KNU Department of Environmental Engineering Research Team led by Professor Woong Kim, Develops Photocatalyst for Efficient Degradation of Organic Pollutants
- Date
- 2021/08/05
- Writer
- Oh
- Hit
- 1274
KNU Department of Environmental Engineering
Research Team led by Professor Woong Kim collaborated in joint research with
global universities such as King Saud University and successfully developed a
photocatalyst for the photodegration of dye-containing wastewater with a
degradation efficiency of more than 98% within 1 hour.
Every year, approximately 1 million tons of
dye is produced, resulting also in the production of a vast amount of dye-containing
wastewater. As a result, there have been many techniques such as adsorption,
chemical oxidation, ozonation, coagulation, membrane process, biological
degradation, electrochemical process, and photocatalytic degradation to
eliminate dye contamination from water and wastewater. Of the existing
techniques, photocatalysis has been considered to be the greenest approach as
well as one of the most broadly utilized due to its high degradation ability,
wide applicability, and recyclability of the photocatalyst. However, the most
commonly used photocatalysts to eliminate organic pollutants for this
technique, such as zinc oxide (ZnO) and titanium dioxide (TiO2), hardly absorb
visible light irradiation because of free surface defects, preventing a higher
photocatalytic efficiency.
To address this challenge, Professor Woong
Kim’s research team modified molybdenum disulfide (MoS2) with the metal-organic
framework (MOF) via solvo-thermal technique to produce an iron (Fe)-based MOF hybrid
photocatalyst, or MoS2@MIL-88(Fe). MoS2 is an alternative for TiO2 and ZnO that
has received remarkable attention because of its superior multi-functional
properties and ability to absorb visible light sources. Nevertheless, it was
anchored onto MOF carriers to improve the photocatalytic performance of dye
degradation, as MoS2 could not be used alone for photodegradation due to its
fast rate of recombination of electron-hole pairs and low operation of the
visible light region.
The team found that upon light
illumination, MoS2 of the created hybrid photocatalyst generates •OH radicals, which perform as prevailing oxidizing agents for the
degradation of dye molecules such as Methylene Blue (MB) and Rhodamine (RhB). Additionally,
variety of radicals such as •OH, −•O2−, e− and h+ are also generated, separating excitons
created in MIL-88(Fe) more efficiently and thereby increasing the MB and RhB
degradation rate. The optimal
profile to produce a degradation efficiency of 98.5% and 97.4% within 60 min for
MB and RhB respectively was as follows: initial concentration of 50 mg/L for
each dye, catalyst dosage of 0.05 mg/L, and initial pH of 5.
On the research, Professor Woong Kim states,
“Through the discovery of this photocatalyst, the degradation process for organic
dyes has been reduced by 1/3. To have developed an innovative yet eco-friendly
way to enhance the efficiency for degrading dye-containing wastewater is
encouraging. We have high hopes that this photocatalyst can be used not only
for the degradation of organic dyes, but also for that of many other organic pollutants
as well.”
The research was published on July 15 in the
internationally recognized journal, Journal of Hazardous Materials. The research was
carried out by BK21 FOUR Center for Smart Circular Infrastructure and was
supported by the Energy Technology Development Project of the Ministry of
Trade, Industry and Energy.