Jeon JY  Cho YB  Kim JW  Shin SG  Jeon JR  Lee YK

Vol. 27,  No. 4, pp. 359-366, Dec.  2021
10.7464/ksct.2021.27.4.359

Halloysite Tubular media Adsorption Methylene blue Thermal stability

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Halloysite nanotubes (HNTs), the multiwalled clay mineral with the composition of Al2Si2O5(OH)4ㆍnH2O, have been highlighted as a low-cost adsorbent for the removal of dyes from wastewater. Although a powder of halloysite presents a high specific surface area, forming media are significantly considered due to sludge-clogging induced by the water-bound agglomeration. However, higher firing temperature to achieve the structural durability of the media and lower utilization rate due to longer penetration depth into the media act as hurdles to increase the dye-adsorption capacity. In this work, the retention of the adsorption capacity of halloysite was evaluated with methylene blue solution after the heat treatment at 750 ℃. In order to improve the utilization rate, tubular media were fabricated by extrusion. The images taken by transmission electron microscopy show that HNTs present excellent structural stability under heat treatment. The HNTs also provide superb capacity retention for MB adsorption (93%, 18.5 mg g-1), while the diatomite and Magnesol XL show 22% (7.65 mg g-1) and 6% (11.7 mg g-1), respectively. Additionally, compositing with lignin enhances adsorption capacity, and the heat treatment under the hydrogen atmosphere accelerates the adsorption in the early stage. Compared to the rod-type, the tubular halloysite media rapidly increases methylene blue adsorption capacity.