In this study, titanium dioxide (TiO2) nanoparticles were synthesized via a sol-gel method and immobilized onto humic acid (HA) extracted from leonardite to enhance their photocatalytic efficiency under both UV and visible light. The nanomaterial containing 0.03 g of HA (per 0.1 g TiO2) exhibited the highest performance, achieving a degradation efficiency of 99.36% for Methyl Orange (MO) under UV irradiation within 25 min and 98.43% under visible light within 180 min. The apparent reaction rate constant (k) of the optimized TiO2/HA nanomaterial reached 1.3252 min−1 under UV irradiation and 0.0957 min−1 under visible light. These values are approximately 39.3 and 15.4 times higher, respectively, than those of pure TiO2, indicating a substantial enhancement in catalytic activity.
AlbaigésJ. Handbook of environmental analysis: chemical pollutants in air, water, soil, and solid wastes. Int J Environ Anal Chem2017; 97(14–15): 1420.
TributschH. Feasibility of toxic chemical waste processing in large scale solar installations. Sol Energy1989; 43: 139–143.
4.
TynerCE. Application of solar thermal technology to the destruction of hazardous wastes. Sol Energy Mater1990; 21: 113–129.
5.
GitaSHussanAChoudhuryT. Impact of textile dyes waste on aquatic environments and its treatment. Environ Ecol2017; 35: 2349–2353.
6.
KhanSMalikA. Environmental and health effects of textile industry wastewater. Environ deterior human health, Springer, Dordrecht,2014; Chapter 4: 55–71. DOI: 10.1007/978-94-007-7890-0_4
7.
MaZ, et al.Research progress and trends on state-of-the-art membrane technologies in textile wastewater treatment. Sep Purif Technol2024; 333: 125853.
8.
Martínez-HuitleCABrillasE. Decontamination of wastewaters containing synthetic organic dyes by electrochemical methods: a general review. Appl Catal, B2009; 87: 105–145.
9.
SiddiqueAB, et al.Carissa macrocarpa extract based greenly synthesized AuNPs: a sustainable approach for lead Ion detection, azo dye degradation, and antimicrobial applications. Water Air Soil Pollut2025; 236: 1–22.
10.
KhalidZ, et al.Causonis trifolia-based green synthesis of multifunctional silver nanoparticles for dual sensing of mercury and ferric ions, photocatalysis, and biomedical applications. RSC Adv2025; 15: 16879–16893.
11.
DengA, et al.Unlocking the potential of MOF-derived carbon-based nanomaterials for water purification through advanced oxidation processes: a comprehensive review on the impact of process parameter modulation. Sep Purif Technol2023; 318: 123998.
12.
Al-QaradawiSSalmanSR. Photocatalytic degradation of methyl orange as a model compound. J Photochem Photobiol A2002; 148: 161–168.
HerrmannJ-M. Heterogeneous photocatalysis: fundamentals and applications to the removal of various types of aqueous pollutants. Catal Today1999; 53: 115–129.
15.
LegriniOOliverosEBraunA. Photochemical processes for water treatment. Chem Rev1993; 93: 671–698.
KatalR, et al.A review on the synthesis of the various types of anatase TiO2 facets and their applications for photocatalysis. Chem Eng J2020; 384: 123384.
19.
PrabakarK, et al.Visible light-active nitrogen-doped TiO2 thin films prepared by DC magnetron sputtering used as a photocatalyst. Renew Energy2008; 33: 277–281.
20.
LeeS-K, et al.Modification and enhanced photocatalytic activity of TiO2 following exposure to non-linear irradiation sources. J Photochem Photobiol A1999; 122: 69–71.
21.
RazaN, et al.Solar-light-active silver phosphate/titanium dioxide/silica heterostructures for photocatalytic removal of organic dye. J Cleaner Prod2020; 254: 120031.
22.
RezaeiSS, et al.Photocatalytic oxidation of tetracycline by magnetic carbon-supported TiO2 nanoparticles catalyzed peroxydisulfate: performance, synergy and reaction mechanism studies. Sep Purif Technol2021; 258: 117936.
23.
AhmadH, et al.Energy bandgap tuning of sr-doped ZnO nanoparticles for photodegradation of azo dyes and antibacterial applications. J Water Process Eng2025; 74: 107855.
24.
PadmanabhanNT, et al.Zno/Mo2TiC2 MXene nanohybrids for enhanced solar-driven photocatalytic degradation of tetracycline and organic pollutants in contaminated water. Energy Environ Sustain2025; 1: 100042.
25.
TakedaN, et al.Effect of inert supports for titanium dioxide loading on enhancement of photodecomposition rate of gaseous propionaldehyde. J Phys Chem1995; 99: 9986–9991.
