CHEMICAL ENGINEERING TRANSACTIONS  
 

VOL. 52, 2016 

A publication of 

 

The Italian Association 
of Chemical Engineering 
Online at www.aidic.it/cet 

Guest Editors: Petar Sabev Varbanov, Peng-Yen Liew, Jun-Yow Yong, Jiří Jaromír Klemeš, Hon Loong Lam 
Copyright © 2016, AIDIC Servizi S.r.l., 

ISBN 978-88-95608-42-6; ISSN 2283-9216 
 

TiO2/Zeolite Composite on Ceramic Tiles: Influence of the 

Amount of Photocatalyst on Adsorption and Photocatalytic 

Properties. 

Giuseppe Sarno, Vincenzo Vaiano, Diana Sannino 

Department of Industrial Engineering, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano (SA), Italy; 

vvaiano@unisa.it 

In this work, TiO2-Ag-zeolite was supported on porous ceramic tiles to enhance the self-cleaning properties. 

The influence on adsorption and photocatalytic properties of the anchored composite with respect to a coating 

with only TiO2  has been evaluated. Functionalized tiles were obtained through a method that involves a sol-

gel preparation followed by calcination at 550 °C for 2 h and different samples at different titanium and silver 

surface loads were prepared. The verification of the self-cleaning properties was conducted through 

adsorption and photocatalytic tests realized using aqueous solutions containing methylene blue (MB). 

Characterization results evidenced that the deposition method induced the formation of TiO2/Ag-zeolite layer, 

strongly adherent to the tile surface, in which TiO2 is present in anatase phase. The photocatalytic 

performances are strongly influenced by the amount of TiO2-Ag-zeolite composite deposited on the tile 

surface. 

1. Introduction 

Photocatalytic functionalization of surfaces involves the conferring of self-cleaning and antibacterial properties 

due to the spontaneous oxidizing power of semiconductors when they are irradiated by a light with a suitable 

range of wavelengths (Banerjee et al., 2015). Titanium dioxide is one of the most used semiconductor since it 

actually well known  that under UV light irradiation it generates electron-hole pairs active for the degradation of 

a wide range of dangerous organic compounds in water (Sacco et al., 2015), air (Hajaghazadeh et al., 2014) 

and for the inactivation of different bacterial strains (Rizzo, 2009). TiO2 has been also widely applied for the 

realization of multifunctional coatings (Ragesh et al., 2014); for this purpose, recently, composites have been 

deposited on the surface of ceramic tiles to attribute self-cleaning characteristics (Sarno et al., 2015). 

However, TiO2 is rarely utilized in indoor environments as photocatalyst, due to the limited availability of light 

irradiation belonging to the UV region. Different approaches have been achieved for the modification of TiO2 

with various heteroatoms which allow to exploit, for photocatalytic reactions, both UV and visible light 

irradiation (Asahi et al., 2001). On the other hand, to improve the photocatalytic efficiencies, the combination 

of a specific photocatalyst with other materials such as clays or porous materials is an interesting opportunity 

for the design of a composite with specific functions (Durga Kumari et al., 2002). 

Adsorption of organic pollutants from air and water on TiO2 surface play an important role in the photocatalytic 

process and leads to an increased removal of organic contaminants both in the air and in water. The 

combination of TiO2 and specific materials, such as alumino-silicates, as already reported, demonstrates that 

the presence of zeolite enhanced photodegradation process because of the favourable adsorption properties 

of the zeolite (Sarno et al., 2015). 

In this work, to enhance the self-cleaning properties, TiO2/Ag-zeolite was supported on highly porous 

traditional ceramic tiles and evaluated the influence on adsorption and photocatalytic properties of the 

anchored composite at different amounts of TiO2/zeolite with respect to a TiO2 coating. We mainly focus our 

results on the application of the composite in the discoloration of methylene blue aqueous solutions as a 

model fouling agent under UV light irradiation. 

                                

 
 

 

 
   

                                                  
DOI: 10.3303/CET1652141 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Please cite this article as: Sarno G., Vaiano V., Sannino D., 2016, Tio2/zeolite composite on ceramic tiles: influence of the amount of 
photocatalyst on adsorption and photocatalytic properties, Chemical Engineering Transactions, 52, 841-846  DOI:10.3303/CET1652141   

841



 

2. Experimental 

2.1 Preparation of composite 

The Ag based zeolite was prepared through ionic exchange in two steps, the first conducted at room 

temperature on Na, K-ferrierite with a solution of NH4NO3 1 M while the second ion exchange at room 

temperature with AgNO3 aqueous solution for 24 h, followed by calcination at 550 °C.  

