Springer Nature is making SARS-CoV-2 and COVID-19 research free. View research | View latest news | Sign up for updates

Comparison and mechanism of photocatalytic activities of N-ZnO and N-ZrO2 for the degradation of rhodamine 6G


N-doped ZnO (N-ZnO) and N-doped ZrO2 (N-ZrO2) are synthesized by novel, simple thermal decomposition methods. The catalysts are evaluated for the degradation of rhodamine 6G (R6G) under visible and UV light. N-ZnO exhibits higher dye degradation under both visible and UV light compared to N-ZrO2 due to possessing higher specific surface area, lower crystalline size, and lower band gap. However, it is less reusable than N-ZrO2 and its photocatalytic activity is also deteriorated at low pH. At the same intensity of 3.5 W/m2, UVC light is shown to be a better UV source for N-ZnO, while UVA light is more suitable for N-ZrO2. At pH 7 with initial dye concentration of 10 mg/L, catalyst concentration of 1 g/L, and UVC light, 94.3 % of R6G is degraded by N-ZnO within 2 h. Using UVA light under identical experimental conditions, 93.5 % degradation of R6G is obtained by N-ZrO2. Moreover, the type of light source is found to determine the reactive species produced in the R6G degradation by N-ZnO and N-ZrO2. Less oxidative reactive species such as superoxide radical and singlet oxygen play a major role in the degradation of R6G under visible light. On the contrary, highly oxidative hydroxyl radicals are predominant under UVC light. Based on the kinetic study, the adsorption of R6G on the catalyst surface is found to be the controlling step.

This is a preview of subscription content, log in to check access.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5


  1. Alford R, Simpson HM, Duberman J, Hill GC, Ogawa M, Regino C, Kobayashi H, Choyke PL (2009) Toxicity of organic fluorophores used in molecular imaging: literature review. Mol Imaging 8:341

  2. Anderson C, Bard AJ (1995) An improved photocatalyst of TiO2/SiO2 prepared by a sol–gel synthesis. J Phys Chem 99:9882–9885

  3. Andreozzi R, Caprio V, Insola A, Marotta R (1999) Advanced oxidation processes (AOP) for water purification and recovery. Catal Today 53:51–59

  4. Antonopoulou M, Giannakas A, Deligiannakis Y, Konstantinou I (2013) Kinetic and mechanistic investigation of photocatalytic degradation of the N, N-diethyl-m-toluamide. Chem Eng J 231:314–325

  5. Buthelezi SP, Olaniran AO, Pillay B (2012) Textile dye removal from wastewater effluents using bioflocculants produced by indigenous bacterial isolates. Molecules 17:14260–14274

  6. Chu W, Wong C (2004) The photocatalytic degradation of dicamba in TiO2 suspensions with the help of hydrogen peroxide by different near UV irradiations. Water Res 38:1037–1043

  7. Dionysiou DD, Suidan MT, Bekou E, Baudin I, Laı̂né J-M (2000) Effect of ionic strength and hydrogen peroxide on the photocatalytic degradation of 4-chlorobenzoic acid in water. Appl Catal B Environ 26:153–171

  8. Doong R-A, Chang W-H (1998) Photodegradation of parathion in aqueous titanium dioxide and zero valent iron solutions in the presence of hydrogen peroxide. J Photochem Photobiol A Chem 116:221–228

  9. Georgekutty R, Seery MK, Pillai SC (2008) A highly efficient Ag-ZnO photocatalyst: synthesis, properties, and mechanism. J Phys Chem C 112:13563–13570

  10. Ghazzal M, Kebaili H, Joseph M, Debecker DP, Eloy P, De Coninck J, Gaigneaux EM (2012) Photocatalytic degradation of Rhodamine 6G on mesoporous titania films: combined effect of texture and dye aggregation forms. Appl Catal B Environ 115:276–284

  11. Han J, Liu Y, Singhal N, Wang L, Gao W (2012) Comparative photocatalytic degradation of estrone in water by ZnO and TiO2 under artificial UVA and solar irradiation. Chem Eng J 213:150–162

  12. Ji P, Zhang J, Chen F, Anpo M (2009) Study of adsorption and degradation of acid orange 7 on the surface of CeO2 under visible light irradiation. Appl Catal B Environ 85:148–154

  13. Konstantinou IK, Albanis TA (2004) TiO2-assisted photocatalytic degradation of azo dyes in aqueous solution: kinetic and mechanistic investigations: a review. Appl Catal B Environ 49:1–14

  14. Li X, Chen C, Zhao J (2001) Mechanism of photodecomposition of H2O2 on TiO2 surfaces under visible light irradiation. Langmuir 17:4118–4122

  15. Lutic D, Coromelci-Pastravanu C, Cretescu I, Poulios I, Stan C-D (2012) Photocatalytic treatment of Rhodamine 6G in wastewater using photoactive ZnO. Int J Photoenergy, Article ID 475131.

