Comparison of the adsorption kinetics of methylene blue using rice husk ash activated with different chemical agents

Josiane Pinheiro Farias; Carolina Faccio Demarco; Thays França Afonso; Leandro Sanzi Aquino; Mery Luiza Garcia Vieira; Tito Roberto Cadaval Junior; Maurizio Silveira Quadro; Robson Andreazza

doi:10.5327/Z2176-94781195

Authors

Josiane Pinheiro Farias Universidade Federal de Pelotas (UFPEL) - Brazil https://orcid.org/0000-0002-8933-4984
Carolina Faccio Demarco Universidade Federal de Pelotas (UFPEL) - Brazil https://orcid.org/0000-0002-3826-404X
Thays França Afonso Universidade Federal de Pelotas (UFPEL) - Brazil https://orcid.org/0000-0002-7803-7319
Leandro Sanzi Aquino Universidade Federal de Pelotas (UFPEL) - Brazil https://orcid.org/0000-0002-2516-6539
Mery Luiza Garcia Vieira Universidade Federal de Pelotas (UFPEL) - Brazil https://orcid.org/0000-0002-3865-1031
Tito Roberto Cadaval Junior Universidade Federal de Rio Grande (FURG) - Brazil https://orcid.org/0000-0002-0414-0591
Maurizio Silveira Quadro Universidade Federal de Pelotas (UFPEL) - Brazil https://orcid.org/0000-0001-8236-7479
Robson Andreazza Universidade Federal de Pelotas (UFPEL) - Brazil https://orcid.org/0000-0001-9211-9903

DOI:

https://doi.org/10.5327/Z2176-94781195

Keywords:

bioenergy; application of rice husk ash; dyes.

Abstract

Activated carbon is widely used in several industrial sectors and has a high production cost. To reduce costs, different materials have been studied, for example, rice husks (RH). RH is an abundant, low-cost residue of the agricultural sector and can be used to generate energy due to its high calorific value. However, burning husk generates waste, the ashes. Thus, the objective of this work was to optimize the synthesis of activated carbon using pre-carbonized RH with different chemical agents as activators (KOH, NaOH, NaCl, H₂SO₄, and Na₂CO₃), at different particle sizes. Subsequently, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), and energy dispersive spectroscopy (EDS) were used to characterize the materials. Of these, KOH was the best activating agent. The adsorption kinetics for the adsorbents was 30 min, reaching equilibrium after 70 min. Of the three fitted kinetic models, pseudo-second-order and Elovich best fit the data. The FT-IR shows that the adsorbents have oxygenated surface groups such as alcohol, ester, ether, and phenol. From the point of zero charge, the predominance of negative charges on the surface of the adsorbents is observed. Therefore, the activated carbon from rice husk ash (RHA) showed potential in the adsorption of the methylene blue dyes.

Downloads

Download data is not yet available.

References

Ahmad, A.; Khan, N.; Giri, B. S.; Chowdhary, P.; Chaturvedi, P., 2020. Removal of methylene blue dye using rice husk, cow dung and sludge biochar: characterization, application, and kinetic Studies. Bioresource Technology, v. 306, 123202. https://doi.org/10.1016/j.biortech.2020.123202.

Alvarez, J.; Lopez, G.; Amutio, M.; Bibao, J.; Olazar, M., 2014. Upgrading the rice husk char obtained by flash pyrolysis for the production of amorphous silica and high quality activated carbon. Bioresource Technology, v. 170, 132-137. https://doi.org/10.1016/j.biortech.2014.07.073.

An, D.; Guo, Y.; Zou, B.; Zhu, Y.; Wang, Z., 2011. A study on the consecutive preparation of silica powders and active carbon from rice husk ash. Biomass And Bioenergy, v. 35, (3), 1227-1234. https://doi.org/10.1016/j.biombioe.2010.12.014.

Andrade-Siqueira, C.T.; Zanette da Silva, I.; Rubio, J.A.; Bergamasco, R.; Gasparotto, F.; Aparecida, de Souza Paccola, E.; Ueda Yamaguchi, N., 2020. Sugarcane bagasse as an efficient biosorbent for methylene blue removal: kinetics, isotherms and thermodynamics. International Journal of Environmental Research and Public Health, v. 17, (2), 526. https://doi.org/10.3390%2Fijerph17020526.

