Abstract
This work describes the simulation of the continuous lead adsorption over a fixed bed of activated tea waste (or biosorbent) through a convective-dispersive model. Model capturing convection, axial dispersion, and uptake of lead metal (via linear model and Langmuir isotherm) on biosorbent is solved in gPROMS. The influence flow rate, initial metal concentration, and bed height on lead breakthrough curves are evaluated. Transport (axial dispersion coefficient, distribution coefficient, and mass transfer zone) and adsorption (breakthrough and exhaustion times, and adsorption column capacity) characteristics were estimated. The maximum adsorber column capacity was estimated as 1.587 mg/g at breakthrough time 133 min, and exhaustion time 567 min. The axial dispersion coefficient values were found in the range of 1-4 x 10(-5) m(2)/s, indicating no constraint for the transport of lead on the biosorbent surface. Mass transfer zone assessment suggested a higher adsorption rate of lead than its transport initially, and in about 300 min, the mass transfer zone reached the column exit due to saturation. For validation purposes, a comparison was made with the experimental data (Mondal, J Environ Manage 90:3266-3271, 2009) by calculating the coefficient of determination, root mean square error, and chi-squared values. The mass transfer parameters estimated in the present study could be crucial for designing and upscaling of lead-tea waste biosorbent adsorption system.