Tiles, with dimensions 100 mm × 100 mm × 12 mm, were ultrasonically cleaned in surfactant and washed with 

water prior to the deposition process. Tiles surface functionalization was achieved with a TiO2 sol obtained 

through a sol gel method (Sarno et al., 2015) mixing the reagents in the following order: titanium (IV) 

isopropoxide, (Ti(C3H7O)4, Sigma Aldrich), ethanol (C2H5OH, Fluka Analytical), acetyl acetone 

(CH3(CO)CH2(CO)CH3, Sigma Aldrich), acetic acid (CH3COOH, Aldrich Chemistry), urea (NH2CONH2, Sigma 

Aldrich), polyethylene glycol, (HO(C2H4O)nH, MW = 5,000 – 7,000, Aldrich Chemistry) and water. In the 

obtained sol, Ag-zeolite and TRITON X 100, as non-ionic surfactant, were added. The functionalized ceramic 

tiles were finalized via steps-coating technique followed by heat-treatment in air at 550 °C. Mass ratio between 

zeolite and TiO2 is equal to 0.4 g g-1. 

Different samples with different titanium and zeolite content were obtained increasing the number of coating 

steps. A functionalized tile without zeolite and Triton X 100 was also realized (tile T1). 

Table 1 reports the list of the obtained samples with their titanium surface concentration and the number of 

coating steps realized to accomplish the achieved surface composition. 

Table 1: List of samples with their titanium surface concentration. 

Sample Ti surface conc. (%) Coating steps (n°) 

Raw Tile 1.24 0 

Tile T1 7.87 2 

Tile R 7.96 2 

Tile P 13.31 5 

Tile BE 17.06 7 

 

2.2 Characterizations of functionalized tiles 
Chemical-physical characterisation of the samples was performed by different techniques. 

Laser Raman spectra were obtained at room temperature with a Dispersive MicroRaman (Invia, Renishaw), 

equipped with 514 nm diode-laser, in the range 100 - 800 cm-1 Raman shift. 

X-Ray fluorescence spectroscopy (XRF) was performed using a ThermoFischer ARL QUANT’X EDXRF 

spectrometer equipped with a rhodium standard tube as the source of radiation and with Si-Li drifted crystal 

detector. 

2.3 Adsorption tests 
Methylene blue (MB) is used as model stain dissolved in water; since it shows good chemical stability and the 

concentration can be easily monitored using a UV-Vis spectrophotometer. 

An aqueous solution of MB with a concentration equal to 5 ppm was prepared. Ceramic tiles were placed in a 

plate reactor (0.2 L in volume) realized in stainless steel (Sannino et al., 2013). The reactor was filled with the 

solution of methylene blue and was kept in dark. Liquid samples were monitored in continuous mode by 

spectrophotometric measurement. A special assembly with a flow cuvette and an external pump for the 

recirculation of liquid was realized, permitting to analyse continuously the change of MB concentration, 

measured with a Perkin Elmer UV-Vis spectrophotometer at λ = 663 nm. 

2.4 Photocatalytic tests 
Photocatalytic tests were performed at atmospheric pressure and ambient temperature using a steel reactor 

with a pyrex window of size 100 mm × 100 mm. The irradiation of photoreactor was realized by four UV lamps 

(nominal power 8 W each) with the main peak of emission spectrum centred at 365 nm. The photoreactor is 

provided of temperature controlling system, consisting of a thermal exchanger within the metal body and a 

cooling system. 

Pre-adsorption of MB on the tiles surface was performed using an aqueous solution of MB with a 

concentration equal to 10 ppm. Tiles and 200 mL of the adsorption solution were placed in contact in a glass 

beaker and the dye was adsorbed in dark conditions for 24 h. When the remaining concentration of the dye in 

the solution was larger than that of the test solution, the adsorption was considered to be completed. 

Otherwise, the procedure was repeated for another 12 h using a fresh adsorption solution. 

842



 

The initial concentration of MB for photocatalytic tests was 5 ppm. The changes of MB concentration in liquid 

samples were analysed in continuous way by spectrophotometric measurement at λ = 663 nm with the same 

device described in section 2.3. 

3. Results and discussion 

3.1 Samples characterization 
Raman spectroscopy has been applied to evidence TiO2 crystallographic phases since the crystal structure is 

an important parameter in the efficacy of the MB photo-discoloration (Vaiano et al., 2014). 

