Facile preparation of covalent organic frameworks@alginate composite beads for enhanced uranium(Ⅵ) adsorption

Covalent organic frameworks(COFs) have broad application prospects in adsorption and separation.Yet,as COFs are generally in powder form,their superior performance at the laboratory scale is difficult to transfer into pilot-or industrial-scale use.Thus,there is a strong and urgent need to structure COFs into monolithic materials.Herein,a facile strategy was developed to prepare COFs@alginate composite beads.Three composite beads comprising different COFs including TpPa-1(2,4,6-triformylphloroglucinol(Tp) and p-phenylenediamine(Pa-1)as monomers),TpDb(Tp and 2,5-diaminobenzonitrile(Db)as monomers) and TpTt(Tp and 1,3,5-triazine-2,4,6-triamine(Tt) as monomers) with controlled COF loading and product size have been facilely achieved via this strategy,validating the applicability of this method.Furthermore,the representative TpDb@alginate composite beads showed good adsorption performance of uranium(VI) in aqueous solution with high adsorption capacity(635 mg·g^(-1)),good interference immunity and recyclability.This work offers a practical approach for incorporation of COFs into polymer matrix,which can serve as potential adsorbents for radioactive wastewater treatment.

Mesoporous TiO_2/Carbon Beads: One-Pot Preparation and Their Application in Visible-Light-Induced Photodegradation

Mesoporous Ti O2/Carbon beads have been prepared via a facile impregnation-carbonization approach, in which a porous anion-exchange resin and K2 Ti O(C2O4)2were used as hard carbon and titanium source, respectively.Characterization results reveal that the self-assembled composites have disordered mesostructure, uniform mesopores,large pore volumes, and high surface areas. The mesopore walls are composed of amorphous carbon, well-dispersed and confined anatase or rutile nanoparticles. Some anatase phase of Ti O2 was transformed to rutile phase via an increase of carbonization temperature or repeated impregnation of the resin with Ti O(C2O4)22-species. X-ray photoelectron spectroscopy, carbon, hydrogen, and nitrogen element analysis, and thermal gravity analysis results indicate the doping of carbon into the Ti O2 lattice and strong interaction between carbon and Ti O2 nanoparticles. A synergy effect by carbon and Ti O2 in the composites has been discussed herein on the degradation of methyl orange under visible light. The dye removal process involves adsorption of the dye from water by the mesopores in the composites, followed by photodegradation on the separated dye-loaded catalysts. Mesopores allow full access of the dye molecules to the surface of Ti O2 nanoparticles.Importantly, the bead format of such composite enables their straightforward separation from the reaction mixture in their application as a liquid-phase heterogeneous photodegradation catalyst.