Degradation of Toluene in Treatment of Refinery Wastewater by Photocatalytic Oxidation Technology in a Bubble Column Reactor Using ZnO-TiO2 Composite Nanocatalyst and Packing Material

Huda H. Al-Muqhdadi; karrar A. Deabl

doi:10.52716/jprs.v16i1.1125

Authors

Huda H. Al-Muqhdadi Branch of Najaf Gas, State Company for Gas Filling and Services, Ministry of Oil, Najaf, Iraq.
karrar A. Deabl Najaf Refinery, Midland Refineries Company, Ministry of Oil, Najaf, Iraq

DOI:

https://doi.org/10.52716/jprs.v16i1.1125

Keywords:

Toluene removal; oxidation reaction; Bubble column reactor; ZnO–TiO₂ nanocatalyst; packing material; hydroxyl radicals.

Abstract

Oxidation bubble column reactors (BCRs) are useful for treating wastewater because of their effective mass transfer and mixing capabilities. However, because of the low oxidation level of the pollutants, the BCRs' ability to remove toluene is restricted. A packing material and a ZnO-TiO₂ composite nanocatalyst in the BCR were used in this study to improve the degradation of toluene. Additionally, the superficial gas velocity (i.e., 0.4, 0.8, 1.2, 1.6, 2, 2.4, and 2.8 cm/s) was used to assess the gas holdup, pressure decrease, and diameter of the bubble. The optimal superficial gas velocity was determined to be 2.4 cm/s. Using packing materials and a ZnO-TiO₂ composite nanocatalyst in the BCR, a total (100 %) removal of toluene was accomplished at toluene concentrations of 10, 20, 30, and 40 ppm at reaction periods of 50, 60, 70, and 80 minutes, respectively. Additionally, two ZnO-TiO₂ composite nanocatalyst dosages (i.e., 0.04 and 0.12 g/L) were added to the reaction mixture; the ideal dose was determined to be 0.12 g/L. Therefore, four treatment methods (air and H₂O₂) alone, (air and H₂O₂/ packing), (air and H₂O₂/ZnO-TiO₂ composite nanocatalyst), and (air and H₂O₂/ packing/ZnO-TiO₂ composite nanocatalyst) were used to evaluate four toluene concentrations in the BCR (i.e., 10, 20, 30, and 40 ppm). Last but not least, the results gave a clear reaction mechanism explaining the oxides BCR, and the applied treatment process can be employed effectively to remove toluene from wastewater at a cheap cost, with minimal energy consumption, and with a straightforward operation.

References

M. Al-Nuaim, A. A. Al-Wasiti, Z. Y. Shnain, and A. K. Al-Shalal, “The combined effect of bubble and photo catalysis technology in BTEX removal from produced water”, Bull. Chem. React. Eng. Catal., vol. 17, no. 3, pp. 577–589, 2022. https://doi.org/10.9767/bcrec.17.3.15367.577-589.

S. Jafarinejad, "Petroleum waste treatment and pollution control", Butterworth-Heinemann, 2016.

A. K. Zanki, F. H. Mohammad, K. S. Hashim, M. Muradov, P. Kot, M. M. Kareem, and B. Abdulhadi, “Removal of organic matter from water using ultrasonic-assisted electrocoagulation method”, in IOP Conference Series: Materials Science and Engineering, IOP Publishing, vol. 888, no. 1, p. 012033, 2020. https://doi.org/10.1088/1757-899X/888/1/012033.

B. H. Diya’uddeen, W. M. A. W. Daud, and A. R. A. Aziz, “Treatment technologies for petroleum refinery effluents: A review”, Process Safety and Environmental Protection, vol. 89, no. 2, pp. 95–105, 2011. https://doi.org/10.1016/j.psep.2010.11.003.

