Enhanced chromium adsorption capacity via plasma modification of natural zeolites. (30th November 2016)

• Record Type: Journal Article
• Authors: Cagomoc, Charisse Marie D.; Vasquez, Magdaleno R.
• Is Part Of: Japanese journal of applied physics. Volume 56:Number 1(2017)Supplement
• Publication Date: 2016-11-30
• Subjects: Physics -- Periodicals; 621.05
• DOI: 10.7567/JJAP.56.01AF02
• Languages: English
• ISSNs: 0021-4922

Abstract

Abstract: Natural zeolites such as mordenite are excellent adsorbents for heavy metals. To enhance the adsorption capacity of zeolite, sodium-exchanged samples were irradiated with 13.56 MHz capacitively coupled radio frequency (RF) argon gas discharge. Hexavalent chromium [Cr(VI)] was used as the test heavy metal. Pristine and plasma-treated zeolite samples were soaked in 50 mg/L Cr solution and the amount of adsorbed Cr(VI) on the zeolites was calculated at predetermined time intervals. Compared with untreated zeolite samples, initial Cr(VI) uptake was 70% higher for plasma-treated zeolite granules (50 W 30 min) after 1 h of soaking. After 24 h, all plasma-treated zeolites showed increased Cr(VI) uptake. For a 2- to 4-month period, Cr(VI) uptake increased about 130% compared with untreated zeolite granules. X-ray diffraction analyses between untreated and treated zeolite samples revealed no major difference in terms of its crystal structure. However, for plasma-treated samples, an increase in the number of surface defects was observed from scanning electron microscopy images. This increase in the number of surface defects induced by plasma exposure played a crucial role in increasing the number of active sorption sites on the zeolite surface.