Investigation of phosphate adsorption from aqueous solution using Kanuma mud: Behaviors and mechanisms

The laboratory-scale batch experiments were conducted to investigate the phosphate adsorption capacity through Kanuma mud (an inexpensive available volcanic geomineral in Japan) from aqueous solution. The adsorption isotherms, kinetics, desorption rate and other factors such as pH, temperature, and dosage were discussed. The phosphate adsorption results fitted the Freundlich isotherm model very well, and the adsorption process was an exothermic reaction, which could be described by a pseudo-second-order kinetic model. A maximum phosphate adsorption capacity of 2.13 mg g−1 was achieved, and effective phosphate uptake could be attained in 90 min. The adsorption capacity was the best at an initial pH value of 6. The optimum dosage was ranging from 10 to 20 g L−1, and the adsorbed phosphate on the Kanuma mud could be easily desorbed when 0.05 mol L−1 NaOH solution was used as eluant. These results showed that Kanuma mud processes great potential for use as an absorbent on phosphate removal from aqueous solution.