Piyamongkala, kowit, and วัจนะรัตน์ พ. “Adsorption of Copper and Lead Ions by Chitosan Powder and Sodium Tripolyphosphate-Modified Chitosan Resin: Kinetics, Mechanism and Mass Transfer”. Naresuan University Engineering Journal, vol. 12, no. 1, July 2017, pp. 83-96, doi:10.14456/nuej.2017.4.