Anal. Methods Environ. Chem. J. 4 (4) (2021) 5-19

Research Article, Issue 4

Analytical Methods in Environmental Chemistry Journal

Journal home page: www.amecj.com/ir

AMECJ

Photocatalytic degradation of Perchloroethylene by a lab-

scale continuous-ow annular photoreactor packed with

glass beads carbon-doped TiO2 nanoparticles

Hojjat Kazemi a,*, Mahboubeh Rabbani b, Haniye Kashafroodi b and Hossin kazemi a

aAnalytical Chemistry Research Group, Research Institute of Petroleum Industry (RIPI), Tehran, Iran

bDepartment of Chemistry, Iran University of Science and Technology, Narmak, Tehran, Iran

ABSTRACT

In this study, the amount of photocatalytic degradation of

perchloroethylene in the gas phase was investigated by a xed bed

continuous-ow tubular photoreactor. The photoreactor consists

of a cylindrical glass tube, was lled with glass beads coated with

nanoparticles of TiO2, and TiO2 doped carbon (TiO2-C). These

nanoparticles were synthesized by the sol-gel method and deposited

on glass beads using the sol-gel dip technique. X-ray diffraction

(XRD), scanning electron microscopy (SEM), Fourier transforms

infrared spectroscopy (FT-IR), and diffuse reectance spectroscopy

(DRS) were used for the characterization of synthesized materials.

The effect of different parameters such as relative humidity, residence

time, PCE concentration on the photocatalytic degradation process

was investigated by ultraviolet irradiation to achieve the highest

possible degradation efciency. The PCE degradation and byproduct

species were monitored and identied with a gas chromatography-

mass spectrometer device (GC-MS). Under the optimum

experimental conditions, the photocatalytic activities of TiO2, TiO2-C

were investigated and compared together. The results showed that

photocatalytic activity of TiO2 for degradation of PCE was extremely

increased when doped with carbon. For TiO2-C catalyst, under UV

irradiation (3000 ppm initial PCE concentration, 30% humidity and

1 min residence time) approximately 96% of the initial PCE was

degraded. Also, the catalyst showed high stability over 48 h without

a decrease in catalytically efciency. All results show that TiO2-C is a

good candidate for application PCE degradation.

Keywords:

TiO2 nanoparticles,

Photocatalyst,

Chlorinated volatile organic compounds,

Pollutant degradation,

Sol-gel,

Gas chromatography-mass spectrometer

ARTICLE INFO:

Received 14 Aug 2021

Revised form 28 Oct 2021

Accepted 7 Nov 2021

Available online 28 Dec 2021

*Corresponding Author: Hojjat Kazemi

Email: hojjatkazemi4@yahoo.com

https://doi.org/10.24200/amecj.v4.i04.159

------------------------

1. Introduction

Among volatile organic compounds (VOCs)

chlorinated volatile organic compounds, such as

perchloroethylene (PCE), are important because of

widely used as solvents at industrial scale in metal

parts, semiconductors washing, dry cleaning, etc.

This extensive use leads to their being extremely

present in the water and air. These compounds

are toxic, carcinogenic and have many other

adverse effects on humans [1, 2]. Therefore,

there are great efforts to develop inexpensive and

effective processes that can completely degrade

these compounds. In the physical methods, the

pollutants are only transferred from one phase to

another without any degradation. The chemical

6Anal. Methods Environ. Chem. J. 4 (4) (2021) 5-19

methods are expensive, require high doses of

chemicals, and produce large amounts of sludge

[3]. In recent years, advanced oxidation processes

(AOPs) have been used for the degradation and

mineralization of the potentially toxic organic and

inorganic contaminants in industrial wastewaters

[4, 5]. Some AOPs are the photo-catalytic [6],

Fenton and photo-Fenton [7, 8], UV/H2O2

[9] processes. Heterogeneous photocatalytic

oxidation (PCO) appears to be a promising

process for eliminating VOCs from the air

because of operation at ambient temperature and

ability to complete degradation/mineralization

of VOCs (by-products are generally harmless

CO2, H2O and mineral acids) [10, 11]. Many

reports described the degradation of PCE through

PCO [11, 12]. In these reports, TiO2 is the most

widely used as a photocatalyst because of its high

photocatalytic activity, non-toxicity, and stability

[13, 14]. Although TiO2 itself has been proved to

be a suitable photocatalyst for oxidation of PCE

through PCO, more efforts are needed for further

improvement of photocatalytic performance of

TiO2-based catalysts. Supporting on materials with

large surface areas such as glass ber [15], paint

[16], thin-lm TiO2 [17], TiO2 pellet [18], carbon

black or activated carbon [19], carbon nanobers

[20], carbon nanotube [21] is one approach.

