Source: School of Chemistry
Written by: School of Chemistry
Edited by: Wang Dongmei

The removal and prevention of organic pollutants in water has attracted great attention in chemistry and materials science because of human health and water ecosystems. For this reason the construction of porous materials, like porous silica, polymers, metal-organic frameworks (MOFs) and surface-modified carbons with desired size and properties are actively investigated as advanced sorbents for pollutant extraction and preconcentration. Among them, activated carbons are the most widespread adsorbent materials to remove organic pollutants due to their biocompatibility, the high surface area and the ease to handle. Although ordered or disordered carbons with micro-, meso-, and macro-pores have been successfully employed and showed advanced capacity, the regenerating spends enough water or organic solvent to take place secondary contamination and does not fully restore performance. Furthermore, the carbons could not fully remove relatively hydrophilic micropollutants because of their low dispersity, inducing difficulty of grabbing pollutants from water, which limited their capacity and applications. Aromatic rod amphiphiles consisting of conjugated carbon and hydrophilic coil segments as the conjugated carbon family can easily aggregate to form porous capsules that are well-suited as scaffolds for the sorption of solvent or drug molecules. Particularly, the supramolecular dynamic assembly have been proved as a promotion for their spontaneous encapsulation and selective release or targeting delivery because the formation of supramolecular architectures are completely reversible.

Recently, Huang’s group extended the conjugation of carbazole to obtain a folded propeller-shaped aromatic amphiphiles that aggregate into hollow spheres. In contrast to traditional supramolecular porous materials based on 1D aromatic assembly, the self-assembled pores of two-dimensional π-conjugations provide excellent carbon environment to adsorb dissolved organic contaminants. For the high surface area and mesoporosity, the removal efficiency of porous adsorbents was found to be 92 and 90 % for Eo and BPA. Notably, the folded architecture of propeller was observed to be flatten by salt addition, which resulted in the strong π-π interaction driving the porous materials closed and formed solid fibers. Consequently, both pollutants are able to be removed by porous absorbents by switchable porous assembly, and subsequent dialysis triggered the porous materials to be recovered.
This work has been published in Advanced Materials. The master student Siying Xie is first author. (Intelligent Mesoporous Materials for Selective Adsorption and Mechanical Release of Organic Pollutants from Water, Adv. Mater., 2018, 10.1002/adma.201800683)

The work was suppoted by Hundred-Talent Program of Sun Yat-sen University, Guangzhou Science and Technology and Natural Science Foundation of Guangdong Province. Huang’s group has researched on the super-hydrophobic soft mesoporous materials mainly around supramolecular assembly and functionalization, supramolecular catalysis, pollutant adsorption, intelligent drug delivery. 

Link to the paper: https://onlinelibrary.wiley.com/doi/pdf/10.1002/adma.201800683