Associação Brasileira de Normas Técnicas (ABNT), 1991. Carvão ativado pulverizado - Especificação - EB-2133. ABNT, Rio de Janeiro.

Bankole, M.T.; Abdulkareem, A.S.; Mohammed, I.A.; Ochigbo, S.S.; Tijani, J.O.; Abubakre, O.K.; Roos, W.D., 2019. Selected heavy metals removal from electroplating wastewater by purified and polyhydroxylbutyrate functionalized carbon nanotubes adsorbents. Scientific Reports, v. 9, 4475. https://doi.org/10.1038/s41598-018-37899-4.

Belhachemi, M., 2021. Chapter 14 - Adsorption of organic compounds on activated carbons. Sorbents Materials for Controlling Environmental Pollution, Current State and Trends, 355-385. https://doi.org/10.1016/B978-0-12-820042-1.00006-7.

Cheng, S.; Zhang, L.; Xia, H.; Peng, J.; Shu, J.; Li, C.; Jiang, X.; Zhang, Q., 2017. Adsorption behavior of methylene blue onto waste-derived adsorbent and exhaust gases recycling. RSC Advances, v. 7, (44), 27331-27341. https://doi.org/10.1039/C7RA01482A.

Chien, S.H.; Clayton, W.R., 1980. Application of elovich equation to the kinetics of phosphate release and sorption in soils. Soil Science Society of America Journal, v. 44, (2), 265-268. https://doi.org/10.2136/sssaj1980.03615995004400020013x.

Companhia Nacional de Abastecimento (Conab), 2021. Acompanhamento da safra brasileira de grãos, v. 8, safra 2020/21, n. 10, Conab, Brasília (Accessed in July, 2021) at:. http://www.conab.gov.br.

Costa, J.A.S.; Paranhos, C.M., 2019. Evaluation of rice husk ash in adsorption of remazol red dye from aqueous media. SN Applied Sciences, v. 1, 397. https://doi.org/10.1007/s42452-019-0436-1.

Da Silva, J.E.; Rodrigues, F.I.L.; Pacífico, S.N.; Santiago, L.F.; Munix, C.R.; Saraiva, G.D.; Nascimento, R.F.; Viente Neto, O.S., 2018. Study of kinetics and adsorption equilibrium employing chemically modified coconut shell for the removal of Pb(Ii) from synthetic bath. Revista Virtual de Química, v. 10, (5), 1248-1262. https://doi.org/10.21577/1984-6835.20180086.

Da Silva, P.R.N.; Gonçalves, G.R.; Freitas, J.C.C., 2016. Preparation, characterization and evaluation in gasification of cellulignins derived from sugar cane bagasse and rice husks: reuse case of lignocellulosic waste. Revista Virtual de Química, v. 8, (5), 1262-1276. https://doi.org/10.21577/1984-6835.20160091.

De Oliveira, F.M.; Coelho, L.M.; De Melo, E.I., 2018. Evaluation of the adsorption process using green coconut mesocarp for removal of methylene blue dye. Revista Matéria, v. 23, (4), e12223. https://doi.org/10.1590/s1517-707620180004.0557.

Della, V.P.; Kühn, I.; Hotza, D., 2001. Caracterização de cinza de casca de arroz para uso como matéria-prima na fabricação de refratários de sílica. Química Nova, v. 24, (6), 778-782. https://doi.org/10.1590/S0100-40422001000600013.

Duarte Neto, J.F.; Pereira, I.D.S.; Da Silva, V.C.; Ferreira, H.C.; Neves, G.A.; Menezes, R.R., 2018. Study of equilibrium and kinetic adsorption of rhodamine b onto purified bentonite clays. Cerâmica, v. 64, (372), 598-607. https://doi.org/10.1590/0366-69132018643722429.

Fooladgar, S.; Teimouri, A.; Nasab, S.G., 2019. Highly efficient removal of lead ions from aqueous solutions using chitosan/rice husk ash/nano alumina with a focus on optimization by response surface methodology: isotherm, kinetic, and thermodynamic studies. Journal of Polymers and the Environment, v. 27, (5), 1025-1042. https://doi.org/10.1007/s10924-019-01385-3.