M. M. Emamjomeh, S. Kakavand, H. A. Jamali, S. M. Alizadeh, M. Safdari, S. E. S. Mousavi, K. S. Hashim, and M. Mousazadeh, “The treatment of printing and packaging wastewater by electrocoagulation–flotation: the simultaneous efficacy of critical parameters and economics,” Desalination and Water Treatment, vol. 205, pp. 161–174, 2020. https://doi.org/10.5004/dwt.2020.26339.

M. M. Emamjomeh, M. Mousazadeh, N. Mokhtari, H. A. Jamali, M. Makkiabadi, Z. Naghdali, K. S. Hashim, and R. Ghanbari, “Simultaneous removal of phenol and linear alkylbenzene sulfonate from automotive service station wastewater: Optimization of coupled electrochemical and physical processes”, Separation Science and Technology, vol. 55, no. 17, pp. 3184–3194, 2020. https://doi.org/10.1080/01496395.2019.1675703.

S. D. César, D. De Jager, and M. Njoya, “Environmental trade-offs in energy production: A review of the produced water life cycle and environmental footprint”, Marine Pollution Bulletin, vol. 203, p. 116480, 2024. https://doi.org/10.1016/j.marpolbul.2024.116480.

I. Akmirza, C. Pascual, A. Carvajal, R. Pérez, R. Muñoz, and R. Lebrero, “Anoxic biodegradation of BTEX in a biotrickling filter”, Science of The Total Environment, vol. 587, pp. 457–465, 2017. https://doi.org/10.1016/j.scitotenv.2017.02.130.

J. Lu, X. Wang, B. Shan, X. Li, and W. Wang, “Analysis of chemical compositions contributable to chemical oxygen demand (COD) of oilfield produced water”, Chemosphere, vol. 62, no. 2, pp. 322–331, 2006. https://doi.org/10.1016/j.chemosphere.2005.04.033.

L. Mohammadi, A. Rahdar, E. Bazrafshan, H. Dahmardeh, M. A. B. H. Susan, and G. Z. Kyzas, “Petroleum hydrocarbon removal from wastewaters: a review”, Processes, vol. 8, no. 4, p. 447, 2020. https://www.mdpi.com/2227-9717/8/4/447#.

M. Caselli, G. de Gennaro, A. Marzocca, L. Trizio, and M. Tutino, “Assessment of the impact of the vehicular traffic on BTEX concentration in ring roads in urban areas of Bari (Italy)”, Chemosphere, vol. 81, no. 3, pp. 306–311, 2010. https://doi.org/10.1016/j.chemosphere.2010.07.033.

P. T. J. Scheepers, J. Konings, G. Demirel, E. O. Gaga, R. Anzion, P. G. M. Peer, T. Dogeroglu, S. Ornektekin, and W. Doorn, “Determination of exposure to benzene, toluene and xylenes in Turkish primary school children by analysis of breath and by environmental passive sampling”, Science of The Total Environment, vol. 408, no. 20, pp. 4863–4870, 2010. https://doi.org/10.1016/j.scitotenv.2010.06.037.

S. Bonvicini, G. Antonioni, P. Morra, and V. Cozzani, “Quantitative assessment of environmental risk due to accidental spills from onshore pipelines”, Process Safety and Environmental Protection, vol. 93, pp. 31–49, 2015. https://doi.org/10.1016/j.psep.2014.04.007.

P. Singh, A. Borthakur, N. Srivastava, R. Singh, D. Tiwary, and P. K. Mishra, “Photocatalytic degradation of benzene and toluene in aqueous medium”, Pollution, vol. 2, no. 2, pp. 199-210. 2016. https://doi.org/10.7508/pj.2016.02.008.

O. Fayemiwo, K. Moothi, and M. Daramola, “BTEX compounds in water–future trends and directions for water treatment”, Water Sa, vol. 43, no. 4, pp. 602–613, 2017. https://doi.org/10.4314/wsa.v43i4.08.

