At present, advanced oxidation based on radical process has become a concern in degradation methods for organic compounds because of its oxidation potential values are equal to or even higher than hydroxyl radicals. In addition, this method can overcome the weaknesses that exist in the hydroxyl radical-based method (Fenton). A homogeneous UV-C irradiated persulfate system is used to treat benzoic acid (BA) and N-methyl-2-pyrrolidone (NMP) in this study. Benzoic acid can be found in a variety of foods, especially dairy products. Meanwhile, NMP can be found in paint stripper, graffiti remover, pesticides, and some cleaning products. Direct contact with both BA and NMP might irritate eyes, nose and throat. Direct touch might cause dermatitis. In long-term exposure of NMP, it might raise the risk of liver damage.
Parameters such as pH, initial target concentration, irradiation light, oxidant dosage, •OH and SO4• radical scavenger presence, and the presence of transition metal ion were investigated to achieve the optimum mineralization and degradation efficiency. In order to determine the dominating radicals, whether •OH or SO4• is dominating, radical scavengers tert-butyl-alcohol and methanol were applied in the system. The purpose of this study was to see how effective UV-C light activated persulfate degrade and mineralize benzoic acid and N-methyl-2-pyrrolidone which represent organic compounds. Each organic compound used has 100 mg/L initial concentration, where the initial TOC for benzoic acid is 68.78 mg/L and for NMP is 60.52 mg/L.
The experimental results indicate that the benzoic acid degradation and mineralization efficiency reached 100% and 95.38% after 10 and 60 min operation time, respectively, under the initial pH of 3 and initial [PS]/[BA] ratio of 12. However, the experimental results for NMP revealed that degradation and mineralization efficiency reached 100% and 98%, respectively after 20 min operation time under its natural pHi of 6.24 and initial [PS]/[NMP] ratio of 16. Note that all experiments were conducted done under UV-C light irradiation, given initial concentrations of 100 mg/L BA and NMP. The scavenging reaction shows that the •OH active radicals, produced from sulfate radical hydrolysis, was observed as the dominating species that contribute 60% and 40% of BA and NMP degradation efficiency, respectively.

[1] S. Xiao et al., “Iron-mediated activation of persulfate and peroxymonosulfate in both homogeneous and heterogeneous ways: A review,” Chem. Eng. J., vol. 384, no. July 2019, p. 123265, 2020, doi: 10.1016/j.cej.2019.123265.
[2] J. Yang, M. Zhu, and D. D. Dionysiou, “What is the role of light in persulfate-based advanced oxidation for water treatment?,” Water Res., vol. 189, 2021, doi: 10.1016/j.watres.2020.116627.
[3] UNESCO, “The United Nations world water development report 2020: Water and climate change,” Paris, France, 2020. Accessed: Mar. 23, 2021. [Online]. Available: https://unesdoc.unesco.org/in/documentViewer.xhtml?v=2.1.196&id=p::usmarcdef_0000372985&file=/in/rest/annotationSVC/DownloadWatermarkedAttachment/attach_import_d4573ca6-3763-42be-93c0-619ea879933f%3F_%3D372985eng.pdf&locale=en&multi=true&ark=/ark:/48223/p.
[4] R. J. Huston, R. R. Marquez, and K. H. Waite, “Total Organic Carbon ( TOC ) Guidance Manual,” 2002.
[5] S. M. Kumar, “Degradation and mineralization of organic contaminants by Fenton and photo- Fenton processes : Review of mechanisms and effects of organic and inorganic additives D e g r a d a t i o n a n d m i n e r a l i z a t i o n o f o r g a n i c c o n t a m i n a,” no. August, 2017.
[6] “Heterogeneous Degradation of Organic Pollutants by Persulfate Activated by CuO-Fe3O4: Mechanism, Stability, and Effects of pH and Bicarbonate Ions,” Environ. Sci. Technol., vol. 49, no. May 2015, pp. 6838–6845, 2015, doi: 10.1021/acs.est.5b00623.
