负载醋酸甘蔗渣对镍离子的吸附性能

Adsorption properties of acetate-loaded bagasse for removal of nickel ion

以无毒、价格低廉的原料甘蔗渣及醋酸制备环保型吸附剂用于吸附镍离子。考察了时间、温度、浓度等相关因素对吸附剂吸附性能的影响,研究结果表明:负载醋酸甘蔗渣对镍离子具有较好的吸附性能,随着吸附温度的升高,吸附量减少;吸附为放热过程,吸附焓为-65 285.7 J/mol,属物理吸附;吸附熵为-190.8 J/(K·mol),表明吸附过程自由度减少;在温度30~60℃区间,吸附自由能范围为-7473.3^-1749.3 J/mol,说明吸附过程能自发进行。甘蔗渣对镍离子的吸附方式符合多分子层吸附模型,最大吸附量为133.98 mg/g。由实验结果分析推测镍离子在负载醋酸甘蔗渣上吸附方式可能属于离子交换及合并纤维间毛细作用的多分子层吸附。

An environmental-friendly adsorbent of acetate-loaded bagasse for the removal of nickel ion from aqueous solution was synthesized by the non-toxic and low cost materials of bagasse and acetic acid. The influences of time, temperature and concentration on the adsorption properties were investigated. The research results indicated that the acetate-loaded bagasse adsorbent had good ad- sorption ability and the adsorption capacity decreased with the increase of temperature. The adsorp- tion process of nickel ion on acetate-loaded bagasse was exothermic. The adsorption enthalpy change was -65285.7 J/mol which showed the adsorption belonged to physical adsorption. That the adsorp- tion entropy change was -190. 8 J/（K.mol） demonstrated the degree of freedom decreased during the process. The Gibbs free energy change of adsorption ranged from -61048.9 to -66772. 9 J/mol in the temperatures between 30 to 60 ℃ which revealed the adsorption process could occur spontane- ously. The adsorption isotherm could be better described by the polymolecular layer model and the maximum adsorption capacity was 133.98 mg/g. The experiment results suggested the adsorption mechanism of nickel ion on acetate-loaded bagasse belonged to physical adsorption of polymolecular layer between bagasse fibers.