Investigation of the Process Parameters and Breakthrough Modeling of Thorium Biosorption on Orange Peel in a Fixed-Bed Column

The aim of this research work is the investigation of process parameters and breakthrough modeling of thorium biosorption on orange peel in a fixed-bed column. For this purpose, a number of  experiments have been performed on the surbents with diameters (0.4–2 mm), flow rates (1.5-6 mL/min), bed heights (4-8 cm) and feed inlet concentration (30-90 mg/L) at 25˚C and optimized pH of 3.8. The highest sorption capacity of 87.7 mg/g, occurred for the sorbents with 0.4-0.8 mm in diameter. The breakthrough point decreased with decreasing the bed height, increasing feed inlet concentration and increasing flow rate. Meanwhile, the sorption capacity increased with decreasing the bed height and flow rate. The experimental results were fitted by Thomas, Yan and Modified Dose-Response (MDR) models. Based on the experimental outcomes, the Yan and MDR models showed better results in comparison with the Thomas model. The XRF analysis results and calcium and potassium concentrations in the outlet stream of the bed showed that the ion exchange mechanism of the thorium biosorption by the orange peel sorbent is superior.