Photocatalytic decolorization of auramine and its kinetics study in the presence of two different sizes titanium dioxide nanoparticles at various buffer and non-buffer media
Introduction
Undoubtedly, today the environmental pollutants are as important problems in the human society. Massive amounts of untreated organic pollutants from different industrial companies (especially industrial dyes) represent an increasing environmental danger due to toxicity and carcinogenic properties [1], [2], [3]. All attempts for removal of the chemical pollutants are considered as current active fields in green chemistry point of view. There are many ways for pollutants elimination such as adsorption on activated carbon, ultrafiltration, reverse osmosis, coagulation by chemical agents, ion exchange on synthetic adsorbent resins and etc. [4], [5]. These methods generally cause transferring the organic pollutants from water to other media that naturally produce a new pollution. Therefore further treatment of the used adsorbent is required to regenerate it which will induce more cost to the removal processes. One of the effective low cost ways is photocatalytic degradation [6], [7], [8], [9], [10], [11], [12] that applies irradiation and semi-conductor oxides to eliminate the pollutant materials. The aim of photocatalysis process is effectively eliminating of the toxic materials from wastewaters under mild conditions [13]. Among many proposed semiconductors for photocatalytic treatment, titanium dioxide is a suitable photocatalyst because of its acceptable band gap energy, easily availability and low cast [14]. Such photocatalysts apply UV or visible light to generate electron–hole pairs at their conduction and valence bands [15]. Then the electrons in conduction band react with molecular oxygen in bulk solution to generate active oxidant species such as superoxide radical anions and hydrogen peroxide. On the other hand, the holes at valence band can oxidize surface hydroxyl groups to form OH radicals or even organic pollutant molecules. The mentioned oxidant species attack to the organic pollutant targets leading to eventually oxidation of them to CO2, H2O, and etc. Auramine as a diarylmethane dye is an industrial dye [16] that because of its stability in the nature is environmentally dangerous in human health point of view. The extra deaths from bladder cancer have been caused in people by use of this dye [17], [18], [19]. Therefore, degradation of this dye may be of interested for environmental researchers. The auramine dye is found in two chemical formula: not-salted(trade name: auramine O base) and mono-hydrochloride salt (trade name: auramine O). There are some reports on photocatalytic degradation of auramine hydrochloride [20], [21], [22], [23] under sunlight or low Pressure irradiation but to the best of our knowledge, there is no report on photocatalytic decolorization and its kinetics of not-salted auramine under high pressure mercury lamp at various buffer or non-buffer pHs using nano-titanium dioxide(anatase) under aerobic conditions. In continuation of our previous studies on dye removal [24], [25], [26], [27], [28], [29], in this work, we report photocatalytic decolorization and kinetic studies of auramine at various aqueous buffer and non-buffer solutions using nano-titanium dioxide in two different sizes of 15 and 70 nm in a photocatalyic reactor equipped with 400 W high pressure mercury lamp under aerobic condition. Furthermore the kinetics behavior of photocatalytic process was studied and then kinetics parameters were evaluated at all conditions.
Section snippets
Chemicals
Auramine (C17H21N3, Yellow powder, C. I. 41000B), and other chemicals such as NaOH, HCl, KCl, K2HPO4, KH2PO4, Na2B4O10.10 H2O were purchased from Merck, Fluka and/or Aldrich. Two different sizes nano-Titanium dioxide (anatase) with average sizes of 15 and 70 nm (from Sigma-Aldrich) were used for all photocatalytic experiments. The SEM and TEM of these nanoparticles are illustrated at (Fig. 1).