Frantz, T.S.; Silveira Jr., N.; Quadro, M.S.; Andreazza, R.; Barcelos, A.A.; Cadaval Jr., T.R.S.; Pinto, L.A.A., 2017. Cu(ii) adsorption from copper mine water by chitosan films and the matrix effects. Environmental Science and Pollution Research, v. 24, (6), 5908-5917. https://doi.org/10.1007/s11356-016-8344-z.

Gatabi, M.P.; Moghaddam, H.M.; Ghorbani, M., 2016. Point of zero charge of maghemite decorated multiwalled carbon nanotubes fabricated by chemical precipitation method. Journal of Molecular Liquids, v. 216, 117-125. https://doi.org/10.1016/j.molliq.2015.12.087.

Ghaedi, M.; Nasab, A.G.; Khodadoust, S.; Rajabi, M.; Azizian, S., 2014. Application of activated carbon as adsorbents for efficient removal of methylene blue: kinetics and equilibrium study. Journal of Industrial and Engineering Chemistry, v. 20, (4), 2317-2324. https://doi.org/10.1016/j.jiec.2013.10.007.

Giacomni, F.; Menegazzo, M.A.B.; Da Silva, M.G.; Da Silva, A.B.; De Barros, M.A.S.D., 2017. Point of zero charge of protein fibers, an important characteristic for dyeing. Revista Materia, v. 22, (2), e11827. https://doi.org/10.1590/S1517-707620170002.0159.

Hassan, W.; Farooq, U.; Ahmad, M.; Athar, M.; Khan, M.A., 2017. Potential biosorbent, haloxylon recurvum plant stems, for the removal of methylene blue dye. Arabian Journal of Chemistry, v. 10, (Suppl. 2), S1512-S1522. https://doi.org/10.1016/j.arabjc.2013.05.002.

He, W.Y.; Liao, W.; Yang, J.Y.; Jeyakumar, P.; Abderson, C., 2020. Removal of vanadium from aquatic environment using phosphoric acid modified rice straw. Bioremediation Journal, v. 24, (1), 80-89. https://doi.org/10.1080/10889868.2020.1724073.

Heidarinejad, Z.; Dehghani, M.H.; Heidari, M.; Javedan, G.; Ali, I.; Sillanpaa, M., 2020. Methods for preparation and activation of activated carbon: a review. Environmental Chemistry Letters, v. 18, 393-415. https://doi.org/10.1007/s10311-019-00955-0.

Ho, Y.S.; McKay, G., 1998. Sorption of dye from aqueous solution by peat. Chemical Engineering Journal, v. 70, (2), 115-124. https://doi.org/10.1016/S0923-0467(98)00076-1.

Ho, Y.S.; McKay, G., 1999. Pseudo-second order model for sorption processes. Process Biochemistry, v. 34, (5), 451-465. https://doi.org/10.1016/S0032-9592(98)00112-5.

Hoareau, W.; Trindade, W.G.; Siegmund, B.; Castellan, A.; Frollini, E., 2004. Sugar cane bagasse and curaua lignins oxidized by chlorine dioxide and reacted with furfuryl alcohol: characterization and stability. Polymer Degradation and Stability, v. 86, (3), 567-576. https://doi.org/10.1016/j.polymdegradstab.2004.07.005.

Huang, Y.F.; Zhu, J.M.; Liu, H.E.; Wang, Z.Y.; Zhang, X.X., 2019. Preparation of porous graphene/carbon nanotube composite and adsorption mechanism of methylene blue. SN Appled Sciences, v. 1, (1), 37. https://doi.org/10.1007/s42452-018-0035-6.

Hubbe, M.; Azizian, S.; Douven, S., 2019. Implications of apparent pseudo-second-order adsorption kinetics onto cellulosic materials: a review. Bioresources, v. 14, (3), 7582-7626.

Hummadi, K.K.; Luo, S.; He, S., 2022. Adsorption of methylene blue dye from the aqueous solution via bio-adsorption in the inverse fluidized-bed adsorption column using the torrefied rice husk. Chemosphere, v. 287, (Part 1), 131907. https://doi.org/10.1016/j.chemosphere.2021.131907.

Jyoti, A.; Singh, R.K.; Kumara, N.; Amana, A.K.; Kar, M., 2021. Synthesis and properties of amorphous nanosilica from rice husk and its composites. Materials Science and Engineering, v. 263, 114871. https://doi.org/10.1016/j.mseb.2020.114871.

