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Foods and beverages with excessive tannins acid (TA) content taste astringent and bitter. The overconsumption of TA could result in nutritional and digestive problems. In this study, the cellulose nanocrystals (CNC)/fish swim bladder gelatin (FG) composite sponge was prepared with glutaraldehyde as a crosslinking agent. The TA adsorption performance of the sponge was discussed. The freeze-dried CNC/FG composite sponge had a porous network structure. CNC was combined into the FG matrix as a reinforcing phase. The mechanical strength, thermal stability, and swelling properties of the composite sponge were improved with the addition of an appropriate amount of CNC. Although CNC decreased the porosity of composite sponge, the increase in active adsorption sites resulted in an overall positive effect on its TA adsorption properties. Under the optimal adsorption conditions, the TA removal rate of 1.0 % CNC composites reached 80.4 %. Furthermore, the sponge retained a TA removal rate of 54 % after five cycles of adsorption and desorption using 50 % ethanol. The results demonstrated that CNC/FG composite sponge has application potential in the field of adsorption materials for TA. [Display omitted] • Porous fish gelatin sponge is capable of removing tannic acid. • Cellulose nanocrystals additives bonded with fish gelatin through hydrogen bonds. • Additives improved mechanical strength, thermal stability, and swelling property. • 1 % cellulose nanocrystals addition achieved best tannic acid removal (80.4 %). • Composite sponge's adsorption follows the pseudo-second-order kinetic model. [ABSTRACT FROM AUTHOR]

Highlights: [•] Comparison of chelating agent and surfactant as surface impregnation agents. [•] Mechanisms of EDTA and SDS impregnation proposed. [•] Batch and column tests for lead adsorption and chemical regeneration were studied. [Copyright &y& Elsevier]

Abstract: Monodisperse Fe3O4@silica core–shell microspheres have been successfully prepared by using a two step method. Due to their exceptional properties, these composite microspheres can be removed conveniently from water via an external magnet. These composite microspheres can be applied to remove heavy metal ions from industrial wastewater because the surface of the microspheres is covered with SiO2, and the SiO2 is inactive and can adsorb heavy metal ions (such as Hg2+, Pb2+). Furthermore, the interaction between SiO2 and heavy metal ions is reversible, which means that the adsorbed ions can be removed from SiO2 in weak acidic deionized water with the assistance of ultrasound radiation. It is noteworthy that the adsorption ability of the composite microspheres is so strong that any further modification of the composite microspheres is unnecessary. On the basis of the above points, we consider that the synthesized Fe3O4@silica composite microspheres can be used as a useful recyclable tool for heavy metal ion removal. This work provides a potential and unique technique for heavy metal ion removal from industrial wastewater. [Copyright &y& Elsevier]