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Membrane Water Treatment Volume 14, Number 3, May 2023 , pages 121-128 DOI: https://doi.org/10.12989/mwt.2023.14.3.121 |
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Selective removal of cationic dye pollutants using coal ash-derived zeolite/zinc adsorbents |
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Chatchai Rodwihok, Mayulee Suwannakaew, Sang Woo Han, Siyu Chen, Duangmanee Wongratanaphisan and Han S. Kim
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| Abstract | ||
| This study introduces a NaOH/Zn-assisted hydrothermal method for the synthesis of zeolites derived from coal ash (CA). A zeolite/Zn adsorbent is successfully prepared by the activation of CA with NaOH and Zn; it is characterized by a high surface area and a negative surface charge. Methylene blue (MB) and methyl orange (MO) are selected as dye pollutants, and their adsorption onto the zeolite/Zn adsorbent is investigated. Results show the high adsorption capacities of MB and MO and that the negative surface charge facilitates electrostatic interactions between the adsorbates and adsorbents. The zeolite/Zn adsorbents shows the selective adsorption of positively charged dye MB via electrostatic interactions between the =NH+ group (positive dipole) and the oxygen functional group of the adsorbents (negative dipole). The selectivity for the positively charged dye is sufficiently high, with the removal efficiency reaching 99.41% within 10 min. By contrast, the negatively charged dye MO exhibits negligible absorption. These findings confirm the role of electrostatic interactions in the adsorption of MB, in addition to the effect of a large surface area. The results of this study are expected to facilitate the development of simple, eco-friendly, and cost-effective zeolite-based adsorptive composites from CA residuals for the selective removal of dye pollutants from CA waste. | ||
| Key Words | ||
| coal ash; surface modification; zeolite; organic dyes; selective adsorption | ||
| Address | ||
| Chatchai Rodwihok, Mayulee Suwannakaew, Sang Woo Han, Siyu Chen and Han S. Kim: Civil and Environmental Engineering, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 05029, Republic of Korea Duangmanee Wongratanaphisan: Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand | ||