26.
SzczepanikB. Photocatalytic degradation of organic contaminants over clay-TiO2 nanocomposites: a review. Appl Clay Sci2017; 141: 227–239.
27.
MesonesS, et al.Synergistic and antagonistic effects in the photoelectrocatalytic disinfection of water with TiO2 supported on activated carbon as a bipolar electrode in a novel 3D photoelectrochemical reactor. Sep Purif Technol2020; 247: 117002.
28.
VaianoVSaccoOMatarangoloM. Photocatalytic degradation of paracetamol under UV irradiation using TiO2-graphite composites. Catal Today2018; 315: 230–236.
YuY, et al.Enhancement of adsorption and photocatalytic activity of TiO2 by using carbon nanotubes for the treatment of azo dye. Appl Catal, B2005; 61: 1–11.
31.
KanwalM, et al.Dual colorimetric sensing of Hg(II) and Fe(III) using sulfanilamide-stabilized silver nanoparticles and evaluating their photodegradation and antibacterial properties. J Water Process Eng2025; 75: 107981.
32.
ZengY, et al.Illuminated fulvic acid stimulates denitrification and As(III) immobilization in flooded paddy soils via an enhanced biophotoelectrochemical pathway. Sci Total Environ2024; 912: 169670.
33.
Alvarez-PueblaRValenzuela-CalahorroCGarridoJ. Theoretical study on fulvic acid structure, conformation and aggregation: a molecular modelling approach. Sci Total Environ2006; 358: 243–254.
34.
VelascoM, et al.Analysis of humic acid from compost of urban wastes and soil by fluorescence spectroscopy. Agriscientia2004; 21: 31–38.
35.
RashedMEl-AminA. Photocatalytic degradation of methyl orange in aqueous TiO2 under different solar irradiation sources. Int J Phys Sci2007; 2: 073–081.
36.
HamadanianMReisi-VananiAMajediA. Preparation and characterization of S-doped TiO2 nanoparticles, effect of calcination temperature and evaluation of photocatalytic activity. Mater Chem Phys2009; 116: 376–382.
37.
ScienceSDAo. Proceedings of the South Dakota Academy of Science10, Wermillion, South dakota, USA: South Dakota Academy of Sciences, 1927.
38.
ZhouC, et al.Facile synthesis of humic acid-coated iron oxide nanoparticles and their applications in wastewater treatment. Funct Mater Lett2011; 4: 373–376.
39.
GuL, et al.Synthesis of nano-sized anatase TiO2 with reactive {001} facets using lamellar protonated titanate as precursor. Chem Commun2012; 48: 6978–6980.
40.
BanerjeeS. Enhanced removal of methylene blue dye from its aqueous solutions using humic acid-functionalized alumina nanoparticles. Res Chem Intermed2018; 44: 4119–4148.
41.
Al-TaweelSSSaudHR. New route for synthesis of pure anatase TiO2 nanoparticles via utrasound-assisted sol-gel method. J Chem Pharm Res2016; 8: 620–626.
42.
KoesnarpadiS, et al.Synthesis and characterizatation of magnetite nanoparticle coated humic acid (Fe3O4/HA). Proc Environ Sci2015; 30: 103–108.
43.
JabbariV, et al.In, V-codoped TiO2 nanocomposite prepared via a photochemical reduction technique as a novel high efficiency visible-light-driven nanophotocatalyst. RSC Adv2015; 5: 78128–78135.
44.
GaoLWangSZhaoX. Synthesis and characterization of agricultural controllable humic acid superabsorbent. J Environ Sci2013; 25: S69–S76.
45.
WangS, et al.Structure and photocatalytic property of MO-doped TiO2 nanoparticles. Powder Technol2013; 244: 9–15.
46.
WangSZhouS. Photodegradation of methyl orange by photocatalyst of CNTs/P-TiO2 under UV and visible-light irradiation. J Hazard Mater2011; 185: 77–85.
47.
RajKViswanathanB. Effect of surface area, pore volume and particle size of P25 titania on the phase transformation of anatase to rutile, 2009.
48.
LuJY, et al.Facile microwave-assisted synthesis of Sb2O3-CuO nanocomposites for catalytic degradation of p-nitrophenol. J Mol Liq2024; 409: 125503.
49.
LiY, et al.Efficient degradation of norfloxacin by synergistic activation of PMS with a three-dimensional electrocatalytic system based on Cu-MOF. Sep Purif Technol2025; 356: 129945.
50.
QiZ, et al.Visible-light-catalyzed synthesis of 1, 3-benzoxazines via formal [4 + 2] cycloaddition of oximes with o-hydroxybenzyl alcohols. Org Biomol Chem2023; 21: 6419–6423.
