The skin of Iron stick yam (ISY) was modified with Polyethyleneimine (ISY@PEI) and evaluated for use as a potential biosorbent to remove the anionic dyes Sunset yellow (SY), Lemon yellow (LY), and Carmine (CM) from wastewater under low temperature conditions (5-15 degrees C) in single and ternary dye systems. Both in the single and ternary systems, experimental data showed that adsorption capacity reached the highest value at 5 degrees C, and adsorption capacity decreased when the temperature increased (10-50 degrees C). The equilibrium data fitted very well to the Langmuir model and the extended Langmuir isotherm, for the single and ternary systems, respectively. The maximum adsorption capability was 138.92, 476.31, and 500.13 mg/g for LY, SY, and CM, respectively, in a single system and 36.63, 303.31, and 294.12 mg/g for LY, SY, and CM, respectively, in a ternary system. The adsorption followed pseudo-second-order kinetics. The thermodynamic parameters indicated that it was a spontaneous and exothermic process. (C) 2016 Elsevier Ltd. All rights reserved.