Photo-reduction of hexavalent chromium in aqueous solution in the presence of zinc oxide as semiconductor catalyst

Chakrabarti, Sudipta; Chaudhuri, Basab; Bhattacharjee, Sekhar; Ray, Ajay K.; Dutta, Binay K.

doi:10.1016/j.cej.2009.06.021

Cited by 142 publications

(79 citation statements)

References 37 publications

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“…Reason of this problem could be that the number of active sites on the catalyst increases by increasing the amount of catalyst in a solution with a fixed substrate amount, which attracts more UV radiation and increases the reaction speed, thereby increasing the removal efficiency. A similar phenomenon has been reported by Chakrabarti et al (24) and Das et al (25). By increasing the catalyst dose (from 0.5 to 0.7 g/L), the efficiency did not increase so much or decreases; this can be due to opacity increases in high concentrations of nanoparticles and reduce the effect of UV light on the nanoparticles.…”

Section: Discussionsupporting

confidence: 61%

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Removal of bromide from aqueous solutions using the UV/ZnO process based on the multivariate analysis model

Moradi

Dindarloo

Alipour

et al. 2016

Environ Health Eng Manag

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Background: Bromide is found naturally in groundwater and surface water. The rapid growth of industrial activities, drainage of surface runoff, and use of methyl bromide in pesticides has increased bromide discharge to the environment. Disinfection of water-containing bromide causes the creation of additional products of organo-halogenated that are considered cancer-causing agents. In this study, the effect and optimization of factors in removal of this ion was evaluated by using the nano-photocatalytic UV/ZnO process. Methods: This analytical study was conducted in a batch system by the phenol-red method. The test design was performed through the analysis model of multi-factor variance with 99 subjects, while the main, interactive, and reciprocal effects of variables, such as reaction time, catalyst concentration, bromide concentration, and pH at different levels of each factor, were analysed by using SPSS version 16. Results: The main, interactive, and reciprocal effects of factors were significant in three different levels with P < 0.001, and the optimal level of the factors reaction time, catalyst concentration, bromide concentration, and pH were 120 minutes, 0.5, 0.1, and 7 mg/L, respectively, by using the Schaffer test. The highest removal efficiency of 95% was obtained at least 91.56 and a maximum of 94.76% was obtained under optimal conditions of all factors. Conclusion:The results show that by optimization of factors, this process can be effectively used to remove bromide from aquatic environments. Keywords: Bromides, Water, Reaction Time, UV/Zn Citation: Moradi KM, Dindarloo K, Alipour V, Heidari M. Removal of bromide from aqueous solutions using the UV/ZnO process based on the multivariate analysis model.

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Section: Discussionsupporting

confidence: 61%

“…A similar phenomenon has been reported by Chakrabarti et al (24,25). By increasing the catalyst dose (from 0.5 to 0.7 g/L), the efficiency did not increase so much or decreases; this can be due to opacity increases in high concentrations of nanoparticles and reduce the effect of UV light on the nanoparticles.…”

Section: Ethical Issuessupporting

confidence: 61%

Removal of bromide from aqueous solutions using the UV/ZnO process based on the multivariate analysis model

Moradi

Dindarloo

Alipour

et al. 2016

Environ Health Eng Manag

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“…This observation has been reported in literature. [52][53][54] It should be mentioned that TiO 2 is more resistant to lower solution pH. In presented work optimum for cold vapour generation in presence of TiO 2 was 3.5.…”

Section: Catalyzed Photo-reduction Of Mercury By Znomentioning

confidence: 98%

“…53,55 In this paper the photocatalytic activities of TiO 2 , Ag-TiO 2 and ZnO for reduction of mercury was compared. In optimized parameters the highest activity was obtained for modified TiO 2 .…”

Section: Comparison Of Optimized Procedures For the Catalyzed Reductimentioning

confidence: 99%

Evaluation of the catalyzed photo-cold vapour generation for determination of mercury by AAS