Another trend is combining or doping TiO2 with

other materials such as Ag [22], Au [23], Sn [24],

Pb [25], Ni [26] metal oxides [27] to improve the

performance of the photocatalyst. Among these

attempts, TiO2 doping with transition metals ions

such as V, Co, or Fe has been a common approach

for improving the photocatalytic performance of

the catalyst. However, some key problems remain

unresolved, for example, doped materials suffer

from thermal instability, photo-corrosion, and an

increase in the carrier-recombination probability.

Non-metal (B, F, N, C etc.) doping has since

proved to be far more successful. Especially, in

the process of carbon doping, the C element is

always suggested permeating to the lattice of TiO2

substituting a lattice O atom and forming O–Ti–C

species [28-31]. Another approach is to change or

design new reactor congurations. Some reactor

congurations are honeycomb monolith, plate,

uidized bed, packed bed, and annular tube ow

[32, 33]. The design of the photocatalytic reactor

plays an important role in its photocatalytic

performance. Some factors such as specic surface

area, pass-through channels, air velocity, direction

and angle of irradiance of UV light on the catalyst

surface, contact area and a mass transfer should

be considered in the design of a photocatalytic

reactor [32, 33].

In this project, a xed substrate lled photocatalytic

system was used, with a light source in its center,

which in other words, is a combination of a

lled and ring-shaped system. On one hand, the

advantage of ring-shaped tube systems was used

for direct light radiation to the reaction surface

taking into account placing the light source in the

center of the system, which reduces the number

of bulbs as well as the effective use of diffused

light from an optical source in different directions

and, on the other hand, a greater contact surface

between the catalyst and the pollutant in the

xed substrate system was created. The rotating

center system is designed for two rows of glass

balls to be placed nearby each other, this design

increases the contact surface of the pollutant with

the catalyst compared to other systems. Also,

direct light radiation to glass balls can cause light

fractions in any ball and increase light intensity

throughout the system. In general, the system is

designed to utilize all the power and efciency

of the catalysts by increasing the reaction surface

and the immediate light exposure. That’s why

in this work, we report an experimental study of

the photocatalytic oxidation of PCE in the gas

phase using a lab-scale continuous-ow annular

photoreactor packed with glass beads. TiO2, C

doped TiO2 nanoparticles synthesized with the

sol-gel method and deposited at the surface of

glass beads with dip-coating technique. The

performance of the photoreactor was evaluated

for different operating conditions, such as feed

ow rate, PCE concentration, residence time and

relative humidity. To prove efciency in industrial

Photocatalytic degradation of Perchloroethylene by TiO2-C Hojjat Kazemi et al

applications, the effect of these parameters was

investigated under the same industrial condition.

For this propose, High concentrations of PCE

(between 574 and 2442 ppm), a large range of

air stream ow rates contaminated with PCE

(59–300 mL min-1, measured at 298 K and 1 bar)

and different water vapour contents (12–40%,

measured at 298 K and 1 bar) were employed.

2. Experimental

2.1. Materials

All the solvents and chemicals were purchased

from Merck and Sigma-Aldrich Companies and

used without further purication. The glass beads

with a diameter of 5-6 mm were used as a support

material and deionized (DI) water was used to

prepare the different solutions and washing steps.

