Basic Research In Thermocatalytic Degradation Of Methylene Blue/Rhodamine B Under Near Room Temperature

The paper researched the key technology problems during thermalcatalytic degradation of organic pollutants process, and two different thermal catalysts were synthesized. Thermocatalytic degradation of methylene blue and rhodamine B considered as model organic pollutant was investigated at near room-temperature, and further discussed the crystal form and appearance characteristics of thermal catalysts, including the effects of concentration, temperature on degradation rate under thermocatalytic activity. The corresponding interaction regarding free radicals throughout the degradation process was further discussed. Finally, the degradation products were detected and the possible degradation mechanism was also proposed, aiming at solving the decontamination of organic pollutants using thermocatalytic route. Therefore, this study may provide a new insight into environmental problems. The realated results obtained were as follows:(1) Different BET specific surface area of Mo/S/BiOCl heterostructures were successfully prepared by a facile one-step reflux method, and found the optimum pH was 9.3. The crystal structure and morphology structure characterization showed the thermal catalyst of Mo/S/BiOCl was consisted of nano piece cross self-assembly which stacked into a ball. The valence of each element and chemical environment were analysised by XPS carefully, which affirmed the Mo/S/BiOCl synthesized successfully. Eventually, the band gap of 2.6 eV was found by Uv-vis diffuser reflectance.(2) The degradation tests of Mo/S/BiOCl were developed. The photocatalysis degradation tests were developed under the similar conditions, compared with thermocatalytic degradation. The measurement results signify that, the photodegradatic and thermocatalytic rate of methylene blue were 99.9% and 96.5%, respectively, and the photocatalytic degradation showed an excellent rate compared with thermocatalytic degradation. In addition, the degradation rate of thermocatalytic degradation rhodamine B was up to 90%. The pseudo-first order kinetics regarding photocatalytic and thermocatalytic degradation of methylene blue, thermocatalytic degradation of rhodamine B, were all monitored, preferentially fitting to Langmuir-Hinshelwood behavior.(3) A facile and effective co-precipitation hydrothermal method was used to fabricate Ag3PO4/?-Bi2O3 hierarchical heterostructures. The samples were evaluated by XRD, SEM, TEM and XPS, and the results obtained showed that rod-like ?-Bi2O3, with a diameter of 2 mm, and a length of 10 mm, was used as the backbone material. Ag3PO4 possessed a polyhedral morphology with an average diameter of 200 nm was observed, which tightly attached on the surface of ?-Bi2O3.(4) In additional, the methylene blue, rhodamine B, methyl orange were also chosen as representative model dyes to evaluate the adsorption and degradation activity of Ag3PO4/?-Bi2O3. And the results showed that Ag3PO4/?-Bi2O3 is better in deteriorating the cationic dyes than the anionic dyes with regards to degradation rate.(5) The recycling test and ICP-MS data obtained showed that the combination of Ag3PO4 and ?-Bi2O3 could enhance the stability of Ag3PO4, which contribute to the reuse of Ag3PO4/?-Bi2O3 and improve its application in practical production.(6) Radical capture experiments of thermal catalysts of Mo/S/BiOCl and Ag3PO4/?-Bi2O3 were developed, respectively, and the results showed electrons and holes were both participated in the whole test, but the holes formed from degradation reactions were strongly considered as the major reactive active species in the thermocatalytic degradation process.