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Azolla imbircata dry powder (Ai-dp) was prepared by collecting wild Azolla imbircata, drying and grinding. SEM, FTIR and XPS have been used to characterize it. Batch biosorption experiments studied pH, contact time, initial U(VI) concentration, adsorbent dosage and temperature effects on U(VI) biosorption. These results indicated that the maximum biosorption capacity was 4.55 mg L−1 under conditions of 303 K, pH 2.0, initial U(VI) concentration 15 mg L−1 and adsorbent dosage 3.75 g L−1. The biosorption process fit pseudo-second-order kinetics and Langmuir isotherm, it showed the adsorption process was monolayer chemisorption. The thermodynamic fitting results showed the adsorption process was spontaneous and exothermic.

Abstract Chitosan is an amorphous translucent substance with a structural unit similar to the polysaccharide structure of the extracellular matrix, It has good antibacterial, biocompatible, and degradable properties. It has important application value in leather, water treatment, medicine, food and other fields, so chitosan and its modified products have received widespread attention. This article reviewed the preparation methods of chitosan-based antibacterial composites in recent years, including chitosan/collagen, chitosan/graphene, chitosan/tannic acid, and chitosan/polyethylene glycol composite materials, elaborates their modification methods and antibacterial mechanism were reviewed in detail, and its applications in the leather industry as antibacterial auxiliaries and water treatment antibacterial adsorption materials were discussed. Finally, the future development and challenges of chitosan-based composite materials in the leather industry were forecasted. Graphical abstract

Graphene oxide was encapsulated into sodium alginate to prepare SA-GO composite hydrogel for U(VI) adsorption, which characterized by SEM, FTIR, and XPS. The effects of pH, reaction time, initial U(VI) concentration and adsorbent amount on U(VI) adsorption were studied by batch adsorption experiments. The results showed that the maximum adsorption capacity was 149.76 mg/L when pH 5.0, adsorbent 0.1 g/L, 30 °C and initial U(VI) concentration 15 mg/L. The adsorption process accords with pseudo-second-order kinetic models and Langmuir isotherm. After five cycles of desorption and reuse experiments, the adsorption capacity of SA-GO for U(VI) was still higher than 85%.

The surface of Bacillus megaterium was modified by coating sodium alginate. The modified B. megaterium before and after adsorption were characterized by SEM, FTIR and XPS. The effects of pH, reaction time, initial U(VI) concentration and adsorbent dosage on the adsorption of U(VI) by the modified B. megaterium were studied by batch adsorption experiments. The adsorption process was studied by pseudo-first-order kinetics and pseudo-second-order kinetic models, Langmuir and Freundlich isotherms. The results showed that the maximum adsorption capacity of U(VI) was 74.61 mg g −1 under the conditions of pH 5.0, adsorbent 0.2 g l −1 , 30°C and initial U(VI) concentration of 15 mg l −1 . The adsorption process accords with pseudo-first-order kinetics and Langmuir isotherm. The adsorption capacity of U(VI) by the modified B. megaterium was still higher than 80% after five times of desorption and reuse experiments. In conclusion, the sodium alginate modified B. megaterium was an ideal material for U(VI) biosorption.