Effect of Solution pH on the Photo-Oxidation of 4-Chlorophenol by Synthesized Silver-Zinc Oxide Photocatalyst


Nur Syafiqa Hazirah Razali(1), Hayati Mohamad Mukhair(2), Kian Mun Lee(3), Mohd Izham Saiman(4), Abdul Halim Abdullah(5*)

(1) Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43300 UPM Serdang, Selangor Malaysia
(2) Institute of Nanoscience and Nanotechnology, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia
(3) Nanotechnology and Catalysis Research Centre (NANOCAT), University of Malaya, 50603 Kuala Lumpur, Malaysia
(4) Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43300 UPM Serdang, Selangor Malaysia
(5) Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43300 UPM Serdang, Selangor Malaysia; Institute of Nanoscience and Nanotechnology, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia
(*) Corresponding Author


Due to its toxicity, 4-chlorophenol (4CP) must be removed from the wastewater before discharging into open water. In this work, ZnO and Ag-ZnO photocatalysts were prepared via a solvothermal method under mild conditions (150 °C), followed by calcination at 300 °C and then characterized. The addition of Ag resulted in a change of the ZnO morphologies, which exhibited wurtzite structure, from irregular to rod-like shape, lower bandgap energy, and a lower electron-hole recombination rate. The 0.6 Ag-ZnO catalyst showed the highest efficiency in the photooxidation of 4CP under UV irradiation. Molecular 4CP exists in acidic and near-neutral conditions (pH 4 and 6) and is stable towards UV irradiation. Photooxidation of 2.3 × 10–4 mol/L 4CP by 0.8 g of 0.6% Ag-ZnO resulted in 67% removal of molecular 4CP at pH 6 with a rate constant of 4.0 × 10–3 min–1. Under similar conditions, a complete photooxidation of the anionic 4CP was observed at pH 11 with a rate constant of 1.4 × 10–2 min–1. The holes and superoxide radicals are the species responsible for molecular 4CP photoooxidation, while hydroxyl radicals are the dominant species for anionic 4CP. The prepared Ag/ZnO photocatalyst exhibit good potential to efficiently oxidize 4CP in both acidic and alkaline conditions.


Ag-ZnO; photooxidation; 4-chlorophenol; endocrine disruptor chemicals; photocatalyst

Full Text:

Full Text PDF


[1] Castañeda, C., Tzompantzi, F., Gómez, R., and Rojas, H., 2016, Enhanced photocatalytic degradation of 4-chlorophenol and 2,4-dichlorophenol on in situ phosphated sol-gel TiO2, J. Chem. Technol. Biotechnol., 91 (8), 2170–2178.

[2] Lavand, A.B., and Malghe, Y.S., 2015, Visible light photocatalytic degradation of 4-chlorophenol using C/ZnO/CdS nanocomposite, J. Saudi Chem. Soc., 19 (5), 471–478.

[3] Mahrouqi, H.K.N., Nawi, M.A., and Nawawi, W.I., 2014, Photodegradation of 4-chlorophenol using carbon coated TiO2 under solar irradiation, Int. J. Sci. Res. Publ., 4 (6), 1–7.

[4] Munshi, G.H., Ibrahim, A.M., and Al-Harbi, L.M., 2018, Inspired preparation of zinc oxide nanocatalyst and the photocatalytic activity in the treatment of methyl orange dye and paraquat herbicide, Int. J. Photoenergy, 2018, 5094741.

[5] Li, L., Sun, S.Q., Wang, Y.X., and Wang, C.Y., 2018, Facile synthesis of ZnO/g-C3N4 composites with honeycomb-like structure by H2 bubble templates and their enhanced visible light photocatalytic performance, J. Photochem. Photobiol., A, 355, 16–24.

[6] Mendoza-Mendoza, E., Nuñez-Briones, A.G., García-Cerda, L.A., Peralta-Rodríguez, R.D., and Montes-Luna, A.J., 2018, One-step synthesis of ZnO and Ag/ZnO heterostructures and their photocatalytic activity, Ceram. Int., 44 (6) 6176–6180.

[7] Kavitha, R., and Kumar, S.G., 2019, A review on plasmonic Au-ZnO heterojunction photocatalysts: Preparation, modifications and related charge carrier dynamics, Mater. Sci. Semicond. Process., 93, 59–91.

