Degradations of acetaminophen via a K
2
S
2
O
8
-doped TiO
2
photocatalyst under visible light irradiation
Justin Chun-Te Lin
a
, Mark Daniel G. de Luna
b
, Graziel L. Aranzamendez
b
,
Ming-Chun Lu
c, *
a
Department of Environmental Engineering and Science, Feng Chia University, Taichung 407, Taiwan
b
Department of Chemical Engineering, University of the Philippines Diliman, Quezon City 1101, Philippines
c
Department of Environmental Resources Management, Chia Nan University of Pharmacy and Science, Tainan 717, Taiwan
highlights graphical abstract
Doping TiO
2
with K
2
S
2
O
8
extends
visible-light activity and facilitates to
degrade ACT.
Four parameters utilizing as-doped
photocatalyst were systematically
examined.
Optimal conditions can achieve 100%
ACT degradation efficiently.
Three types of degradation kinetic
models were computed and studied.
article info
Article history:
Received 31 December 2015
Received in revised form
13 April 2016
Accepted 15 April 2016
Handling Editor: Shane Snyder
Keywords:
Potassium persulfate
TiO
2
Visible light active catalyst
Acetaminophen
Doping
Photocatalytic degradation parameters
abstract
Acetaminophen (ACT) is a mild analgesic commonly used for relief of fever, headache and some minor
pains. It had been detected in both fixed factory-discharged wastewaters, and diverse sources, e.g. sur-
face waters during festival events. Degradation of such trace emergent pollutants by titanium dioxide
(TiO
2
) photocatalysts is a common approach; however, the band gap that can be utilized in the UV range
is limited. In order to extend downward the energy required to excite the photocatalytic material, doping
with potassium peroxodisulfate (K
2
S
2
O
8
) by a sol-gel method was done in this work. The visible-light
active photocatalyst was tested on the degradation of ACT under four parameters including: initial
ACT concentration, catalyst dose, initial pH, and system temperature. Optimal conditions, which achieved
100% ACT degradation, were obtained by using 0.1 mM ACT initial concentration, catalyst dose of 1 g L
1
,
initial pH of 9.0 and system temperature of 22
C at the end of 9-h irradiation. Meanwhile, three types of
degradation kinetic models (i.e. zero, pseudo first and second order) were tested. The feasible model
followed a pseudo-first order model with the computed constant (k
app
) of 7.29 10
3
min
1
. The present
study provides a better photocatalytic degradation route by K
2
S
2
O
8
-modified TiO
2
in comparison with
pristine TiO
2
, in wastewater treatment dealing with ACT and other persistent organic pollutants.
© 2016 Elsevier Ltd. All rights reserved.
1. Introduction
Pharmaceuticals and their metabolites are regarded as one of
persistent organic pollutants (POPs) with impacts on the * Corresponding author.
E-mail address: mmclu@mail.cnu.edu.tw (M.-C. Lu).
Contents lists available at ScienceDirect
Chemosphere
journal homepage: www.elsevier.com/locate/chemosphere
http://dx.doi.org/10.1016/j.chemosphere.2016.04.059
0045-6535/© 2016 Elsevier Ltd. All rights reserved.
Chemosphere 155 (2016) 388e394