## 3 Results and Discussion
### Characterization of Electrospun PET, WPET, PET-SiAMPy, and WPET-SiAMPy Nanofibres
The successive thermal degradation of the PET nanofibres begins at \(\sim\)380 \({}^{\circ}\)C and ends at \(\sim\)450 \({}^{\circ}\)C, where 70.40% weight of the PET nanofibres was lost. The depolymerization of the PET nanofibres was occurring at this second stage, forming a carbon black residue. The last stage of the thermal decomposition in the range of \(\sim\)450 \({}^{\circ}\)C to 900 \({}^{\circ}\)C, (8.63% weight) is ascribed to the loss of the carbon by-products that formed [23]. The first stage of the thermal decomposition for the WPET nanofibres started at approximately 290 \({}^{\circ}\)C to \(\sim\)350 \({}^{\circ}\)C, which may be the result of the evaporation of volatile gases in the WPET nanofibres. The WPET nanofibres lost approximately 4.55% of their weight in the first stage. Then, the weight of the WPET nanofibres was constant until a successive degradation occurred from 400 \({}^{\circ}\)C to \(\sim\)460 \({}^{\circ}\)C. At this stage, the WPET weight loss was approximately 72.96%. The gradual weight loss of 9.10% from \(\sim\)460 \({}^{\circ}\)C to 900 \({}^{\circ}\)C in the last stage of thermal decomposition was the loss of carbon by-products that formed during the degradation of the WPET nanofibres [23]. The shape of the TGA profiles of PET and WPET nanofibres were found to be consistent with the increase in temperature. The first derivative plots corresponds with the TGA plots as the PET and WPET nanofibres pyrolysis at \(\sim\)380 \({}^{\circ}\)C to \(\sim\)460 \({}^{\circ}\)C are shown with the endothermic peak degradation in the first derivative plot. Finally, the PET and WPETnanofibres thermal decomposition ended with a residue accumulation of \(\sim\)9%. This corresponds with the thermal degradation investigation of waste polyethylene terephthalate (PET) under inert and oxidative environments [24]. Figure 3b the thermal decomposition of the SiAMPy starts with the dehydration process from 15 \({}^{\circ}\)C to \(\sim\)200 \({}^{\circ}\)C, the weight loss is quite insignificant. The SiAMPy weight loss was due to loss of moisture. Thereafter, the successive thermal decomposition of the SiAMPy occurred in sequential stages over a temperature range from 200 \({}^{\circ}\)C to 580 \({}^{\circ}\)C, where a sharp weight loss of approximately 39.76% was evident. Subsequently, the thermal decomposition rate slowed down with the weight loss of 8.61% between 500 \({}^{\circ}\)C and 900 \({}^{\circ}\)C as the SiAMPy reached its thermal decomposition end point [24]. The first derivative peaks present the three decomposition stages exhibited by SiAMPy. The first stage represents the elimination of adsorbed moisture as  
\[\text{SiAMPy}\cdot\text{nH}_{2}\text{O}\rightarrow\text{SiAMPy}\]  
followed by the decomposition of aminopropyl groups which slowly occurred at approximately 300 \({}^{\circ}\)C that led to the rapid degradation that occurred at \(\sim\)440 \({}^{\circ}\)C yielding H\({}_{2}\)O, HNO\({}_{3}\) and ethylene groups. The final stage was the formation of residue containing ethylene, ammonia, methane, and hydrazine. [PERSON] et al. reported similar data for the amino-functionalized silica nanoparticles used in an investigation of efficient and rapid removal of COD from pre-treated palm oil effluent [25].