Use of titanium dioxide nanoparticles and aqueous methylene blue on ECF bleaching of bagasse pulp

This research was carried out with the aim of bleaching of soda-bagasse pulp, produced in the Pars paper industry, with oxygen (O), chlorine dioxide (D), and hydrogen peroxide (P) in the presence of titanium dioxide nanoparticle (T) as photo catalyzer and methylene blue (M) as an alternative to sodium hypochlorite (H). Bleaching of pulp was performed in sequences of O, OD, OD (Ep) T1, OD (Ep) T2, OD (EP) T1m and OD (Ep) T2m. The physical and mechanical properties of pulp and handsheets were measured as well as COD of effluents. According to the results, the kappa number of the pulp was reduced in two treatments of OD (EP) T1m, and OD (Ep) T2m and was the same as the control sample, bleached with HH conventional sequence in the Pars paper industry. However, the degree of polymerization of the two recent treatments was twice more than that of the control sample. The results of degree of brightness showed that the OD (Ep) T1, OD (Ep) T2, OD (EP) T1m, and OD (Ep) T2m sequences can result in the same degree as the bleached control sample of the Pars paper industry (75% ISO). Also, results showed that by replacing the HH sequence with OD (Ep) T1m and OD (Ep) T2m sequences with the same kappa number, an improvement in bleached pulp yield (3%), viscosity (207%), degree of polymerization (213%) of pulp, opacity (5%), tensile strength index (2.7%) and tear index (49%) of the paper can be expected, while the COD of effluent would decrease by 30%. In general, the use of titanium dioxide nanoparticles and aqueous methylene blue in OD (Ep) bleaching sequence can result in the higher pulp brightness and strength properties of paper.