J Clust Sci DOI 10.1007/s10876-017-1175-3 ORIGINAL PAPER Rapid Synthesis and Characterization of Zinc Oxide Nanoparticles with Albumen as Photodegradation of Congo Red Under Microwave Irradiation Faezeh Farzaneh1 • Zahra Asgharpour1 Fatemeh Nouroozi1 • Sara Haghshenas1 • Received: 3 December 2016  Springer Science+Business Media New York 2017 Abstract In this study, ZnO nanoparticles were synthesized using metal acetate, egg white as bio-template in water under microwave irradiation followed by calcination at 700 C. The obtained ZnO nanoparticles with hexagonal wurtzite structure were characterized by XRD, SEM, TEM, TGA/DSC, FT-IR techniques. The photocatalytic activity of ZnO nanoparticles was evaluated by photocatalytic degradation of Congo red as organic dye pollutant under UV-light irradiation within 40 min. It was found that, the kinetic of photocatalytic behaviour of ZnO is first order. The stability and reusability of the prepared catalyst was considerable. Keywords ZnO nanoparticles
Bio-template
Photo catalytic activity
Congo red Introduction Dye pollutants from the textile industry are an important source of environmental contamination [1]. Releasing of these colored wastewaters in the ecosystem is a dramatic source of aesthetic pollution, eutrophication and perturbations in aquatic life [2]. In order to reduce the risk of environmental pollution from wastewater, it is necessary to treat them before discharging it into the environment. A number of technologies have been developed and used for removal of the dye contaminants from wastewater; including adsorption [3], coagulation/flocculation [4], advanced oxidation processes (AOPs) [5], ozonation [6], membrane filtration [7] and biological treatment [8]. AOPs oxidize a broad range of organic pollutants quickly and non-selectively. Among AOPs, heterogeneous photocatalysts has received & Faezeh Farzaneh faezeh_farzaneh@yahoo.com; farzaneh@alzahra.ac.ir 1 Department of Chemistry, Faculty of Physics and Chemistry, Alzahra University, Vanak, Tehran, P. O. Box 1993891176, Iran 123 F. Farzaneh et al. considerable attention for the degradation of various families of organic pollutants, including the dyes [9]. ZnO is a semiconductor with a wide band gap (3.3 eV), n-type conductivity, abundant in nature and environmentally friendly. These characteristics make this material attractive for many applications, such as solar cells [10], photo catalysts [11], electrical devices [12] and in gas sensors [13]. In recent years, nano-ZnO, as an excellent semiconductor photocatalyst, was prepared and used in treatment of dye wastes, because different morphology, crystallite size and crystallographic orientation of the photocatalyst affects the photocatalytic activity. Morphology controlled growth is one of the important steps in the fabrication of ZnO nanostructures. There are numerous described methods to the synthesis of ZnO nanostructures such as electrochemical deposition [14], sol–gel process [15, 16], microwave irradiation [17], hydrothermal process [18, 19], laser ablation [20] and precipitation [21]. Amongst these, microwave irradiation is efficient, cost effective and easy to manipulate. However, simple synthetic routs using bio-templates are interested because of their natural quality and abundance leading to a simple and low cost process. Egg white proteins (Albumen) are well known for their gelling and foaming characteristics. Due to its solubility in water and good ability to associate with metal ions in solution, it can be a good template for both synthesis and stabilization of