A. M. Ferrari-Lima, R. P. De Souza, S. S. Mendes, R. G. Marques, M. L. Gimenes, and N. R. C. Fernandes-Machado, “Photodegradation of benzene, toluene and xylenes under visible light applying N-doped mixed TiO2 and ZnO catalysts”, Catalysis Today, vol. 241, part A, pp. 40–46, 2015. https://doi.org/10.1016/j.cattod.2014.03.042.

S. W. Yao and H. P. Kuo, “Photocatalytic degradation of toluene on SiO2/TiO2 photocatalyst in a fluidized bed reactor”, Procedia Engineering, vol. 102, pp. 1254–1260, 2015. https://doi.org/10.1016/j.proeng.2015.01.254.

O. A. Nanadeinboemi, O. O. Fasanya, O. A. Ajayi, A. S. Olawale, and M. S. Olakunle, “Photocatalytic Degradation of Toluene (Component of Crude Oil) Contaminated Water Using Titanium Dioxide Based Catalyst: A Review”, Journal of Innovative Research, vol. 1, no. 1, pp. 4-11, 2023. https://doi.org/10.54536/jir.v1i1.1532.

R. A. Grmasha, O. J. Al-sareji, J. M. Salman, and K. S. Hashim, “Polycyclic aromatic hydrocarbons (PAHs) in urban street dust within three land-uses of Babylon governorate, Iraq: Distribution, sources, and health risk assessment”, Journal of King Saud University - Engineering Sciences, vol. 34, no. 4, pp. 231–239, 2022. https://doi.org/10.1016/j.jksues.2020.11.002.

K. S. Hashim, R. AlKhaddar, A. Shaw, P. Kot, D. Al-Jumeily, R. Alwash, and M. H. Aljefery, “Electrocoagulation as an eco-friendly River water treatment method”, in Advances in Water Resources Engineering and Management: Select Proceedings of TRACE 2018, Springer, pp. 219–235, 2019. https://doi.org/10.1007/978-981-13-8181-2_17.

F. S. Abdulraheem, Z. S. Al-Khafaji, K. S. Hashim, M. Muradov, P. Kot, and A. A. Shubbar, “Natural filtration unit for removal of heavy metals from water”, in IOP Conference Series: Materials Science and Engineering, IOP Publishing, p. 12034, 2020. https://doi.org/10.1088/1757-899X/888/1/012034

I. I. Omran, N. H. Al-Saati, K. S. Hashim, Z. N. Al-Saati, P. Kot, R. Al Khaddar, D. Al-Jumeily, A. Shaw, F. Ruddock, and M. Aljefery, “Assessment of heavy metal pollution in the Great Al-Mussaib irrigation channel”, Desalination and Water Treatment, vol. 168, pp. 165–174, 2019. https://doi.org/10.5004/dwt.2019.24600.

A. H. Mohammed, A. H. Hussein, D. Yeboah, R. Al Khaddar, B. Abdulhadi, A. A. Shubbar and K. S. Hashim, “Electrochemical removal of nitrate from wastewater”, in IOP Conference Series: Materials Science and Engineering, IOP Publishing, p. 12037, 2020. https://doi.org/10.1088/1757-899X/888/1/012037.

K. Aqeel, H. A. Mubarak, J. Amoako-Attah, L. A. Abdul-Rahaim, R. Al Khaddar, M. Abdellatif, A. Al-Janabi and K. S. Hashim “Electrochemical removal of brilliant green dye from wastewater”, in IOP Conference Series: Materials Science and Engineering, IOP Publishing, p. 12036, 2020. https://doi.org/10.1088/1757-899X/888/1/012036.

G. Alhakimi, L. H. Studnicki, and M. Al-Ghazali, “Photocatalytic destruction of potassium hydrogen phthalate using TiO2 and sunlight: application for the treatment of industrial wastewater”, Journal of Photochemistry and Photobiology A: Chemistry, vol. 154, no. 2–3, pp. 219–228, 2003. https://doi.org/10.1016/S1010-6030(02)00329-5.

