Application of simplex-centroid mixture design in developing and optimizing ceramic adsorbent for As(V) removal from water solution

A novel ceramic adsorbent, developed with a mixture of akadama mud, wheat starch, and Fe2O3, has been used for arsenic (V) removal from the water solution. The simplex-centroid mixture design (SCMD) method was used to determine the optimum mixture proportion for both arsenic adsorption efficiency and ceramic mechanical strength. The analysis of variance (ANOVA) results and the predicted values were in good agreement with the experiment data, indicating that the SCMD is a reliable method for determining the optimum mixture proportion of ceramic. A batch adsorption experiment using the developed ceramic indicated high efficiency for removing As(V) at neutral pH (6.9) and room temperature (25 °C). Langmuir and Freundlich adsorption isotherms were measured for a range of As(V) initial concentrations of 5–100 mg/L under the same conditions. The equilibrium data fitted very well to both isotherms, indicating that As(V) adsorption by the ceramic was complex multilayer adsorption. The developed ceramic is a cost-effective adsorbent for As(V) removal from water solution, especially from low-level phosphate and fluoride solution, and no secondary pollution caused by the adsorbent was observed after adsorption.