[7] S. Guerra-Rodríguez, E. Rodríguez, D. N. Singh, and J. Rodríguez-Chueca, “Assessment of sulfate radical-based advanced oxidation processes for water and wastewater treatment: A review,” Water (Switzerland), vol. 10, no. 12, 2018, doi: 10.3390/w10121828.
[8] M. I. Pariente et al., “Heterogeneous photo-Fenton oxidation of benzoic acid in water: Effect of operating conditions, reaction by-products and coupling with biological treatment,” Appl. Catal. B Environ., vol. 85, no. 1–2, pp. 24–32, 2008, doi: 10.1016/j.apcatb.2008.06.019.
[9] S. Wang and J. Wang, “Comparative study on sulfamethoxazole degradation by Fenton and Fe(II)-activated persulfate process,” RSC Adv., vol. 7, no. 77, pp. 48670–48677, 2017, doi: 10.1039/c7ra09325j.
[10] J. Wang and S. Wang, “Activation of persulfate (PS) and peroxymonosulfate (PMS) and application for the degradation of emerging contaminants,” Chem. Eng. J., vol. 334, no. July 2017, pp. 1502–1517, 2018, doi: 10.1016/j.cej.2017.11.059.
[11] Q. Zhao et al., “Metal-free carbon materials-catalyzed sulfate radical-based advanced oxidation processes : A review on heterogeneous catalysts and applications,” Chemosphere, vol. 189, pp. 224–238, 2017, doi: 10.1016/j.chemosphere.2017.09.042.
[12] J. Lee, U. Von Gunten, and J. H. Kim, “Persulfate-Based Advanced Oxidation: Critical Assessment of Opportunities and Roadblocks,” Environ. Sci. Technol., vol. 54, no. 6, pp. 3064–3081, 2020, doi: 10.1021/acs.est.9b07082.
[13] B. Zhang, Y. Zhang, Y. Teng, and M. Fan, “Technology Sulfate Radical and Its Application in Decontamination Technologies,” Environ. Sci. Technol., vol. 3389, no. May, pp. 1756–1800, 2015, doi: 10.1080/10643389.2014.970681.
[14] L. W. Matzek and K. E. Carter, “Activated persulfate for organic chemical degradation: A review,” Chemosphere, vol. 151, pp. 178–188, 2016, doi: 10.1016/j.chemosphere.2016.02.055.
[15] S. Wacławek, H. V. Lutze, K. Grübel, V. V. T. Padil, M. Černík, and D. D. Dionysiou, “Chemistry of persulfates in water and wastewater treatment: A review,” Chem. Eng. J., vol. 330, no. June, pp. 44–62, 2017, doi: 10.1016/j.cej.2017.07.132.
[16] M. Coha, G. Farinelli, A. Tiraferri, M. Minella, and D. Vione, “Advanced oxidation processes in the removal of organic substances from produced water: Potential, configurations, and research needs,” Chem. Eng. J., vol. 414, no. September 2020, p. 128668, 2021, doi: 10.1016/j.cej.2021.128668.
[17] K. Davididou, J. M. Monteagudo, E. Chatzisymeon, A. Durán, and A. J. Expósito, “Degradation and mineralization of antipyrine by UV-A LED photo-Fenton reaction intensified by ferrioxalate with addition of persulfate,” Sep. Purif. Technol., vol. 172, pp. 227–235, 2017, doi: 10.1016/j.seppur.2016.08.021.
[18] P. H. Sreeja and K. J. Sosamony, “A Comparative Study of Homogeneous and Heterogeneous Photo-fenton Process for Textile Wastewater Treatment,” Procedia Technol., vol. 24, pp. 217–223, 2016, doi: 10.1016/j.protcy.2016.05.065.
