| The paper was supported by the project of National Science and Technology Support Program of China (Grant No.:2007BAE42B04). Thermal catalyst synthesized was a source responding to heat, thermocatalytic degradation of Methylene Blue (MB) considered as model organic pollutant was investigated at near room-temperature, and further discussed the thermocatalytic degradation of polymeric films. To tackle with the issue by thermocatalysis route concerning the parts under inadequate light or no light, which was very difficult to be degraded in terms of traditional polyethylene mulching film. The method above was applied in no hazardous treatment field for industrial wastewater. The results obtained were as follows:(1) The degradation tests were developed in model wastewater using thermal catalyst synthesized by high temperature calcinations at room temperature. At the optimal component condition, the removal rate of adsorption and thermocatalytic degradation processes can reach the highest level of82.07%solely response to temperature in the dark. Moreover, the kinetics of degradation rate was modeled considering that it was found similarly to Langmuir-Hinshelwood behavior which degree of correlation was up to0.9598, and a tentative mechanism was objectively established, describing reasonably well in line with the experimental results. On the other hand, it was found that high amount of MB adsorbed onto thermal catalyst was of unambiguous importance to subsequent thermocatalytic performance. Briefly, all above suggest that the feasibility to the thermodegradation means has been successfully verified under room temperature excitation. Herein the insight into degradation patterns of organic pollutant over thermal excitation may further enlarge applications for wastewater treatment.(2) The fracture or "hole" destructions of TCPE (LDPE/TC), DPE (LDPE/DPK), and AIPE (LDPE/AIBN)(Details in Chapter four) films surfaces were observed under model degradation process, presenting the phenomena of "scaly-like’and "needle-like", thus the effect of thermocatalyitc degradation on films is significant with respect to the degradation of film materials. However, LDPE (Neat low density polyethylene) group as the blank changed slightly undergoing the same degradation process owing to the traditional artificial phenomenon. In addition, the mechanical tests were performed, tensile strength and max extend of TCPE, DPE and AIPE groups posed a dominant drop trend with the time went on, approximately the portion of66%, while the blank one changed very slowly.(3) By means of AFM (Atomic Force Microscope) analysis, the surface roughness values to the LDPE blank group were2.6and8.7nm after the treatment of0and21days, respectively. However, the corresponding values of TCPE, DPE and AIPE groups were3.1and34.7nm,2.7and31.3nm,4.1and29.8nm, respectively. The number average molecular weight of TCPE, DPE and AIPE groups decreased from20011,19375and20734to12301,12308, and14009, respectively. Simultaneously, the LDPE group was almost steady in terms of the average molecular weight. Besides, the crystallization temperature of TCPE, DPE and AIPE groups, excluding the blank one, closed to the direction of high temperature regions, and the crystallization ability above with a drop trend.(4) The surfaces of two polymeric films of thermocatalytic degradation were also destroyed through thermocatalytic reactions after degradation process under ambient conditions, and the surface roughness values at0and60days changed from3.4and3.7nm to78.9and81.3nm. Compared to the blank one, the average molecular weights of polymeric films appeared an apparent decrease. Additionally, the changes of chemical groups to the corresponding polymeric films were monitored as well under degradation process.(5) On the basis of the result obtained, the likely mechanisms of the degradation for polymeric films were established in details, under the model conditions and ambient conditions, respectively. |
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