Unbleached chemi-mechanical pulp of 85% pulp yield and produced from hornbeam, beech and populus woods respectively by 3: 1: 1 ratio, was used for peroxide bleaching. Two bleaching systems, alkali peroxide (conventional bleaching) and activated peroxide by TAED activator, were used for pulp bleaching. Bleaching treatments included different percentages of hydrogen peroxide and caustic soda consumption. In this research, the hydrogen peroxide consumption rate, pulp yield, process selectivity, bleached pulp brightness and bleaching effluent pollution load (COD) were investigated. Results showed that, brightness values were increased by bleach chemicals charge rising, in both bleaching systems, but the increasing trend was downward. Also, pulp yield was decreased by increase of chemical charges, but residual peroxide was raised. The activated peroxide process compare to conventional process had lower efficiency and brightness improvement values of pulp were less than those of alkali peroxide process. But pulp yield and effluent pollution load was less by activated peroxide bleaching.

Cultivation of rapeseed plant is expanding and larger volume of residues from its stalk is produced which necessitate its proper utilization. Therefore, properties of APMP pulps from rapeseed stalks are investigated. A combination of 2, 3 and 4% NaOH and 3, 4, 5, and 6% H2O2 is used for chemical pretreatment of stalks. Pretreatment time and temperature as well as DTPA and sodium silicate were kept constant at 35 minutes , 75oC, 0.5% and 3% (O.D. basis ) respectively. Treated stalks were defiberated using 25 cm laboratory disk refiner and total yield range was measured between 61.24 – 69.56%. Since both NaOH and H2O2 charge did not significantly affect the total yield, based on visual indication of pulp brightness, Then pulp samples produced using 3% NaOH and 3-6% H2O2 were selected for further analysis. All pulps were refined to 400 ml CSF and then 60 g/m2 handsheets were made. Tear index and tensile index of handsheets varied between 4.48-6.02 mN.m2/g and 12.53-22.71 N.m/g respectively. The influence of H2O2 addition on these properties was significant at 99% level. Optical properties of handsheets including brightness, opacity, yellowness, color factors L*, a* and b* were measured at 66.1-68.44%, 87.20–89.55%, 14.53-17.65, 90.01-90.045, 1.02-1.34 and 8-9.68 respectively. The effect of H2O2 addition on measured properties was significant at 99%. Overall the results indicate that the newsprint paper could be produced from APMP of rapeseed stalks.

Preparation and pre-treatment of raw material influences the pulp production time and color elimination. Pulp consistency during the treatment also influences the color reaction. In the preparation of the APMP pulp, bagasse was pretreated by boiling water, 1% NaOH as well as 1% NaOH + 1% H2O2. The liquor to bagasse ratio, treatment time and temperature of alkaline peroxide treatment were constant as 10:1, 30 min, and 70oC respectively. The treatment duration was determined so that at least five percent of the initial hydrogen peroxide remained at the end of chemical treatment. Characteristics of hand sheets were determined according to the TAPPI standard. The results showed that, the duration of the treatment for pulp consistency of 10, 15 and 20% was 50, 30 and 10 minute, for sample pretreated with boiling water and 290, 230 and 170 minute for the sample pretreated with 1% NaOH + 1% H2O2. The highest brightness of the paper reached with bagasse pretreated in boiling water at 20 % consistency.

Mixed Office Waste DIP produced at Latif Paper Company was used as reinforcement pulp to substitute part of imported long fiber pulp in White Poplar APMP furnish produced at Maraghe Paper Company. Each pulp was separately refined to about 250 CSF and then, handsheets were made applying 0(control sample), 5, 10, 15, 20 and 25 percent DIP mixed with APMP and LF pulps. The control sample contained 30 percent LF and 70 percent APMP pulps. Mechanical and optical properties of the handsheets, including tensile, tear and burst strengths, brightness and opacity were determined according to relevant TAPPI standard test methods. Comparison of the data was done using ANOVA and the best treatment, was determined using scoring method based on normalization equation. The results showed that 5 to 15 percent Mixed Office Waste DIP can be properly used in mixtures with 15 to 25 percent LF and 70 percent White Poplar APMP pulps to produce writing and printing paper with suitable mechanical and optical properties.

The present study was carried out aiming to investigate the effect of using Deinked Mixed Office Waste Pulp (MOW) on the properties of Alkaline Peroxide Mechanical Pulp (APMP) from cotton stalk. APMP pulps was prepared using chelating agents such as Na2SiO3 and DTPA (control sample) and without these agents in two-stage pulping with L/W ratio 6: 1 (ml/g), 20 minutes impregnation time at 70 oC for first stage, 60 minutes impregnation at 75 oC for second stage. Also, pulp was prepared from mixed office waste paper, which were deinked with conventional flotation and then each pulp was separately refined up to about 300 ml CSF. The handsheets were made from control sample pulps, APMP without chelating agents, MOW deinked pulp and mixing with 10%, 20% deinked pulp with control APMP. Physical and mechanical properties were determined using TAPPI standard methods. Deinked MOW pulp had the maximum values of density, brightness, strength properties and APMP pulp without chelating agents had the minimum values. Among mixed pulps, APMP pulp containing 20% deinked MOW pulp showed the maximum value of density, brightness, burst index and tear index.

