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Paper performance qualities strongly depend on the origin of cellulose fibers. Awareness of environmental issues and sustainable development has led to the increase in the use of recycled printing papers. Recovered fibers are often used as a substitute for virgin wood fibers in the production of certain types of papers. As recovered fibers cannot provide the same quality level of paper products as virgin wood fibers, alternative sources of virgin cellulose fibers need to be identified. The aim of this research was to analyze the printability of laboratory papers made of different contents of straw pulp. Therefore, the printing papers were formed using straw pulp of three different cereal species (wheat, barley, and triticale) and mixing them with recycled newsprint in different weight ratios. The printability of these laboratory papers was analyzed by classifying dot reproduction quality based on four dot reproduction attributes. Printed dot reproduction greatly affects the quality of reproduction in graphic products, as dots are the most important element in multi-color reproduction of texts and images. It was confirmed that laboratory papers containing straw pulp provide the same or even better dot reproduction quality than laboratory control papers formed only of recycled newsprint.

The modified bleaching sequence OPAPPO from short-sequence bleaching OAP and OQP was studied in an effort to achieve higher quality straw pulp (with brightness 84.5% and acceptable viscosity 669 mL/g), which will be appropriate for more situations than straw pulp as presently produced. Though the OP and PO stages are recognized as the key processes used to increase the pulp’s brightness, addition of hydrogen peroxide in acid pretreatment with polyoxometalate (POM) as catalyst (AP stage) was mainly considered in this work. Phosphomolybdic acid was applied to improve straw pulp’s brightness, which was 4.8% ISO higher than the pulp treated without POM. The optimum conditions of the AP stage were: initial pH value 3, temperature 90 °C, H2O2 1.5%, and phosphomolybdic acid 1.0%. Comparison of the sequences OPQPO, OPAPO, and OPAPPO showed that the brightness of pulp bleached by OPAPPO was 2% and 4.7% higher than the same pulp subjected to OPAPO and OPQPO sequences, respectively. Four lignin samples (LOP, LOPA, LOPAP, LOPAPPO) were characterized by 31P NMR spectroscopy. The spectroscopic investigation showed that in LOPA and LOPAP, aliphatic hydroxyls, p-coumaryl units, and guaiacyl phenol moieties were degraded when compared with that in LOP. In LOPAPPO, all these aliphatic hydroxyls and guaiacyl phenols had been destroyed and carboxylic acid functionalities increased.