2.2. Instruments

The X-ray diffraction (XRD) patterns were

recorded by a Philips Xpert X-ray diffractometer

(Model PW1729) with Cu Kα radiation. The

Structures and morphologies of nanoparticles were

determined using scanning electron microscopy

(SEM, TE-SCAN model MIRA3). The Fourier

transform-infrared (FT-IR) spectra were obtained

using BRUKER spectra VERTEX apparatus. The

UV-VIS diffuse reectance spectra (DRS) were

recorded by a DRS apparatus (Shimadzu UV-

1800). The identication of photodegradation by-

products was done by a gas chromatography-mass

spectrometry (GC-MS) system (Shimadzu, QP-

2010SE).

2.3. GC/MS analysis

The identication of product gas streams and

intermediate products were analyzed employing a

gas chromatography-mass spectrometry (GC/MS)

system operating in electron impact mode using an

HP-5 (30m × 0.25mm × 250µm) capillary column.

The GC column was operated in a temperature-

programmed mode with an initial temperature of

35º C held for 5 min, ramp at 4º C min-1 up to 250º

C and held at that temperature for 5 min. Injector

temperature was 280º C with helium serving as

the carrier gas at the ow rate of 2 mLmin-1. The

identication of photodegradation products was

done by comparing the GC/MS spectra patterns

with those of standard mass spectra in the National

Institute of Standards and Technology (NIST)

library.

2.4. Catalyst base preparation method

Before the synthesis, transparent glass beads

(with a diameter of 5-6 mm) were roughened

mechanically by sandblasting method to increase

surface area and adherence between the catalyst

and the support. The surface glass beads were

physically roughened in a mixture of water,

sandblasting sand and sanding powder using a

mechanical mixer and then etched in 1M NaOH

solution. After sandblasting, the glass beads were

washed sequentially and thoroughly with acetone,

ethanol and deionized water (DW). Then they

were dried at 80 °C for 1 h in the oven [34].

2.5. Synthesis of TiO2, C doped TiO2 supported

on roughened glass bead

TiO2, C doped TiO2 were prepared via sol-gel

method according to the previous reports [34]

with few modications. Briey, for preparation

of carbon-doped TiO2, 50 mmol of Tetrabutyl

Orthotitanate (TBOT) was slowly added to a

solution of ethanol and water under continuous

magnetic agitation at room temperature. Then

4 ml of Hydrochloric acid 1M was added. The

resulting mixture was kept stirred for 3 hours at

a speed of 500 rpm and then the roughened glass

beads were added to the liquid mixture. After 10

minutes, glass beads were separated and dried at

80 ° C for 1 hour and calcinated at 200 ° C for 5

hours, using a heating rate of 1° C min-1. Pure TiO2

was also synthesized with the same procedures as

described above, except calcination temperature

for the synthesis of pure TiO2 was set at 350° C.

2.6. Photocatalytic reactor

In this study, Photocatalytic degradation of PCE

in the air using titanium oxide base (TiO2, TiO2-C)

catalysts was evaluated in a lab-scale continuous-

ow tubular UV-photoreactor packed with coated

glass beads. The continuous gas ow photoreactor

with the length of 40 cm has consisted of two

coaxial tubes. The coated glass beads lled the

void in-between two coaxial tubes and the inner

tube was made of quartz glass housing the light

source. The outer tube was a Pyrex tube packed

with catalyst coated glass beads to a height of 27

cm which provided an effective volume of 200 ml

in the reactor. The external wall of the cylinder

was completely covered with a layer of aluminum

sheet, so that the light is constantly reected

inside the cylinder. The light source was an 8-watt

uorescent lamp (Philips UVC 8W T5) to provide

light with appropriate energy in the ultraviolet

region. The reactor feed was prepared by mixing

of PCE vapors, humid and dry air which were

generated via passing the air through two glass

impingers containing pure liquid PCE and distilled

water. PCE concentration and humidity were

adjusted by controlling ow rate of dry air into

the impingers and the amount of dry air entering

the mixing tank. The concentration of PCE in the

inlet and outlet streams of the photoreactor and

degradation byproduct were measured by a GC/

MS. humidity and CO2 content were measured by

a SAMWON ENG SU-503B device and a KIMO

AQ-100 CO2 meter, respectively and rechecked

by titration methods (Fig.1). All ow rate of

was adjusted by a rotameter and the degradation

efciency was measured by equation 1:

(Eq.1)

Cinlet, Coutlet and Ctotal were concentrations of inlet

and outlet and total of PCE respectively.