S. Guo, Z. Yang, H. Zhang, W. Yang, J. Li, and K. Zhou, “Enhanced photocatalytic degradation of organic contaminants over CaFe2O4 under visible LED light irradiation mediated by peroxymonosulfate”, Journal of Materials Science & Technology, vol. 62, pp. 34–43, 2021. https://doi.org/10.1016/j.jmst.2020.05.057.

A. Haarstrick, O. M. Kut, and E. Heinzle, “TiO2-assisted degradation of environmentally relevant organic compounds in wastewater using a novel fluidized bed photoreactor”, Environmental Science & Technology, vol. 30, no. 3, pp. 817–824, 1996. https://doi.org/10.1021/es9502278.

D. W. Bahnemann, S. N. Kholuiskaya, R. Dillert, A. I. Kulak, and A. I. Kokorin, “Photodestruction of dichloroacetic acid catalyzed by nano-sized TiO2 particles”, Appl. Catal. B Environ., vol. 36, no. 2, pp. 161–169, 2002. https://doi.org/10.1016/S0926-3373(01)00301-0.

I. J. Ani, U. G. Akpan, M. A. Olutoye, and B. H. Hameed, “Photocatalytic degradation of pollutants in petroleum refinery wastewater by TiO2-and ZnO-based photocatalysts: recent development”, Journal of cleaner production, vol. 205, pp. 930–954, 2018. https://doi.org/10.1016/j.jclepro.2018.08.189.

D. R. Shinde, P. S. Tambade, M. G. Chaskar, and K. M. Gadave, “Photocatalytic degradation of dyes in water by analytical reagent grades ZnO, TiO2 and SnO2: A comparative study”, Drinking Water Engineering and Science, vol. 10, no. 2, pp. 109–117, 2017. https://doi.org/10.5194/dwes-10-109-2017.

O. Abdelwahab, N. K. Amin, and E. S. Z. El-Ashtoukhy, “Electrochemical removal of phenol from oil refinery wastewater”, Journal of hazardous materials, vol. 163, no. 2–3, pp. 711–716, 2009. https://doi.org/10.1016/j.jhazmat.2008.07.016.

L. Lin, W. Jiang, L. Chen, P. Xu, and H. Wang, “Treatment of produced water with photocatalysis: Recent advances, affecting factors and future research prospects”, Catalysts, vol. 10, no. 8, p. 924, 2020. https://doi.org/10.3390/catal10080924.

M. S. Lawan, R. Kumar, J. Rashid, and M. A. E.-F. Barakat, “Recent advancements in the treatment of petroleum refinery wastewater”, Water, vol. 15, no. 20, p. 3676, 2023. https://doi.org/10.3390/w15203676.

V. S. Santana and N. R. C. F. Machado, “Photocatalytic degradation of the vinasse under solar radiation”, Catalysis Today, vol. 133-135, pp. 606–610, 2008. https://doi.org/10.1016/j.cattod.2007.12.131.

A. M. Ferrari-Lima, R. G. Marques, N. R. C. Fernandes-Machado, and M. L. Gimenes, “Photodegradation of petrol station wastewater after coagulation/flocculation with tannin-based coagulant,” Catalysis Today, vol. 209, pp. 79–83, 2013. https://doi.org/10.1016/j.cattod.2012.10.022.

A. Di Paola, E. García-López, G. Marcì, and L. Palmisano, “A survey of photocatalytic materials for environmental remediation”, Journal of Hazardous Materials, vol. 211-212, pp. 3–29, 2012. https://doi.org/10.1016/j.jhazmat.2011.11.050.

F. E. Oropeza, J. Harmer, R. G. Egdell, and R. G. Palgrave, “A critical evaluation of the mode of incorporation of nitrogen in doped anatase photocatalysts”, Physical Chemistry Chemical Physics, vol. 12, no. 4, pp. 960–969, 2010. https://doi.org/10.1039/B914733K.

