Leaching Performance and Zinc Ions Removal from Industrial Slag Leachate Using Natural and Biochar Walnut Shell
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Leaching Performance and Zinc Ions Removal from Industrial Slag Leachate Using Natural and Biochar Walnut Shell Sevda Esma Darama
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Elif Hatice Gürkan2 Özlem Terzi3 Semra Çoruh1 ●
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Received: 5 May 2020 / Accepted: 28 October 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract This study aims to investigate leaching characteristics of zinc slag according to leaching tests, including; TCLP (Toxicity Characteristic Leaching Procedure), SPLP (Synthetic Precipitation Leaching Procedure), ASTM-D3987 (American Society for Testing and Materials), and TS EN-12457-4 (Turkish Standards Institute) tests methods. The present study describes the adsorption potential of natural and biochar walnut shells for removing ions from the zinc leachate. TCLP leachate, with a value of 38.575 mg/L, has a high zinc (Zn+2) concentration compared to other methods. Therefore, TCLP leachate was used in the adsorption experiments. Adsorption experiments were carried out at different adsorbent dosages, pH values, and contact time conditions. In the dosage study, the highest removal efficiency was obtained as 84% and 92% in natural and biochar walnut shell adsorbents, respectively. As a result of pH study, it was observed that adsorption under alkaline conditions had a much higher removal efficiency. Moreover, adsorption studies performed against contact time were applied to four different kinetic models and both adsorbents were found to be fit with the pseudo-second-order model. This kinetic model showed that the Zn+2 adsorption mechanism of natural and biochar walnut shells is chemical adsorption. With this study, it was shown that a very high 96% zinc removal can be achieved under optimum adsorption conditions. This may be the first study of zinc removal after leaching from industrial slag in the literature. This study has shown that high removal efficiencies can be obtained by an economical adsorbent. Keywords Zinc slag Leachability Immobilization Biochar Walnut shell ●
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Introduction The rapid growth of the metallurgical industry generates large amounts of metallurgical waste. The discharge and accumulation of many metallurgical wastes are essential from both economic and environmental points of view. These wastes contain generally valuable elements that may be reduced, reused, recovered, and recycled. Zinc is one of these valueable metals (Rudnik 2019; Ng et al. 2016). Increased global zinc consumption is decreasing the amount
* Sevda Esma Darama [email protected] 1
Department of Environmental Engineering, Faculty of Engineering, Ondokuz Mayıs University, Samsun, Turkey
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Department of Chemical Engineering, Faculty of Engineering, Ondokuz Mayıs University, Samsun, Turkey
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Department of Public Health, Faculty of Medicine, Ondokuz Mayıs University, Samsun, Turkey
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of primary zinc resources (Song et al. 2019). Therefore, zinc should be recovered from metallurgical waste as a secondary source for the sustainability of the zinc industry (Perez et al. 2018). S
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