nanostructure metal oxides [22]. In this study, synthesis of zinc oxide nanoparticles using egg white albumen as a biotemplate under microwave irradiation and its photocatalytic activity as photocatalyst for degradation of Congo red (CR) in the presence of UV light is described. Experimental Materials All the chemical reagents used in our experiments were of analytical grade and used without further purification. Zinc acetate dihydrated and Cr were purchased from Merck Chemical company. Synthesis ZnO Nanoparticles In a typical procedure, egg white albumen (1.5 g) was slowly added into a magnetically stirred solution of Zn (II) acetate (25 mg, 0.136 mmol). After 10 min, the resulting foam was irradiated by microwave for 1 min. Finally, the white product was dried at room temperature and calcinated at 700 C for 3 h. Experimentally, utilization of Zn salt to albumen ratios of 1/5, 1/10/, 1/15, 1/30 and 1/60 revealed that the optimized result is obtained using the last ratio. 123 Rapid Synthesis and Characterization of Zinc Oxide Nanoparticles… Photo Catalytic Activity Determination Catalytic activity of the prepared ZnO nanoparticles was evaluated by the degradation of CR. In a typical procedure, the prepared ZnO (0.05 g) was added to the solution of CR (5 ppm, in 100 mL deionized water). A 30 W UV-lamp was used as light source. The distance between the UV lamp reaction flask was fixed at 8 cm. Air was bubbled into the solution throughout the entire experiment to provide a constant source of dissolved oxygen. The dye solution was continuously stirred with a magnetic stirrer. Prior to irradiation, the set up was kept in the dark for approximately 15 min in order to reach an adsorption/desorption equilibrium among the photocatalyst particles, Cr and atmospheric oxygen. During irradiation, the degraded dye was sampled in regular intervals. The photocatalytic degradation was monitored by measuring the absorbance of the solution samples with UV–Vis spectrophotometer. Characterization The resulting white powder was characterized with XRD (Philips PW 1800 diffractometer using Cu Ka radiation), SEM (Hitachis-4160), TEM (Philips CM120, 120 kV), FT-IR(BRUKER, Tensor 27 DTGS, 400–4000 nm), PL photoluminescence (CaryEclipse–Fluoresence spectrophotometer, Xe lamp), TGA/DSC (STA 1500) and UV–Vis (perkin Elmer lamda35, double beam spectrophotometer). Results and Discussion In this study ZnO nanoparticles was prepared with Zn(II) acetate and albumin in water as solvent under microwave irradiation followed by calcination at 700 C. The XRD pattern of the zinc oxide nanoparticles as white powder is shown in Fig. 1. The peaks at scattering angles of 31.56, 34.48, 36.22, 45.42, 56.49, 62.87, 66.42, 67.88 and 69.11(2h) correspond to the crystal plans of 100, 002, 101, 102, Fig. 1 The XRD pattern of the synthesised ZnO nanoparticles 123 F. Farzaneh et al. 110, 103, 200, 112 and 201 respectively is matched with JCPD standard card No.361451. The obtained results confirm the formation of ZnO nanoparticles with wurtzite- like structure. (with P63mc space group, unit cell parameters: a = 0.324 nm, c = 0.5192 nm and Z = 2). Typical SEM, TEM and EDX pattern of ZnO/albumen hybrid are shown in Fig. a–c, respectively. The SEM results shows the uniform particle size with 40–50 nm. The TEM image approves the formation of nanoparticles with hexagonal prism structure, consistent with XRD results. The EDX spectra confirm the presence of Zn in sample (Fig. 2c). In order to reveal the changes occur during heat treatment of the prepared hybrid powder, the thermal behaviour up to 