Modelling of heavy metals adsorption to a chelating resin in a fluidized bed reactor

Abstract

Adsorption to a chelating resin is a method for recovering heavy metals from wastewater containing very light quantities of heavy metals ( B0.3 mol m − 3 , which approximately corresponds to 20 ppm). A thermodynamical study in a closed vessel showed that equilibrium is well represented by a Langmuir isotherm. Adsorption kinetics in a continuous stirred tank reactor were also conducted. Experiments were simulated by a global kinetics model comprising mass transfer in a liquid film around the resin particles, with diffusion through the pores and reaction on the adsorption sites. Kinetics has been found to be limited by film mass transfer for all metals studied (Cu 2 + , Ni 2 + , Co 2 + and Zn 2 + ). The mass transfer coefficient k L was found to be around 10 − 4 m s − 1 . Adsorption of heavy metals was then carried out at mini-pilot scale. Problems due to a decrease in particles mean radius during the adsorption prompted us to use a fluidized bed. It is also possible with this reactor to treat solutions containing suspended solids which would clog fixed beds. The decrease in particle radius (or increase in apparent density of the resin) produces a contraction of the fluidized bed: unloaded particles remain at the top of the bed and a density gradient appears throughout the column, leading to a stabilization of the fluidized bed. The measured phenomenon is well described by a liquid plug flow model with immobile resin in the column. As for the adsorption in the continuous stirred tank, the Langmuir model and the kinetics limited by film mass transfer were considered. The mass transfer coefficient k L was adjusted to a value around 10 − 5 m s − 1 .

Preparation of novel nano-adsorbent based on organic–inorganic hybrid and their adsorption for heavy metals and organic pollutants presented in water environment

“…There are many methods to remove metal ions and phenol from aqueous solutions, such as adsorption, ion exchange, chemical precipitation, and membrane processes [7][8][9][10][11][12]. Adsorption is the most popular way in which activated carbon or ion exchange resins are usually applied.…”

Ion Exchange

“…Although, fixed bed process is easy to operate, channeling and formation of dead zones are common phenomena, which reduce the operation performance. Fluidized bed operation in adsorption and ion exchange has been studied for heavy metals removal from liquid phase to a chelating resin and for the determination of mass transfer rates in a liquid magnetically stabilized fluidized bed of magnetic ion exchange particles (Hausmann et al, 2000;Menoud et al, 1998). Fluidized bed is able to minimize or even eliminate this disadvantage because of the intense contact between the solid and the fluid phases that can be achieved.…”

Heavy Metal Adsorption to a Chelating Resin in a Binary Solid Fluidized Bed

“…The governing equations for the adsorption of copper ion in a fluidized bed can be derived on the base of the research results of the equilibrium isotherm and hydrodynamics of liquid and solid particles [15]. In the development of the mathematical model, several simplifying assumptions are made as follows :…”