Toward Higher Resource Efficiency in Solid–Fluid Reactions: Dye Adsorption Study on the Planetary Rotating Bed Reactor

Abstract

Most circular processing pathways involve solid− fluid reactions, such as adsorption, catalysis, degradation, and extraction. The reaction-harboring plant technology is crucial to the performance and resource efficiency of these processes. Therefore, this study investigates the technoecological characteristics of the planetary rotating bed reactor (PRBR) as a novel approach to solid−fluid reactions. Given its relevance in wastewater treatment, the adsorption of methylene blue (MB) from aqueous solution onto powdered activated carbon (PAC) served as a model process. Semicontinuous kinetic experiments were performed in a 2 L laboratory-scale PRBR by varying the amount of PAC, the rotational motion pattern, and the speed level. DIY inline photometry and volume flow control enabled a constant vessel concentration of MB and thus the acquisition of comparable adsorption rates. Torque measurement delivered the mechanical power consumption and allowed calculation of the emission cost per adsorbate. The results revealed a significant superiority of the distinctive planetary motion compared to a static particle bed in terms of mass transfer and energy efficiency. The adsorption rate increased up to a factor of 10 with the same power input. Furthermore, an optimal chamber filling was observed, reflecting the interplay between the particle mobility and available adsorption sites.