Typical Synthesis and Environmental Application of Novel Ti Nanoparticles - Advanced Materials for Agriculture, Food and Environmental Safety - page 428

Exhaust

Hg-lamp

Reddish- Orrange

Methyl

Colorless
Orangesoln Orrange

Figure 15.6 Photocatalytic reactor; color changes of methyl orange solution in presence
of Hg lamp.

the reactor contained a number of small holes for cool air to enter inside
the reactor. h e front side of the reactor was i xed with a sliding door for
collecting the reaction solutions. All four sides were made of black col-
ored wood to protect the UV irradiation outside of the reactor. Inside the
photoreactor, the distance between the 200 ml quartz glass beaker and the
UV lamp was maintained at approximately 5 cm. All the experiments were
carried out at 28 ± 2 C. In every case, the 5 cc solutions were collected

from each of the beakers at the same time interval; at er the solutions
were sonicated 3-4 times they were used for UV measurement (UV-1601,
SHIMADZU).

°

15.3.2 Sol-Gel Method

h e sol-gel method is a versatile process used in making various ceramic
materials [74-76]. In a typical sol-gel process, a colloidal suspension, or
a sol, is formed from the hydrolysis and polymerization reactions of the
precursors, which are usually inorganic metal salts or metal organic com-
pounds such as metal alkoxides. Complete polymerization and loss of sol-
vent leads to the transition from the liquid sol into a solid gel phase. For
sol-gel processes there are three key steps [95 ,96].
Step I: h e method ot en uses metal organic precursors where the var-
ious components are mixed together in a solvent to get a solution. h is
“solution,” which has a multicomponent composition, is a true ionic or