  16. Ma H, Wallis LK, Diamond S, Li S, Canas-Carrell J, Parra A (2014) Impact of solar UV radiation on toxicity of ZnO nanoparticles through photocatalytic reactive oxygen species (ROS) generation and photo-induced dissolution. Environ Pollut 193:165–172

  17. Moezzi A, Cortie M, McDonagh A (2011) Aqueous pathways for the formation of zinc oxide nanoparticles. Dalton Trans 40:4871–4878

  18. Nashim A, Parida K (2013) Novel Sm2Ti2O7/SmCrO3 heterojunction based composite photocatalyst for degradation of Rhodamine 6G dye. Chem Eng J 215:608–615

  19. Ollis DF, Pelizzetti E, Serpone N (1991) Photocatalyzed destruction of water contaminants. Environ Sci Technol 25:1522–1529

  20. Quesada-Cabrera R, Sotelo-Vazquez C, Darr J, Parkin IP (2014) Critical influence of surface nitrogen species on the activity of N-doped TiO2 thin-films during photodegradation of stearic acid under UV light irradiation. Appl Catal B Environ 160:582–588

  21. Robinson T, McMullan G, Marchant R, Nigam P (2001) Remediation of dyes in textile effluent: a critical review on current treatment technologies with a proposed alternative. Bioresour Technol 77:247–255

  22. Schmidt-Mende L, MacManus-Driscoll JL (2007) ZnO–nanostructures, defects, and devices. Materials Today 10:40–48

  23. Seery MK, George R, Floris P, Pillai SC (2007) Silver doped titanium dioxide nanomaterials for enhanced visible light photocatalysis. J Photochem Photobiol A Chem 189:258–263

  24. Tang J, Li D, Feng Z, Tan Z, Ou B (2014) A novel AgIO4 semiconductor with ultrahigh activity in photodegradation of organic dyes: insights into the photosensitization mechanism. RSC Advances 4:2151–2154

  25. Tantak NP, Chaudhari S (2006) Degradation of azo dyes by sequential Fenton’s oxidation and aerobic biological treatment. J Hazard Mater 136:698–705

  26. Thaler S, Haritoglou C, Choragiewicz TJ, Messias A, Baryluk A, May CA, Rejdak R, Fiedorowicz M, Zrenner E, Schuettauf F (2008) In vivo toxicity study of rhodamine 6G in the rat retina. Invest Ophthalmol Vis Sci 49:2120–2126

  27. Wang Y, Feng C, Zhang M, Yang J, Zhang Z (2011a) Visible light active N-doped TiO2 prepared from different precursors: origin of the visible light absorption and photoactivity. Appl Catal B Environ 104:268–274

  28. Wang Z, Yuan R, Guo Y, Xu L, Liu J (2011b) Effects of chloride ions on bleaching of azo dyes by Co2+/oxone regent: kinetic analysis. J Hazard Mater 190:1083–1087

  29. Yang L-Y, Dong S-Y, Sun J-H, Feng J-L, Wu Q-H, Sun S-P (2010) Microwave-assisted preparation, characterization and photocatalytic properties of a dumbbell-shaped ZnO photocatalyst. J Hazard Mater 179:438–443

Download references


The first author would like to thank Sirindhorn International Institute of Technology for financial support through EFS-Ph.D. scholarship.

Author information

Correspondence to Sandhya Babel.

Additional information

Responsible editor: Philippe Garrigues

Electronic supplementary material

Below is the link to the electronic supplementary material.


(PDF 135 kb)

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Sudrajat, H., Babel, S. Comparison and mechanism of photocatalytic activities of N-ZnO and N-ZrO2 for the degradation of rhodamine 6G. Environ Sci Pollut Res 23, 10177–10188 (2016).

Download citation


  • Reactive radical
  • Rhodamine 6G
  • Photocatalytic degradation
  • Nitrogen doping
  • Visible light active
  • UV irradiation