Figure 1 shows the Raman spectra of the functionalized tiles in comparison with raw tile in the range 100 - 900 

cm-1. No bands are present for raw tile; functionalized tiles display bands at 144, 396, 514 and 637 cm-1 and a 

weak shoulder at 195 cm-1, due to the Raman-active fundamental modes of titania in anatase phase 

(Ciambelli et al., 2008). Figure 2 reports the results of XRF analysis for raw tile in comparison with titanium 

functionalized tile (T1) and the tiles functionalized with the composite TiO2/Ag-zeolite (P, R and BE samples). 

The surface concentration of titanium and silver in the functionalized samples reached a value of about 17 % 

and 0.053 % respectively for tile functionalized with the highest number of coating steps (tile BE), indicating a 

good performance of the deposition process under the experimental conditions employed. Moreover, as it can 

be seen from Figure 3 the increase of the surface concentration for these two metals is almost linear with the 

increase of the number of coating steps realized. These evidences clearly show that the tile surface is not 

completely saturated with the functionalizing composite and that the deposition method is able to induce the 

formation of TiO2/Ag-zeolite layer, strongly adherent to the tile surface, in which anatase TiO2 was present. 

 

 

Figure 1: Raman spectra of functionalized and raw tile in the range 100 – 900 cm-1 

843



 

Figure 2: XRF analysis of surface for raw tile and functionalized tiles. 

 

Figure 3: Behavior of the surface concentration as a function of the coating steps realized 

3.2 Adsorption tests 
Figure 4 shows that the relative concentration of the dye in aqueous solution decreases along the time 

because of the adsorption of MB on the functionalized tiles. From a certain time onwards, it reaches a 

constant value beyond which MB is no longer removed from the solution. For T1 sample the relative 

concentration of the dye decreases slower than the raw sample; this data clearly indicate that titania is able to 

occlude partially the porosity of the support. On the other hand the functionalization with the composite 

TiO2/Ag-zeolite causes an increase of the adsorption capacity; in particular it increased of about 50 % for the 

sample BE with respect to the raw tile. This behaviour can be associated with an increase in the total porosity 

of the composite generated by the zeolite. Moreover, this capacity is directly correlated to the amount of the 

composite deposited on the substrate. 

844



 

Figure 4: Behavior of MB relative concentration as a function of run time 

3.3 Photocatalytic activity tests 
The changes in the concentration of MB recorded in continuous mode are shown in Figure 5a. Control 

experiment carried out on the raw tile shows that MB relative concentration reached a maximum value and 

then decreased, indicating desorption phenomena of MB from the tile surface. For tile T1 the relative 

concentration of the dye slightly decreases reaching a discoloration of about 35 % only after 48 h of irradiation 

time. For the samples functionalized with the composite TiO2/Ag-zeolite the relative concentration of MB 

decreases rapidly, reaching the complete discoloration in less than 42 h. At fixed irradiation time the presence 

of zeolite leads to higher discoloration rate (obtained following the first order kinetic with respect to the MB 

relative concentration). The values of kinetic constant are plotted in Figure 5b as a function of the titanium 

surface concentration. As it can be seen there is an optimum in the titanium surface concentration equal to 

13.31 %, for which the highest value of kinetic constant is obtained. The lower photocatalytic performance at 

higher tile surface coverage is probably due to an aggregation of the deposited particles which shields part of 

the active species. 

 

 

Figure 5: Behavior of MB relative concentration as a function of irradiation time (a) and kinetic constant as a 

function of the titanium surface concentration (b). 

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4. Conclusions 

In this work, TiO2-Ag-zeolite composite was supported on porous ceramic tiles to enhance the self-cleaning 

properties. The deposition method is able to induce the formation of a layer, strongly adherent to the tile 

surface, in which TiO2 results in anatase form. 

For the tile functionalized with the highest number of coating steps (tile BE) the surface concentration of 

titanium and silver in the functionalized samples reached a value of about 17 % and 0.053 %, respectively, 

indicating a good performance of the deposition process under the experimental conditions employed. 

The functionalization causes an increase of the adsorption capacity; in particular MB amount adsorbed on tile 

surface increases of about 50 % for the sample with the highest titanium content with respect to the raw tile. 

On the other hand the application of the TiO2/Ag-zeolite composite resulted in the increasing of the 

degradation rate of the dye with respect to the tile coated with TiO2 alone; anyway, an optimum in the titanium 

surface concentration (13.31 %) for which the highest value of kinetic constant is obtained, was found. Up to 

this nanocomposite load, the formed coating from the adsorbent and photocatalytic particles, was completely 

active, being the photocatalyst well exposed to the irradiation, without self-shielding effects. 

Acknowledgments 

The authors wish to thanks “Ceramiche Il Pavone” for having provided the tiles used in this work. 

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