聚丙烯酸/氧化石墨烯复合水凝胶制备及对亚甲基蓝吸附

Synthesis of Poly(acrylic acid)/Graphene Oxide Composite Hydrogels with High Hydroscopicity for Adsorption of Methylene Blue Dye

摘要:

以丙烯酸（AA）为原料，二丙烯酸酯（PulDA）分散的氧化石墨烯（GO）纳米胶粒（GO-PulDA）为增强剂，通过自由基共聚合制备了一系列结构均一的聚丙烯酸/氧化石墨烯复合水凝胶（PAA/GO-PulDA）。考察了交联剂N,N’-亚甲基双丙烯酰胺 (BIS)含量和GO含量对复合水凝胶力学性能的影响，研究了BIS和GO含量以及溶液pH值对复合水凝胶吸水性和亚甲基蓝（MB）吸附量的影响，并考察了复合水凝胶的吸附动力学和吸附-解吸附重复使用性能。结果表明，通过改变复合凝胶中BIS或GO的含量可方便地调控其拉伸强度，当GO质量浓度从0.1 mg/mL增加至1.0 mg/mL时，复合水凝胶拉伸强度从5.0 kPa增加至10.4 kPa，断裂伸长率高于100 %，当GO的质量浓度为0.3 mg/mL时，复合水凝胶的断裂伸长率最高为151 %。复合水凝胶表现出明显的pH敏感的高吸湿性，pH从3.0增加至6.8时，溶胀比（SR）变化可达386 g/g，pH 6.8时最大溶胀比高达490 g/g。复合水凝胶对MB的吸附表现出明显的pH敏感性，当溶液pH值从3.0增加至11.0时，MB的吸附量（qe）可增加1400～1500 mg/g，pH 11.0时最大的qe高达1789 mg/g。复合水凝胶对MB的吸附行为符合准一级动力学模型，为物理吸附过程。复合水凝胶具有良好的重复使用性，5次吸附-解吸附循环后对MB的吸附能力仍高于60 %，解吸附效率高于90%。

Abstract:

The poly(acrylic acid)/graphene oxide (GO) composite hydrogels (PAA/GO-PulDA) with homogeneous structure was synthesized by the radical copolymerization between acrylic acid (AA) and Pluronic F127 diacrylate (PulDa) dispersive graphene oxide (GO-PulDA). The GO-PulDA colloid was used as an enhancer in the composite hydrogels. The effect of the concentration of corsslinker N,N'-methylenebisacrylamide (BIS) and GO in composite hydrogels and the solution pH on the strength, hydroscopicity of composite hydrogels and the adsorption capacity for methylene blue (MB) were investigated in detail. The adsorption-desorption properties of the composite hydrogels were tested. The results show that the strength of composite hydrogels can be tailored by controlling the concentration of BIS or GO in the hydrogels. The breaking strength of composite hydrogels increased from 5.0 kPa to 10.4 kPa with increasing the concentration of GO, and the elongation at break was greater than 100 %. The composite hydrogels exhibited pH-sensitive high hydroscopicity, and the increment of swelling ratio (SR) of composite hydrogels was 386 g/g with increasing the solution pH from 3.0 to 6.8. The maximum swelling ration was 490 g/g in pH 6.8 solution. The composite hydrogels exhibited obvious pH-sensitive adsorption properties for methylene blue. The increment of adsorption capacity (qe) of composite hydrogels for methylene blue was 1400 ~ 1500 mg/g with increasing the solution pH from 3.0 to 11.0. The maximum adsorption capacity was 1789 mg/g in pH 11.0 solution. The composite hydrogels displayed excellent regenerated and reused performance. The adsorption capacity for MB retained more than 60 % and the efficiency of desorption was larger than 90 % after five adsorption-desorption cycles.