Removal of Pyridine from Aqueous Solutions Using Lignite, Coking Coal, and Anthracite: Adsorption Kinetics

Abstract

A novel coking wastewater treatment technique is proposed based on the principles of the circular economy. By utilizing coal as an adsorbent for organic pollutants in coking wastewater, the treated coal can be introduced into the coking system after the adsorption and flocculation sedimentation processes. This creates a closed-loop system with zero coking wastewater emissions. We investigated the potential of adsorption for the removal of pyridine. Batch experiments were conducted using lignite, coking coal, and anthracite as adsorbents. Both coking coal and anthracite showed favorable adsorption properties for the chosen contaminants. The experimental data were analyzed utilizing various models, including pseudo-first-order and pseudo-second-order kinetic equations, as well as intraparticle diffusion and Bangham. This study aimed to identify the rate-limiting step in the adsorption process. The results revealed that the adsorption of pyridine onto the three coal types followed pseudo-second-order kinetics. The rate-limiting mechanisms may include both boundary-layer diffusion and intraparticle diffusion. The effect of pH on coal adsorption and the activation energy of pyridine adsorption by coking coal were also examined. Adsorption offers a promising approach in advanced wastewater treatment, with coking coal emerging as a cost-effective adsorbent for addressing persistent organic pollutants during the adsorption process.