Adsorption Behavior of Hydroquinone by Diatomite-based Porous Ceramsite

Abstract

Diatomite-based porous ceramsite is a new kind of environmental material. In this study, ceramsite was prepared by wet grinding, a rolling-ball method, and high temperature-calcination using diatomite as the main raw material with the addition of a pore-forming agent and sintering assistant. X-ray diffraction, scanning electron microscopy, and mercury injection, were used to analyze the structure and characteristics of the prepared materials. Using hydroquinone as the target pollutant, the adsorption behavior of diatomite-based porous ceramsite was investigated. Results indicated that the diatomite-based porous ceramsite had a pore size ranging from 500 to 3000 nm, a specific surface area of 6.14 m2.g-1, and a porosity of 47.8%. When pH was 7, the removal rate and adsorption capacity of the hydroquinone by the diatomite-based porous ceramsite was 91.2% and 4.56 m2.g-1, respectively. In the adsorption process of hydroquinone by diatomite-based porous ceramsite, the diffusion of a liquid membrane was dominant, which could be better described by the quasi-first-order kinetic equation. The Langmuir and Koble-Corrigan equations had a higher fitting degree of data for the adsorption isotherms. The adsorption characteristics of the diatomite-based porous ceramsite are in accordance with the fixed-point adsorption of a single molecular layer and belong to a heterogeneous composite adsorption system. The correlation coefficient R2 and k value of hydroquinone adsorption by the diatomite-based porous ceramsite determined by the liquid film diffusion model were 0.848 and 0.0417, respectively.

Keywords

• diatomite-based porous ceramsite, hydroquinone adsorption kinetics, moving-boundary model liquid film diffusion