多胺改性PGMA-DAAM树脂的合成及对Pb2+的吸附性能

甲基丙烯酸缩水甘油酯(GMA)与双丙酮丙烯酰胺(DAAM)发生共聚,生成一种含环氧基和DAAM亲水链节的PGMA-DAAM共聚物,再与三乙烯四胺反应,合成了一种多胺改性的PGMA-DAAM树脂(TETA-PGMA-DAAM)。树脂的结构经元素分析、红外光谱和热重分析进行表征。探讨了合成树脂对Pb2+的吸附性能,考察了吸附温度、pH、金属离子浓度等因素对吸附效果的影响。结果表明,树脂对Pb2+的吸附量随着温度的升高而略有增大,在pH约为4.7、温度为40℃和Pb2+平衡浓度为0.01299 mol/L时其最高吸附量可达到1.581 mmol/g。树脂对Pb2+的吸附符合Boyd模型,表现为液膜扩散控制,其扩散系数在30℃和35℃时分别为0.0131 min-1和0.0175 min-1。吸附过程符合Langmuir和Freundlich等温吸附式。吸附热力学参数ΔG,ΔH和ΔS分别为-3.912 kJ/mol(25℃)、2.058 kJ/mol和20.025 J/mol,表明吸附过程为自发进行的吸热过程。

Synthesis and adsorption properties of polyamine modified PGMA-DAAM resin for Pb2+

The copolymer with sufficient epoxy groups and hydrophilic DAAM segments was obtained via copolymerization of glycidyl methacrylate(GMA) and diacetone acrylamide(DAAM),named as PGMA-DAAM.The final resin was yielded via modification with triethylene tetramine(TETA) on the basis of PGMA-DAAM,named as TETA-PGMA-DAAM.The structure and components of TETA-PGMA-DAAM resin were investigated by elemental analysis,infrared spectrum analysis and thermogravimetric analysis.The adsorption performances of Pb2+ on the resin were discussed in detail,including adsorption temperatures,pH values and various concentrations of Pb2+.The optimal adsorption capacity was 1.581 mmol/g under the conditions that equilibrium concentration of Pb2+ was 0.01299 mol/L,pH was 4.7 and temperature was 40℃.Boyd model was better to describe the adsorption mechanism.Film diffusion was the key procedure during the adsorption process and the diffusion were 0.0131 and 0.0175 min-1,respectively at 30℃ and 35℃.Langmuir and Freundlich models were appropriate to apply to the adsorption process.Three thermodynamic parameters of adsorption ΔG,ΔH and ΔS were calculated to be-3.912 kJ/mol(25℃),2.058 kJ/mol and 20.025 J/k.mol,respectively.The adsorption procedure can proceed spontaneously with endothermic phenomenon.