[19] C. H. Yen, K. F. Chen, C. M. Kao, S. H. Liang, and T. Y. Chen, “Application of persulfate to remediate petroleum hydrocarbon-contaminated soil: Feasibility and comparison with common oxidants,” J. Hazard. Mater., vol. 186, no. 2–3, pp. 2097–2102, 2011, doi: 10.1016/j.jhazmat.2010.12.129.
[20] S. W. Benson, “Thermochemistry and Kinetics of Sulfur-Containing Molecules and Radicals,” Chem. Rev., vol. 78, no. 1, pp. 23–35, 1978, doi: 10.1021/cr60311a003.
[21] Y. H. Guan et al., “Efficient degradation of atrazine by magnetic porous copper ferrite catalyzed peroxymonosulfate oxidation via the formation of hydroxyl and sulfate radicals,” Water Res., vol. 47, no. 14, pp. 5431–5438, 2013, doi: 10.1016/j.watres.2013.06.023.
[22] D. F. Evans and M. W. Upton, “Studies on Singlet Oxygen in Aqueous Solution. Part 3. The decomposition of Peroxy-acids,” Photochemistry, vol. 25, pp. 1151–1153, 1985.
[23] Z. Chen et al., “Overlooked Role of Peroxides as Free Radical Precursors in Advanced Oxidation Processes,” Environ. Sci. Technol., 2019, doi: 10.1021/acs.est.8b05901.
[24] J. Costanza, G. Otaño, J. Callaghan, and K. D. Pennell, “PCE oxidation by sodium persulfate in the presence of solids,” Environ. Sci. Technol., vol. 44, no. 24, pp. 9445–9450, 2010, doi: 10.1021/es100997a.
[25] C. Liang and C. J. Bruell, “Thermally activated persulfate oxidation of trichloroethylene: Experimental investigation of reaction orders,” Ind. Eng. Chem. Res., vol. 47, no. 9, pp. 2912–2918, 2008, doi: 10.1021/ie070820l.
[26] Q. Yang et al., “Recent advances in photo-activated sulfate radical-advanced oxidation process (SR-AOP) for refractory organic pollutants removal in water,” Chem. Eng. J., vol. 378, no. June, p. 122149, 2019, doi: 10.1016/j.cej.2019.122149.
[27] G. Matafonova and V. Batoev, “Recent advances in application of UV light-emitting diodes for degrading organic pollutants in water through advanced oxidation processes: A review,” Water Res., vol. 132, pp. 177–189, 2018, doi: 10.1016/j.watres.2017.12.079.
[28] A. Rastogi, S. R. Al-Abed, and D. D. Dionysiou, “Effect of inorganic, synthetic and naturally occurring chelating agents on Fe(II) mediated advanced oxidation of chlorophenols,” Water Res., vol. 43, no. 3, pp. 684–694, 2009, doi: 10.1016/j.watres.2008.10.045.
[29] W. Li et al., “ROS reevaluation for degradation of 4-chloro-3,5-dimethylphenol (PCMX) by UV and UV/persulfate processes in the water: Kinetics, mechanism, DFT studies and toxicity evolution,” Chem. Eng. J., vol. 390, no. January, p. 124610, 2020, doi: 10.1016/j.cej.2020.124610.
[30] T. Olmez-Hanci and I. Arslan-Alaton, “Comparison of sulfate and hydroxyl radical based advanced oxidation of phenol,” Chem. Eng. J., vol. 224, no. 1, pp. 10–16, 2013, doi: 10.1016/j.cej.2012.11.007.
[31] C E W Steinberg and A Paul, “Photolysis,” Encyclopedia of Ecology. pp. 2724–2732, 2008.
[32] J. G. Speight, Chemical Transformations in the Environment, no. 1. 2017.