[8] Jefri, S.N.S., Abdullah, A.H., and Muhamad, E.N., 2019, Response surface methodology: photodegradation of methyl orange by CuO/ZnO under UV light irradiation, Asian J. Green Chem., 3 (2), 271–287.

[9] He, R., Hocking, R.K., and Tsuzuki, T., 2012, Co-doped ZnO nanopowders: Location of cobalt and reduction in photocatalytic activity, Mater. Chem. Phys., 132 (2-3) 1035–1040.

[10] Ravishankar, T.N., Manjunatha, K., Ramakrishnappa, T., Nagaraju, G., Kumar, D., Sarakar, S., Anandakumar, B.S., Chandrappa, G.T., Reddy, V., and Dupont, J., 2014, Comparison of the photocatalytic degradation of trypan blue by undoped and silver-doped zinc oxide nanoparticles, Mater. Sci. Semicond. Process., 26, 7–17.

[11] Sapian, N.A.M., Nor, R.M., Rafaie, H.A., Sani, S.F.A., and Osman, Z., 2018, Photocatalytic degradation of methylene blue with silver doped ZnO nanoparticles grown on microscopic sand particles, Malaysi. J. Anal. Sci., 22 (2), 270–278.

[12] Chitradevi, T., Lenus, A.J., and Jaya, N.V., 2020, Structure, morphology and luminescence properties of sol-gel method synthesized pure and Ag-doped ZnO nanoparticles, Mater. Res. Express, 7, 015011.

[13] AL-Jawad, S.M.H., Sabeeh, S.H., Taha, A.A., and Jassim, H.A., 2018, Studying structural, morphological and optical properties of nanocrystalline ZnO:Ag films prepared by sol–gel method for antimicrobial activity, J. Sol-Gel Sci. Technol., 87 (2), 362–371.

[14] Alshamsi, H.A.H., and Hussein, B.S., 2018, Hydrothermal preparation of silver doping zinc oxide nanoparticles: Study, characterization and photocatalytic activity, Orient. J. Chem., 34 (4) 1898–1907.

[15] Behera, T.K., Pradhan, S., Satapathy, P.K., and Mohapatra, P., 2021, Synthesis and characterization of ZnO-Ag plasmonic nanocomposite: An efficient photocatalyst for the degradation industrial pollutant, Mater. Today: Proc., 47, 1159–1162.

[16] Singh, R., Barman, P.B., and Sharma, D., 2017, Synthesis, structural and optical properties of Ag doped ZnO nanoparticles with enhanced photocatalytic properties by photo degradation of organic dyes, J. Mater. Sci.: Mater. Electron., 28 (8), 5705–5717.

[17] Shojaei, A.F., Tabatabaeian, K., Zanjanchi, M.A., Moafi, H.F., and Modirpanah, N., 2015, Synthesis, characterization and study of catalytic activity of silver doped ZnO nanocomposite as an efficient catalyst for selective oxidation of benzyl alcohol, J. Chem. Sci., 127 (3), 481–491.

[18] Rasaki, S.A., Zhao, C., Wang, R., Wang, J., Jiang, H., and Yang, M., 2019, Facile synthesis approach for preparation of robust and recyclable Ag/ZnO nanorods with high catalytic activity for 4-nitrophenol reduction, Mater. Res. Bull., 119, 110536.

[19] Xu, Z., Liu, N., Han, Y., Zhang, P., Hong, Z., and Li, J., 2021, Preparation of Ag/ZnO microspheres and study of their photocatalytic effect on dichloromethane, Desalin. Water Treat., 216, 162–169.

[20] Ong, C.B., Ng, L.Y., and Mohammad, A.W., 2018, A review of ZnO nanoparticles as solar photocatalysts: Synthesis, mechanisms, and applications, Renewable Sustainable Energy Rev., 81 (1), 536–551.

[21] Igbinosa, E.O, Odjadjare, E.E., Chigor, V.N., Igbinosa, I.H., Emoghene, A.O., Ekhaise, F.O., and Idemudia, O.G., 2013, Toxicological profile of chlorophenols and their derivatives in the environment: The public health perspective, Sci. World J., 2013, 460215.

[22] Byrne, C., Subramanian, G., and Pillai, S.C., 2018, Recent advances in photocatalysis for environmental applications, J. Environ. Chem. Eng., 6 (3), 3531–3555.