Fig.1. Schematic of photocatalytic system 1) Air reservoir 2) Rotamer 3) Impinger containing water

4) impinger containing Perchloroethylene 5) Mixing chamber 6) Tee 7) Tap 8) Reactor 9) Light source

Anal. Methods Environ. Chem. J. 4 (4) (2021) 5-19

3. Results and discussion

3.1. Photocatalyst characterization

The synthesized materials were first characterized

with X-ray diffraction as shown in Figure 2. Fig.

2 shows a typical XRD pattern of the pure TiO2

and TiO2-C which is in good agreement with the

standard patterns for anatase titanium dioxide

(JCPDS 21-1272) [35] and confirm the absence

of any other impurity. The XRD pattern of the

TiO2-C was identical to pure TiO2 but strongest

peak at 2θ = 25.3◦ (representative of (101)

plane). Compared with pure TiO2 shifted slightly

to a higher 2θ value. Also for all synthesized

materials, diffraction peaks were weakened and

broadened, suggesting distortion of the crystal

lattice. Greater change can be seen with the

addition of carbon and vanadium, indicating that

vanadium and carbon were incorporated into the

lattice and greater distortion of the crystal lattice

was accorded [36, 37].however, this is favorable

for photodegradation purposes because of

increasing pathways for gas-phase penetration

into the inner spaces of the active materials and

increasing of material transportation.

The IR spectrum of TiO2 and TiO2-C were shown

in Figure 3. The FT-IR spectrum of both spectra

displays absorption bands between 700 and

800 cm−1, which can be assigned to the metal-

oxygen stretching vibrations of Ti-O [38]. The

broad peak in the range of 3400 nm and sharp

peak in the range of 1620 nm corresponds to

the stretching and bending bonds of the water

molecule, respectively, which occur due to

lack of inter-tissue water or the absorption of

moisture on the surface of the synthesized

materials. The two peaks appearing in 1350 and

1200 nm of the TiO2-C compound are related to

the CH3 and CH2 bending bonds, which confirms

the presence of carbon in the structure of this

compound [18, 39].

Photocatalytic degradation of Perchloroethylene by TiO2-C Hojjat Kazemi et al

Fig.2. XRD pattern of the pure TiO2 and TiO2-C

The optical absorption property is an important

factor to inuence the photocatalytic activity of

the catalysts. Thus, the absorbance properties of

as-prepared TiO2 and TiO2-C were analyzed by the

UV–vis diffuse reection spectra (DRS), and the

results are shown in Figure 4. Pure TiO2 shows the

absorbance in the UV region, in which the absorption

start point of TiO2 is around 400nm. While TiO2-C

exhibits good absorption in the UV region and the

broad absorption region with less intense in the

visible light. Compared with pure TiO2, TiO2-C

absorbed photon energy in the visible region up to

700 nm indicating that the incorporated elemental

carbon was acting as a photosensitizer [40]. The

results suggest that TiO2 and TiO2-C photocatalysts

have higher photocatalytic performances in the UV

region.

The morphology of the fabricated products was

characterized by scanning electron microscopy

(SEM) and the results are shown in Figure 5. As

seen in Figure 5 the synthesized particles have

mostly a spherical morphology with the obtained

size in the range of about 14-45 nm for TiO2 and

TiO2-C.

Anal. Methods Environ. Chem. J. 4 (4) (2021) 5-19

Fig.3. FT-IR spectrum of A) TiO2 and B) TiO2-C

Fig.4. UV–vis diffuse reection spectra A) TiO2 and B) TiO2-C

3.2. Investigating the reaction conditions of

photocatalytic system

3.2.1.Concentration effect

First, the degradation efciency of PCE using

TiO2-C photocatalyst in different inlet feed

concentrations from 400 to 5000 ppm under UV

irradiation, the residence time of 1 min and ow rate

200 mL min-1 investigated. Figure 6 is illustrated

the effect of increasing PCE feed concentrations

on photocatalytic degradation efciency. As

shown, degradation efciency increased by

increasing PCE concentration up to 3000 ppm and

rich to 99%, indicating higher PCE means higher

adsorption in the surface of the photocatalyst,

and higher mass transfer between the PCE gas

and the catalyst surface which increased the PCE

degradation. Further PCE concentration caused

a decrease in the degradation efciency, because

of surface ooding of photocatalyst [41s, this

referenceshowed in supporting nformation page,

SIP]. It was seen that the degradation capacity of

this system is 3000 ppm, which is much higher

than that other of reported photocatalytic systems

with the same lamp.