800 C was investigated by TGA/DSC. A typical profile of the as-prepared Zn(II)/albumen hybrid is shown in Fig. 3. The thermal decomposition takes place in three steps. The first endothermic process, with weight loss of 5%, is observed up to 100 C and can be assigned to the loss of the weakly bonded water molecules. The second exothermic event occurred in a much broader temperature range of 250–400 C, encompassing a weight loss of 42%, consistent with the decomposition of the albumen template. The third process occurs at temperature range of 460–560 C, perhaps due to the organic residue Fig. 2 a SEM and b TEM images and c EDX spectra of ZnO nanoparticles 123 Rapid Synthesis and Characterization of Zinc Oxide Nanoparticles… Fig. 3 TGA and DSC curves of as-prepared Zn(II)/albumen hybrid Fig. 4 FTIR spectra of a albumen, b as-prepared Zn(II)/albumen hybrid, c nano particle of ZnO obtained after calcination at 700 C, for 3 h decomposition (38%), leading to the formation of zinc oxide with wurtzite-like structure, which is stable up to 800 C. This reaction is consistent with the sharp exothermic peak observed in the corresponding DSC curve. 123 F. Farzaneh et al. The FTIR spectra of pure albumen, as-prepared Zn(II)/albumen hybrid and ZnO nanoparticles are shown in Fig. 4a–c, respectively. The characteristic peaks of albumen appeared at 3250, 3050, 2950, 1725 and 1622 cm-1, are attributed to O–H, N–H, C–H, C=O and C=C stretching vibrational modes, respectively (Fig. 4a). The corresponding peaks in Zn(II)/albumen hybrid shifted to shorter wavenumbers and appeared at 3200, 2987, 2850, 1675 and 1525 cm-1 respectively (Fig. 4b), confirm the presence of the biotemplate in the hybrid material. After heat treatment up to 700 C for 3 h, these peaks disappeared (Fig. 4c), indicating the decomposition of the biotemplate and formation of ZnO. The strong absorption band displaying at 650 cm-1 is due to Zn–O vibrations in nanoparticles [23]. A broad band appearing at 3250 cm-1 is related either to water or hydroxyl groups adsorbed on the ZnO surface. This proposal is confirmed by observation of signals at 1287 and 1100 cm-1, due to the bending modes of hydroxyl groups [24]. The UV–Vis spectrum of the as-synthesized ZnO nanoparticles dispersed in ethanol, showed a broad absorption band at 374 nm (Fig. 5). No such absorption was observed in the UV–Vis spectrum of bulk ZnO [25]. PL signals of the prepared ZnO is shown in Fig. 6. In most cases, it consists an ultra violet emission peak in the range of 370–390 nm, together with a broad visible emission band centered at around 500–560 nm, associated with oxygen vacancies [26, 27]. Whereas the UV emission band appears at about 386 nm is due to the recombination of photo generated electrons and holes, the blue and blue-green emission peaks display at 408, 435 and 485, 520, 541 nm, respectively are possibly associated with oxygen vacancies (Fig. 6) [28, 29]. Fig. 5 UV–Vis spectra of nano particle of ZnO 123 Rapid Synthesis and Characterization of Zinc Oxide Nanoparticles… Fig. 6 PL spectra of ZnO nano particles Photocatalytic Activity The photocatalytic activity of the prepared ZnO nanoparticles was evaluated by degredation of CR (Fig. 7). The UV–Vis spectrum of CR shows two maximum absorption at 347 and 497 nm. Upon irradiation of UV light onto the aqueous solution of CR with ZnO nanoparticles, the two bands due to the azo linkage and naphthalene ring at 374 nm decreased within 40 min and finally disappeared. Therefore, destruction of chromophor in the vicinity of azo-linkage has occurred during 40 min. The