以固体废物粉煤灰(fly ash,FA)为原料,通过负载壳聚糖和钙离子制得一种新型吸附剂(Ca/CTS/FA),将其用于模拟染料废水中直接桃红12B(direct pink 12B,DP 12B)和直接蓝2B(direct blue 2B,DB 2B)的吸附,对吸附剂进行了EDS表征,并详细探讨了吸附条件、吸附动力学和热力学.结果表明,染料溶液pH、吸附时间和温度均对吸附有影响.不同温度下,Ca/CTS/FA对DP 12B和DB 2B的吸附过程完全符合准二级吸附速率方程,表观活化能分别为61.85kJ·mol^-1和46.83kJ·mol^-1.Ca/CTS/FA对DP 12B和DB 2B的等温吸附数据分别符合Freundlich模型和Langmuir模型.热力学参数吸附自由能变、焓变和熵变的结果表明,吸附剂对DP 12B为自发的放热吸附,而对DB 2B则为自发的吸热吸附.EDS分析表明CTS和Ca2+成功负载到FA上,且所得Ca/CTS/FA对DP12B和DB 2B的去除率分别比FA增大了1.4倍和85倍.Ca/CTS/FA能用蒸馏水再生,可循环使用1次以上.
A new adsorbent,Ca/CTS/FA composite prepared by loading chitosan and calcium ion onto solid waste fly ash was used for the removal of direct pink 12B and direct blue 2B from aqueous solution. The characterization of EDS was carried out and the adsorption conditions of direct pink 12B and direct blue 2B were discussed in detail. The adsorption kinetics and equilibrium was studied, too. The results show that solution pH, contact time and temperature all affect the adsorption. At different temperature, the adsorption processes of direct pink 12B and direct blue 2B were both adapted to pseudo-second-order kinetic equation and the apparent activation were 61.85 kJ · mol^1 and 46.83 kJ · mo1^-1 , respectively. Besides, the adsorption behavior of direct pink 12B and direct blue 2B were fitted with Freundlich equation and Langmuir equation,respectively. The thermodynamic parameters of the value of adsorption gibbs free energy changes,adsorption enthalpy changes and adsorption entropy change show that the adsorption processes of direct pink 12B has spontaneous and exoteric properties. The adsorption processes of direct blue 2B has spontaneous and endothermic properties. The picture of EDS indicates that chitosan and calcium ion are loaded onto fly ash and the removal rate of Ca/CTS/FA for direct pink 12B and direct blue 2B are fly's 1.4 times and 85 times,respectively. Ca/CTS/FA can be regenerated by distilled water and it can be reused at least once more than once.