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Öğe Characterization of littered face masks in the southeastern part of Turkey(Springer Heidelberg, 2021) Akarsu, Ceyhun; Madenli, Ozgecan; Deveci, Ece UmmuA possible source of microplastics has started to be released into nature because of the single-use face masks that protect us against the spread of COVID-19 and are being thrown onto the streets and into seas and nature. This study aims to estimate the amount of face mask use during the COVID-19 pandemic in Turkey, thereby expressing our concerns about waste management and plastic pollution and calling on appropriate solid waste management policies and governments to take the necessary measures to formulate their strategies at all levels. In this context, the number of masks in an area of 1 km(2) in 3 different cities was determined theoretically and experimentally. Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM) were also used to evaluate plastic polymer characteristics of the single-use face mask. It was determined that the three cities produce roughly 10 tons of face masks in a day. With the increasing use of single-use plastics, the impact of face masks on microplastic pollution is of great concern. Although studies on the recovery of disposable masks continue, the level is insufficient. Therefore, studies to be carried out on technologies that will enable the repeated use of masks are important.Öğe Effective removal of hexavalent chromium by novel modified alginate-based biocomposites: Characterization, kinetics and equilibrium studies(Elsevier Sci Ltd, 2023) Madenli, Ozgecan; Akarsu, Ceyhun; Deveci, Ece UmmuThis study aims to synthesise novel biocomposites by combining fungal hyphae (Aspergillus oryzae or Penicillium roqueforti) and reduced graphene oxide to evaluate their adsorption potential for hexavalent chromium (Cr(VI)) from synthetic solutions and real wastewater. Fourier-transform infrared spectroscopy, scanning electron mi-croscopy, X-ray diffraction, and thermogravimetric analyses were used to characterize the effects of the carbon -based materials on microbial structure. In addition, independent variables including with a contact time (1-11 h), reduced graphene oxide concentration (0.1-1 g.L-1), and initial Cr(VI) concentration (10-50 mg L-1) were tested in batch-scale laboratory experiments by response surface methodology. Accordingly, maximum adsorp-tion was achieved at 11 h contact time, 1.0 g L-1 rGO, and 50 mg L-1 Cr(VI) with a removal rate of 98.9%. The pseudo-first-order and Freundlich isotherm models were well fitted. The results show that these biocomposites can serve as novel adsorbent for the removal of Cr(VI) from wastewater.Öğe Pre-treatment optimization of barley straw as agro-industrial waste via alkaline peroxide and ultrasound for soluble sugar production and degradation(Springer Heidelberg, 2021) Deveci, Ece Ummu; Gonen, Cagdas; Akarsu, CeyhunPre-treatment of biomass is of great importance to maximize the recovery of fermentable sugars and minimize the amount of enzyme inhibitors formed. There are several processes that can be applied for pre-treatment of agricultural industrial waste such as chemical, physical, physico-chemical, biological, and combined pre-treatments. Alkaline hydrogen peroxide (AHP) and ultrasonication are two of this pre-treatment process. The aim of this study was to investigate the pre-treatment performance of barley straw biomass using AHP and combined ultrasonic-hydrogen peroxide process via Box-Behnken design as a response surface methodology (RSM). The factors of time (30-120 min), particle size (0.2-1 mm), peroxide dosage (1-5%), and temperature (50-100 degrees C) are investigated for optimum operating conditions. For ultrasonication process, factors are time (5-30 min), particle size (0.2-1.0 mm) and US power (20-100 Kj/kgDM). During AHP pre-treatment, maximum total and reduced sugar concentration was found as 14 g/L and 660 mg/L, respectively, at maximum level of time and minimum level of dosage factors which are 120 min and 1%, respectively. Maximum total and reduced sugar concentration can be reached nearly 7.6 g/L and 810 mg/L, respectively, at minimum level of time which is 5 min and almost minimum level of chemical dosage in ultrasound-hydrogen peroxide process, respectively.Öğe Synthesis of graphite/rGO-modified fungal hyphae for chromium (VI) bioremediation process(Taylor & Francis Ltd, 2024) Madenli, Ozgecan; Akarsu, Ceyhun; Adiguzel, Ali Osman; Altuntepe, Ali; Zan, Recep; Deveci, Ece UmmuBioremediation is a promising technology that can eliminate the drawbacks of conventional treatment methods in removing harmful toxic metals including chromium(VI). Therefore, in this study, fungal hyphae modified with graphite and reduced graphene oxide were synthesized and assessed for their potential to bioremediate heavy metals for the first time in the literature. The effects of the carbon-based materials on microbial structure were characterized using scanning electron microscopy analysis. Thermogravimetric, RAMAN, X-ray diffraction, and enzymatic analyzes were performed to determine the role of functional groups. In addition, batch adsorption experiments utilizing response surface methodology were conducted to optimize operating parameters such as time (1-11 h), chromium (10-50 mg/L), and graphite/reduced graphene oxide (0.1-1 g/L). The maximum adsorption capacity with the graphene fungal hyphae was determined to be 568 mg.g(-1), which is 9.7 times that of the crude fungal hyphae. The Cr(VI) removal for fungal hyphae-graphite and fungal hyphae-reduced graphene oxide biocomposites was 98.25% and 98.49%, respectively. The isothermal and kinetic results perfectly matched the 2nd order pseudo-model and Langmuir model in terms of the nature of the adsorption process. The laboratory scale test results indicate that fungal hyphae modified with graphite and reduced graphene oxide have a high adsorption capacity, suitable for the removal of chromium (VI) from wastewater.Öğe Treatment of slaughterhouse wastewater by electrocoagulation and electroflotation as a combined process: process optimization through response surface methodology(Springer Heidelberg, 2021) Akarsu, Ceyhun; Deveci, Ece Ummu; Gonen, Cagdas; Madenli, OzgecanThe contamination of water with organic compounds has become an increasing concern in today's world. The cost-effective and sustainable treatment of industrial wastewaters is a major challenge. Advanced treatment techniques such as electrocoagulation-electroflotation offer economic and reliable solutions for the treatment of industrial wastewater. In this study, the electrocoagulation-electroflotation method was investigated for the simultaneous removal of chemical oxygen demand, total phosphorus, total Kjeldahl nitrogen, and color via response surface methodology. Factors such as electrode combination (Fe and Al), current density (10-20 mA/cm(2)), pH (3.0-9.0), and electrode distance (1-3 cm) were investigated in the treatment of wastewater to obtain maximum treatment efficiency. It was determined that chemical oxygen demand, total Kjeldahl nitrogen, total phosphorus, and color removal reached up to 94.0%, 77.5%, 97.0%, and 99.0%, respectively. Treatment costs were found as $0.71 with the Al-Fe electrode combination.
