(UNESCO / Japan Young Researchers' fellowships programme)

Using TiO2 with sunlight and H2O2 to eliminate some organic pollutants in water and wastewaters

Summary of research carried out: 
Using TiO2 with sunlight and H2O2 to eliminate some organic pollutants in water and wastewaters

The lack of operational and efficient wastewater treatment plants makes wastewater the main source of pollution in the Gaza Strip coastal zone and aquifer.

About 90% of all wastewater is discharged into the environment either untreated or inadequately treated. Thus, there is a great need for drastic improvement in collection and treatment in Palestine. Our system will study the treatment of organic pollutants, which are the main pollutants of wastewater, considered to be the most threatening problem in the Gaza Strip.

I recently introduced advanced oxidation method (AOM), which includes hydrogen peroxide with TiO2 under sunlight, is suggested to treat a variety of industrial wastes containing a range of toxic organic compounds (phenols, formaldehydes, complex wastes derived from dyestuffs, pesticides, wood preservatives, plastics additives, and rubber chemicals). AOM may be applied to wastewater, sludge or contaminated soils. Our treatment in the laboratory was conducted under the supervision of Dr Khaled El-Sousy in order to study the results of our system, which is considered to be the only solution for organic chemical pollutant. Organic pollutants cannot be treated in the biological system (bacteria) of municipal wastewater treatment, in which account is also taken of toxic chemicals that kill the bacteria so it reduces the efficacy of the treatment plant. Some of the chemical analysis was conducted at Al-Aqsa University. Other analyses that were not conducted at Al-Aqsa University, such as ESR, will be conducted at Ain Shams University (Egypt) under the supervision of Professor Samia Mokhtar.

A thermostated water bath was connected to a thermo-jacket for fixing temperatures. Locally computed apparatus, 600 ml pyrexbeaker surrounded by thermal jacket with magnetic stirrer below, the whole system was installed in a dark wood box. A light source (300 watts, 82 volts APOFHS lamp) was installed and focused on the reaction bath. A photo-catalytic oxidation study was conducted for similar samples of different pollutants, which were treated identically under the same conditions, such as stirring power, working temperature (40.0 Co), [H2O2]0, amount of TiO2 per litre of the treated water, and the same light source in the same situation. Substrates concentrations were followed spectrophotometrically.

In this project, five substrates with various oxidation potentials were examined as model pollutants. A detailed kinetic study was conducted on one of them (picric acid). The oxidation kinetics were investigated; the influences of different parameters such as light intensity, pH, temperature, the amount of catalyst per litre of treated water, and the initial concentration of H2O2 were studied seeking the optimum conditions of the process. The spectrophotometer method was used for the kinetic study.

The results demonstrated that in the studied ranges the process is efficient and practical even for the most persisting pollutants. Oxidation is directly proportional to: light intensity, amount of catalyst per litre of treated water, and the initial concentration of H2O2. The process was found to be of the Arrhenius type. Increasing pH increased the process rate. Electron Spin Resonance (ESR) measurements were conducted concerning the presence of free radicals and the test was positive.


May 2007