Kang, S.; Quin, L.; Zhao, Y.; Wang, W.; Zhang, T.; Yang, L.; Rao, F.; Song, S., 2020. Enhanced removal of methyl orange on exfoliated montmorillonite/chitosan gel in presence of methylene blue. Chemosphere, v. 238, 124693. https://doi.org/10.1016/j.chemosphere.2019.124693.

Kaykioğlu, G.; Güneş, E., 2016. Kinetic and equilibrium study of methylene blue adsorption using H2SO4− activated rice husk ash. Desalination And Water Treatment, v. 57, (15), 7085-7097. https://doi.org/10.1080/19443994.2015.1014859.

Khodaie, M.; Ghasemi, N.; Moradi, B.; Rahimi, M., 2013. Removal of methylene blue from wastewater by adsorption onto ZnCl2 activated corn husk carbon equilibrium studies. Journal of Chemistry, v. 2013, 383985. https://doi.org/10.1155/2013/383985.

Kieling, A.G., 2009. Influência da segregação no desempenho de cinzas de casca de arroz como pozolanas e material adsorvente. Doctora thesis, Unisinos, São Leopoldo.

Kishor, R.; Saratale, G.D.; Saratale, R.G.; Ferreira, L.F.R.; Bilal, M.; Iqbal, H.M.N.; Bharagava, R.N., 2021. Efficient degradation and detoxification of methylene blue dye by a newly isolated ligninolytic enzyme producing bacterium Bacillus albus MW407057. Colloids and Surfaces B: Biointerfaces, v. 206, 111947. https://doi.org/10.1016/j.colsurfb.2021.111947.

Labaran, A.N.; Zango, Z.U.; Armaya, U.; Garba, Z.N., 2019. Rice husk as biosorbent for the adsorption of methylene blue. Science World Journal, v. 14, (2), 66-70.

Lestari, A.Y.D.; Chafidz, A., 2020. Production of activated carbon from agro-industrial wastes and its potential use for removal of heavy metal in textile industrial wastewater. In: Zakaria, Z.; Aguilar, C.; Kusumaningtyas, R.; Binod, P. (Eds.), Valorisation of agro-industrial residues. Applied environmental science and engineering for a sustainable future. Springer, Cham, pp. 127-144, v. 2. https://doi.org/10.1007/978-3-030-39208-6_6.

Lima, H.H.C.; Maniezzo, R.S.; Llop, M.E.G.; Kupfer, V.L.; Arroyo, P.A.; Guolherme, M.R.; Rubira, A.F.; Girotto, E.M.; Rinaldi, A.W., 2019. Synthesis and characterization of pecan nutshell-based adsorbent with high specific area and high methylene blue adsorption capacity.Journal of Molecular Liquids, v. 276, 570-576. https://doi.org/10.1016/j.molliq.2018.12.010.

Low, M.J.D., 1960. Kinetics of chemisorption of gases on solids. Chemical Reviews, v. 60, (3), 267-312. https://doi.org/10.1021/cr60205a003.

Ma, P.; Wang, S.; Wang, T.; Wu, J.; Xing, X.; Zhang, X., 2019. Effect of bifunctional acid on the porosity improvement of biomass-derived activated carbon for methylene blue adsorption. Environmental Science and Pollution Research, v. 26, (29), 30119-30129. https://doi.org/10.1007/s11356-019-06177-9.

Mamaní, A.; Ramírez, N.; Deiana, C.; Giménez, M.; Sardella, F., 2019. Highly micro porous sorbents from lignocellulosic biomass: different activation routes and their application to dyes adsorption. Journal of Environmental Chemical Engineering, v. 7, (5), 103148. https://doi.org/10.1016/j.jece.2019.103148.

Mashhadi, S.; Javadian, H.; Ghasemi, M.; Saleh, T.A.; Gupta, V.K., 2016. Microwave-induced H2so4 activation of activated carbon derived from rice agricultural wastes for sorption of methylene blue from aqueous solution. Desalination And Water Treatment, v. 57, (44), 21091-21104. https://doi.org/10.1080/19443994.2015.1119737.

Meili, L.; Lins, P.V.S.; Costa, M.T.; Almeida, R.L.; Abud, A.K.S.; Soletti, J.I.; Dotto, G.L.; Tanabe, E.H.; Sellaoui, L.; Carvalho, S.H.V.; Erto, A., 2019. Adsorption of methylene blue on agroindustrial wastes: experimental investigation and phenomenological modelling. Progress in Biophysics and Molecular Biology, v. 141, 60-71. https://doi.org/10.1016/j.pbiomolbio.2018.07.011.