[33] J. A. Khan, X. He, H. M. Khan, N. S. Shah, and D. D. Dionysiou, “Oxidative degradation of atrazine in aqueous solution by UV/H2O2/Fe2+, UV/S2O82-/Fe2+ and UV/HSO5-/Fe2+ processes: A comparative study,” Chem. Eng. J., vol. 218, pp. 376–383, 2013, doi: 10.1016/j.cej.2012.12.055.
[34] L. O. Simonsen, H. Harbak, and P. Bennekou, “Cobalt metabolism and toxicology-A brief update,” Sci. Total Environ., vol. 432, pp. 210–215, 2012, doi: 10.1016/j.scitotenv.2012.06.009.
[35] V. Kavitha and K. Palanivelu, “The role of ferrous ion in Fenton and photo-Fenton processes for the degradation of phenol,” Chemosphere, vol. 55, no. 9, pp. 1235–1243, 2004, doi: 10.1016/j.chemosphere.2003.12.022.
[36] D. A. Friesen and J. V Headley, “The Photooxidative Degradation of N -Methylpyrrolidinone in the Presence of Cs 3 PW 12 O 40 and TiO 2 Colloid Photocatalysts,” vol. 33, no. 18, pp. 3193–3198, 1999.
[37] J. Wang et al., “Crucial roles of oxygen and superoxide radical in bisulfite-activated persulfate oxidation of bisphenol AF: Mechanisms, kinetics and DFT studies,” J. Hazard. Mater., vol. 391, no. November 2019, p. 122228, 2020, doi: 10.1016/j.jhazmat.2020.122228.
[38] Q. Wang, B. Wang, Y. Ma, and S. Xing, “Enhanced superoxide radical production for ofloxacin removal via persulfate activation with Cu-Fe oxide,” Chem. Eng. J., vol. 354, no. August, pp. 473–480, 2018, doi: 10.1016/j.cej.2018.08.055.
[39] G. D. Fang, D. D. Dionysiou, S. R. Al-Abed, and D. M. Zhou, “Superoxide radical driving the activation of persulfate by magnetite nanoparticles: Implications for the degradation of PCBs,” Appl. Catal. B Environ., vol. 129, pp. 325–332, 2013, doi: 10.1016/j.apcatb.2012.09.042.
[40] M. A. Cashman, L. Kirschenbaum, J. Holowachuk, and T. B. Boving, “Identification of hydroxyl and sulfate free radicals involved the reaction of 1,4-dioxane with peroxone activated persulfate oxidant,” J. Hazard. Mater., vol. 380, no. June, p. 120875, 2019, doi: 10.1016/j.jhazmat.2019.120875.
[41] A. Zolfaghari, H. R. Mortaheb, and F. Meshkini, “Removal of N -Methyl-2-pyrrolidone by photocatalytic degradation in a batch reactor,” Ind. Eng. Chem. Res., vol. 50, no. 16, pp. 9569–9576, 2011, doi: 10.1021/ie200702b.
[42] W. Da Oh, Z. Dong, and T. T. Lim, “Generation of sulfate radical through heterogeneous catalysis for organic contaminants removal: Current development, challenges and prospects,” Appl. Catal. B Environ., vol. 194, pp. 169–201, 2016, doi: 10.1016/j.apcatb.2016.04.003.
[43] Y. Zhang, Q. Zhang, and J. Hong, “Sulfate radical degradation of acetaminophen by novel iron–copper bimetallic oxidation catalyzed by persulfate: Mechanism and degradation pathways,” Appl. Surf. Sci., vol. 422, pp. 443–451, 2017, doi: 10.1016/j.apsusc.2017.05.224.
[44] Y. qiong Gao, N. yun Gao, Y. Deng, Y. qiong Yang, and Y. Ma, “Ultraviolet (UV) light-activated persulfate oxidation of sulfamethazine in water,” Chem. Eng. J., vol. 195–196, pp. 248–253, 2012, doi: 10.1016/j.cej.2012.04.084.
