Rizzo Carla, Andrews Jessica L, Steed Jonathan W, D'Anna Francesca
Università degli Studi di Palermo, Dipartimento di Scienze e Tecnologie Biologiche Chimiche e Farmaceutiche, Viale delle Scienze, Ed. 17, 90128 Palermo, Italy.
Department of Chemistry, Durham University, South Road, Durham DH1 3LE, UK.
J Colloid Interface Sci. 2019 Jul 15;548:184-196. doi: 10.1016/j.jcis.2019.04.034. Epub 2019 Apr 11.
To overcome the contamination of water by heavy metals the adsorption of the pollutant on gel phases is an attractive solution since gels are inexpensive, potentially highly efficient and form a distinct phase while allowing diffusion of the contaminated water throughout the material. This work tests the chromium(VI) adsorbent capacity of new supramolecular gels for Chromium(VI) removal from wastewater.
First hydrophobic imidazolium salts of carbohydrate anions were synthesised as new gelators. Subsequently, they were dissolved in a solvent by heating and, after cooling overnight, to give the formation of supramolecular gels. The properties of the resulting gels, such as thermal stability, mechanical strength, morphology, rheology, and kinetics of gel formation, were studied as a function of gelator structure, gelation solvent and pollutant removal efficiency.
Carbohydrate-derived gels showed the best removal capacity, i.e. 97% in 24 h. Interestingly, in one case, the reduction of chromium(VI) to chromium(III) also occurred after the adsorption process, and this phenomenon has been analysed using H NMR spectroscopy, IR spectroscopy, and SEM. The most efficient gel can reach an adsorption capacity of 598 mg/g in contrast to a value of 153 mg/g for the most effectively best hydrogels reported to date. The new gel can be also recycled up to 4 times. These findings suggest that these new, supramolecular hydrogels have potential applications in environmental remediation.
为了克服重金属对水的污染，污染物在凝胶相上的吸附是一种有吸引力的解决方案，因为凝胶价格低廉、可能高效，并且在允许受污染的水在整个材料中扩散的同时形成一个独特的相。这项工作测试了新型超分子凝胶对废水中六价铬的吸附能力。
首先合成了碳水化合物阴离子的疏水咪唑盐作为新型凝胶剂。随后，通过加热将它们溶解在溶剂中，并在过夜冷却后形成超分子凝胶。研究了所得凝胶的性质，如热稳定性、机械强度、形态、流变学和凝胶形成动力学，作为凝胶剂结构、凝胶化溶剂和污染物去除效率的函数。
碳水化合物衍生的凝胶表现出最佳的去除能力，即在24小时内达到97%。有趣的是，在一种情况下，吸附过程后还发生了六价铬还原为三价铬的现象，并且已经使用核磁共振氢谱、红外光谱和扫描电子显微镜对这一现象进行了分析。最有效的凝胶的吸附容量可达598毫克/克，而迄今为止报道的最有效的水凝胶的值为153毫克/克。这种新型凝胶还可以循环使用多达4次。这些发现表明，这些新型超分子水凝胶在环境修复方面具有潜在应用。
