Abstract: Abstract:Static batch experiments were performed to evaluate the combined effects of pH, ionic strength, γ-MnO₂ dosage, contact time, Tl(Ⅰ) initial concentration and temperature on Tl(Ⅰ) sorption toward γ-MnO₂. The adsorption of Tl(Ⅰ) on γ-MnO₂ is pH-dependent; it dropped significantly with pH rise from 2 to 3, was followed by rapid promotion with further increased pH from 4-6, and finally attained equilibrium with pH>6. The adsorption of Tl(Ⅰ) on γ-MnO₂ was strongly affected by changes in ionic strength and γ-MnO₂ dosage, increasing with the decrease of the ionic strength and the sorbent dosage. The experimental data of Tl(Ⅰ) adsorption on γ-MnO2 reached equilibrium within 15 minutes and were fitted well by the pseudo-second-order model. Moreover, when initial concentrations of Tl(Ⅰ) ranged from 10 to 1000 mg/L, under temperatures of 288,3 and 318 K, the adsorptions were fitted well by the Freundlich isotherm, and the maximum adsorption capacities of γ-MnO₂ for Tl(Ⅰ) were up to 53.04,9.05 and 45.03 mg/g, respectively. The adsorption of Tl(Ⅰ) on γ-MnO₂ was essentially an exothermic and spontaneous process. Studies of desorption showed that the adsorption behavior of γ-MnO₂ surface is ionic exchange, which is affected by the ionic strength. The results indicated that γ-MnO₂ could be a promising adsorbent for Tl(Ⅰ) in water environments.