J. Ananpattarachai, P. Kajitvichyanukul, and S. Seraphin, “Visible light absorption ability and photocatalytic oxidation activity of various interstitial N-doped TiO2 prepared from different nitrogen dopants”, Journal of Hazardous Materials, vol. 168, no. 1, pp. 253–261, 2009. https://doi.org/10.1016/j.jhazmat.2009.02.036.

N. E. Mousa, S. S. Mohammed, Z. Y. Shnain, M. F. Abid, A. A. Alwasiti, and K. A. Sukkar, “Catalytic photodegradation of cyclic sulfur compounds in a model fuel using a bench-scale falling-film reactor irradiated by a visible light”, Bull. Chem. React. Eng. Catal., vol. 17, no. 4, pp. 755–767, 2022. https://doi.org/10.9767/bcrec.17.4.15838.755-767.

T. Muddemann, R. Neuber, D. Haupt, T. Graßl, M. Issa, F. Bienen, M. Enstrup, J. Möller, T. Matthée, M. Sievers, and U. Kunz, “Improving the treatment efficiency and lowering the operating costs of electrochemical advanced oxidation processes”, Processes, vol. 9, no. 9, p. 1482, 2021. https://doi.org/10.3390/pr9091482.

K. S. Hashim, P. Kot, S. L. Zubaidi, R. Alwash, R. Al Khaddar, A. Shaw, D. Al-Jumeily, and M. H. Aljefery, “Energy efficient electrocoagulation using baffle-plates electrodes for efficient Escherichia Coli removal from Wastewater”, J. Water Process Eng., vol. 33, p. 101079, 2020. https://doi.org/10.1016/j.jwpe.2019.101079.

K. S. Hashim, S. S. M. Ali, J. K. AlRifaie, P. Kot, A. Shaw, R. Al Khaddar, I. Idowu, and M. Gkantou, “Escherichia coli inactivation using a hybrid ultrasonic–electrocoagulation reactor”, Chemosphere, vol. 247, p. 125868, 2020. https://doi.org/10.1016/j.chemosphere.2020.125868.

S. Zhang, L. Zhou, Z. Li, A. A. Esmailpour, K. Li, S. Wang, R. Liu, X. Li, and J. Yun, “Efficient treatment of phenol wastewater by catalytic ozonation over micron-sized hollow MgO rods”, ACS omega, vol. 6, no. 39, pp. 25506–25517, 2021. https://doi.org/10.1021/acsomega.1c03497.

R. Almukhtar, S. I. Hammoodi, H. S. Majdi, and K. A. Sukkar, “Managing transport processes in thermal cracking to produce high-quality fuel from extra-heavy waste crude oil using a semi-batch reactor”, Processes, vol. 10, no. 10, p. 2077, 2022. https://doi.org/10.3390/pr10102077.

X. Li, W. Chen, L. Ma, H. Wang, and J. Fan, “Industrial wastewater advanced treatment via catalytic ozonation with an Fe-based catalyst”, Chemosphere, vol. 195, pp. 336–343, 2018. https://doi.org/10.1016/j.chemosphere.2017.12.080.

L. Zhang, M. Qin, W. Yu, Q. Zhang, H. Xie, Z. Sun, Q. Shao, X. Guo, L. Hao, Y. Zheng, and Z. Guo, “Heterostructured TiO2/WO3 nanocomposites for photocatalytic degradation of toluene under visible light”, Journal of The Electrochemical Society, vol. 164, no. 14, p. H1086, 2017. https://doi.org/10.1149/2.0881714jes.

C. S. D. Rodrigues, R. A. C. Borges, V. N. Lima, and L. M. Madeira, “p-Nitrophenol degradation by Fenton’s oxidation in a bubble column reactor”, Journal of Environmental Management, vol. 206, pp. 774–785, 2018. https://doi.org/10.1016/j.jenvman.2017.11.032.

S. D. NGALA, A. SALIM, S. JERROUMI, B. LEKHLIF, and E. H. MALIL, “Study of oxygen transfer processes improvement for domestic wastewaters treatment”, African Journal of Biotechnology, vol. 18, no. 12, pp. 265–274, 2019. https://doi.org/10.5897/AJB2018.16654.

