Separation of Pb2+ from Cu2+-Pb2+ mixed solution by a newly-developed ion separating agent was examined, which was obtained by clothing chitin whiskers (ChW) on the surface of potassium tetratitanate whiskers (PTW). The separation capability and mechanism of the ion separating agent (ChW-PTW) was determined, based on the difference of the adsorption isotherm pattern and the adsorption kinetics model between ChW and PTW on Cu2+ and Pb2+, respectively. The results showed that the adsorption process of ChW could be described by Freundlish isotherm. The adsorption affinity of Cu2+ (kF = 0.085·g-1) on ChW was greater than Pb2+ (kF = 0.077 g-1). The adsorption pattern of PTW was inclined to the Langmuir isotherm, and Pb2+ (kL = 310.59 L·mmol-1) could be obviously more easily adsorbed on PTW than Cu2+ (kL = 25.85 L·mmol-1). The experimental data both fitted well with the pseudo-second order kinetics. The reaction rate of Pb2+ (k₂ = 4.442 for ChW and k₂ = 0.846 for PTW) was greater than that of Cu2+ on both ChW and PTW, while the diffusion rate of intra-particles of PTW was much higher than ChW. The adsorption model of ChW and PTW could illustrate well the separation mechanism of ChW-PTW and allowed for relevant results.
Keywords: chitin whisker; coating; ion separating; potassium tetratitanate whisker.