Cilt:63 Sayı:01 (2021)

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    Adsorption of neutral red dye from aqueous solutions by natural adsorbent: an equilibrium, kinetic and thermodynamic study
    (Ankara Üniversitesi Mühendislik Fakültesi, 2021) Kul, Ali Rıza; Other; Other
    This study investigates the adsorption of neutral red (NR) on the natural clayey material of Adilcevaz/ Bitlis located the northwest of Van Lake in Eastern Anatolia (Turkey). The adsorbent used was characterized by XRD, XRF, FTIR, SEM and TG-DTA analyzes. The effect of various parameters such as pH, contact time, initial concentration and temperature on NR removal was investigated using a batch process to optimize the maximum adsorption conditions. Equilibrium data for NR adsorption were analyzed using nonlinear two-parameter isotherms such as Langmuir, Freundlich, Dubinin-Radushkevich, and Tempkin, and three-parameter isotherm models, such as nonlinear Redlich-Peterson, Sips, and Koble-Corrigan. The modelling results showed that it was best adapted to the Freundlich isotherm model for the NR dye, with relatively higher R2 values and smaller S.E. The maximum adsorption capacity obtained from the experimental data was determined to be 4.2810 mg g-1. The adsorption process follows pseudo-second-order kinetics with a rate constant of 0.0110 g mg-1 min-1. The thermodynamic parameters indicate that a physical mechanism controls the NR adsorption on the natural clay and spontaneously occurs.
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    Evaluation study on the sequential extraction and eco-toxicological profile of heavy metals in sediment along the coastline of Nigeria
    (Ankara Üniversitesi Mühendislik Fakültesi, 2021) Akinnawo, Solomon; Other; Other
    Evaluation study of sediment samples collected from the coastline of Nigeria was investigated in order to assess the ecological impact of anthropogenic activities in the studied area. Sequential extraction, digestion and quantification were done using standard methods. The eco-toxicological assessment of heavy metals was performed using risk assessment indices, sediment quality guideline, fractionation study and total concentration of heavy metals. The risk assessment indices revealed that amid the analyzed heavy metals, Cu has the least probability of been toxic to the environment, however the fractionation study revealed that the mobility and bioavailability of the heavy metals followed the order: Cr ˃ Cd ˃ Pb ˃ Ni ˃ Cu. The sediment quality guidelines posited the analyzed heavy metals to be 8% toxic to the environment. Finally, the total concentration of heavy metals fell below the maximum permissible limit of USEPA.