A. Jonidi-Jafari, M. Shirzad-Siboni, J.-K. Yang, M. Naimi-Joubani, and M. Farrokhi, “Photocatalytic degradation of diazinon with illuminated ZnO–TiO2 composite”, Journal of the Taiwan Institute of Chemical Engineers, vol. 50, pp. 100–107, 2015. https://doi.org/10.1016/j.jtice.2014.12.020.

V. N. Lima, C. S. D. Rodrigues, E. F. S. Sampaio, and L. M. Madeira, “Insights into real industrial wastewater treatment by Fenton’s oxidation in gas bubbling reactors”, Journal of Environmental Management, vol. 265, p. 110501, 2020. https://doi.org/10.1016/j.jenvman.2020.110501.

S. A. Alattar, K. A. Sukkar, and M. A. Alsaffar, “Enhancement of ozonation reaction for efficient removal of phenol from wastewater using a packed bubble column reactor”, Indonesian Journal of Chemistry, vol. 23, no. 2, pp. 383–394, 2023. https://doi.org/10.22146/ijc.78271.

M. Tokumura, R. Nakajima, H. T. Znad, and Y. Kawase, “Chemical absorption process for degradation of VOC gas using heterogeneous gas–liquid photocatalytic oxidation: Toluene degradation by photo-Fenton reaction”, Chemosphere, vol. 73, no. 5, pp. 768–775, 2008. https://doi.org/10.1016/j.chemosphere.2008.06.021.

S. Sharma, N. Chokshi, and J. P. Ruparelia, “Effect of Operating Parameters on O3, O3/UV, O3/UV/PS Process Using Bubble Column Reactor for Degradation of Reactive Dyes”, J. Inst. Eng. India Ser. A, vol. 104, no. 3, pp. 565–578, 2023. https://doi.org/10.1007/s40030-023-00735-8.

S. A. Alattar, K. A. Sukkar, and M. A. Alsaffar, “The role of TiO2 NPs catalyst and packing material in removal of phenol from wastewater using an ozonized bubble column reactor”, Acta Innovations, vol. 46, pp. 90–101, 2023.

J. Sun, X. Li, Q. Zhao, J. Ke, and D. Zhang, “Novel V2O5/BiVO4/TiO2 nanocomposites with high visible-light-induced photocatalytic activity for the degradation of toluene”, The Journal of Physical Chemistry C, vol. 118, no. 19, pp. 10113–10121, 2014. https://doi.org/10.1021/jp5013076.

T. N. Jaber, K. A. Sukkar, and A. A. Karamalluh, “Specifications of heavy diesel lubricating oil improved by MWCNTs and CuO as nano-additives”, in IOP Conference Series: Materials Science and Engineering, vol. 579, IOP Publishing, 2019, p. 12014. https://doi.org/10.1088/1757-899X/579/1/012014.

N. A. Al-Rubaiey and M. G. Al-Barazanjy, “Ultrasonic technique in treating wastewater by electrocoagulation”, Engineering and Technology Journal, vol. 36, no. 1 Part C, pp. 54–62, 2018. http://dx.doi.org/10.30684/etj.36.1C.9.

X. Yang, Z. Liu, D. Manhaeghe, Y. Yang, J. Hogie, K. Demeestere, and S. W. H. Van Hulle, “Intensified ozonation in packed bubble columns for water treatment: Focus on mass transfer and humic acids removal”, Chemosphere, vol. 283, p. 131217, 2021. https://doi.org/10.1016/j.chemosphere.2021.131217.

H. Hassani, N. Nazarpour, and G. Pourtaghi, “The Comparison of Toluene Removal Rate in Two Photocatalytic Oxidation Systems of ZnO and TiO2 Nanoparticles on SiO2 bed”, Iranian Journal of Health, Safety & Environment, vol. 6, no. 3, pp. 1281–1288, 2019.

