewater up to the lower limit of the appropriate value (260 Pt-Co) of the Turkish Water Pollution Control Regulation.
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    Reuse of waste welding powder in Fenton-like process for RO16 dye removal and Cr(VI) reduction
    (Springer, 2024) Bulut, Hande; Eskikaya, Ozan; Belibagli, Pinar; Isik, Zelal; Arslan, Hudaverdi; Dizge, Nadir
    Waste minimization is one of the important issued nowadays. In this study, the usability of waste welding powders (WWPs) was investigated in the Fenton-like process for Cr(VI) and reactive orange 16 (RO16) dye removal from aqueous solution. Solution pH, amount of catalyst, amount of H2O2, initial pollutants concentrations, reaction time and temperature parameters were optimized. 100% RO16 dye removal efficiency was obtained at pH: 2, dye concentration: 100 mg/L, catalyst amount: 1 g/L, and H2O2 amount: 2.5 & mu;L/L. Besides, 99.7% Cr(VI) removal efficiency was obtained at pH: 2, Cr(VI) concentration: 10 mg/L, catalyst amount: 0.25 g/L, and H2O2 amount: 2.5 & mu;L/L. In addition, the characterization of WWP was also carried out by SEM, EDX, XRD, XRF, and zeta potential analyses. WWP can be considered to be a viable catalyst for both dye and Cr(VI) removal from aqueous solution. WWP's effectiveness was also tested in real wastewater. As a result of the experiments with real wastewater, 100% removal efficiency was obtained both textile wastewater for 60 min and Cr(VI) containing wastewater for 45 min. These results have revealed that WWP is a promising catalyst for the treatment of real wastewater.