Meya, E.; Olupot, P.W.; Storz, H.; Lubwama, M.; Kiros, Y.; John, M.J., 2020. Optimization of pyrolysis conditions for char production from rice husks and its characterization as a precursor for production of activated carbon. Biomass Conversion and Biorefinery, v. 10, (53), 57-72. https://doi.org/10.1007/s13399-019-00399-0.

Moraes, C.A.; Fernandes, I.J.; Calheiro, D.; Kieling, A.G.; Brehm, F.A.; Rigon, M.R.; Berwanger Filho, J.A.; Schneider, I.A.; Osório, E., 2014. Review of the rice production cycle: by-products and the main applications focusing on rice husk combustion and ash recycling. Waste Management and Research, v. 32, (11), 1034-1048. https://doi.org/10.1177/0734242X14557379.

Muniandy, L.; Adam, F.; Mohamed, A.R.; Ng, E.P., 2014. The synthesis and characterization of high purity mixed microporous/mesoporous activated carbon from rice husk using chemical activation with NaOH and KOH. Microporous and Mesoporous Materials, v. 197, 316-323. https://doi.org/10.1016/j.micromeso.2014.06.020.

Nascimento, G.C.; Dominguini, L.; Mello, J.M.M.; Magro, J.D.; Riella, H.G.; Fiori, M.A., 2015. Caracterização físico-química da cinza de casca de arroz oriunda do processo termelétrico do Sul de Santa Catarina – Brasil. Ciência e Natura, v. 37, (3), 634-640. https://doi.org/10.5902/2179460X15262.

Nunes, O.M.; Borges, G.R.; Wohlemberg, J.; Rodrigues, E.D.; Mathias, L.R.; Lopes, L., 2017. Rice hull as alternative energy: A case study in the municipality of dom Pedrito – RS. Igepec Toledo, v. 21, (2), 42-62.

Pezoti Jr., O.; Cazetta, A.L.; Souza, I.P.A.F.; Bedin, K.C.; Martins, A.C.; Silva, T.L.; Almeida, V.C., 2014. Adsorption studies of methylene blue onto zncl2-activated carbon produced from buriti shells (Mauritia Flexuosa L). Journal of Industrial and Engineering Chemistry, v. 20, (6), 4401-4407. https://doi.org/10.1016/j.jiec.2014.02.007.

Piccin, J.S.; Gomes, C.S.; Feris, L.A.; Gutterres, M., 2012. Kinetics and isotherms of leather dye adsorption by tannery solid waste. Chemical Engineering Journal, v. 183, 30-38. https://doi.org/10.1016/j.cej.2011.12.013.

Schettino Jr., M.A.; Freitas, J.; Cunha, A.; Emmerich, F.; Soares, A.; Silva, P.R., 2007. Preparação e caracterização de carvão ativado quimicamente a partir da casca de arroz. Química Nova, v. 30, (7), 1663-1668. https://doi.org/10.1590/S0100-40422007000700031.

Senthilkumaar, S.; Varadarajan, P.R.; Porkodi, K.; Subbhuraam, C.V., 2005. Adsorption of methylene blue onto jute fiber carbon: kinetics and equilibrium studies. Journal of Colloid and Interface Science, v. 284, (1), 78-82. https://doi.org/10.1016/j.jcis.2004.09.027.

Shamsollahi, Z.; Partovinia, A., 2019. Recent advances on pollutants removal by rice husk as a bio-based adsorbent: a critical review. Journal of Environmental Management, v. 246, 314-323. https://doi.org/10.1016/j.jenvman.2019.05.145.

Shrestha, L.M.; Thapa, R.; Shrestha, R.G.; Maji, S.; Pradhananga, R.R.; Ariga, K., 2019. Rice husk-derived high surface area nanoporous carbon materials with excellent iodine and methylene blue adsorption properties. Journal of Carbon Research, v. 5, (1), 10. https://doi.org/10.3390/c5010010.

