Carbohydrate-supramolecular gels: Adsorbents for chromium(VI) removal from wastewater

Abstract

Francesca (2019) 'Carbohydrate-supramolecular gels : adsorbents for chromium(VI) removal from wastewater.', Journal of colloid and interface science., 548 . pp. 184-196. Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractHypothesis. 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.Experiments. 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.Findings. 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 1 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.

Carbon Nanomaterial Doped Ionic Liquid Gels for the Removal of Pharmaceutically Active Compounds from Water

“…When weaker colloidal forces are active, and the gel exhibits the lowest stiffness (tan δ), the matrix is likely more able to accept PhAC molecules and reorganize around them. This also agrees well with the more pronounced self-healing ability of the above gel and is in line with some hydrogels’ adsorption capacities for metal ions [24].…”

Environmentally Friendly Eutectogels Comprising l‐amino Acids and Deep Eutectic Solvents: Efficient Materials for Wastewater Treatment

“…Interestingly, with the exception of L‐Trp‐based eutectogel, higher efficiencies were detected in the presence of mechanically stronger gels, as accounted for by G’ values. The above result is different from the one we previously collected by using gels for dyes or Cr(VI) removal and sheds light on the effect of the solvent nature in determining materials performance . Furthermore, taking in consideration the side chain structure of the gelators, the above trend evidences a clear superior performance of the gels formed by amino acids with aromatic side chains over those with aliphatic ones, suggesting that adsorption of RhB, in this case, is mainly driven by π‐π stacking interactions.…”

“…Supramolecular gels have proven successful to remove a diverse range of dissolved pollutants or oil spills from water . In this context, we have recently shown that these materials allow fast and thorough removal of dyes from water with high recyclability, fuel desulfurization, as well as remediation of Cr(VI) polluted waters . Although the obtainment and use of ionic liquid gels has recently gathered a certain interest, the attention for eutectogels is less common .…”

“…[7] In this context, we have recently shown that these materials allow fast and thorough removal of dyes from water with high recyclability, [12] fuel desulfurization, [13] as well as remediation of Cr(VI) polluted waters. [14] Although the obtainment and use of ionic liquid gels has recently gathered a certain interest, [9,15] the attention for eutectogels is less common. [11,15d,16] These can be ideal candidates as materials for environmental applications, considering the very low toxicity of solvent components.…”

Recently Developed Carbohydrate Based Gelators and Their Applications

“…The solidified gasoline layer was then scooped out of the biphasic mixture and distillation was used to separate the gasoline from the gelator, so the gasoline could be recovered and the gelator could be recycled. Rizzo et al designed and synthesized imidazolium salt carbohydrate derivatives as supramolecular ionic liquid gelators ( Figure 74) [132]. The imidazolium cations contain long alkyl chains, making them the component that contributes to aromatic-aromatic interactions as well as the hydrophobic interactions.…”