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Cellulose (2018) 25:1353–1364
Table 1 The content of prepared paper materials
Sample
Active material
Description
Silver content in paper, wt%
P
n/a
n/a
n/a
PAg 0
Silver nanoparticles
0.51 g of silver nitrate sonicated for 10 min and suspended in paper pulp
0.5 ± 0.02
PAg ?
Silver cations
0.51 g of silver nitrate suspended in paper pulp
0.3 ± 0.02
PZ0
Y-type zeolite (Na form)
1.77 g of zeolite suspended in paper pulp
n/a
PZAg ?
Exchanged Y-type zeolite
1.77 g of zeolite suspended in paper pulp
1.5 ± 0.02
PZAg ? _EDTA Exchanged Y-type zeolite washed with Na 2 EDTA
1.77 g of zeolite suspended in paper pulp
1.1 ± 0.02
according to the D685 ASTM standard, at 23 C and 50%RH.
Prior to sonication, the suspensions were purged with an inert gas (Ar) for 60 min, after which ultrasound at a frequency of 20 kHz was applied (the average power of the ultrasound was equal to 90W) • PZAg ? —paper with AgFAU prepared as described above but with no additional washing withNa 2 EDTA
Texture
Surface topology was analysed by optical microscopy (Leica DM2000) equipped with a digital camera. Imaging was carried out using reflected and transmit- ted light modes, respectively. To obtain representative images, imaging was carried out at five different places of the material (test of material homogeneity).
Testing paper properties
Ageing
SEM analysis
Ageing was carried out in a climatic chamber (MEMMERT HCP246) at 90 C and with a relative humidity of 59%, for 12 days. All samples were aged under the same conditions.
The surface topography of the prepared materials was examined by using scanning electron microscopy (SEM) equipped with a probe for chemical analysis of specimens in microareas with energy dispersive X-ray spectroscopy. A scanning electron microscope (Nova Nano SEM 300 FEI Company) was used for high- quality magnification of the paper morphology.
pH measurements
The pH measurements of the paper samples were carried out according to the TAPPI T 529 om-88 norm using a flat plate electrode (Flatrode Hamilton, 809 Titrando from Metrohm). Samples were cut out from the prepared paper sheets, and a drop of water was placed on their surfaces. The electrode was then applied to each sample, and the pH was measured until a stable value was reached.
Colour
Measurements were carried out using the Colour- QuestXE (HunterLab) colorimeter. Measurement con- ditions were as follows: measuring surface [ = 9.5 mm, observer 2 , illuminant D65, specular reflection excluded.
Mechanical properties
Lightfastness
The zero-span breaking strength was measured according to the TAPPI T236 norm (TAPPI 1996). Before measurements, samples were conditioned
A micro fading tester was used to assess the lightfast- ness of the prepared paper samples. The micro fading
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