The present study was fulfilled with the aim of investigating the effects of process variables on APMP (alkaline peroxide mechanical pulping) pulp brightness and yields of P.alba to produce high yield pulps suitable for making writing and printing papers. The wood samples have been prepared from the poplar plantation fields in the area of Maragheh Paper Company and converted to acceptable chips by MWPI industrial chipper. Based on the results obtained in the preliminary experiments (1), chips prostrating time of 20 minutes, impregnation times of 20 minutes for first stage and 90 and 105 minutes for second stage, total caustic soda charge of 6 and 7 % with usage rations of 40, 50 and 60% of total caustic in first impregnation stage, total hydrogen peroxide charge of 5% with usage ratio of 25% in first impregnation stage, pulp consistency of 32-34 and 23% in first and second impregnation stages, respectively, were selected and studied as effective process variables to achieve high yield APMP pulps with pulp brightness of about 80%. The results have shown that; at caustic soda charge level of 6% with usage ratio of 60% of total caustic in first impregnation stage and treatment time of 105 minutes at second impregnation stage, it would be possible to produce APMP pulp with 81.9% brightness and relatively high pulp yield of about 88%. At total caustic charge of 7% with similar usage ratio, APMP pulp of 79.9% brightness at pulp yield of 86.8% in treatment time of 90 minutes, and APMP pulp of 80.2% brightness at relatively low pulp yield of 85.3% can be produced in treatment time of 105 minutes at second impregnation stage. By reducing the treatment time at second impregnation stage and using lower usage ratio of total caustic in the first impregnation stage, APMP pulps have higher yields but at lower brightness.

In this study the effect of different values of peroxide in three levels 3%, 4%, 5% and sodium hydroxide in two levels 2%, 3%, on bleaching of kenaf (Hibiscus cannabinus) bast soda pulp was investigated. Kenaf bast was soda pulped using 20% alkali in 170oC for 1 hour. Produced pulp had 55% yield and kappa number 12. Bleaching process included two stages: 1-chelating 2-alkali peroxide bleaching. Results indicated that brightness increased and kappa number decreased by increasing peroxide level. Data also showed that increasing of the percentage of caustic soda does not have any effects on the brightness and kappa number of the pulp, but yield decreased. The data related to 3% caustic soda and 5% peroxide treatment without chelating stage, indicated that initial chelating stage significantly affected on the brightness, kappa number and yield of the bleached pulp, and this treatment had the lowest brightness and the highest kappa number and yield among all treatments. Finally, 3% caustic soda-5% peroxide treatment with initial chelating stage had the highest brightness (73%) and the lowest yield (92%), and 2% caustic soda-5% peroxide treatment with initial chelating stage which had 70% brightness and 95% yield was selected as the best treatment, due to the appropriate brightness and yield values and lower consumption of the bleaching chemicals.

The objective of this study was the evaluation of optical, and mechanical properties of chemi-mechanical pulp which was bleached using one and two stage bleaching sequence with hydrogen peroxide and sodium hypochlorite. Also the environmental effects of effluents from bleaching liquor were studied. For this purpose, unbleached CMP pulp produced using mixture of hardwoods was obtained from Mazandaran Wood and Paper mill. Then, the pulps were bleached using P (hydrogen peroxide), H (Sodium Hypochlorite), PH (Hydrogen Peroxide and Sodium Hypochlorite) and HP (Sodium Hypochlorite and hydrogen peroxide) sequences. 60 gr/m2 hand sheets were prepared and the optical, mechanical properties of hand sheets and also the effluent characteristics from bleaching were measured and analyzed based on TAPPI and APHA Standard method. The results showed that when peroxide was applied at the last stage of bleaching, the properties such as tear, tensile and brightness were increased and yellowness was decreased. Generally, the role of single sequence of bleaching using P and two stages bleaching with HP were more effective than single stage H on unbleached pulp. Based on the results, the highest and lowest COD load was related to bleaching effuent of H and PH respectively. Moreover, bleaching liquor of hydrogen peroxide had the highest BOD load and the lowest amount of BOD was related to PH sequence.

This study was investigated the effect of Trametes versicolor on chemimechanical pulp (CMP) delignification. CMP were obtained from Mazanderan wood and paper industries. Circle mats were made from CMP (diameter, 7cm; thickness, 1mm) and fortified with 1g/Lit yeast juice. After sterilized, pulp mats were incubated with two disks punched from mycelium. The duration of incubate were 5, 10, 15 & 20 days as well as temperature and moisture 25oC and 40%, respectively. Standard hand sheets were made from biodelignification pulp, and was measured mechanical and optical properties. The portion of biodelignification pulp was alkaline extracted under condition of pulp consistency, 10%; temperature, 70oC; time, 80min and 2% sodium hydroxide, and then bleached under conditions of pulp consistency, 10%; temperature, 50oC; time, 60min and 4% hydrogen peroxide. Finally, mechanical and optical properties of standard hand sheet were measured. Results showed optimum time was 10 days that decreased 5.9% lignin. Mechanical properties of treated samples were lower than control samples, but statically were not significant. Optical properties of treated samples were lower than control samples but alkaline extraction and then bleaching with sodium peroxide was increase it.