[45] W. Li, R. Orozco, N. Camargos, and H. Liu, “Mechanisms on the Impacts of Alkalinity, pH, and Chloride on Persulfate-Based Groundwater Remediation,” Environ. Sci. Technol., vol. 51, no. 7, pp. 3948–3959, 2017, doi: 10.1021/acs.est.6b04849.
[46] M. Von Piechowski, M.-A. Thelen, J. Hoigné, and R. E. Bühler, “tert-Butanol as an OH-Scavenger in the Pulse Radiolysis of Oxygenated Aqueous Systems,” Berichte der Bunsengesellschaft für Phys. Chemie, vol. 96, no. 10, pp. 1448–1454, 1992, doi: 10.1002/bbpc.19920961019.
[47] X. Yang et al., “New insights into clopyralid degradation by sulfate radical: Pyridine ring cleavage pathways,” Water Res., vol. 171, p. 115378, 2020, doi: 10.1016/j.watres.2019.115378.
[48] G. Mark, M. N. Schuchmann, H. P. Schuchmann, and C. von Sonntag, “The photolysis of potassium peroxodisulphate in aqueous solution in the presence of tert-butanol: a simple actinometer for 254 nm radiation,” J. Photochem. Photobiol. A Chem., vol. 55, no. 2, pp. 157–168, 1990, doi: 10.1016/1010-6030(90)80028-V.
[49] J. M. Monteagudo, H. El-taliawy, A. Durán, G. Caro, and K. Bester, “Sono-activated persulfate oxidation of diclofenac: Degradation, kinetics, pathway and contribution of the different radicals involved,” J. Hazard. Mater., vol. 357, no. June, pp. 457–465, 2018, doi: 10.1016/j.jhazmat.2018.06.031.
[50] “organic compound | Definition | Britannica.” https://www.britannica.com/science/organic-compound (accessed May 03, 2021).
[51] M. P. Rayaroth, C. S. Lee, U. K. Aravind, C. T. Aravindakumar, and Y. S. Chang, “Oxidative degradation of benzoic acid using Fe0- and sulfidized Fe0-activated persulfate: A comparative study,” Chem. Eng. J., vol. 315, pp. 426–436, 2017, doi: 10.1016/j.cej.2017.01.031.
[52] C. Wibbertmann, A. Kielhorn, G. Koennecker, I. Mangelsdorf, and Melber, “Concise International Chemical Assessment Document 26 Benzoic Acid and Sodium Benzoate,” in In Vitro, 2005, p. 4.
[53] N. Zrinyi and A. L. T. Pham, “Oxidation of benzoic acid by heat-activated persulfate: Effect of temperature on transformation pathway and product distribution,” Water Res., vol. 120, pp. 43–51, 2017, doi: 10.1016/j.watres.2017.04.066.
[54] K. Chai and H. Ji, “Dual functional adsorption of benzoic acid from wastewater by biological-based chitosan grafted β-cyclodextrin,” Chem. Eng. J., vol. 203, pp. 309–318, 2012, doi: 10.1016/j.cej.2012.07.050.
[55] M. Aliabadi, H. Ghahremani, F. Izadkhah, and T. Sagharigar, “Photocatalytic degradation of n-methyl-2-pyrrolidone in aqueous solutions using light sources of UVA, UVC and UVLED,” Fresenius Environ. Bull., vol. 21, no. 8, pp. 2120–2125, 2012.
[56] H. Hazard, “N-Methylpyrrolidone (NMP) (NMP),” 2014.
[57] H. L. Campbell and B. A. Striebig, “Evaluation of N-methylpyrrolidone and its oxidative products toxicity utilizing the microtox assay,” Environ. Sci. Technol., vol. 33, no. 11, pp. 1926–1930, 1999, doi: 10.1021/es981061o.
[58] J. Wang et al., “Nitrate stimulation of N-Methylpyrrolidone biodegradation by Paracoccus pantotrophus: Metabolite mechanism and Genomic characterization,” Bioresour. Technol., vol. 294, no. September, p. 122185, 2019, doi: 10.1016/j.biortech.2019.122185.