Apparatus
SEM and TEM of titanium dioxide nano-particles were recorded on instruments of Hitachi Japan-S4160,
The effect of catalyst dosage
The a photocatalytic decolorization of auramine solution at each pH (pHs of 5, 7 and 9) was performed both at buffer and non-buffer media with different dosages of nano-titanium dioxide for two different sizes (15 and 70 nm) at the same conditions under high pressure 400 W mercury lamp irradiation at room temperature. Fig. 2, Fig. 3 show the residual absorbance as a function of irradiation time in the presence of different dosages of photocatalysts at all above buffer and non-buffer pHs. It was
Conclusion
In this research, photocatalytic decolorization of auramine dye was investigated in the presence of nano-titanium dioxide in two different sizes (15 and 70 nm). The effects of UV light (400 W high pressure Hg lamp), buffer and non-buffer pHs, irradiation time and nano-titanium dioxide amount (in two different sizes) were examined. After appointment of suitable catalyst amount, photocatalytic decolorization of Auramin in water was performed under UV light irradiation. Based on the resultants data
Acknowledgments
Partial support of this work by Yasouj University is acknowledged.
References (41)
- et al.
Appl. Catal., B: Environ.
(2004) - et al.
Appl. Catal., B: Environ.
(2007) - et al.
J. Hazard. Mater.
(2004) - et al.
Appl. Catal., B: Environ.
(2007) - et al.
J. Photochem. Photobiol., A: Chem.
(2006) - et al.
Appl. Catal., B: Environ.
(2004) - et al.
Catal. Today
(2004) - et al.
J. Mol. Catal. A: Chem.
(2006) - et al.
Appl. Catal., B: Environ.
(2008) - et al.
J. Photochem. Photobiol., C: Photochem. Rev.
(2008)
Desalination
Dyes Pigm.
J. Hazard. Mater.
Appl. Catal., B Environ.
Chemosphere
J. Hazard. Mater. B
Appl. Catal., B: Environ.
J. Catal.
Dyes Environmental Chemistry” in Kirk–Othmer Encyclopedia of Chemical Technology
Cited by (15)
Different shape-controlled synthesis and catalytic property studies on bismuth nanomaterials
2023, Materials Chemistry and PhysicsTiO<inf>2</inf> quantum dots: Energy consumption cost,germination, and phytotoxicity studies, recycling photo and solar catalytic processes of reactive yellow 145 dye and natural industrial wastewater
2023, Advanced Powder TechnologyCitation Excerpt :Therefore, it is necessary to purify textile factory effluent before permitting it to be released into freshwater streams or utilized for irrigation. In many nations, the majority of presently available decolorization procedures are insufficient to effectively remove hazardous colors, necessitating the implementation of more stringent regulations governing the discharge of wastewater Fields [18–21]. The World Health Organization (WHO) notes a lack of clarity on the water quality necessary for all life forms.
S-scheme heterojunction g-C<inf>3</inf>N<inf>4</inf>/TiO<inf>2</inf> with enhanced photocatalytic activity for degradation of a binary mixture of cationic dyes using solar parabolic trough reactor
2021, Chemical Engineering Research and DesignCitation Excerpt :But TiO2 has a serious disadvantage and cannot absorb visible light owing to its large band gap of 3.2 eV. The decrease of band gap composite nanomaterials content of TiO2 can yield high responsiveness under visible light for photocatalytic degradation (Song et al., 2016; Montazerozohori et al., 2015). The requirement of lower energy consumption and easy and low-cost wastewater treatment processes, encourage researchers to synthesize photocatalysts that are green and have band gap applicable for activation under solar irradiation.
Improved performance of immobilized TiO<inf>2</inf> under visible light for the commercial surfactant degradation: Role of carbon doped TiO<inf>2</inf> and anatase/rutile ratio
2020, Catalysis TodayCitation Excerpt :Photocatalysis is one of several advanced oxidation process remediation techniques that represents an alternative treatment technology that can completely degrade different organic contaminants to mineral products based on highly reactive radicals [14–19]. In recent years, titanium dioxide has been widely used as a suitable photocatalyst due to its non-toxic nature, easy availability, environmentally friendly, cost-effectiveness, chemical stability and capabilities to purify pollution [20–23]. So far, many studies have reported that a major disadvantage of titanium dioxide nanoparticles (nTiO2) is its large band gap (3.2 eV).