H. AlMohamadi et al., “Photocatalytic activity of metal-and non-metal-anchored ZnO and TiO2 nanocatalysts for advanced photocatalysis: comparative study”, Catalysts, vol. 14, no. 7, p. 420, 2024. https://doi.org/10.3390/catal14070420.

H. A. Rangkooy, F. Jahani, and A. Siahi Ahangar, “Photocatalytic removal of xylene as a pollutant in the air using ZnO-activated carbon, TiO2-activated carbon, and TiO2/ZnOactivated carbon nanocomposites”, Environmental Health Engineering and Management Journal, vol. 7, no. 1, pp. 41–47, 2020. https://doi.org/10.34172/EHEM.2020.06.

D. K. Mohammad Reza, “Activity enhancement of copper doped TiO2/ZnO photo catalyst for degradation of recalcitrant pollutants/Mohammad Reza Delsouz Khaki”, phd Thesis. University of Malaya, 2017.

W. Wang, H. Yao, and L. Yue, “Supported-catalyst CuO/AC with reduced cost and enhanced activity for the degradation of heavy oil refinery wastewater by catalytic ozonation process”, Environmental Science and Pollution Research, vol. 27, pp. 7199–7210, 2020. https://doi.org/10.1007/s11356-019-07410-1.

R. Ghamarpoor, A. Fallah, and M. Jamshidi, “A review of synthesis methods, modifications, and mechanisms of ZnO/TiO2-based photocatalysts for photodegradation of contaminants”, ACS omega, vol. 9, no. 24, pp. 25457–25492, 2024. https://doi.org/10.1021/acsomega.3c08717.

P. K. Pandis et al., “Key points of advanced oxidation processes (AOPs) for wastewater, organic pollutants and pharmaceutical waste treatment: A mini review”, ChemEngineering, vol. 6, no. 1, p. 8, 2022. https://doi.org/10.3390/chemengineering6010008.

D. A. Aljuboury, and F. Shaik, “Assessment of TiO2/ZnO/H2O2 Photocatalyst to treat wastewater from oil refinery within visible light circumstances”, South African J. Chem. Eng., vol. 35, pp. 69–77, 2021. https://doi.org/10.1016/j.sajce.2020.11.004.

S. Javed, C. R. Mirza, A. H. A. Khan, W. Khalifa, B. Achour, R. Barros, S. Yousaf, T. A. Butt, and M. Iqbal, “Limited phosphorous supply improved lipid content of Chlorella vulgaris that increased phenol and 2-chlorophenol adsorption from contaminated water with acid treatment”, Processes, vol. 10, no. 11, p. 2435, 2022. https://doi.org/10.3390/pr10112435.

C. Von Sonntag and H. Schuchmann, “The elucidation of peroxyl radical reactions in aqueous solution with the help of radiation‐chemical methods”, Angewandte Chemie International Edition in English, vol. 30, no. 10, pp. 1229–1253, 1991. https://doi.org/10.1002/anie.199112291.

S. Sitkiewitz and A. Heller, “Photocatalytic oxidation of benzene and stearic acid on sol-gel derived TiO2 thin films attached to glass”, New J. Chem., vol. 20, no. 2, pp. 233–242, 1996.

C. von Sonntag and A. B. Ross, “Pulse radiolysis of nucleic acids and their base constituents: Bibliographies on radiation chemistry. XI”, Int. J. Radiat. Appl. Instrumentation. Part C. Radiat. Phys. Chem., vol. 30, no. 5–6, pp. 331–338, 1987. https://doi.org/10.1016/1359-0197(87)90102-0.

S. S. Shinde, C. H. Bhosale, and K. Y. Rajpure, “Photocatalytic degradation of toluene using sprayed N-doped ZnO thin films in aqueous suspension”, Journal of Photochemistry and Photobiology B: Biology, vol. 113, pp. 70–77, 2012. https://doi.org/10.1016/j.jphotobiol.2012.05.008.