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A new synthetic method was designed to prepare poly (trimesoyl chloride-co-polyethyleneimine) (PEI-TMC). Characterization of PEI-TMC was investigated by FTIR, SEM, EDS, XPS, TGA, and BET. TGA test revealed that the PEI-TMC had excellent thermal stability. The BET specific surface area (4.74 ​m2 ​g−1) and pore diameter of about 9.44 ​nm indicated that PEI-TMC possessed a mesoporous structure. The adsorption behavior of U(VI) on the PEI-TMC was investigated. The thermodynamic analysis showed that the process of PEI-TMC adsorption of U(VI) was endothermic and spontaneous, and the adsorption efficiency was better at higher temperatures. The U(VI) sorption on PEI-TMC was conformed to the Langmuir adsorption isotherm and pseudo-second-order kinetic models. The adsorption mechanism of U(VI) with PEI-TMC was systematically elucidated by XPS and FTIR. Under the best condition, the maximum adsorption capacity of PEI-TMC could reach 212.8 ​mg ​g−1 ​by calculating the Langmuir isothermal model. It indicated that PEI-TMC was a potential adsorbent for the treatment of U(VI)-containing wastewater. Diagram of PEI synthesis and its adsorption mechanism for U(VI). Image 1 • A new and facile method is used to prepare PEI-TMC. • The application field of PEI-TMC was expanded for the separation of U(VI). • Excellent adsorption performance was demonstrated. [ABSTRACT FROM AUTHOR]

The preparation of easily synthesized and cheap composite materials for the efficient removal of toxic oxoanions still remains challenging in sewage treatment. Herein, a new carbonized manganese-crosslinked sodium alginate (Mn/SA-C) was fabricated for the removal of arsenite (As(III)), arsenate (As(V)) and hexavalent chromium (Cr(VI)) in water. The results indicated that the Mn/SA-C pretreated with MnSO 4 solution (Mn/SA-C-S) exhibited a rapid adsorption toward As(III) and As(V) with the removal efficiency of >98% within 10 min, and had a high adsorption capacity toward As(III), As(V), and Cr(VI) with the maximum value of 189.29, 193.29, and 104.50 mg/g based on the Langmuir model, respectively. The removal efficiency of As(III), As(V), and Cr(VI) could be further significantly enhanced by coupling a photocatalytic process. For example, the time in which >98% of Cr(VI) (10 mg/L) was removed dramatically shortened from 360 min (adsorption) to 45 min (adsorption-photocatalysis), and the removal efficiency of As(III) increased by ∼10% within initial 5 min. This was primarily attributed to the Mn-catalyzed production of the photocatalytic excitons for Cr(VI) reduction, and the superoxide (•O 2 −) and hydroxyl (•OH) radicals for As(III) oxidation. The adsorption removal of arsenic (As) was primarily ascribed to surface complexation with MnO and precipitation by MnS 2 , and oxidative adsorption because of Mn valence cycle. The removal mechanisms of Cr(VI) mainly contained reduction by MnO and MnS 2 , complexation with MnO and carboxyl/hydroxyl groups as well as Cr(OH) 3 precipitation. Our research provides a promising Mn/SA-C-S material for rapid and efficient removal of As(III), As(V), and Cr(VI) in contaminated water through an adsorption-photocatalysis synergistic strategy. [Display omitted] • A novel carbonized manganese-crosslinked sodium alginate (Mn/SA-C) was prepared. • >98% of As(III) and As(V) was rapidly adsorbed within 10 min under dark condition. • As(III), As(V) and Cr(VI) adsorption fitted well to pseudo-second-order models. • The removal of As(III), As(V) and Cr(VI) was enhanced by coupling a photocatalysis. • Adsorption-photocatalysis mechanisms of As(III), As(V) and Cr(VI) were proposed. [ABSTRACT FROM AUTHOR]