Modified titanium dioxide removes over 80 per cent of dye pollutants from industrial wastewater

Titanium dioxide can be used cheaply and effectively to remove dye pollutants from industrial wastewater without light irradiation. This is the finding of a new study conducted in the Lappeenranta University of Technology, LUT.

The study shows that utilizing modified titanium dioxide in an adsorption process is an effective treatment method for removing dye compounds from wastewater. It removed over 80 percent of various dyes, including methyl orange, methylene blue, methyl violet, and Orange II, from aqueous solution.

In the study, titanium dioxide was modified with nitrogen, sulphur, iodic silver and carbon to improve adsorption performance. This made it a good adsorbent as it improved its high surface reactivity and adsorption capacity.

The results also show that modified titanium dioxide could be reused five times before its removal efficiency decreased. This combined with the simplicity of the process makes it an economical option for removing dyes.

"The use of titanium dioxide is a low-cost adsorbent compared to other common absorbents such as activated carbon. Also, the process is fairly simple and does not require expensive and complicated equipment," says Shila Jafari, who conducted the study.

Efficient removal of dye pollutants from wastewater is significant because discharge of colored wastewater from industrial plants into natural streams can causes many environmental hazards. Dyes interfere with aquatic plant life and hinder photosynthesis by absorbing and reflecting sunlight through the entering water. Dyes also have a tendency to sequester metals, which are toxic to fish and other organisms.

Dyes can also cause health issues. Some dyes are carcinogenic and mutagenic, inert and non-biodegradable when discharged into the waste streams. The presence of such dyes in underground and surface water is dangerous to human health. For example, MV (an alkaline dye) and MB (a cationic dye) have harmful effects on living organisms, and their inhalation may cause headaches, diarrhea, eye irritation and skin irritation in people with sensitive skin.

Shila Jafari, Master of Science, will defend her doctoral dissertation at the Lappeenranta University of Technology on July 12 at 12:00, Mikkeli University Consortium, Mikkeli. His dissertation is titled Investigation of adsorption of dyes onto modified titanium dioxide. Professor William Kjell Hans Hogland from Linnaeus University, Sweden will act as opponent. Professor Mika Sillanpää of Lappeenranta University of Technology will act as custos.

The dissertation has been published in the Acta Universitatis Lappeenrantaensis research series number 704 of the university. ISBN 978-952-265-969-9, ISBN 978-952-265-970-5 (PDF), ISSN 1456-4491. The electronic version can be found from LUT Pub-database: A printed version of the dissertation may be purchased from the Aalef bookstore, tel. +358 44 744 5511, or at or online from the LUT Shop:

Doctoral candidate:

Name: Shila Jafari

Year and place of birth: 1983, Hamedan, Iran

Education: Master of physical chemistry, 2010, Bu-Ali Sina University, Hamedan, Iran

Places of employment: Doctoral student, 2012-2016, Lappeenranta University of Technology

Further information:

Shila Jafari, +358 44 34 72 404,