[23] de Moraes, N.P., Marins, L.G.P., de Moura Yamanaka, M.Y., Bacani, R., da Silva Rocha, R., and Rodrigues, L.A., 2021, Efficient photodegradation of 4-chlorophenol under solar radiation using a new ZnO/ZnS/carbon xerogel composite as a photocatalyst, J. Photochem. Photobiol., A, 418, 113377.

[24] Rajendran, S., Pachaiappan, R., Hoang, T.K.A., Karthikeyan, S., Gnanasekaran, L., Vadivel, S., Soto-Moscoso, M., and Gracia-Pinilla, M.A., 2021, CuO-ZnO-PANI a lethal p-n-p combination in degradation of 4-chlorophenol under visible light, J. Hazard. Mater., 416, 125989.

[25] Welderfael, T, Yadov, O.P., Taddesse, A.M., and Kaushal, J., 2013, Synthesis, characterization and photocatalytic activities of Ag-N-codoped ZnO nanoparticles for degradation of methyl red, Bull. Chem. Soc. Ethiop., 27 (2), 221–232.

[26] Lupan, O, Chow, L., Ono, L.K., Cuenya, B.R., Chai, G., Khallaf, H., Park, S., and Schulte, A., 2010, Synthesis and characterization of Ag- or Sb-doped ZnO nanorods by a facile hydrothermal route, J. Phys., Chem. C, 114 (29), 12401–12408.

[27] Jung, D., 2010, Syntheses and characterization of transition metal-doped ZnO, Solid State Sci., 12 (4), 466–470.

[28] Fatima, S., Ali, S.I., Iqbal, M.Z., and Rizwan, S., 2017, The high photocatalytic activity and reduced band gap energy of La and Mn co-doped BiFeO3/graphene nanoplatelet (GNP) nanohybrids, RSC Adv., 7 (57), 35928–3593.

[29] Murali, A., Sarswat, P.K., Perez, J.P.L., and. Free, M.L, 2020, Synergetic effect of surface plasmon resonance and schottky junction in Ag-AgX-ZnO-rGO (X= Cl & Br) nanocomposite for enhanced visible-light driven photocatalysis, Colloids Surf., A, 595, 124684.

[30] Patil, S.S., Mali, M.G., Tamboli, M.S., Patil, D.R., Kulkarni, M.V., Yoon, H., Kim, H., Al-Deyab, S.S., Yoon, S.S., Kolekar, S.S., and Kale, B.B., 2016, Green approach for hierarchical nanostructured Ag-ZnO and their photocatalytic performance under sunlight, Catal. Today, 260, 126–134.

[31] Zhang, X., Wang, Y., Hou, F., Li, H., Yang, Y., Zhang, X., Yang, Y., and Wang, Y., 2017, Effects of Ag loading on structural and photocatalytic properties of flower-like ZnO microspheres, Appl. Surf. Sci., 391, 476–483.

[32] Jia, Z., Peng, K., Li, Y., and Zhu, R., 2012, Preparation and photocatalytic performance of porous ZnO microrods loaded with Ag, Trans. Nonferrous Met. Soc. China, 22 (4), 873–878.

[33] Dehdar, A., Asgari, G., Leili, M., Madrakian, T., and Seid-mohammadi, A., 2021, Step-scheme BiVO4/WO3 heterojunction photocatalyst under visible LED light irradiation removing 4-chlorophenol in aqueous solutions, J. Environ. Manage., 297, 113338.

[34] Matafonova, G., Philippova, N., and Batoev, V., 2011, The effect of wavelength and pH on the direct photolysis of chlorophenols by ultraviolet excilamps, Eng. Lett., 19 (1), 20–23.

[35] Kumar, T.K.M.P., Mandlimath, T.R., Sangeetha, P., Sakthivel, P., Revathi, S.K., Kumar, S.K.A., and Sahoo, S.K., 2015, Highly efficient performance of activated carbon impregnated with Ag, ZnO, and Ag/ZnO nanoparticle as antimicrobial materials, RSC Adv., 5 (130), 108034–108043.

DOI: https://doi.org/10.22146/ijc.71763

Article Metrics

Abstract views : 2417 | views : 1079

Copyright (c) 2022 Indonesian Journal of Chemistry

Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.


Indonesian Journal of Chemistry (ISSN 1411-9420 /e-ISSN 2460-1578) - Chemistry Department, Universitas Gadjah Mada, Indonesia.

Analytics View The Statistics of Indones. J. Chem.