Crystal Phase and Morphology-Controlled Synthesis of Tungsten Oxide Nanostructures for Remarkably Ultrafast Adsorption and Separation of Organic Dyes

Abstract

Simple inorganic routes for the synthesis of WO3 nanostructures with variable crystal phases, WO3·(H2O)0.5 and (NH4)0.33WO3, and their self-assembled structures as nanoplates and nanospheres, respectively, were reported. The morphologies and formation of nanoplates and nanospheres were controlled by changing the solvent amount (H2O/n-propanol) in the solvothermal reactions without any stabilizing agent or surfactant. The adsorption properties of the WO3 nanostructures were studied, and it was found that nanospheres show remarkably higher and ultrafast adsorption of methylene blue (MB) in comparison to nanoplates and commercial WO3. The adsorption isotherms, kinetics, mechanism, and reusability of (NH4)0.33WO3 nanospheres were systematically studied. The nanospheres exhibited an exceptionally high adsorption rate K 2 of 17.24 g·mg–1·min–1 and the maximum adsorption capacity of 116 mg·g–1 for MB. The adsorption cycle of nanospheres was examined, and the removal efficiency of MB remained at ∼98–99% even after three regeneration cycles. In addition, (NH4)0.33WO3 nanospheres exhibited excellent selective adsorption performance toward several cationic dyes, including MB, malachite green (MG), safranin O (SO), crystal violet (CV), and separate MO, a negatively charged dye, with a separation efficiency of 99.93 and 77.31% from binary and pentanary dye mixture solutions, respectively, at neutral pH.

Remarkable SO2 and H2S Resistant Ability on CO Oxidation by Unique Pd/WO3 3D Hollow Sphere Nanocatalyst: Correlating Structure–Activity Relationships on SO2 Exposure

“…The solution was then kept under constant heating and stirring at 90 °C to reduce the solution volume from 11 to 2 mL, as reported earlier by our group. 34 After cooling to room temperature, the 2 mL reaction mixture was transferred to a Teflon-lined stainless-steel autoclave. Then, the previously prepared PdCl 2 solution (2.5 mg/1 mL EtOH) was added to the solution mixture, followed by further addition of 15 mL EtOH to keep the final volume of the reaction mixtures at 18 mL, in a 25 mL autoclave.…”

Selective Adsorption of Methyl Orange and Methylene Blue by Porous Carbon Material Prepared From Potassium Citrate

“…The adsorption capacities of the obtained MOF-235 for CR and LY were 1131 and 209 mg g –1 , respectively. Jeyarani et al synthesized WO 3 nanostructures with variable crystal phases, WO 3 (H 2 O) 0.5 and (NH 4 ) 0.33 WO 3 , which can self-assemble into structures such as nanoplates and nanospheres . The nanospheres of the WO 3 nanostructure exhibited a maximum adsorption capacity of 116 mg g –1 for MB.…”

“…The adsorbent is the pivotal factor in determining the adsorption treatment performance . A large number of adsorbents such as metal–organic frameworks (MOF), self-assembled nanostructures, porous polymer, layered double hydroxide, zeolite, and porous carbon have been developed for dye adsorption. − Duo et al prepared an iron-based metal–organic framework (MOF-235) to remove the Congo red (CR) and lemon yellow (LY) in the water . The adsorption capacities of the obtained MOF-235 for CR and LY were 1131 and 209 mg g –1 , respectively.…”

Synthesis of 2D MoO3−x/N-doped-carbon nanocomposites via in situ carbonization of layered (NH4)Mo3O9–(NH4)2Mo4O13-organic hybrid nanomaterials for exceptionally efficient adsorption and separation of organic dyes

“…[18][19][20][21][22][23][24][25][26][27][28] To the best of our knowledge, the effective separation of a single dye from a four/ five-component mixed interfering analyte system by oxide-based nanomaterials via a simple separation method in an aqueous medium at neutral pH is rare; recently reported by our group using tungsten oxide nanostructures. 43 2 Experimental section , technical grade 70%, Sigma Aldrich), octadecene (ODE, technical grade, Sigma Aldrich), ethyl alcohol (absolute EtOH, A.R., 99.9%), hexane (SRL, 99% pure), methylene blue (MB, Sigma-Aldrich, ≥95%), rhodamine-B (RhB, Sigma-Aldrich, dye content 97%), malachite green (MG, Loba Chemie), crystal violet (CV, Loba Chemie, 96%), safranin O (SO, Sigma-Aldrich, dye content 85%), methyl orange (MO, British Drug Houses Ltd.), and MoO 3 (puriss p.a. 99.5%, Sigma Aldrich) were used as received without further purification.…”

“…18–28 To the best of our knowledge, the effective separation of a single dye from a four/five-component mixed interfering analyte system by oxide-based nanomaterials via a simple separation method in an aqueous medium at neutral pH is rare; recently reported by our group using tungsten oxide nanostructures. 43…”