Semifluidized Bed Adsorption Column Studies for Simultaneous Removal of Aqueous Phase Pb2+ and Cd2+ by Composite Adsorbents: an Experimental and Mass Transfer Dynamic Model–Based Approach

Abstract

In this present work, the performance of a semifluidized bed adsorption column has been evaluated for the removal of Pb 2+ and Cd 2+ in a semi-continuous mode. The composite adsorbents have been synthesized from waste biomass–based biochar and alginate-based biopolymer. Synthesized adsorbent characterized and finally tested its effectiveness in the removal of both Pb 2+ and Cd 2+ metal ions by batch and semifluidized bed column adsorption studies. The adsorptive removal efficiencies were found to be dependent on solution pH, initial metal ion concentration, adsorbent dose or initial bed height, static bed height, system temperature and inlet flow rate of semifluidized bed operation. Pseudo-second-order kinetic model was fitted to the batch adsorption experimental data by non-linear and linear regression method and it was found that the non-linear method gives a better way of obtaining the various kinetic parameters and its applicability. A solute phase mass transfer–based dynamic model has been developed to explain the adsorptive behaviour of metal ions onto adsorbents during the semi-continuous mode of operation of a semifluidized bed system. Various mass transfer parameters and degree of dispersion coefficients for the individual packed and fluidized section were obtained from the developed model. Graphical abstract