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 o o was 7.29 %, volatile solid at 550 C was 96.88 % and volatile solids at 1200 C was 99.44 %. Ash contents of the o o PCCS were 3.13 %, and 0.52 % at 550 C and 1200 C 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 % 2+ confidence level. It was concluded that the adsorption processes of Pb 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

In this study, aluminosilicate rich clay soils were prepared through mechanochemical activation. The chemical and mineralogical properties were investigated using X-Ray Fluorescence (XRF) and X-ray diffraction (XRD). The functional groups, morphology and surface area were evaluated using Fourier Transform Infra-Red (FTIR), Scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) analysis. Batch experiments were used to evaluate its defluoridation efficiency while antibacterial activities were assessed using well diffusion method. Maximum adsorption capacity was found to be 1.87 mg/g with 32% fluoride removal. Fluoride adsorption was found to reduce in the presence of Cl−, PO42− and CO32− while it increased in the presence of SO42− and NO3−. Adsorption data fitted well to Freundlich isotherms, hence, confirming heterogeneous multilayer adsorption. Kinetic studies revealed that fluoride adsorption fitted well to pseudo-second order model. The sorption of F− onto the clays’ surface followed intra-particle diffusion mode. High correlation coefficient indicates that the sorption process was greatly controlled by particle diffusion while it is minimal in pore diffusion model. Antibacterial studies revealed no zone of inhibition for all the activated clays, hence indicating that they are not active against the bacterial strains of Escherichia coli used in this study. The results showed activated clays’ potential for defluoridation. Its effectiveness in pathogen removal is limited. Hence further modifications of the clays’ surfaces are hereby recommended.

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