Silva, A.B.C.; Andrade, R.M.F.; Freire, F.B.; Nagalli, A.; Carvalho, K.; Passig, F.H.; Kreutz, C., 2017. Análise da utilização de cerâmica vermelha como adsorvente na remoção do corante têxtil direct blue de uma solução aquosa. Revista. Matéria, v. 22, (3), 1-14. https://doi.org/10.1590/s1517-707620170003.0202.

Silva, T.; Barbosa, C.; Gama, B.; Nascimento, G.; Duarte, M.M.M.B., 2018. Agregação de valor a resíduo agroindustrial: remoção de fenol utilizando adsorvente preparado a partir de casca de amendoim. Revista Matéria, v. 23, (1), e11947. https://doi.org/10.1590/s1517-707620170001.0283.

Srivastava, V.C.; Mall, I.D.; Mishra, I., 2007. Adsorption thermodynamics and isosteric heat of adsorption of toxic metal ions onto bagasse fly ash (BFA) and rice husk ash (RHA). Chemical Engineering Journal, v. 132, (1-3), 267-278. https://doi.org/10.1016/j.cej.2007.01.007.

Stracke, M.P.; Girardello, V.C.; Zwirtes, E.; Nagel, J.C.; Tusset, B.T.K., 2020. Rice bark gray as a molecular water reservoir for soy production. Brazilian Journal of Development, v. 6, (1), 949-962. https://doi.org/10.34117/bjdv6n1-066.

Subha, R.; Namasivayam, C., 2009. Zinc chloride activated coir pith carbon as low-cost adsorbent for removal of 2,4-dichlorophenol: equilibrium and kinetic studies. Indian Journal of Chemical Technology, v. 16, (6), 471-479.

Tarley, C.R.T.; Arruda, M.A.Z., 2004. Biosorption of heavy metals using rice milling by-products. Characterisation and application for removal of metals from aqueous effluents. Chemosphere, v. 54, (7), 987-995. https://doi.org/10.1016/j.chemosphere.2003.09.001.

Tongpoothorn, W.; Sriuttha, M.; Homchan, P.; Chanthai, S.; Ruangviriyachai, C., 2011. Preparation of activated carbon derived from Jatropha curcas fruit shell by simple thermo-chemical activation and characterization of their physico-chemical properties. Chemical Engineering Research and Design, v. 89, (3), 335-340. https://doi.org/10.1016/j.cherd.2010.06.012.

Vieira, M.G.A.; De Almeida Neto, A.F.; Da Silva, M.G.C.; Nóbrega, C.C.; Melo Filho, A.A., 2012. Characterization and use of in natura and calcined rice husks for biosorption of heavy metals ions from aqueous effluents. Brazilian Journal of Chemical Engineering, v. 29, (3), 619-633. https://doi.org/10.1590/S0104-66322012000300019.

Wei, H.; Wang, H.; Heqing, L.; Cui, D.; Dong, M.; Lin, J.; Fran, J.; Zhang, J.; Hou, H.; Shi, Y.; Zhou, D.; Guo, Z., 2020. Advanced porous hierarchical activated carbon derived from agricultural wastes toward high performance supercapacitors. Journal of Alloys And Compounds, v. 820, 153111. https://doi.org/10.1016/j.jallcom.2019.153111.

Zhang, S.; Zhu, S.; Zhang, H.; Liu, X.; Xiong, Y., 2020. Synthesis and characterization of rice husk-based magnetic porous carbon by pyrolysis of pretreated rice husk with FeCl3 And ZnCl2. Journal of Analytical and Applied Pyrolysis, v. 147, 104806. https://doi.org/10.1016/j.jaap.2020.104806.

Zhang, Y.; Zheng, R.; Zhao, J.; Ma, F.; Zhang, Y.; Meng, Q., 2014. Characterization Of H3PO4-treated rice husk adsorbent and adsorption of copper (Ii) from aqueous solution. Biomed Research International, v. 2014, 496878. https://doi.org/10.1155%2F2014%2F496878.

Zyoud, A.H.; Asaad, S.; Samer, H.; Zyoud, S.H.; Zyoud, S.H.; Helal, M.A.; Qamhieh, N.; Hajamohideen, A.; Hilal, H.S., 2020. Raw clay supported ZnO nanoparticles in photodegradation of 2-chlorophenol under direct solar radiations. Journal of Environmental Chemical Engineering, v. 8, (5), 104227. https://doi.org/10.1016/j.jece.2020.104227.