Polyaniline coated magnetic carboxymethylcellulose beads for selective removal of uranium ions from aqueous solution

Construction of oxime-functionalized PCN-222 based on the directed molecular structure design for recovering uranium from wastewater

The directed construction of productive adsorbents is essential to avoid damaging human health from the harmful radioactive and toxic U(VI)-containing wastewater. Herein, a sort of Zr-based metal organic framework (MOF) called PCN-222 was synthesized and oxime functionalized based on directed molecular structure design to synthesize an efficient adsorbent with antimicrobial activity, named PCN-222-OM, for recovering U(VI) from wastewater. PCN-222-OM unfolded splendid adsorption capacity (403.4 mg·g-1) at pH = 6.0 because of abundant holey structure and mighty chelation for oxime groups with U(VI) ions. PCN-222-OM also exhibited outstanding selectivity and reusability during the adsorption. The XPS spectra authenticated the -NH and oxime groups which revealed a momentous function. Concurrently, PCN-222-OM also possessed good antimicrobial activity, antibiofouling activity, and environmental safety; adequately decreased detrimental repercussions about bacteria and Halamphora on adsorption capacity; and met non-toxic and non-hazardous requirements for the application. The splendid antimicrobial activity and antibiofouling activity perhaps arose from the Zr6(μ3-O)4(μ3-OH)4(H2O)4(OH)4 clusters and rich functional groups within PCN-222-OM. Originally proposed PCN-222-OM was one potentially propitious material to recover U(VI) in wastewater on account of outstanding adsorption capacity, antimicrobial activity, antibiofouling activity, and environmental safety, meanwhile providing a newfangled conception on the construction of peculiar efficient adsorbent.

Highly effective sustainable membrane based cyanobacteria for uranium uptake from aqueous environment

Wastewater from industrial process of uranium ore mining contains a large amount of this radioactive pollutant. Regarding the advantages of biosorption, it was found that varieties of biomasses such as agricultural waste, algae and fungi are effective for uranium removal. However, there is limited research on cyanobacteria, therefore, cyanobacteria, Anagnostidinema amphibium (CAA) was investigated by batch method for the first time for biosorption of uranium (VI). Optimization of biosorption parameters showed that maximum removal efficiency of 92.91% was reached at pH range of 9-11 with 50 mg of cyanobacteria to 100 mg/L U(VI) initial concentration, at 25 °C within 40 min. Used biosorbent exhibited very good selectivity for U(VI) ions and reusability in IV sorption/desorption cycles. Characterization of CAA surface was performed by FTIR, EDS, EDXRF and SEM analysis and it has shown various functional groups (CONH, COOH, OH, PO alkyl group) and that it is very rich in elements such as iron, potassium and calcium. In binary systems, contained of U(VI) and selected ions, CAA exhibits very good selectivity towards U(VI) ions. Kinetic data revealed the best accordance of experimental data with the pseudo-second-order model and isotherms data agreed with Freundlich model. Thermodynamic data implied that U(VI) biosorption process by A. amphibium exhibited spontaneity and modelling of the investigated process showed that the adsorption of uranium ions occurs mainly via peptidoglycan carboxyl groups. Overall results show that these cyanobacteria with a maximum sorption capacity of 324.94 mg/g have great potential for the processing of wastewater polluted with uranium (VI).

Synthesis of wheat bran sawdust/Fe3O4 composite for the removal of methylene blue and methyl violet

Magnetically modified nanomaterials have recently gained a great attention in wastewater treatment. In this study, the uptake process of methylene blue (MB) and methyl violet (MV) from aqueous media using wheat bran sawdust/Fe₃O₄ composite was studied. To specify the surface and structural properties of the wheat bran sawdust/Fe₃O₄ composite, various analyses such as FTIR, XRD, EDX, Map, TGA/DTG, SEM, VSM, and BET were performed. The results of BET analysis indicated that the specific surface area of the aforementioned composite was 74.25 m²/g, and the average pore size was 65.7A, which indicates that the composite has a mesoporous structure. Also, VSM analysis indicated that the composite has a paramagnetic property with a magnetic saturation of 28.29 emu/g and can be easily eliminated from the aqueous solution by a magnet. Moreover, the highest removal efficiency of MB and MV dyes using the wheat bran/Fe₃O₄ composite was obtained as 97.46 and 98.75%, respectively, which were significant values. These removal efficiencies were obtained at contact time of 50 min and pH values of 9 and 8 for MB and MV, respectively. Furthermore, the outcomes of equilibrium study showed that the Langmuir model with a correlation coefficient greater than 0.98 describes the equilibrium behavior of the uptake process better than the Freundlich and Dubinin-Radushkevich models. Besides, the maximum sorption capacity of MV and MB dyes using the Langmuir model was obtained as 46.08 and 51.28 mg/g, respectively. Also, the uptake process followed the pseudo-second-order kinetic model, and the thermodynamic study indicated that the uptake process is exothermic and spontaneous.

Ultrasonic-assisted synthesis of natural clay/Fe3O4/graphene oxide for enhance removal of Cr (VI) from aqueous media

In this study, Fe3O4/graphene oxide (GO)/clay composite was used to remove chromium (VI) ion from aqueous media. The structure and characteristics of the Fe3O4/GO/clay composite were investigated using FT-IR, SEM, EDX/Map, VSM, BET, and XRD analyses. The BET analysis indicated that the specific surface area and mean pore size of the Fe3O4/GO/clay composite were calculated as 61.64 m2/g and 16.2 nm respectively, which indicate that the composite has a mesoporous structure. Also, the VSM analysis showed that the Fe3O4/GO/clay composite has a superparamagnetic property. Moreover, the highest removal efficiency of Cr (VI) from aqueous media was obtained to be 98.84%, which achieved at pH 3, Cr (VI) ion concentration of 10 mg/L, the composite dosage of 1 g/L, contact time of 60 min, and temperature of 25 °C. Furthermore, the kinetic and equilibrium studies showed that the quasi second-order kinetic model and the Langmuir model could better describe the sorption behavior of the clay and the Fe3O4/clay composite, while the behavior of the Fe3O4/GO/clay composite can be better explained by the Freundlich model. Besides, the maximum sorption capacities of the clay, Fe3O4/clay, and Fe3O4/GO/clay composite were obtained to be 49.61, 62.26, and 71.47 mg/g, respectively, which shows that the maximum sorption capacity of the clay increases with improving the surface properties of the clay. Also, the thermodynamic study indicated that the Cr (VI) sorption process was exothermic and spontaneous in nature. In general, the results indicated that the Fe3O4/GO/clay composite was more effective than the clay and the Fe3O4/clay in Cr (VI) ion removal.

Preparation of montmorillonite grafted polyacrylic acid composite and study on its adsorption properties of lanthanum ions from aqueous solution

Montmorillonite grafted polyacrylic acid composite (GNM) was prepared by using ultraviolet radiation grafting method in this work. The synthesized materials were characterized by XRF, SEM, FTIR, XRD, TG, and XPS. The experimental equilibrium data indicates that the adsorbent is suitable for the Langmuir model and belongs to the pseudo-second-order kinetic model. The entire adsorption process is spontaneous, endothermic, and chaotically enhanced by thermodynamic analysis. The maximum adsorption capacity of La(III) by GNM was 280.54 mg/g at 313.15 K. In addition, the regeneration experiment shows that the adsorbent has good reusability and stable desorption efficiency. This study demonstrates that GNM has high adsorption performance and La(III) adsorption and regeneration capabilities to solve the water pollution caused by rare earth ions and regeneration capabilities for La(III).