The Photocatalytic Degradation of Methomyl over TiO₂ Nanopowder Prepared by the Low Temperature Solvothermal Route

Abstract

Titanium dioxide (TiO2) nanopowder was prepared by the low temperature solvothermal route with starting chemicals containing titanium isopropoxide, ammonium hydroxide, nitric acid and ethanol in a PTFE–lined autoclave. The final pH of the mixed solution was 1 and treated at 100 °C for 2–6 h. The white precipitated was filtered and dried in an oven at 80 °C for 24 h. The phase transition was characterized by X–ray diffractometer (XRD). Single phase anatase structure was obtained without calcination step. The morphology and particle size of TiO2nanopowder was investigated by scanning electron microscope (SEM). The average of TiO2nanopowder size was 80–120 nm. The average particle size increased with temperature and time increased. The photocatalytic degradation of methomyl in natural water was studied by high performance liquid chromatograph (HPLC). The percentage of methomyl was decreased in the presence of 34, 23 and 24 over TiO2nanopowder prepared by the low temperature solvothermal route at 100 °C for 2, 4 and 6 h, respectively.

TiO₂ Powder Synthesized via the Solvothermal Method and Enhanced Photocatalytic Degradation of Methomyl

“…XRD pattern of TiO 2 powder synthesized via the solvothermal method at 100°C for 5h as shown in [11], which corresponded to the previously reported [12]. The crystal size of anatase TiO 2 was calculated from the X-ray diffraction peak according to the Scherrer's equation [13]:…”

“…These results are reasonably explained by in term of light-shielding effect, while excessive amounts of TiO 2 powder in solutions would decrease the light penetration [8]. The photocatalytic degradation efficiency was better than the previously reported [12]. For the degradation mechanism has reported that the bonds of methomyl are cleaved to produced the intermediates C 2 H 4 NO and C 3 H 6 NS as well as a small amount of NO 2 are formed.…”

Photocatalytic Degradation of Methylene Blue and Methyl Orange over TiO₂ Powder Synthesized via the Solvothermal Method

“…TiO 2 powder was synthesized via the single step solvothermal method without calcination. The synthesis of TiO 2 was carried out following the method reported elsewhere [9]. Titanium isopropoxide (97%, Aldrich, England), ammonium hydroxide (NH 4 OH, 29.4%, J.T.Baker, U.S.A.), nitric acid (65%, Merck, Germany) were used as the starting materials and ethanol (99.9%, Merck, Germany) was used as solvent.…”

Effects of multiple environmental factors on the elimination of methomyl in aquaculture water

“…It is well known that pesticide degradation is a process whereby activation energy is released. The increase in temperature destroys the former steady-state equilibrium, resulting in the degradation equilibrium shifting to the elimination reaction in which a lot of energy is absorbed (Tao & Tang 2004, Pookmanee et al 2014. As a result, the amount of methomyl decreased with increasing temperature.…”