Photocatalytic degradation of Perchloroethylene by TiO2-C Hojjat Kazemi et al

Fig.5. SEM image of (A, C) TiO2 and (B,D) TiO2-C

3.2.2.Residence time effect

Figure 7 shows the residence time effect on

degradation efciency of TiO2-C photocatalyst

over the range of the residence times from 0.2

min to 2 min at a 3000 ppm PCE concentration.

Residence time in the reactor was controlled by

changing the ow rate. As shown for photocatalyst,

the PCE degradation increased with increasing

residence time, because PCE stays longer inside

the reactor and have more opportunity to react with

photocatalyst [18]. The increasing residence time

of more than 1 min for photocatalyst did not only

increase signicantly in the degradation efciency

of PCE but also increased the elimination time. As

a result, the time of one minute was chosen as the

optimal time.

Anal. Methods Environ. Chem. J. 4 (4) (2021) 5-19

Fig.6. The effect of concentration on degradation efciency of TiO2-C at a xed time of 1 min

Fig.7. the effect of time on degradation efciency of TiO2-C at 3000 ppm

3.2.3. Moisture Effect

Due to Figure 8, the effect of the water content on

the PCE degradation over TiO2-C was evaluated

under ve relative humidity (RH) conditions (10,

15, 30, 50 and 70%), 3000ppm PCE concentration,

one-minute resistance time and UV irradiation.

Figure 8 shows that the degradation efciency of

PCE attained under each RH condition. As shown,

a signicant change in degradation efciency was

not observed as the RH increased from 10 to 15

% but when RH increased up to 30% degradation

efciency increased and rich to approximately 99%.

Further increasing of RH reduced the degradation

efciency due to competitive adsorption of PCE

and water molecules on the photocatalytic surface.

Actually, by more increasing the moisture content

of the incoming gas, most photocatalytic active

surfaces are coated with water and remaining less

surface to contact with PCE and its degradation

[14, 42s, SIP]. The opposing effect of the water

content has already been discussed in several

research works and even so it still is a matter of

debate [42s-45s, SIP]. Several authors reported that

the absence of water vapour can seriously retard

the degradation of several chemicals and their

mineralization to CO2 may become incomplete, but

excessive water vapor may inhibit the degradation

by competitive adsorption on the photocatalyst

surface [14].

3.3. Photocatalytic degradation

The photocatalytic performance of prepared

samples was evaluated by the PCE degradation

under UV light. For comparison, the photocatalytic

activity of pure TiO2, TiO2-C 2 was also determined

under the optimal conditions (eg. 1 min residence

time, 30% RH and 3000 ppm PCE concentration).

First, the photocatalytic system was lled with glass

balls without a photocatalyst coating. Then, the

degradation efciency was studied in the presence

of photocatalysts coated glass balls. When the

lamp was illuminated, the output of the system was

sampled at different times, and the process of changes

in concentration, efciency and output products

was investigated by the GC-MS. For the photolysis

process (without using any photocatalyst), the

system’s efciency was determined 99% based on

the reduction of perchloroethylene concentration in

Photocatalytic degradation of Perchloroethylene by TiO2-C Hojjat Kazemi et al

Fig.8. The effect of relative humidity on degradation efciency of TiO2-C at constant

concentration and time of 3000 ppm, 1 min respectively

120 min. At rst, it seemed that the lamp alone was

able to degrade perchloroethylene and perform the

complete reaction of converting perchloroethylene

to carbon dioxide, water and hydrochloric acid.

But after a long time, we observed a large volume

of solid crystals at the end of the system and the

outlet pipe. By identifying these materials with

GC-MS, we realized that most of the material has

converted into compounds that result from a simple

breakdown of Perchloroethylene bonds. That’s why

we measured system efciency based on CO2 gas.

