(1. 遼寧大學(xué) 化學(xué)學(xué)院，沈陽 110036；2. 海軍裝備部 駐沈陽軍事代表局，沈陽 110031)
摘 要: 通過吸附實(shí)驗(yàn)研究納米TiO2對Cd(Ⅱ)的吸附行為，考察溶液的pH值、吸附時間和溫度等因素對吸附的影響。結(jié)果表明：在pH為 4~7范圍內(nèi)，納米TiO2對Cd(Ⅱ)的吸附率均超過97%，吸附于納米TiO2上的Cd(Ⅱ)可用7.0 mL 0.1 mol/L HCl于70 ℃恒溫水浴中定量洗脫；該吸附過程符合準(zhǔn)二級反應(yīng)動力學(xué)模型，其反應(yīng)的表觀活化能為3.16 kJ/mol，粒子內(nèi)部擴(kuò)散過程是其吸附過程的速率控制步驟，但液相邊界層向粒子表面的擴(kuò)散過程亦不能忽略；等溫吸附數(shù)據(jù)與Langmuir和D-R等溫模型擬合較好。在室溫下，納米TiO2對Cd(Ⅱ)的飽和吸附容量為6.34 mg/g，平均吸附能為11.54 kJ/mol；吸附反應(yīng)的焓變和熵變均為正值，自由能為負(fù)值，說明該吸附過程為自發(fā)的吸熱過程。
關(guān)鍵字: Cd(Ⅱ)；納米TiO2；吸附；動力學(xué)；熱力學(xué)
（1. College of Chemistry, Liaoning University, Shenyang 110036, China;
2. Military Representative Bureau in Shenyang, Navy Equipment Department, Shenyang 110031, China）
Abstract:The titanium dioxide nanoparticles were employed for the sorption of Cd(Ⅱ) ions from aqueous solution. The process was studied by varying the pH, sorption time and temperature. The adsorption rate of Cd(II) by the sorbent is over 97% at pH of 4−7. The adsorbed Cd(Ⅱ) are desorbed by 7.0 mL 0.1 mol/L HCl in constant temperature water bath at 70 ℃. The kinetic experimental data properly correlate with the second-order kinetic model. The apparent activation energy is 3.16 kJ/mol. The overall rate process is mainly controlled by the intraparticle diffusion, while the boundary layer resistance cannot be ignored. The sorption data can be well interpreted by the Langmuir and D-R type sorption isotherms. At room temperature, the static saturated adsorption capacity is 6.34 mg/g, and the average sorption energy is 11.54 kJ/mol. The thermodynamic parameters: ∆HΘ＞0, ∆SΘ＞0 and ∆GΘ＜0, which indicates a spontaneous and decalescence adsorption process.
Key words: Cd(Ⅱ); nano-TiO2; adsorption; kinetics; thermodynamics
