Evaluation of Microsoft excel solver as a tool for adsorption kinetics determination

Abstract

The paper contains a study of adsorption kinetics of lead ions on powdered corn cobs (PCCS). Corn cobs were collected within Obafemi Awolowo University, Ile-Ife, Nigeria, washed with distilled water, air dried, powdered and sieved into different particle sizes (630 - 300μm, 300 - 212 μm, 212 - 150 μm and 150 -75 μm) and stored for use. Lead solutions were prepared from lead salt using standard methods. Physical and chemical properties of PCCS, and adsorption kinetics of lead onto PCCS were studied. Effects of pH, particle size and initial lead concentrations on the kinetics models and their constants were studied and analysed using Analysis of Variance (ANOVA). Kinetics models' constants were determined using least square, graphical and Microsoft Excel Solver (MES) methods. Statistical evaluations of the three methods were conducted using Akaike Information Criterion (AIC) and Model of Selection Criterion (MSC). The study showed that moisture content of the PCCS was 7.29 %, volatile solid at 550 ^oC was 96.88 % and volatile solids at 1200 ^oC was 99.44 %. Ash contents of the PCCS were 3.13 %, and 0.52 % at 550 ^oC and 1200 ^oC respectively. Kinetics constants varied with pH, particle size of the adsorbent and initial lead concentrations. The study showed that pH, particle size and initial lead concentrations were significant factors that influence adsorption kinetics of lead ions on PCCS at 95 % confidence level. It was concluded that the adsorption processes of Pb²⁺ onto the adsorbents followed two steps, mode of adsorption and transport are affected by more than one process. The order of accuracy of the methods was in Microsoft Excel Solver > Least Squared > Graphical method based on the value of MSC and AIC

Keywords: lead; adsorption kinetics; low-cost adsorbents; solution; adsorption