[59] S. Cai et al., “Biodegradation of N-Methylpyrrolidone by Paracoccus sp. NMD-4 and its degradation pathway,” Int. Biodeterior. Biodegrad., vol. 93, pp. 70–77, 2014, doi: 10.1016/j.ibiod.2014.04.022.
[60] G. Lennon et al., “Assessing the oxidative degradation of n-methylpyrrolidone (nmp) in microelectronic fabrication processes by using a multiplatform analytical approach,” J. Anal. Methods Chem., vol. 2020, 2020, doi: 10.1155/2020/8265054.
[61] S. T. Chow and T. L. Ng, “The biodegradation of N-methyl-2-pyrrolidone in water by sewage bacteria,” Water Res., vol. 17, no. 1, pp. 117–118, 1983, doi: 10.1016/0043-1354(83)90292-0.
[62] H. L. and P. N. V. Madhavan, “Decarboxylation by Sulfate Radicals,” vol. 76, no. 1, pp. 15–22, 1978.
[63] M. Muruganandham, S. H. Chen, and J. J. Wu, “Mineralization of N-methyl-2-pyrolidone by advanced oxidation processes,” Sep. Purif. Technol., vol. 55, no. 3, pp. 360–367, 2007, doi: 10.1016/j.seppur.2007.01.009.
[64] C. M. Dominguez, V. Rodriguez, E. Montero, A. Romero, and A. Santos, “Methanol-enhanced degradation of carbon tetrachloride by alkaline activation of persulfate: Kinetic model,” Sci. Total Environ., vol. 666, pp. 631–640, 2019, doi: 10.1016/j.scitotenv.2019.02.223.
[65] M. A. Lominchar, A. Santos, E. de Miguel, and A. Romero, “Remediation of aged diesel contaminated soil by alkaline activated persulfate,” Sci. Total Environ., vol. 622–623, pp. 41–48, 2018, doi: 10.1016/j.scitotenv.2017.11.263.
[66] R. Zhang, P. Sun, T. H. Boyer, L. Zhao, and C. H. Huang, “Degradation of pharmaceuticals and metabolite in synthetic human urine by UV, UV/H2O2, and UV/PDS,” Environ. Sci. Technol., vol. 49, no. 5, pp. 3056–3066, 2015, doi: 10.1021/es504799n.
[67] O. S. Furman, A. L. Teel, and R. J. Watts, “Mechanism of base activation of persulfate,” Environ. Sci. Technol., vol. 44, no. 16, pp. 6423–6428, 2010, doi: 10.1021/es1013714.
[68] A. Khlyustova, N. Khomyakova, N. Sirotkin, and Y. Marfin, “The Effect of pH on OH Radical Generation in Aqueous Solutions by Atmospheric Pressure Glow Discharge,” Plasma Chem. Plasma Process., vol. 36, no. 5, pp. 1229–1238, 2016, doi: 10.1007/s11090-016-9732-3.
[69] S. Verma, S. Nakamura, and M. Sillanpää, “Application of UV-C LED activated PMS for the degradation of anatoxin-a,” Chem. Eng. J., vol. 284, pp. 122–129, 2016, doi: 10.1016/j.cej.2015.08.095.
[70] H. Benhebal et al., “Photocatalytic degradation of phenol and benzoic acid using zinc oxide powders prepared by the sol-gel process,” Alexandria Eng. J., vol. 52, no. 3, pp. 517–523, 2013, doi: 10.1016/j.aej.2013.04.005.
[71] M. Kebir, A. Boudjemaa, and K. Bachari, “Enhancement photo-catalytic degradation of benzoic acid using the heterosystem NiCo2O4/ZnO,” Mater. Sci. Semicond. Process., vol. 39, pp. 300–307, 2015, doi: 10.1016/j.mssp.2015.05.036.