Also, the system’s efciency was calculated 10%

based on the produced amount of CO2 gas. So that

the lamp was not capable of completely degrading

PCE, merely transforming it into other materials

with more complex structures and converting has

a small fraction of it into complete degradation

reaction products. Also, the system’s efciency

was obtained 58% and 95.6% for TiO2 and TiO2-C,

respectively based on the produced amount of CO2

gas. The results indicate that in the case of using

TiO2-C, the PCE degradation is almost complete

and turns into completed reaction products in its

output, which indicates the correct choice of the

pollutant, ie carbon in improving photocatalyst.

Table 1 summarizes the major intermediate

compounds identied.

3.4. Photocatalytic mechanism for PCE

degradation

For photocatalytic oxidation, an important step of

photoreaction is the formation of the hole-elect

pairs which need the energy to overcome the band

gap between the valence band (VB) and conduction

band (CB) [41s,SIP]. TiO2 as a semiconductor

has a valence band and a conduction band. When

photocatalyst exposes to UV light, TiO2 can absorb

UV light and electrons transfer from the valence

band (VB) to the conduction band (CB) and generate

electron-hole pairs (Eq.2) [46s, SIP]. Electrons of

CB can react with oxygen adsorbed on the catalyst

surface to produce oxygen radicals (O2

.-) (Eq.3).

Holes of VB can react with H2O to produce .OH

radicals (Eq.4, 5). Also, the electrons and the holes

Anal. Methods Environ. Chem. J. 4 (4) (2021) 5-19

Table.1. Products obtained from photocatalytic degradation of perchloroethylene

with UV lamp alone and UV lamp with, TiO2 and TiO2-C

Compound namePhotocatalyst

H2O

UV lamp

C2Cl4

Dichloroacetic acid

Trichloro dehydrate

Trichloroacetic acid

H2O

UV lamp -TiO2

HCl

C2Cl4

Trichloroacetyl chloride

Methyl trichloroacetate

Trichloroacetic acid

H2O

UV lamp -TiO2-C

CO2

HCl

C2Cl4

may react directly with PCE molecules leading

to the formation of oxidizing species (Eq.6) [14,

31, 47s, 48s, SIP]. The radicals (.OH )as a strong

oxidizing species and O2

.- are responsible for the

degradation of PCE. These .OH and O2

.- which

are produced as shown, further react with C2Cl4 to

produce CO2 and water, as represented in (Eq.7, 8)

[31, 49s, SIP]. In the absence of suitable electron

and hole scavengers, the stored energy is dissipated

in a few nanoseconds, through recombination. In

some works [50s-52s, SIP], researchers believe that

carbon materials can generate photoelectrons and

photo holes under UV irradiation. The C element is

not directly involved in the photocatalytic process

but can absorb UV light. After absorbing enough

energy, these regions can generate photoelectrons

and photoholes that can be transferred to TiO2.

The results obtained show enhancement in the

photocatalytic activity when the C element is doped

on the surface of TiO2 nanoparticles.

Based on observed products for TiO2-C, several

mechanisms of PCE degradation and intermediates

have been described in the literature [14, 53s, 54s].

3.5. Photocatalyst stability

The stability of photocatalyst TiO2-C was

investigated for a relatively long time to evaluate

its capability of being applied in real systems in

addition to examining its stability (Fig. 9). Figure

9 shows the change of degradation efciency

over relatively long periods for TiO2-C with 3000

ppm input concentration of PCE, 1min residence

time and 30% RH under UV irradiation by the

full intensity of the 8W 365 nm lamp. As seen for

photocatalysts, rst the degradation efciency was

increased and rich to 95% for TiO2-C respectively.

No change over 5 hours’ periods of time of

irradiation were observed. Long term stability was

also investigated for TiO2-C photocatalyst over 7

days (result not shown) at the same condition. No

change in the stability and degradation efciency

were discernible over this period. These results

showed degradation efciency of TiO2-C was better

than TiO2 and relatively50% more than TiO2 and

also a good stability over long period of time for

TiO2-C, indicating TiO2-C has good efciency for

photocatalytic degradation of PCE and is a good

candidate for use in real systems.