photodegredation percentage with and without ZnO nanoparticles are compared in Fig. 7a, b, respectively. Based on the obtained results, whereas 22% of CR was phtodegreded after 1 h in the absence of ZnO catalyt, photocatalytic degredation proceeded to completion in 40 min. The photocatalytic Fig. 7 Variation of the UV absorption spectra of Congo red solution in the presence of ZnO nano particles a efficiency of photo degradation (%) as a function of time at 497 nm (b) 123 F. Farzaneh et al. efficiency is expressed in terms of percent of degredation using the following equation: Percent of degredation ¼ ½ðC0 C=C0 Š  100 ð1Þ or ¼ ½ðA0 A=A0 ފ  100 where C0 represents the initial concentrations of the CR, C is the concentration after illuminating by UV–Vis light. A and A0 is the initial and variable absorbance respectively. In fact the addition of catalyst leads to obvious degredation of CR. The heterogeneous photocatalysis kinetic models have proven to obey the Langmuir–Hinshelwood (L–H) kinetic (Eq. 2) [30, 31]. r ¼ d C =d t ¼ k KC= 1 þ KC ð2Þ where r, C, t, k and K are reactant oxidation rate (mg/l min), reactant concentration (mg/l), illumination time (s), reaction rate constant (mg/l min) and reactant adsorption coefficient (l/mg), respectively. If one works with low initial concentrations, the equation is simplified to an apparent first-order equation (Eq. 3). Ln ðC0 =CÞ ¼ k t ð3Þ where C0 and C are the dye concentrations at zero and t time, respectively. A plot of Ln C0/C versus time then represents a straight line, the slope of which upon linear regression equals the apparent first-order rate constant k. As illustrated in Fig. 8, a plot of Ln (C0/C) versus irradiation time of CR using ZnO nanoparticles as catalyst was linear (correlation constant, R2 = 0.99828). Therefore, it can be concluded that the photo degradation reaction follows the first order kinetic. The slopes of Ln (C0/C) versus time plots in optimized conditions gives k = 0.0397 min-1 as the corresponding rate constant. Fig. 8 The relationship between ln C0/C and time of Congo red solution 123 Rapid Synthesis and Characterization of Zinc Oxide Nanoparticles… The photocatalytic activity involves the generation of conduction band electrons and valence band holes on the surface of the ZnO nanoparticles aqueous suspension under UV irradiation (Eq. 4). The photoelectrons trapped by adsorbed O2 followed by reduction to superoxide radicals (Eq. 5) and holes at the ZnO valence band can oxidize adsorbed water or hydroxide ions to hydroxyl radicals (Eqs. 6 and 7) to further oxidize dye pollutant (Eq. 8) [32, 33]. ZnO þ hmðUV lightÞ ! eCB þ hþ VB ð4Þ eCB þ O2 ! O
2 ð5Þ þ
hþ VB þ H2 O ! H þ OH ð6Þ
hþ VB þ OH ! OH ð7Þ O
2 þ OH
þ dye ! degraded dye ð8Þ Generally, recombination of electron–hole pairs would decrease the photocatalytic activity. In ZnO crystallinity, defects of oxygen vacancy can act as the recombination centres to capture photoelectrons [34]. Conclusion Zinc oxide nanoparticles with size distribution of 40-50 nm were synthesized using metal salt, egg white (albumen) as a biotemplate under microwave irradiation followed by calcination up to 700 C. The white product characterized by different techniques as ZnO nanoparticles successfully catalyse the photodegradation of Congo red (CR) within 40 min. It was found that, the kinetic of photocatalytic behavior of ZnO is first order. The stability and reusability of the prepared catalyst was considerable. In conclusion, we have developed a simple, cost-effective, and environmentally friendly synthesized method using water soluble egg white proteins. Acknowledgements The financial support from the Alzahra University is gratefully acknowledged. References 1. C. Galindo, P. Jacques, and A. Kalt (2001). Chemosphere 45, 997–1005. 