Solar Photocatalytic production of hydrogen from aqueous polystyrene-Pt/TiO2 Suspension

Hasan Sabeeh Jabur,Jamal Harbi Hussien Alsaadi

doi:10.24297/jac.v11i10.2182

Abstract

In the present work, the Photocatalytic production of hydrogen from aqueous suspension of polystyrene is studied using titanium dioxide doped with platinum as photocatalyst. The parameters affecting the efficiency of Photocatalytic hydrogen production are Pt-loading (%), solution pH and the Pt/TiO2 loading and particle size. Under optimum conditions, 78 micro moles of hydrogen gas is generated after about 25 hr, irradiation in deacrated solution ( pH=13, Pt weight % load is 6% and Pt/TiO2 load and particle size are 4 gm/l and 400 mesh size respectively). Negligible amounts of hydrogen gas were noticed in the presence of unplatinized TiO2 at pH lower than 4. The apparent quantum yield of the Photocatalytic production of hydrogen was also determined and is affected by the % load of Pt on TiO2. The number average molecular weight of polystyrene decreases with irradiation time which indicates the photo degradation process under the condition employed. Carbon dioxide is also evolved at the later stage of photolysis process which suggests the partial mineralization of the polymer during the photolysis process. According to the experimental results a mechanism of hydrogen generation and polymer degradation is suggested.

Highlights

Dispersed semiconductor surface provides both fixed environment to influence a chemical reactivity of wide range of adsorbates and mean to initiate light induced redox reactivity in these weakly associated molecules
Initial interest in these photo induced redox reactions was prompted by Fujishima and Honda[1] in 1972 discovery that water could be split to hydrogen and oxygen simultaneously upon illumination of TiO2 with UV-Light
It was Kawai and Sakata[7] who first in 1981 discovered that aqueous suspension of polyethylene and ploy could be photo-oxidized to CO2, mineral acids and hydrogen gas when irradiated with Pt/TiO2 aqueous suspension system

Summary

Introduction

Dispersed semiconductor surface provides both fixed environment to influence a chemical reactivity of wide range of adsorbates and mean to initiate light induced redox reactivity in these weakly associated molecules. Beside the platinized TiO2 photocatalyst used for water splitting to H2 and O2 gases, it is used successfully for the photo-oxidation of organic compounds such as primary alcohols, amines, or sugar...etc with the simultaneous formation of hydrogen gas ( for review see reference[6]). Nishimoto and Coworkers[8] have studied the possibility of H2 gas production from the catalytic photodegradation of poly(vinyl chloride) and other vinyl polymers in alkaline and acidic solution.In the present work it is intended to utilize the visible light (xenon lamp or solar radiation) to produce hydrogen gas from polystyrene suspended particles using TiO2 (anatase)/Pt aqueous photocatalytic system.

Results

Conclusion