Zohreh Majidnia

Efficiency of barium removal from radioactive waste water using the combination of maghemite and titania nanoparticles in PVA and alginate beads

In this paper, both maghemite (γ-Fe2O3) and titanium oxide (TiO2) nanoparticles were synthesized and mixed in various ratios and embedded in PVA and alginate beads. Batch sorption experiments were applied for removal of barium ions from aqueous solution under sunlight using the beads. The process has been investigated as a function of pH, contact time, temperature, initial barium ion concentration and TiO2:γ-Fe2O3 ratios (1:10, 1:60 and 1). The recycling attributes of these beads were also considered. Furthermore, the results revealed that 99% of the Ba(II) was eliminated in 150min at pH 8 under sunlight. Also, the maghemite and titania PVA-alginate beads can be readily isolated from the aqueous solution after the process and reused for at least 7 times without significant losses of their initial properties. The reduction of Ba(II) with maghemite and titania PVA-alginate beads fitted the pseudo first order and second order Langmuir-Hinshelwood (L-H) kinetic model.

Combination of maghemite and titanium oxide nanoparticles in polyvinyl alcohol-alginate encapsulated beads for cadmium ions removal

Both maghemite (γ-Fe2O3) and titanium oxide (TiO2) nanoparticles were mixed at various ratios and embedded in polyvinyl alcohol (PVA)-alginate beads. These beads were tested for photocatalytic behavior in eliminating toxic Cd(II) from the aqueous solution. The photocatalytic experiments were performed under sunlight irradiation at various pH, initial feed concentrations and γ-Fe2O3: TiO2 ratios. The recycling attribute of these beads was also investigated. The results revealed that 100% of the Cd(II) was eliminated in 150 minutes at pH 7 under sunlight. It shows that maghemite and titania PVA-alginate beads can be readily isolated from the aqueous solution after the photocatalyst process and reused for at least six times without losing their initial properties.

Photo Catalytic Reduction of Pb(II) Using Titanium Oxide PVA-Alginate Beads under Sunlight

Pb(II) which is considered a toxic and common pollutant to the environment was removed from the aqueous solution using the one step photo catalytic reduction with the help of titanium oxide PVA-alginate beads. The photo catalytic reduction was performed in the presence and absence of sunlight at pH 7 and Pb(II) concentration of 50mg/L at the equilibrium contact time of 180 min. The results revealed that the titanium oxide PVA-alginate beads were capable of removing 98% of Pb(II) from the aqueous solution within 150 min. The titanium oxide PVA-alginate beads can be separated from the aqueous solution after photocatalytic process and they can be reused for at least 7 times without significant loss in their initial properties.

Synergistic Effect of Maghemite and Titania Nanoparticles in PVA-Alginate Encapsulated Beads for Photocatalytic Reduction of Pb(II)

In this paper, maghemite (γ-Fe2O3) and titanium oxide (TiO2) nanoparticles were synthesized by hydrothermal and coprecipitation methods, respectively. These nanoparticles were combined together in various ratios (1:10, 1:20, 1:60, 1:80, and 1) and embedded in polyvinyl alcohol (PVA)-alginate beads. These beads were tested for photocatalytic behavior in eliminating toxic Pb(II) from the aqueous solution. The photocatalytic experiments were performed under sunlight irradiation and without sunlight. Several operating conditions such as initial Pb(II) concentration, pH, contact time, and TiO2: γ-Fe2O3 ratios were investigated to evaluate their effect on the process. The recycling attributes of these beads were also investigated. The results revealed that 100% of the Pb(II) was eliminated in 100 min at pH 7 under sunlight when the ratio of TiO2:γ-Fe2O3 was kept to 1. The PVA-alginate maghemite and titania beads showed better efficiency for Pb(II) removal than PVA-alginate titania beads and PVA-alginate maghemite beads. X-ray photoelectron spectroscopy (XPS) analysis also revealed that Pb(II) removal was via photocatalytic reduction due to the presence of Pb(0) in the high-resolution scan at 130–160 eV. Also, the PVA-alginate titania and maghemite beads can be readily isolated from the aqueous solution after the photocatalytic process and reused for at least 6 times without significant losses in their initial properties. The reduction of Pb(II) with PVA-alginate titania and maghemite beads fitted the Langmuir–Hinshelwood (L–H) kinetic model at a correlation coefficient (R2) of 0.9923.

Evaluation of the Cd removal efficacy from aqueous solutions using titania PVA-alginate beads

AbstractAn investigation was conducted on photocatalytic reduction and physical adsorption of Cd(II) in titania PVA-alginate beads. In order to determine the kinetics of photocatalytic process, the influence of the initial concentration was examined in detail. An exact analysis on the percentage of the initial reduction rate versus time at different initial concentrations of Cd(II) showed that with an increase in the initial concentration, the rate of substrate conversion reduced. It was also revealed that the beads containing the TiO2 nanoparticles can be easily isolated from the aqueous solutions after the sorption process and can be reused for at least six times before it loses its initial properties. The reduction of Cd(II) with titania PVA-alginate beads fitted the pseudo-second-order kinetic model with a correlation coefficient (R2) of 0.9993.

Removal of barium from radioactive aqueous solution by PVA–alginate encapsulated titanium oxide using sunlight and other light types

Barium(II) removal with titania PVA–alginate beads was conducted with sunlight, xenon, black light bulb (BLB) and light emitting diode (LED) lamps. The removal was studied as a function of pH, contact time, temperature and initial concentration. The findings show the removal rate of barium(II) achieved a 98% maximum within 130 min under sunlight. The beads were found to be easily isolated from the aqueous solution and could be reused a minimum of 5 times without losing the original properties. Barium(II) reduction fitted best with the pseudo second-order rate model with a coefficient of determination (R2) of 0.9938.