Arsenate Adsorption on Fly Ash, Chitosan and Their Composites and Its Relations with Surface, Charge and Pore Properties of the Sorbents

Abstract

One of the ways to recycle millions of tons of fly ash and chitin wastes produced yearly is their utilization as low-cost sorbents, mainly for heavy metal cations and organic substances. To improve their sorption efficiency, fly ashes have been thermally activated or modified by chitosan. We aimed to deeply characterize the physicochemical properties of such sorbents to reveal the usefulness of modification procedures and their effect on As(V) adsorption. Using low temperature nitrogen adsorption, scanning electron microscopy, mercury intrusion porosimetry, potentiometric titration and adsorption isotherms of As(V) anions, surface, pore, charge and anion adsorption parameters of fly ash activated at various temperatures, chitosan, and fly ash modified by chitosan were determined. Arsenate adsorption equilibrium (Langmuir model), kinetics (pseudo-second order model) and thermodynamics on the obtained materials were studied. Neither temperature activation nor chitosan modifications of fly ash were necessary and profitable for improving physicochemical properties and As(V) adsorption efficiency of fly ash. Practically, the physicochemical parameters of the sorbents were not related to their anion adsorption parameters.

Characterization of the Physical, Chemical, and Adsorption Properties of Coal-Fly-Ash–Hydroxyapatite Composites

“…Generally, depending on the type of procedure used to obtain HAp, the porosimetry parameters of HAp can be diverse (e.g., 12.5-22.9 m 2 /g [71], 26.34-86.15 m 2 /g, and 0.12-0.51 cm 3 /g) [72]. Similarly, depending on its origin, coal fly ash can also have varied parameters (e.g., 12.1 m 2 /g [73], 16.2 m 2 /g and 0.031 cm 3 /g [74], 17.4 m 2 /g [52], 35 m 2 /g and 0.042 cm 3 /g [75], and 39.3 m 2 /g and 0.171 cm 3 /g) [70].…”

Study on characterization technology of porosity and fractal dimension of micro-arc oxidation coating

“…The utilization of Mercury intrusion porosimetry (MIP) has been extensively applied in the analysis of porous materials [8]. Its primary function is to identify the distribution of microscopic pores in various inorganic non-metallic materials, including rock strata [9], cement [10], coal seam [11], electrode materials [12], ceramics [13], concrete [14], adsorption materials [15], refractory materials [16] and some organic materials. Additionally, the Mercury porosimeter can be employed to investigate the impact of microscopic pore structure on material properties.…”