Combined diffusion model for the sorption of cadmium, copper, and zinc ions onto bone char.
The ability of bone char to remove three single-component metals (namely, cadmium, copper and zinc) from aqueous solutions has been studied. Equilibrium isotherms have been measured and analyzed using a Langmuir isotherm model. A series of batch contact time experiments were performed to study the effect of sorbent mass and initial metal ion concentration for the three systems. A new film-pore diffusion model has been applied to the batch contact time results, and good correlation is obtained between theoretical predictions and experimental data. A further extension to the new model was made to include a surface diffusion term. The agreement between theoretical results and experimental data improved as the sum of the squares of the errors (SSE) improved by around 20% for cadmium and zinc but by 50% for copper. Therefore, the sorptions of cadmium and zinc ions onto bone char are primarily film-pore diffusion controlled, but for the copper system film-pore-surface diffusion must be considered.
Cheung
C W
CW
Department of Chemical Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon.
Chan
C K
CK
Porter
J F
JF
McKay
G
G
D000327:Adsorption; D001842:Bone and Bones / Q000737:chemistry; D002104:Cadmium / Q000737:chemistry*; D002606:Charcoal / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D004058:Diffusion; D007477:Ions; D008962:Models, Theoretical; D015203:Reproducibility of Results; D015032:Zinc / Q000737:chemistry*
D007477:Ions; D002104:Cadmium; D002606:Charcoal; D003300:Copper; D015032:Zinc