Simultaneous removal of inorganic and organic pollutants from multicomponent solutions by the use of zeolitic materials obtained from fly ash waste

Abstract

Fly ash is an energy waste considered as a global environmental hazard. Annually, it is generated in the amount of over 50 million tons. One of the ways of fly ash management is its conversion into porous structures, which then can be applied to capture other pollutants from the aquatic environment. This paper presents the adsorption capabilities of four products of hydrothermal reaction of fly ash (HC FA), i.e., zeolites (Na-X, NA-P1) and their composites with carbon (Na-X(C), Na-P1(C)). All five materials were characterized in terms of their structure and used as adsorbents of heavy metals (Pb(II), Zn(II) ions) and organic compounds (diclofenac – popular anti-inflammatory drug, poly(acrylic acid) – polymer commonly used in industry) from their mixed solutions. Adsorption–desorption, electrokinetic and stability measurements were performed to determine the mechanisms driving the formation of the mixed adsorption layers. It was found that Na-X zeolite adsorbed 322.1 mg/g of Pb(II), 332.5 mg/g of Zn(II) and 6.68 mg/g of DCF, whereas Na-P1 bounded 332.9 mg/g of Pb(II), 103.6 mg/g of Zn(II) and 21.19 mg/g of DCF. In the mixed systems of adsorbates, these values were different, but also satisfactory. For example, in the Zn(II) presence, the adsorption of DCF on Na-X increased from 6.68 to 12.86 mg/g and that on Na-X(C), from 8.49 to 21.95 mg/g. The adsorbed pollutants changed the structure of electrical double layer of zeolitic materials. Moreover, they affected the stability of the examined suspensions. The presented results are promising for the further application of obtained zeolitic materials for environmental remediation.Graphical