2. J.-M. Herrmann, M. Vautier, and C. Guillard (2001). J. Catal. 201, 46–59. 3. Z. Karim, A. P. Mathew, M. Grahn, J. Mouzon, and K. Oksman (2014). Carbohydr. Polym. 112, 668–676. 4. K. L. Yeap, T. T. Teng, B. T. Poh, N. Morad, and K. E. Lee (2014). Chem. Eng. J. 243, 305–314. 5. A. A. P. Mansur, H. S. Mansur, F. P. Ramanery, L. C. Oliveira, and P. P. Souza (2014). Appl. Catal. B 158–159, 269–279. 6. S. Wijannarong, S. Aroonsrimorakot, P. Thavipoke, A. Kumsopa, and S. Sangjan (2013). APCBEE Procedia. 5, 279–282. 7. Y. Zheng, G. Yao, Q. Cheng, S. Yu, M. Liu, and C. Gao (2013). Desalination 328, 42–50. 123 F. Farzaneh et al. 8. S. M. de A. G. U. de Souza, K. A. S. Bonilla, and A. A. U. de Souza (2010). J. Hazard. Mater. 179, 35–42. 9. P. Banerjee, S. DasGupta, and S. De (2007). J. Hazard. Mater. 140, 95–103. 10. C. Biswas, Z. Ma, X. Zhu, T. Kawaharamura, and K. L. Wang (2016). Sol. Energy Mater. Sol. Cells. 157, 1048–1056. 11. J. Wang, Y. Xia, Y. Dong, R. Chen, L. Xiang, and S. Komarneni (2016). Appl. Catal. B 192, 8–16. 12. Y. Zeng, Y. Zhao, and Y. Jiang (2016). J. Alloys Compd. 671, 579–584. 13. V. L. Patil, S. A. Vanalakar, P. S. Patil, and J. H. Kim (2017). Sens. Actuators B 239, 1185–1193. 14. B. E. Filali, T. V. Torchynska, G. Polupan, and L. Shcherbyna (2017). Mater. Res. Bull. 85, 161–167. 15. B. Astinchap, R. Moradian, and M. Nasseri Tekyeh (2016). Optik. 127, 9871–9877. 16. L. I. Ali, S. A. El-Molla, M. M. Ibrahim, H. R. Mahmoud, and M. A. Naghmash (2016). Opt. Mater. 58, 484–490. 17. A. Phuruangrat, T. Thongtem, and S. Thongtem (2014). Ceram. Int. 40, 9069–9076. 18. Y. Zhou, C. Liu, X. Zhong, H. Wu, M. Li, and L. Wang (2014). Ceram. Int. 40, 10415–10421. 19. Y. Xua, J. Jin, X. Li, Y. Han, H. Meng, T. Wang, and X. Zhang (2016). Mater. Res. Bull. 76, 235–239. 20. K. N. Abbas, N. Bidin, and R. S. Sabry (2016). Ceram. Int. 42, 13535–13546. 21. R. Pandimurugan and S. Thambidurai (2016). Adv. Powder Technol. 27, 1062–1072. 22. S. Maensiri, C. Masingboon, P. Lackal, W. Jareonboon, V. Promarak, P. L. Anderson, and S. Seraphin (2007). Cryst. Growth Des. 7, 950–955. 23. J. Li, X. Zhao, C. Yan, and L. Yijing (2008). Mater. Chem. Phys. 107, 177–182. 24. Q. Li, V. Kumar, Y. Li, H. Zhang, T. J. Marks, and R. P. H. Chang (2005). Chem. Mater. 17, 1001–1006. 25. F. Nouroozi and F. Farzaneh (2011). J. Braz. Chem. Soc. 22, 484–488. 26. J. J. Wu and S. C. Liu (2002). Adv. Mater. 14, 215–218. 27. K. Vanheusden, W. L. Warren, C. H. Seager, D. R. Tallant, J. A. Voigt, and B. E. Gnade (1996). J. Appl. Phys. 79, 7983–7990. 28. P. Yang, H. Yan, S. Mao, R. Russo, J. Johnson, R. Saykally, N. Morris, J. Pham, R. He, and H. J. Choi (2002). J. Adv. Funct. Mater. 12, 323–331. 29. P. Jiang, J. J. Zhou, H. F. Fang, C. Y. Wang, Z. L. Wang, and S. S. Xie (2007). Adv. Funct. Mater. 17, 1303–1310. 30. J. B. De Heredia, J. Torregrosa, J. R. Dominguez, and J. A. Peres (2001). J. Hazard. Mater. 83, 255–264. 31. C. S. Chiou, J. L. Shie, C. Y. Chang, C. C. Liu, and C. T. Chang (2006). J. Hazard. Mater. 137, 1123–1129. 32. J. Liqiang, Q. Yichun, W. Baiqi, L. Shudan, J. Baojiang, Y. Libin, F. Wei, F. Honggang, and S. Jiazhong (2006). Sol. Energy. Mater. Sol. Cells. 90, 1773–1787. 33. M. Pera-Titus, V. G. Molina, M. A. Banos, J. Gimenz, and S. Esplugas (2004). Appl. Catal. B Environ. 47, 219–256. 34. Z. Zhu, D. Yang, and H. Liu (2011). Adv. Powder Technol. 22, 493–497. 123