Photocatalytic degradation of Perchloroethylene by TiO2-C Hojjat Kazemi et al

TiO2-C+hϑ → h+ (VB) + e- (CB) (Eq.2)

O2+e- (CB) → O2

- (Eq.3)

H2O + h+ (VB) → OH + H+ (Eq.4)

h+ (VB)+OH- → OH . (Eq.5)

h+ (VB) + C2 Cl4 → C2 Cl4

.+ (Eq.6)

OH. + C2 Cl4 → CO2 + H2O (Eq.7)

2 + C2Cl4 → CO2 + H2O (Eq.8)

Fig. 9. Photocatalyst stability of TiO2-C over time 5 h

3.6. Comparison of TiO2-C photocatalyst with

other reported works

In Table 2, the different photocatalysts are compared

in terms of lamp intensity, degradation wavelength,

efciency, and moisture content. Two factors of

lamp power and temperature are very effective in

degradation efciency. On the other hand, in many

previous studies, the method of determining the

efciency is expressed merely based on reducing

the PCE output and does not consider the conversion

of PCE to products and the production of CO2. In

terms of lamp power, the lamp used in the present

study has a power of 8 (wat) and a wavelength of

365 nm in the UV region which was one of the least

powerful lamps used in this eld, indicating the

high efciency of the system due to the design of

the lamp. In the center, its large reection due to the

aluminium sheet in the outer wall, the increase in

contact surface due to the use of glass balls and the

proper selection of carbon contaminant. Also, the

efciency of the present research, despite the low

power consumption (compared to the UV lamps),

and the number of fewer lamps, are more or equal

than to many previous reports.

4. Conclusions

In this project, a photocatalyst system with a xed

substrate and a light source in its center was used.

In general, the system was designed to use all the

power and efciency of the catalysts, by increasing

the reaction surface and the direct impact of light.

In this system, an 8w uorescent lamp with a

wavelength of 365 nm was used as a source of UV

light. The system was lled with glass balls coated

with three catalysts (TiO2, C-TiO2) synthesized by

the sol-gel method and uncoated balls to remove

Anal. Methods Environ. Chem. J. 4 (4) (2021) 5-19

Table.2. Comparison of TiO2-C with photocatalysts reported in previous scientic papers

Lamp Wavelength Efciency Catalyst Humidity Reference

A Philips UV A lamp

(Cleo performance 80W/10

Model)

The wavelength

of 365 nm. Is not limited PC500 45 to 55% [11]

Phillips, 4 W, F4 T5/BLB

type

maximum

emission at 365

50% - - [1]

three 8W black-light

uorescent lamps light 365 nm -P25Pt/TiO2 and

Pd/TiO2,-[55s]

Philips TL 18W/08 F4T5/

BLB 355nm

Predicted conversions

show good Tio248% [56s]

ve black light blue

uorescent lamps (Philips TL

8W/08 F8T5/BLB)

343 and 400 (55%) (P-25) 8% relative

humidity [57s]

seven(Philips TL 4W/08

F4T5/BLB) 310 to 410 nm 24, 50, and 100% Tio2

10, 50, and

90% [58s]

Eight-4W uorescent black

light bulbs (Toshiba, FL

4BLB)

-99.3% Tio2-[59s]

A uorescent black light bulb

(Toshiba, FL 4BLB, 4 W) - 80% Porous TiO2-[60s]

1700 W air-cooled Xenon

Lamps Close to 100% P25 and

PC500 20% [14]

Phillips

UVC/8W/T5)

wavelength 365

nm. 99/6% Tio2 -C 30% Present

study

Photocatalytic degradation of Perchloroethylene by TiO2-C Hojjat Kazemi et al

the pollutants. Among these four samples, the

highest and fastest total photocatalytic degradation

efciency was related to the TiO2-C catalyst. The

catalyst also had the highest stability and highest

degradation efciency. After degradation, all

chemical products were determined by GC-MS

analyzer.

5. Acknowledgements

The authors wish to thank from Research Institute

of Petroleum Industry (RIPI), and University of

Science and Technology, Narmak, Tehran, Iran for

supporting this work.

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