Matusiewicz¹,

Stanisz²

2012

J. Braz. Chem. Soc.

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Nanopartículas de Ag suportadas em TiO 2 (Ag-TiO 2 ) foram usadas como catalisador na geração de vapor frio induzida por radiação UV com ácido fórmico, acoplado à absorção atômica para determinação do mercúrio total em amostras analíticas. A atividade redutora de Ag-TiO 2 foi comparada com dois catalisadores semicondutores: TiO 2 não modificado e ZnO. O efeito do tipo de catalisador, sua concentração na amostra analisada, pH da amostra, concentração do ácido fórmico e tempo de irradiação ultravioleta foi investigado. Na presença de ácido fórmico, Ag-TiO 2 foi o mais eficiente na redução de mercúrio. Nas condições experimentais otimizadas, a recuperação de mercúrio em quatro materiais de referência contendo 0,20-1,99 µg g -1 Hg foi de 95-99% dos valores certificados. O desvio padrão relativo para amostras foi igual ou melhor do que 11%. A análise de materiais de referência certificados (correspondentes a amostras ambientais e biológicas) mostrou a potencialidade do método Ag-TiO 2 -UV-CVGAAS na determinação de mercúrio em amostras analíticas no nível de ultra-traço.Nano-Ag particles loaded on TiO 2 (Ag-TiO 2 ) were used as catalyst for the UV-induced cold vapour generation with formic acid coupled to atomic absorption for determination of total mercury in analytical samples. The reducing activity of Ag-TiO 2 was compared with two semiconductor catalysts: unmodified TiO 2 and ZnO. The effect of catalyst type, its concentration in the analyzed sample, sample pH, formic acid concentration and ultraviolet irradiation time have been investigated. In the presence of formic acid, most effective in the reduction of mercury was Ag-TiO 2 . Under the optimized experimental conditions recovery of mercury in four reference materials containing 0.20-1.99 µg g -1 Hg was 95-99% of certificate values. The relative standard deviation for samples was equal to or better than 11%. Certified reference materials (corresponding to biological and environmental samples) analysis using the Ag-TiO 2 -UV-CVGAAS method revealed that it is promising for mercury determination in analytical samples at ultratrace level.

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“…The reaction cell was bubbled with O 2 at a flow rate of 0.5 mL min -1 in the darkness for 15 min before irradiation. At given irradiation time intervals, the samples (5 mL) were taken out, centrifuged (Hettich EBA) and then Cr(VI) concentration was analyzed by UV-Vis spectrophotometer (Pharmacia Biotech, Ultrospec 2000) at  max = 350 nm (Chakrabarti et al 2009). …”

Section: Photoreactor and Proceduresmentioning

confidence: 99%

Specification of the Operational Parameters Contribution in the Efficiency of TiO2-P25 Nanoparticles in the Photocatalytic Removal of Cr(VI) by Taguchi Method

Sabonian¹,

Behnajady²

2014

Orient J Chem

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Chromium exists in environment both as trivalent [Cr(III)] and hexavalent [Cr(VI)] forms. However, hexavalent form is five hundred times more toxic than the trivalent form. Heterogeneous photocatalysis processes, using aqueous suspensions of semiconductors, have received considerable attention in the removal of toxic metals from aqueous media. In this work the nanoparticles of TiO 2 -P25 in the form of slurry were used for photoreduction of Cr(VI) to the less harmful Cr(III). The process has been conducted in different operational conditions such as different initial concentrations of Cr(VI), dosage of photocatalyst, irradiation times, irradiation intensities of light and pH. For the optimization of the process Taguchi experimental design was used. The results of optimization using the Taguchi method, indicated that the pH with 28%, initial concentration of Cr(VI) with 26.99% and dosage of TiO 2 nanocatalyst with 20.53% have the most effects among the selected factors. The intensity of UV light irradiation has the least effect on the efficiency of the process.

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Photo-reduction of hexavalent chromium in aqueous solution in the presence of zinc oxide as semiconductor catalyst

Cited by 142 publications

References 37 publications

Removal of bromide from aqueous solutions using the UV/ZnO process based on the multivariate analysis model

Removal of bromide from aqueous solutions using the UV/ZnO process based on the multivariate analysis model

Evaluation of the catalyzed photo-cold vapour generation for determination of mercury by AAS

Specification of the Operational Parameters Contribution in the Efficiency of TiO2-P25 Nanoparticles in the Photocatalytic Removal of Cr(VI) by Taguchi Method

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