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[Display omitted] • PEI-functionalized cellulose foam (PEI-CF) with 3D network structure was prepared. • A fluorescence "on–off-on" appeared on the PEI-CF before and after Cr(VI) loaded. • The residual Cr(VI) concentrations in the effluent were below 0.05 mg/L. • Visual recognition of Cr(VI) on the PEI-CF was done in a wide pH range of 2–8. In this work, a novel PEI-functionized cellulose foam (PEI-CF) was prepared by crosslinking polyethyleneimine and cellulose with epichlorohydrin followed freeze drying. The resultant foam not only possessed a three-dimensional network structure but also emitted strong blue fluorescence. It can efficiently remove Cr(VI) from aqueous solution and reduce its concentration below 0.05 mg/L. Other competing anions including NO 3 −, Cl− and H 2 PO 4 − had no remarkable influence on Cr(VI) removal except SO 4 2−. Moreover, the PEI-CF demonstrated good regeneration performance. In addition, a reversible fluorescence "on–off-on" phenomenon was found for the PEI-CF before and after the Cr(VI) loaded under 365 nm UV light. By using the PEI-CF, the visual recognition of Cr(VI) was achieved in a wide pH range of 2–8 and low Cr(VI) concentration of 0.05 mg/L. Coexisting ions (Cu2+, Pb2+, Fe3+, Zn2+, Cr3+, SO 4 2−, Cl−, NO 3 −, H 2 PO 4 − and S2−) had no significant influence on the visual recognition of Cr(VI), exhibiting good selectivity. The PEI-CF showed great promise for the emergency monitoring and Cr(VI) removal in environmental water. [ABSTRACT FROM AUTHOR]

A novel method was developed for the sensitive and visual detection of p-phenylenediamine (PPD) via immobilizing the target specie PPD on dialdehyde cellulose membrane (DCM) followed by the reaction with salicylaldehyde. The obtained solid fluorescent membrane (S-PPD-DCM) emitted yellow fluorescence under 365 nm UV light. DCM was not only used as a solid matrix but also played a vital role in the enrichment of PPD. Experimental variables influencing the fluorescence signal were investigated and optimized. Under the optimum conditions, a detection limit of 5.35 μg L−1 was obtained and two linear ranges were observed at 10–100 and 100–1000 μg L−1, respectively. Moreover, the fluorescence of the resultant membrane can still be visualized by naked eye when PPD concentration was 50 μg L−1. The detection of PPD was hardly affected by the coexistence of 1 mg L−1 of o-phenylenediamine, m-phenylenediamine or p henylamine , exhibiting good selectivity. The developed method involved in a two-step Schiff base reaction and enhanced the fluorescence emission via blocking nonradiative intramolecular rotation decay of the excited molecules. It was applied to determine the PPD in spiked hair dye with satisfactory results. Image 1 • A novel method was developed for the sensitive and visual detection of PPD. • DCM as a solid matrix played a vital role in the enrichment of PPD. • The proposed method gave two linear ranges at 0.01–0.1 and 0.1–1 mg L−1, respectively. • The detection limit of PPD was calculated to be 5.35 μg L−1. • Detection mechanism was involved in two-step Schiff base reaction and AIE effect. [ABSTRACT FROM AUTHOR]

• A novel antibacterial membrane containing polyiodides (I-PEI-DCM) was fabricated. • I-PEI-DCM had excellent antibacterial activity against both E. coli and S. aureus. • The iodine loaded on the I-PEI-DCM was the mixture of I 3 − and I 5 −. • The amino groups of PEI participated in the complex reaction with polyiodide ions. • I-PEI-DCM displayed good stability and reusability. Iodine exhibits a broad antibacterial spectrum, low toxicity, high efficiency and no drug resistance. However, free iodine is unstable and has strong irritation on wounds if applied directly. Hence, a carrier improving the stability of iodine is required. In this study, a branched polyethylenimine (PEI) was employed as an iodine carrier. It was firstly fixed to dialdehyde cellulose membrane (DCM) via Schiff-base reaction. Then the PEI-DCM was immersed in an I 2 -KI aqueous solution to prepare a novel antibacterial cellulose membrane containing polyiodides (I-PEI-DCM). Its structure and properties were characterized by SEM, EDX, XPS, Raman, ATR-FTIR, XRD and antibacterial activity. Results demonstrated that the iodine loaded on the I-PEI-DCM was the mixture of I 3 − and I 5 −, whose distribution on the membrane was uniform. During the iodination treatment, the amino groups of PEI molecular chains participated in the complex reaction with polyiodide ions. The microbiological tests showed that the I-PEI-DCM had excellent antibacterial activity against both E. coli and S. aureus. It can completely inactivate all of two bacteria within 0.5 min even after 30-day storage. Meanwhile, the antibacterial membrane exhibited good stability and reusability. Based on the characteristic features, the I-PEI-DCM can be regarded as a promising wound dressing. [ABSTRACT FROM AUTHOR]