Table 3.

Atomic relative concentration of elements in PS-WPU samples.

Samples	O 1s	N 1s	C 1s	Si 2p
PS-WPU 1	45.02	1.82	53.16	0
PS-WPU 2	45.87	0.79	35.57	17.77
PS-WPU 3	46.42	0.62	34.85	18.11
PS-WPU 4	46.82	0.34	33.26	19.58
PS-WPU 5	46.39	0.30	32.46	20.85