[72] A. Ioannidi, Z. Frontistis, and D. Mantzavinos, “Destruction of propyl paraben by persulfate activated with UV-A light emitting diodes,” J. Environ. Chem. Eng., vol. 6, no. 2, pp. 2992–2997, 2018, doi: 10.1016/j.jece.2018.04.049.
[73] A. J. Eugene and M. I. Guzman, “Production of Singlet Oxygen during the Photochemistry of Aqueous Pyruvic Acid: The Effects of pH and Photon Flux under Steady-State O2 (aq) Concentration,” 2019, doi: 10.1021/acs.est.9b03742.
[74] R. Li et al., “A sulfate radical based ferrous-peroxydisulfate oxidative system for indomethacin degradation in aqueous solutions,” RSC Adv., vol. 7, no. 37, pp. 22802–22809, 2017, doi: 10.1039/c7ra03364h.
[75] W. Hayat, Y. Zhang, I. Hussain, S. Huang, and X. Du, “Comparison of radical and non-radical activated persulfate systems for the degradation of imidacloprid in water,” Ecotoxicol. Environ. Saf., vol. 188, no. July, p. 109891, 2020, doi: 10.1016/j.ecoenv.2019.109891.
[76] X. Zhou et al., “Regulating activation pathway of Cu/persulfate through the incorporation of unreducible metal oxides: Pivotal role of surface oxygen vacancies,” Appl. Catal. B Environ., vol. 286, no. December 2020, p. 119914, 2021, doi: 10.1016/j.apcatb.2021.119914.
[77] G. P. Anipsitakis and D. D. Dionysiou, “Radical generation by the interaction of transition metals with common oxidants,” Environ. Sci. Technol., vol. 38, no. 13, pp. 3705–3712, 2004, doi: 10.1021/es035121o.
[78] A. Rastogi, S. R. Al-Abed, and D. D. Dionysiou, “Sulfate radical-based ferrous-peroxymonosulfate oxidative system for PCBs degradation in aqueous and sediment systems,” Appl. Catal. B Environ., vol. 85, no. 3–4, pp. 171–179, 2009, doi: 10.1016/j.apcatb.2008.07.010.
[79] S. Dhaka et al., “Aqueous phase degradation of methyl paraben using UV-activated persulfate method,” Chem. Eng. J., vol. 321, pp. 11–19, 2017, doi: 10.1016/j.cej.2017.03.085.
[80] A. Delavaran Shiraz, A. Takdastan, and S. M. Borghei, “Photo-Fenton like degradation of catechol using persulfate activated by UV and ferrous ions: Influencing operational parameters and feasibility studies,” J. Mol. Liq., vol. 249, pp. 463–469, 2018, doi: 10.1016/j.molliq.2017.11.045.
[81] Y. H. Huang, Y. F. Huang, C. ing Huang, and C. Y. Chen, “Efficient decolorization of azo dye Reactive Black B involving aromatic fragment degradation oxidative processes with a ppb level dosage of Co2+-catalyst,” J. Hazard. Mater., vol. 170, no. 2–3, pp. 1110–1118, 2009, doi: 10.1016/j.jhazmat.2009.05.091.
[82] C. Liang, C. F. Huang, N. Mohanty, and R. M. Kurakalva, “A rapid spectrophotometric determination of persulfate anion in ISCO,” Chemosphere, vol. 73, no. 9, pp. 1540–1543, 2008, doi: 10.1016/j.chemosphere.2008.08.043.
[83] Y. J. Shih, Y. C. Li, and Y. H. Huang, “Application of UV/persulfate oxidation process for mineralization of 2,2,3,3-tetrafluoro-1-propanol,” J. Taiwan Inst. Chem. Eng., vol. 44, no. 2, pp. 287–290, 2013, doi: 10.1016/j.jtice.2012.10.005.
