Kaolin–Fly Ash Composite for Pb[sup.2+] and AsO[sub.4][sup.3−] Adsorption from Aqueous System

• Published in: Applied sciences Vol. 14; no. 12
• Main Authors: Doušová, Barbora, Bedrnová, Eva, Maxová, Kateřina, Koloušek, David, Lhotka, Miloslav, Pilař, Lukáš, Angelis, Milan
• Format: Journal Article
• Language: English
• Published: MDPI AG 01.06.2024
• Subjects: Clay; Paralysis; Canada; Czech Republic
• ISSN: 2076-3417; 2076-3417
• DOI: 10.3390/app14125358

Featured Application: Composite adsorbents can be applied in water treatment and other environmental technologies. Potential benefits include (i) connection of the surface and binding properties of different materials; (ii) an extended range of selectivity; (iii) the consumption of low-grade and/or waste materials; and (iv) favourable prices. The expected benefit of composite adsorbents generally consists in their growing applicability, thanks to the combination of the adsorption properties of individual components. Composite adsorbents were prepared as mixtures of kaolin from a Czech deposit (kaolin Sedlec, SK) and two fly ashes (FAs) from a fluidised bed boiler in Czech operations differing in fuel type. The mixtures of SK with FA in a ratio of 50:50% wt. were prepared at 20 °C, 65 °C, and 110 °C in an autoclave. The source materials and composite adsorbents were tested for the adsorption of lead as Pb[sup.2+], and arsenic as AsO[sub.4] [sup.3−] from model solutions in laboratory conditions. The adsorption of Pb[sup.2+] proceeded quantitatively on the source materials except SK, and on both the composites, with an adsorption yield of >97% and a low adsorbent consumption (~2 g.L[sup.−1]). The AsO[sub.4] [sup.3−] adsorption proceeded selectively only on both FAs, with an adsorption yield of >97% again. The adsorption of AsO[sub.4] [sup.3−] on the composite adsorbents achieved a worse yield (˂80%), with about ten times more adsorbent consumption (~20 g.L[sup.−1]). An increased preparation temperature did not affect the Pb[sup.2+] adsorption at all, but it reduced the efficiency of AsO[sub.4] [sup.3−] adsorption by up to 30%. The SK–FA composites proved to have promising properties, mostly as cation-active adsorbents.