Abstract:
Benzene is a toxic volatile organic compound which has harmful effects to human health and
environment. This research applied surface photovoltage (SPV), which composed of
Al/n-Si/SiO/Si3N4/Ag multilayer and was coated by mesoporous MCM-41 material synthesized
from rice husk (RH-MCM-4I), as a detector for measuring different concentrations of gaseous
benzene. The effect of silylation using trimethylchlorosilane (TMCS) to reduce hydrophilicity of
RH-MCM-41 was also studied. RH-MCM-41 was synthesized using sol-gel method at molar
compositions of 1.0 Si02: 1.1 NaOH: 0.13 CTAB: 0.12 H2O. Then, the crystallized RH-MCM-41
was reacted with TMCS at 5% v/v and dissolved in toluene 20 g L-1. The silylated RH-MCM-41
was coated on the Spy on the Si3N4 side with the diameter of 6 mm. The Spy sheets coated by
RH-MCM-41 and silylated RH-MCM-41 was tested for measuring benzene vapor (5-250 ppm) in
the closed reactor. Both of materials have ability to detect benzene vapor but have difference in
sensitivity at various concentrations. When 5 volts was applied, the sensitivity of the Spy sheet
coated by RH-MCM-41 increased from 0 to 640% when the concentration of benzene vapor
increased from 0-200 ppm. After silylation, the sensitivity of the Spy was enhanced. The sensitivity
of the Spy sheet coated by silylated RH-MCM-41 increased from 0 to 900% when the
concentration of benzene vapor increased from 0-50 ppm. Thus, the Spy coated by silylated
RH-MCM-41 can be used for measuring benzene vapor at low concentration.