Investigation on the adsorption of phosphorus by Fe-loaded ceramic adsorbent

This aim of this study was to remove phosphorus from aqueous solution using a Fe-loaded ceramic (Fe-LC) adsorbent prepared by mixing dolomite, montmorillonite, FeSO4·7H2O and starch. Simplex-centroid mixture design method was used to determine the optimum mixture proportions by evaluating both phosphorus adsorption efficiency and adsorbent hardness. The study found that the optimum adsorption capacity and the strength can be achieved with the composition of 3.87g dolomite, 3.00g starch, 2.13g montmorillonite and 1.00g FeSO4·7H2O (10g in total). The optimized Fe-LC was evaluated in the batch and the fixed bed experiments. The point of zero charge, pHpzc was found to be 6.0. The adsorption kinetic and isotherm data well agreed with the pseudo-second-order kinetic and the Langmuir isotherm models, respectively. The breakthrough time increased with increasing in the bed depth, whereas inverse relationship was observed with the initial phosphorus concentration in the fixed bed studies. The co-existing anions (SO4(2-), NO3(-) and Cl(-)) had negligible influence on phosphorus removal. The BDST and Thomas model explained the breakthrough behavior for phosphorus removal with a high degree of correlation.