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    Boric acid recovery from wastewater by chromatographic separation and mathematical modeling
    (Elsevier Sci Ltd, 2024) Kole, Zehra; Ocal, Zehra Betul; Omwene, Philip Isaac; Soydemir, Gulfem; Keskinler, Bulent; Karagunduz, Ahmet
    The new approaches in industrial wastewater management underscores the importance of reclaiming valuable materials. Within the boron industry, the generation of substantial wastewater containing preliminary boron species is a significant concern. This study focuses on recovering boric acid from boron production wastewater, addressing the challenge of separating impurities like sulfate, calcium, and magnesium. The methodology adopts chromatographic separation using a cation exchange resin in two forms: (1) Finex CS10GC cation exchanger in Na+ form and (2) Finex CS10GC cation exchanger in Ca2+/Mg2+ form. Notably, the Finex CS10GC ion exchanger in Na+ form achieves a separation efficiency of 95.5 % at a flow rate of 5 mL/min with a 0.20 bed volume (BV) loading. In contrast, the Ca2+/Mg2+ loaded resin achieves a separation efficiency of 23.3 % at the same flow rate. As the boron loading rate decreases to 10 %, the separation efficiency increases to 42.6 %. The flow rate also plays a crucial role, as an increase corresponds to a decrease in separation efficiency. Notably, the Finex CS10GC ion exchanger in Na+ form consistently exhibits superior separation efficiency and band resolution. A mathematical model is introduced to simulate the effective separation of boric acid from other impurities. The quality of the recovered boric acid conforms to the standard grade (Merck KGaA), exhibiting a purity level within the range of 99.5-100 %, suggesting substantial economic value. The proposed recovery process contributes significantly to environmental preservation by mitigating waste discharge, exemplifying a noteworthy commitment to resource conservation.
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    Öğe
    Cerium-Doped CuFe-Layered Catalyst for the Enhanced Oxidation of o-Xylene and N,N-Dimethylacetamide: Insights into the Effects of Temperature and Space Velocity
    (Amer Chemical Soc, 2023) Ocal, Zehra Betul; Keyikoglu, Ramazan; Karagunduz, Ahmet; Yoon, Yeojoon; Khataee, Alireza
    Volatile organic compounds (VOCs) are among the most potential pollutant groups that cause air quality degradation because of their toxic effects on human health. Although catalytic oxidation is an effective method for VOC removal, further studies are required to develop more efficient and affordable catalysts. In this study, cerium (Ce) was doped into a CuFe-layered material (Ce-CuFe) to improve the catalytic oxidation efficiencies of N,N-dimethylacetamide (DMAC) and o-xylene. The synthesized catalyst was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) analysis. XRD analysis confirmed the successful doping of Ce atoms into the CuFe-layered structure, while in the SEM and TEM images the catalyst appeared as uniformly distributed two-dimensional plate-like particles. The catalytic oxidation performance of the Ce-CuFe was investigated at six temperatures between 200 and 450 degrees C and three space velocities in the range of 31000-155000 mLh(-1)g(-1) for the oxidation of DMAC and o-xylene, which functioned as polar and nonpolar solvents, respectively. At 200 degrees C, the Ce-CuFe catalyst performed 50% greater when oxidizing o-xylene while exhibiting a DMAC oxidation efficiency that was 42% greater than that achieved using undoped CuFe. The Ce-CuFe could remove DMAC and o-xylene with an efficiency higher than 95% at 450 degrees C. Furthermore, Ce-doped CuFe exhibited high resistance against moisture and outstanding reusability performance with only a 5.6% efficiency loss after nine reuse cycles. Overall, the incorporation of Ce into a CuFe-layered material is a promising strategy for the oxidation of various VOCs.
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    Öğe
    Sustainable treatment of boron industry wastewater with precipitation-adsorption hybrid process and recovery of boron species
    (Elsevier, 2024) Ocal, Zehra Betul; Oncel, Mehmet Salim; Keskinler, Bulent; Khataee, Alireza; Karagunduz, Ahmet
    Boron removal from wastewater has been investigated by using various processes, including ion exchange resins, membrane processes and adsorption. Each method has various advantages and disadvantages, but most produce excessive waste in addition to high operational costs. Therefore, more sustainable methods are required for wastewater containing high concentrations of boron. In this study, a sustainable treatment process was developed for wastewater containing high concentrations of boron. This study investigated the removal of boron from wastewater by Al(OH)(3) sorption. The reuse of adsorbent (Al(OH)(3)) and the potential recovery of boric acid was the main goal of the study. It was observed that although lower concentrations of boron were obtained at pH 10.5 (980 mg/L and 635 mg/L at pH of 9.0 and 10.5, respectively), the amount of sorbed boron at pH 9 was substantially higher (94.7 mg B/g Al(OH)(3) and 27.8 mg B/g Al(OH)(3) at pH of 9.0 and 10.5, respectively). This was attributed to the higher initial boron concentrations and the formation of boric acid and polyborate complexes at pH 9.0. Results showed that polyborate species sorption was an outer sphere complex formation, which led to the desorption of boron as pH lowered. Adsorbed boron species to Al(OH)(3) could effectively be desorbed at low pH values (pH<5.0); which allows Al(OH)(3) to be used in successive adsorption studies. Approximately 55% of boron recovery from pretreated wastewater was possible with the effective reuse of adsorbent. A net profit of 2.85 $/m(3) could be obtained based on the amounts of chemical consumptions and boron recovery.