Abstract：
A superabsorbent hydrogel was prepared by the free-radical copolymerization of natural rubber (NR) latex with poly(acrylic acid) (PAA) at NR loadings up to 50 wt%. An NR/PAA hydrogel containing 40 wt% of NR (NR-40) had a water absorption capacity of 214 g/g (21,400 %) of its dry weight. The compressive modulus increased 512 % and sample integrity was improved due to the physical entanglement of NR chains. NR-40 hydrogel removed 97 % of methylene blue (MB) from the aqueous solution in 1 h (at initial concentrations of 10-1000 mg/L) and produced a maximum removal of 1191 mg MB/g of hydrogel at an initial MB concentration of 4500 mg/L. The adsorption of MB was an endothermic process. Fourier transform infrared spectroscopy indicated that hydrogen bonding and electrostatic interaction drove the process. After the in-situ incorporation of ZnO into NR-40, absorbed energy from sunlight generated active species that could photocatalytically degrade adsorbed MB in the hydrogel matrix. The scavenger tests indicated that superoxide radical anions and hydroxyl radicals were the main species for this process. The hydrogel composite material showed good stability and could be regenerated and reused over 10 cycles, degrading >80 % of the adsorbed dye. This novel natural-based hydrogel provides double functions of adsorption and photodegradation of toxic dyes without the requirement of chemicals and a separation process.
摘要：
通过天然橡胶（NR）胶乳与聚（丙烯酸）（PAA）的自由基共聚制备高吸水性水凝胶，NR负载量高达50wt％。含有40重量%NR(NR-40)的NR/PAA水凝胶的吸水能力为其干重的214g/g(21,400%)。由于NR链的物理缠结,压缩模量增加了512%,并且样品完整性得到改善。NR-40水凝胶在1小时内（初始浓度为10-1000mg/L）从水溶液中去除97％的亚甲基蓝（MB），并且在初始MB浓度为4500mg/L时最大去除1191mgMB/g水凝胶。MB的吸附是一个吸热过程。傅里叶变换红外光谱表明，氢键和静电相互作用推动了这一过程。在将ZnO原位掺入NR-40中后，从阳光中吸收的能量会产生活性物质，这些活性物质可以光催化降解水凝胶基质中吸附的MB。清除剂测试表明，超氧自由基阴离子和羟基自由基是该过程的主要物种。水凝胶复合材料具有良好的稳定性，可以再生和重复使用10次循环，降解>80%的吸附染料。这种新型的基于天然的水凝胶提供了有毒染料的吸附和光降解的双重功能，而无需化学品和分离过程。