[84] Y. F. Huang and Y. H. Huang, “Behavioral evidence of the dominant radicals and intermediates involved in Bisphenol A degradation using an efficient Co2+/PMS oxidation process,” J. Hazard. Mater., vol. 167, no. 1–3, pp. 418–426, 2009, doi: 10.1016/j.jhazmat.2008.12.138.
[85] J. Criquet and N. K. V. Leitner, “Degradation of acetic acid with sulfate radical generated by persulfate ions photolysis,” Chemosphere, vol. 77, no. 2, pp. 194–200, 2009, doi: 10.1016/j.chemosphere.2009.07.040.
[86] “Absorption spectra of benzoic acid in water at different pH and in the presence of salts.” .
[87] N. N. N. Mahasti, Y. J. Shih, and Y. H. Huang, “Recovery of magnetite from fluidized-bed homogeneous crystallization of iron-containing solution as photocatalyst for Fenton-like degradation of RB5 azo dye under UVA irradiation,” Sep. Purif. Technol., vol. 247, no. April, p. 116975, 2020, doi: 10.1016/j.seppur.2020.116975.
[88] O. Levenspiel, Chemical reaction engineering, vol. 38, no. 11. 1999.
[89] G. Solignac, I. Magneron, A. Mellouki, A. Muñoz, M. Martin Reviejo, and K. Wirtz, “A study of the reaction of OH radicals with N-methyl pyrrolidinone, N-methyl succinimide and N-formyl pyrrolidinone,” J. Atmos. Chem., vol. 54, no. 2, pp. 89–102, 2006, doi: 10.1007/s10874-006-9017-y.
[90] H. Li, F. Liu, H. Zhang, and Y. H. Huang, “Mineralization of N-Methyl-2-Pyrrolidone by UV-Assisted Advanced Fenton Process in a Three-Phase Fluidized Bed Reactor,” Clean - Soil, Air, Water, vol. 46, no. 10, 2018, doi: 10.1002/clen.201800307.
[91] C. Liang and J.-H. Lei, “Identification of Active Radical Species in Alkaline Persulfate Oxidation,” Water Environ. Res., vol. 87, no. 7, pp. 656–659, 2015, doi: 10.2175/106143015x14338845154986.
[92] L. Zhou, C. Ferronato, J. M. Chovelon, M. Sleiman, and C. Richard, “Investigations of diatrizoate degradation by photo-activated persulfate,” Chem. Eng. J., vol. 311, pp. 28–36, 2017, doi: 10.1016/j.cej.2016.11.066.
[93] E. J. Behrman and P. P. Walker, “The Elbs Peroxydisulfate Oxidation: Kinetics,” Journal of the American Chemical Society, vol. 84, no. 18. pp. 3454–3457, 1962, doi: 10.1021/ja00877a007.
[94] R. F. Nunes, F. K. Tominaga, S. I. Borrely, and A. C. S. C. Teixeira, “UVA/persulfate-driven nonylphenol polyethoxylate degradation: effect of process conditions,” Environ. Technol. (United Kingdom), vol. 0, no. 0, pp. 1–15, 2020, doi: 10.1080/09593330.2020.1786166.
[95] S. W. da Silva, C. Viegas, J. Z. Ferreira, M. A. S. Rodrigues, and A. M. Bernardes, “The effect of the UV photon flux on the photoelectrocatalytic degradation of endocrine-disrupting alkylphenolic chemicals,” Environ. Sci. Pollut. Res., vol. 23, no. 19, pp. 19237–19245, 2016, doi: 10.1007/s11356-016-7121-3.
[96] S. Ahmadi, C. A. Igwegbe, and S. Rahdar, “The application of thermally activated persulfate for degradation of Acid Blue 92 in aqueous solution,” Int. J. Ind. Chem., vol. 10, no. 3, pp. 249–260, 2019, doi: 10.1007/s40090-019-0188-1.